THEHUMANANIMAL

PHILOSOPHYOFMINDSERIESSeriesEditor:OwenFlanagan,DukeUniversity

SELFEXPRESSIONSMind,Morals,andtheMeaningofLife

OwenFlanagan

THECONSCIOUSMINDInSearchofaFundamentalTheory

DavidJ.Chalmers

DECONSTRUCTINGTHEMINDStephenP.Stich

THEHUMANANIMALPersonalIdentitywithoutPsychology

EricT.Olson

MINDSANDBODIESPhilosophersandTheirIdeas

ColinMcGinn

THEHUMANANIMALPERSONALIDENTITY

WITHOUTPSYCHOLOGY

EricT.Olson

OXFORDUNIVERSITYPRESSNewYork Oxford

OxfordUniversityPressOxford NewYork

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Copyright©1997byOxfordUniversityPress

Firstpublishedin1997byOxfordUniversityPress,Inc.198MadisonAvenue,NewYork,NewYork10016

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FirstissuedasanOxfordUniversityPresspaperback,1999

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Allrightsreserved.Nopartofthispublicationmaybereproduced,storedinaretrievalsystem,ortransmitted,inanyformorbyanymeans,

electronic,mechanical,photocopying,recording,orotherwise,withoutthepriorpermissionofOxfordUniversityPress,Inc.

LibraryofCongressCataloging-in-PublicationDataOlson,Eric.1963–

Thehumananimal:personalidentitywithoutpsychology/EricT.Olson

p.cm.(Philosophyofmindseries)Includesbibliographicalreferencesandindex.

ISBN0-19-510506-0ISBN0-19-513423-0(pbk.)

1.Man.2.Identity.3.Philosophyofmind.I.Tide.II.Series.BD450.046 1997

128—dc20 96-7018

246897531

PrintedintheUnitedStatesofAmericaonacid-freepaper.

Totheunemployedphilosophers

Acknowledgments

Many people helped me with this project. Without the advice andencouragementofJoséBenardete,JonathanBennett,andPetervanInwagen,thebookwouldneverhavebeenwritten. JonathanBennett andDerekParfitmadeextensivecommentsonearlierdraftsofthebook,manyofwhichledtowhatIhope are significant improvements. Paul Bloomfield, Rocco Gennaro, MarcHight, Chris Knight, Neil Manson, Carol Rovane, and an anonymous refereealsoprovidedvaluablecriticisms.PeterUngerhelpedmegetthebookpublished,andprovidedmuch-neededencouragementinhardtimes.Mywarmestthankstoallofthem.IalsothankSuzanneBertrandofPhilosophyandPhenomenologicalResearch for permission to reprint a few bits frommy article “Was I Ever aFetus?”

Contents

Introduction1.PsychologyandPersonalIdentity

I.HumanVegetablesandCerebrumTransplantsII.ThePsychologicalApproachIII.TheBiologicalApproach

2.PersistenceI.CriteriaofPersonalIdentityII.SubstanceConceptsIII.MoversandThinkersIV.“PersonP1atTimet1”

3.WhyWeNeedNotAcceptthePsychologicalApproachI.TheTransplantIntuitionII.Whole-BrainTransplantsIII.FissionandHemispherectomyIV.PrudentialConcernV.MoralResponsibilityVI.TheTreatmentArgumentVII.SamePersonVIII.PracticalConsequencesoftheBiologicalApproach

4.WasIEveraFetus?I.TheFetusProblemII.PlayingtheProblemDownIII.Future-DirectedIdentityandDisjunctiveCriteria

IV.Second-OrderCapacitiesV.WhenDidIBegin?

5.ArePeopleAnimals?I.HumanPeopleorHumanAnimals?II.AppearancesIII.CoincidenceIV.PersonhoodV.WhyWeAreAnimalsVI.PsychologicalPersistenceConditionsforAnimals?VII.DeathandCeasingtoBeVIII.ACounterattack

6.TheBiologicalApproachI.FurtherQuestionsII.OrganismsIII.TheIdentityofOrganismsIV.LivesV.BrainstemReplacementsandOtherDifficultiesVI.TheBodilyCriterion

7.AlternativesI.AreThereAnyPeople?II.RelativeIdentityIII.TemporalParts

NotesReferencesIndex

Introduction

Mostphilosophicalworkonpersonalidentityofthelasttwenty-fiveyearsorsohas focused around three issues. The first is whether there is any informativecriterionofpersonal identity.Are therenecessaryand sufficient conditions forsomeonetopersistthroughtime?Cantheformula,“Necessarily,ifxisapersonat one time and y is a person at another time, x is y if and only if . . . ,” becompleted in a nontrivialway—by a condition that one could know to obtainwithout knowing beforehand whether x was y? This question is closelyconnected with the ancient debate between dualism and materialism: most ofthosewhoarguethattherearenonontrivialconditionsofpersonalidentitytakethisclaimtogoalongwiththeviewthatyouandIarenotmaterialobjects.Second: Given that there are informative persistence conditions for people,

whatsortofphysicalcontinuity,ifany,isrequiredforapersontopersistfromonetimetoanother?Domypsychologicalfeatures—mymemories,personality,and so forth—have to continue to be realized in a functioning brain, forexample?Could I come to have a numerically different brain, or an inorganicsubstitute for a brain, and still exist?Could you transferme from one humanbody toanothersimplybymoving the informationencoded inmybrain intoanewbrainviaa“brain-statetransfer”device?Andsoon.The third issue is “what matters” in survival. Although most of us are

concerned for thewell-beingofmanypeoplebesidesourselves,ordinarilyyouhaveaspecialattitudetowardsyourownfuturewell-being:youlookforwardtoyourownpleasures,andfearyourownpains,inawayinwhichyoudonotlookforwardtoorfearthingsthatwillhappentoothers.Evenutterlyselfishpeople,whoarecompletelyindifferenttothefateofanyonebutthemselves,careabouttheir own futures. A number of philosophers have denied that this special,prudential concern is essentially concern for oneself. Under unusualcircumstances,itmightberationalforyoutobeprudentiallyconcernedforthefutureofsomeoneotherthanyourself.Alternatively,youmightundergocertainchangesthatmadeyouunworthyofyourownprudentialconcern.Othersarguethatthereisaspecialkindofprudentialconcernthatisnecessarilyconcernfor

oneselfandnooneelse.Ishallhavelittletosayaboutthesethreeissues.Myquestionisonethathas

receivedagreatdeallessattention:whetherpsychologicalconsiderationsareatall relevant to our persistence. I shall argue that they are not: no sort ofpsychologicalcontinuity,withorwithoutfurtherphysicalqualifications,iseithernecessaryorsufficientforustopersistthroughtime.Iamgoingtoassumewithoutargumentthatthereisaninformative,nontrivial

answer to the question ofwhat it takes for you andme to persist. I shall alsoassumewithout argument thatmaterialism is true— that is, that you and I arematerial objects, made up entirely of physical particles. I make theseassumptions not because I consider thematter settled, but simply becausemyproject cannot get off the ground without them, and because a defense ofmaterialismwould takeme too far from thebook’smainpoints (even if Ihadanything original to say about that topic). The assumption that you and I arematerial substances also rules out the view that we are events or processeshappening to an organism, or property instances, or abstract objects akin tocomputer programs. If that were the case, human animals—members of thespeciesHomosapiens—wouldnotbe intelligentorevenconscious,butwouldonlybeassociatedwithsomethingelsethatwasconsciousandintelligent.ThatisjustCartesianisminnaturalisticclothing.Ishallalsoavoidtakingsidesaboutwhatmattersinidentity.Myaimistoget

straight on the metaphysics of personal identity, and to leave the ethicalquestions to thosemore competent to dealwith them.So even though I arguethateachofuswasonceanembryoandafetus,andmightonedaybeahumanvegetable,thisshouldnotbetakenasexpressinganyviewaboutthemoralstatusoffetusesorvegetables.Andifpsychologyisirrelevanttoourpersistence,thereisnopointinasking

whatphysicalrequirementsinadditiontocontinuityofmentalcontentsmustbesatisfiedforapersontosurvive.Ishallalsomake three furtherassumptions,at leastuntil the finalchapterof

thebook.Ishallassumethattherereallyarepeople—rational,consciousbeingssuchas

you and I—and that people reallydopersist through time.Sowhen I say thatthereisapersoninthisroomwhohasexistedformorethanthirtyyears,Itakethatstatementtobetrueinthestrictestandmostliteralsense.Itisnotmerelyaconvenientwayof talkingabout thearrangementof tinyparticles,orabout therelationsamongalargenumberofbeings,eachofwhichexists,orisaperson,for only a brief period. There really is one thing that is now rational andconscious,andhasexisted,andhasbeenrationalandconscious,formanyyears.

Ishallassumethat there issucharelationasstrict,numerical identity. Ifwepickoutabeingtodayandwepickoutabeingnextweek,wecanaskwhetherthisbeingandthatbeingareonethingortwo,andtherewillbeananswertothatquestion(eveniftheansweristhatitisindefinitewhetherwehaveonethingortwo).Ifthisthingandthatthingarebothanimalsandpeople,itcouldnotbethecasethatthisandthatwerethesameanimal,say,butnotthesameperson;oratany rate not unless one of those expressions—”same animal” or “sameperson”—isbeingusedlooselyinawaythatdoesnotimplynumericalidentity,as when we say that Bill Clinton is the same elected official now as RonaldReagan was ten years ago. Identity statements are not concept-relative. (Aterminologicalnote:Ishallusethewords‘persist’and‘survive’interchangeablytoexpress this relation: to say thatyoupersist into the future,or thatyouwillsurviveacertainadventure,istosaythatyouyourself,i.e.,abeingnumericallyidenticalwithyou,existinthefuture,oraftertheadventure.)Third, I shall assume that you and I and other concrete substances endure

throughtimebybeingwhollypresentatdifferenttimes.Wearenotextendedintime,likeevents,byhavingdifferentpartsthat“occur”atdifferenttimes.Yourcareer orhistorymaybe stretchedout in time, andconsistof earlier and laterparts,afirsthalfandasecondhalf;butyouyourselfarenot.Irejecttheontologyoftemporalparts.With the possible exception of the first, these may seem like controversial

points toassumewithoutargument.Butarguing that there reallyarepersistingpeople, or against the relativity of identity or the ontology of temporal parts,wouldbeabookof itsown;and taking thoseviews intoaccountatevery turnwould have made this book far more complicated than it is already. Mostphilosopherssharetheseassumptions,andinanycasetheassumptionsmustbetrue if thereare tobeanymetaphysicalquestionsatallaboutwhat it takesforyouandmetopersist.Iftherearen’treallyanypeople,orifidentityisconcept-relative, or if material objects are temporally extended, then there are nosubstantive metaphysical problems about our identity through time, but onlysemanticquestionsabouthowthelanguageofpersonalidentityworks—apointIshalltakeupinthefinalchapter.Thattherearenometaphysicalproblemsaboutpersonalidentitythroughtime

maybe a conclusion thatmanyphilosopherswillwelcome.Youmayhavenoobjectiontorelativeidentityortemporalparts.Inthatcaseyouarelikelytoseemybookasavainstrugglewithmetaphysicalproblemsthatdonotexist.Atbestyoumayseeitasusefullyillustratingthesortsofmetaphysicaltanglesthatcanbeavoidedbyadoptingrelative identityor theontologyof temporalparts,andthus as a sort of backhanded argument for one or the other of those views.

Alternatively, philosopherswho are committed to a psychological approach topersonalidentitybutwhoweren’tsokeenonrelativeidentityortemporalpartsbefore reading the bookmay endup seeingnewattractions in thoseviews. Inanycase, Ibelieve thatmyargumentsareofsufficient interest to justifymeinmakingtheseassumptions.Finally,afewterminologicalpoints.I shall use the word ‘organism’ in its biological sense: living organisms

compriseplants,animals,fungi,protozoa,andbacteria.By ‘human organism’ or ‘human animal’ I mean simply “member of the

biological speciesHomo sapiens”. For reasons discussed in Chapter 6, I askreadersnottothink“humanbody”whentheyread‘humanorganism’or‘humananimal’.I have used the word ‘people’ as the plural of ‘person’. This was done for

stylisticreasons,andnottomakeanyphilosophicalpoint.Severalfriendshavetried to pursuade me that the correct plural of ‘person’ is ‘persons’, whereas‘people’ is the plural of ‘human being’. Thus conscious, rational, morallyresponsibleMartianswouldbepersonsbutnotpeople;andanencephalicbabiesandhumanvegetablesmight be people but not persons. If that is right, then Ioughttohavewritten‘persons’whereverIwrote‘people’,andIbegthereadertoimaginethismistakesetright.

1

PsychologyandPersonalIdentity

I.HumanVegetablesandCerebrumTransplants

Thetopicofthisbookisouridentitythroughtime.Whatdoesittakeforyouandmetopersistfromonetimetoanother?Whatsortsofchangescouldonesurvive,andwhatwould bring one’s existence to an end?Whatmakes it the case thatsomepastorfuturebeing,ratherthananother,isyouorI?Wecanbringtheseratherabstractquestionstolifebythinkingaboutpossible

situations that leave roomfordisagreementaboutwhetheronehas survivedorperished,oraboutwhichfuturebeingonehasbecome:“puzzlecases”.Considerfirstarathergrimstorycalledthe“VegetableCase”.Imaginethatyoufallintowhatphysiologistscallapersistentvegetativestate.

Asaresultoftemporaryheartfailure,yourbrainisdeprivedofoxygenfortenminutes before circulation is restored, by which time the neurons of yourcerebral cortex have died of anoxia. Because thought and consciousness areimpossibleunlessthecortexisintact,andbecausebraincellsdonotregenerate,yourhighermentalfunctionsareirretrievablylost.Youwillneveragainbeabletorememberthepast,orplanfor thefuture,orheara lovedone’svoice,orbeconsciouslyawareofanythingatall,fortheequipmentyouneededtodothosethings is destroyed and cannot be replaced.You have become, as the clinicalidiomhasit,“irreversiblynoncognitive”.The subcortical parts of the brain, however, such as the thalamus, basal

ganglia,brainstern,andcerebellum,aremoreresistenttodamagefromlackofblood than the cerebrum is, and they sometimes hold out and continuefunctioningevenwhen thecerebrumhasbeendestroyed.Thoseare theorgansthat sustain your “vegetative” functions such as respiration, circulation,digestion, and metabolism. Let us suppose that this happens to you (as ithappenedtoKarenQuinlan,whosurvivedinapersistentvegetativestatefortenyearsafterherrespiratorwasturnedoff).Theresultisahumananimalthatisasmuchlikeyouasanythingcouldbewithouthavingamind.

Theanimalisnotcomatose.Comaisasleep-likestate;butahumanvegetablehasperiodsinwhichitappearstobeawake.Itcanrespondtolightandsound,but not in a purposeful way; it can move its eyes, but cannot follow objectsconsistentlywiththem.Itcanmakereflexmovements:itwillblinkifyoutouchits cornea, and cough when its throat is clogged. If the swallowing reflex isintact, itmaybepossibletofeedtheanimalbypushingfoodtothebackof itsmouth. However, it cannot speak or follow commands, or make any otherbehavioralresponse.Theanimalis,paradoxically,“awakebutunaware”1(“Thelightsareonbutnoone’shome,”thenursessay).Neither is the animal “brain-dead”, for those parts of its brain that direct its

vegetative functions remain fully intact. It is not a mere “ventilated corpse”,whichwouldceasetoshowanysignsoflifeatallwithoutartificialrespiration.Thepatientisverymuchalive,atleastinthebiologicalsenseinwhichoystersandoaktreesarealive.Withthehelpofafeedingtubeinsertedintoitsstomach,itcansurviveinthisstatealmostindefinitely,inonecaseformorethanthirty-sevenyears(Cranford1988,31). Ifyouwanted toburyorcremate theanimal,you would have to kill it, which you could do by removing its feeding tube,causingtheanimaltodieofdehydrationwithinafewdaysorweeks.How canwe be sure that a patient in this state has really lost all cognitive

functions?Couldn’t shebe fully consciousbut simplyparalyzed and thereforeunable to act?And even if thepatient is incapable of thought or awareness atfirst, how can we be certain that the loss is irreversible? Although these arelegitimatequestions,mostneurologistsfeelconfidentthatpatientsinapersistentvegetative state are incapable of any sort of awareness, including pain andsufferingof anykind, and that there is nohopeof recoverywhen this state iscausedbythedeathofcerebralneurons.2Still,theremayberoomfordoubt.Soimaginethatyoulapseintoapersistentvegetativestateandthatasaresultyourhighercognitivefunctionsaredestroyedandthatthelossispermanent.Cases like this raise difficult moral and legal questions: Can we declare a

humanbeing in a persistent vegetative state “dead” and remove its organs fortransplant? Or are we obligated to keep it “alive” as long as possible? Whoshoulddecide?Andsoon.ButIwanttoaskadifferentquestion:Whathappenstoyou inthestory?Couldyousurvivethisadventure?Thatmaysoundlikeanoddthingtoask.Surviveasahumanvegetable?Whybothertocallthatsortofexistence survival?Butmyquestion ismore simple-minded.Forget about thatpathetic being’s quality of life. Never mind whether it deserves to be called“alive” or “dead” in any legal,moral, or psychological sense. Iwant to knowwhetheryouarestillthereinanystateatallbytheendofthestory.Wouldthe

human vegetable in the story be you? If you had said, before the accident, “Ishallonedaybeahumanvegetable,lyingunconsciousonahospitalbed,”wouldyou have said something true? Or would destroying your higher cognitivefunctions bring your existance to an end, just as any ordinarymeans of deathwould?Toseejusthowsimple-mindedthisquestionismeanttobe,consideranother

story.You die and your remains are cremated, but later your admirers erect abronzestatueofyouinyourhonor.Ofcoursethestatueisnotaliveinanyliteralsense;butthatisnotmypoint.Althoughthatstatuemayhavethesameoutwardshapeasyouhaveandbearyournameonitspedestal,thestatueisobviouslynotyou.Youhaveceased to exist, and somethingelse, the statue,hasbeenput inyourplace,asitwere.Therearetwodifferentcharactersinthestory,youandthestatue.Ifyouhadsaid,“Ishallonedaybeabronzestatue,”youwouldhavesaidsomething literally false, for nothing is ever first a human being and later abronze statue. My question in the Vegetable Case is whether the humanvegetable that resultswhen your cerebrum is destroyed is strictly and literallyyou,orwhetheritisnomoreyouthanastatueerectedafteryourdeathwouldbeyou.Doyou come to be a humanvegetable, or do you cease to exist and getreplacedbyavegetable,muchasyoumightbereplacedbyastatue?Nowa secondpuzzlecase. Imagine thatan ingenious surgeon removesyour

cerebrum—that organ that ismost directly responsible for your highermentalcapacitiessuchasreasoningandmemory—andimplantsitintoanotherhead.Byan art that shehas, the surgeonmanages to connect thenerves, bloodvessels,andother tissuesofyourcerebrumwith thecorrespondingnerves,vessels,andtissues inside the skull of another human being so that they grow together.(Physiologiststellusthatbraintissueisespeciallywellsuitedfortransplant,asitis rarely rejected by the immune system. Still, don’t try this at home!) Yourcerebrumcomestobeconnectedtotherestofthathumanbeinginjustthewaythat it was once connected to the rest of you. The surgeon is careful not todamagetheorganinanyway;andsoitisabletofunctionproperlyinsideitsnewheadjustasitoncefunctionedinsideyours.Theresult isahumanbeingwhoispsychologicallymoreorlessexactlylike

you.Shecanapparentlyrememberyourpastandactonyour intentions.Asidefromher cerebrum, of course, shemaybephysically verydifferent fromyou:youmay been aging and overweight, for example,while she is (outwardly, atleast)youngandvigorous;andinthelongrunthismayaffectherpersonality.Atfirst,though,herpersonalitywillbejustlikeyours.Shelovesjustthepeopleandthingsthatyouloved,andsoon;andshe thinkssheisyou.Ontheotherhand,shedoes not remember anything that happened to the person intowhosehead

your cerebrumwas implanted, nor does she acquire anything of that person’scharacter(atleastatfirst).Whatabouttherestofyou,thosepartsthatwereleftbehindwhenthesurgeon

removedyourcerebrum?Actualcasesofpersistentvegetativestateshowthatahumanorganismcanpersist—asalivingbutmentallydebilitatedanimal—evenafteritscerebrumhasbeenmoreorlesscompletelydestroyed;destroyingone’scerebrum does not necessarily bring one’s life-sustaining functions to a halt.Babies born without a cerebrum, usually as a result of a genetic defect(“anencephalics”)oftenliveforseveralweeksorevenyears.Manypeoplehavesurvivedthesurgicalremovalofacerebralhemisphere.Factslikethesesuggestthat the result of removing one’s cerebrummight be a living but “irreversiblynoncognitive”animal—ahumanvegetable—ratherthanabrainlesscorpse.Imagine,then,thatoursurgeonleavestherestofyouintactwhensheremoves

yourcerebrum,sothatyourbrainstemcontinuestodoits jobofdirectingyourheartbeat,circulation,breathing,anddigestion;yourhypothalamuscontinuestocontrol therateofyourmetabolism;andingeneralallofyourorgansbutyourcerebrum continue to carry out their life-sustaining functions as well as thecircumstances allow. Thus, we get a living, breathing human being that isphysiologically just like youwere, and that ismade up of the same cells andorgans that composed you before the operation—excepting, of course, themissingcerebrum.Thosebiologicalfunctionsthatwentoninyouandkeptyoualivebeforetheoperationhavecontinuedwithoutinterruption,andnowanimatetheresultinghumanvegetable.3Thepuzzle,asyouhavenodoubtguessed,iswhathappenstoyouinthisstory

(callitthe“TransplantCase”).Areyouthebiologicallylivingbutempty-headedhumanbeingthathasinheritedyourvegetativefunctions?Orareyouthepersonwho ends up with your cerebrum and your memories? (Or has the operationsimply brought your existence to an end?) When the surgeon moves yourcerebrumfromoneheadtoanother,doesshetakethatorganawayfromyouandgiveittosomeoneelse,asshemightdowithyourliver?Ordoesshetransplantyou from one head to another, first paring you down to a two-poundmass ofyellowish and pinkish tissue, and then grafting all at once a new skull, arms,legs,andotherpartsontoyou?

II.ThePsychologicalApproach

Therearetwosortsofconsiderationsthatwemightappealtointryingtoanswerthese questions. First, there are psychological facts—in particular, facts about

psychological continuity. The human vegetable in the first story has none ofyourmentalcontentsorcapacities.Hecannotrememberanyofyourexperiencesor act on anyof your intentions; nor is hismind related toyours in anyotherinterestingway. In fact he has nomind at all. The same goes for the empty-headedbeingintheTransplantCase.Wemightbeabletogiveheramind,sotospeak, by implanting a new cerebrum into her head. But anymind shemightacquireinthatwaywouldbeasdifferentfromyourmindasyoursisfrommine.Betweenyouand thehumanvegetable in the first story, andbetweenyouandthe empty-headed human animal in the second story, there is completepsychological discontinuity. On the other hand, the person who ends up withyourcerebrumin theTransplantCase is inan important sensepsychologicallycontinuouswithyou.Shehasinheritedyourmind.Shecanapparentlyrememberpastexperiencesofyours,andshehasyourpersonality,yourideals,andsoforth;andshe is thatwaybecauseshehas theveryorgan that lately supported thosepsychologicalfeaturesinyou,namelyyourcerebrum.But there isanotherkindofcontinuity tobeconsidered.Your life-sustaining

functions are not disrupted when you lapse into a persistent vegetative state:yourmetabolism, circulation, breathing, digestion, and the like continue on inthe resulting human vegetable. There is a great deal of biological or animalcontinuitybetweenhimandyou.Nor is thissimply“bodily”continuity.Whenyou die, youmay leave behind a corpse that preserves your gross anatomicalstructureandismadeofthesamematterasyouwererecentlymadeof.Butthehumanvegetableinourstoryisrelatedtoyouinafarmoreinterestingwaythanany corpse could be. The vegetable, but not the corpse, has inherited yourbiologicallife.Youare related in this same“animal”way to theempty-headedbeing in the

TransplantCase:your life-sustainingfunctionscontinuewithout interruptioninher (as long as only the cerebrum is transplanted andnot the entire brain: seeChapter3,SectionII).Eventhoughthepersonwhoendsupwithyourcerebrumhasanorganofyours,sheisnotrelatedtoyouinthisbiologicalway.Yourlife-sustainingfunctionsarenottransferredtothatpersonalongwithyourcerebrum.Fromthepointofviewofbiologicalcontinuity,aswemightcall this relation,transplantingyourcerebrumisnodifferentfromtransplantingakidney,orsomeother organ you could live without. There is continuity of life-sustainingfunctions, or “biological continuity” for short, between you and the empty-headedbeing,butnotyouandthepersonwhoendsupwithyourcerebrum.Thesetwosortsofcontinuityhavenotreceivedequalattentionindiscussions

of personal identity. The dominant view is that psychology is the key toresolvingpuzzleslikethese.YoudonotsurviveintheVegetableCase,itissaid,

becausethosepsychologicalfeaturesthatareessentialtoyouarenotpreserved.Nooneinthesecondhalfofthestoryispsychologicallycontinuouswithyouintheappropriateway,andsonoone,orforthatmatternothing,thatexiststhenisyou.Becauseyourmindhasbeendestroyed,youhaveceasedtoexist.Thefactthatthehumanvegetableinthestoryisbiologicallycontinuouswithyou—thatyour life-sustaining functions continue on in that human animal—counts fornothing. That youmight cease to exist and be outlived by the human animalassociated with you, one philosopher claims, “now enjoys the status ofscientificallyeducatedcommonsense”.4For the same reason,mostphilosophersdeny that youare the empty-headed

human being that has your beating heart, breathing lungs, and other life-sustainingorgansintheTransplantCase.Insteadyouarethepersonwhoendsupwith your cerebrum, for she is the one who has your mind. She ispsychologically continuous with you. That this person is not biologicallycontinuouswithyouisirrelevant.IamgoingtocallthiswayofthinkingthePsychologicalApproachtopersonal

identity.Onthatview,ouridentitythroughtimeconsists,atleastinpart,infactsaboutpsychologicalcontinuity.Whetheronesurvivesorperishesisdeterminedby facts about memory, character, and other mental features and capacities.Roughlyspeaking,onesurvivesjustincaseone’smindcontinueson.AsMarkJohnstonwrites:

Ifanythingdeservesthenameofaconceptualtruthabouttherelationbetweenpersonsandminds,itistheclaimthatapersoncannotbeoutlivedby(whatoncewas)hisownmind. . . .If thisisso,then,wheneverwehave reason to say that a singlemindhascontinuedon,wehave reason to say that asinglepersonhascontinuedon.(1987,77)

Physiological facts aboutmetabolism and other “purely animal” functions arenot relevant to personal identity—or at any rate not directly relevant; if theymatter it is only insofar as they typically accompany and cause psychologicalcontinuity. Usually one’s mind is preserved as long as one’s life-sustainingfunctions continue: when your psychological contents and capacities aredestroyed,yourcirculation,metabolism,andothervitalfunctionsareordinarilydisruptedaswell.ButastheVegetableCaseshows,thisneednotalwaysbeso.Contrariwise,whenyourmindispreserved,thatisusuallybecauseyourpurelyanimal functions continue aswell; it is only in science-fiction stories like theTransplantCasethatthisisnotso(foralthoughyourpurelyanimalfunctionsdocontinue in thestoryaswe told it,yourmental lifewouldcontinueoneven ifthoseanimalfunctionsdidnot—eveniftheempty-headedfellowsimplydiedasa result of the operation). In these unusual situations where biological and

psychological continuity come apart, whether one survives depends onpsychology, not biology. Biological continuity may be good evidence for theclaimthatonehassurvived;butone’ssurvivaldoesnotconsistinthatrelation,andonecouldsurvivewithoutit.The PsychologicalApproach is the view that some psychological relation is

both necessary and sufficient for one to survive. I could exist at another timeonlyifInowstandinsomeinterestingpsychologicalrelationtomyselfasIwas,orshallbe,then.Icouldnotsurviveunlessmymindwerepreserved.Moreover,ifIamnowrelatedinthatwaytosomepastorfuturebeing,thenIamthatbeing.Roughlyspeaking,anypastorfuturebeingthathasmymindisme.Advocates of the Psychological Approach disagree about just what this

psychologicalrelationis.Thetheoryhasmanydifferentversions,andoneofthetraditional problems of personal identity iswhich of these versions is correct.One variant says thatwe persist through time by virtue of a relation betweenmental contents. We can say that the mental contents— memories, beliefs,desires,andsoforth—thatIhavenowarecontinuouswith thementalcontentsthatsomeonehadatanearliertimeifIhavethementalcontentsthatIhavenowbecause of the psychological features that he had then.5 I may rememberexperiences that he had then, and Imight be able to act nowon intentions orplansthathehadthen.Forexample,ImightnowrememberatripheoncetooktoNorway,andImightbewritingthisbooknowbecauseoftheintentionthatheformed years ago to write a book on personal identity. If there are enoughconnections like thesebetweenmycurrentmentalcontentsand thecontentsofhismindthen,thenIamthatpastperson.6Ofcourse,thereareperiodsinanyone’spastthatonedoesn’trememberatall,

sowecannotplausiblysaythatIamsomepastpersononlyifInowremembersomething that happened to him then. I don’t now remember anything thathappened to me between noon and 12:15 last Tuesday, let alone on this daytwentyyearsago.ButIcanrememberatimewhenIrememberedthoseperiods,or remember a time when I remembered a time when I remembered anexperienceIhadthen;andsoon.Amoredifficultobstacle is that thereareperiods inone’s lifeofwhichone

never had any memory. There is no time when I remembered anything thathappened tomewhile Iwasasleepbutnotdreaming,orotherwisecompletelyunconscious.Butthereisstillaninterestingrelationbetweenthecontentsofmymindnowand thementalcontents Ihad lastnightwhiledreamlesslysleeping.Many of the intentions I can act on now are ones that I had while I slept(althoughofcourseIwasn’tawareofthemthen).AndwhileIsleptIretainedthe

memoryofmanyearlierexperiences.SoifIamnowconnectedwithsomepastperson by an overlapping chain ofmemories or by someother connections ofthis sort, then toowe can say thatmy currentmental contents are continuouswith theoneshehad then,even if I can’tdirectlyor indirectly recall anythingthathappenedtohimthen.Whatonecouldnotsurvive,onthisview,istotaloblivion.Imaginethatsome

sort of degenerative brain damage erases all of your memories, so that theresultingpersondoesnotrememberanythingfromyourpast.Norissheabletoactonanyofyour intentionsorcarryoutanyofyourplans,foreverytraceofthosememories,plans,andintentionshasbeendestroyed.Yourmentalcontentsarenotmerelyinaccessibleorgarbled.Noamountofhypnosis,psychoanalysis,oranyothertreatmentcouldbringthemback.7Nevertheless,theresultingbeingisstillconsciousandrational.PerhapsshecanstillspeakEnglish,orsomeotherlanguage;perhapssheknowshowtofeedherselfandtiehershoes.Orperhapsshehasforgottenthosethingstoo.Inanyevent,sheretainsroughlythosementalcapacitiesthateverynormaladulthumanbeinghas,butnothingmore.Hermindresembles yours no more than it resembles mine or anyone else’s (exceptperhapsforafewquirkscausedbyyourparticularphysiology).Insuchacase,itseems,yourmentalcontentswouldhavebeendestroyed;theresultingpersonhasamindwhose contents are verymuchdiscontinuouswith yours.Hence, thosephilosopherswhothinkthatcontinuityofone’smentalcontentsisnecessaryforus to survive would say that you have ceased to exist and been replaced bysomeonenumericallydifferentfromyou.However,evenhere therearecertainpsychologicalconnectionsbetweenyou

and the resultingperson.Someofyour rudimentarymentalcapacities seem tohave been preserved. The resulting person has your brain, and that braincontinued to function as the brain of a living person throughout the story.Although your mind has been emptied of all or most of its content, it stillcontinuestofunctionandhasnotbeendestroyed.Many philosophers who think that you could survive oblivion nevertheless

alsoholdaversionof thePsychologicalApproach.Theysaythatwepersist invirtueofa relationbetweenourbasicmentalcapacities rather thanourmentalcontents.Here,forexample,isasuggestionofPeterUnger’s:

Foryoutoexistatafuturetime...,theremustbethecontinuousexistence,fromnowuntilthen,ofyour particular basic mental capacities. For there to be the continuous existence of just thosecapacities, theremust be, in thiswholly or largely physicalworld of ours, the continuous physicalrealization of them in a physically continuous realizer or, at the least, in a physically continuoussuccession of physical realizers. Consequently, for you to exsist at a future time, there must beappropriatephysicalcontinuity.8

Nowthisdistinctionbetweencontinuityofmentalcontentsandcontinuityofmentalcapacitiesmightbearedherring.Manyofthosementalcapacitiessharedby all ordinary adult people essentially involve a certain amount of mentalcontentaswell;ifallofmymemorieswereerased,perhapsIshouldnotbeabletofeedmyselfortiemyshoesorspeakEnglishordomuchelseofanyinterest.And in that case I might be incapable of rational thought or reflective self-awareness.Perhapsitisnotpossibletoloseallofone’smentalcontentsandstillretainanyofthosementalcapacitiescharacteristicofadulthumanbeings.However that may be, a closely related source of disagreement among

advocates of the Psychological Approach is whether any sort of materialcontinuityisnecessaryforyoutosurvive.Accordingtosome,abeingwhoexistsinthefutureorthepastisyouonlyifshehasyourcerebrum,orenoughofyourcerebrum to support the thoughts of a conscious, rational being. Or if yourcerebrumneednotbepreserved,atleastyourmentalcapacitiesmustcontinuetobe realized in some structure or other that is physically or spatio-temporallycontinuouswithyourcerebrum.Imagineadevicethaterasesallofthecontentsofyourbrainandtransfersthatinformation,inanunspecifiedbutreliableway,toanotherbrain inLatvia.The result is someone inLatviawhocan remember(or “quasi-remember”) your past, who thinks she is you, and so forth. Somephilosophersbelievethatthispersonwouldbeyou,eventhoughnomatterwastransferredfromheretoLatvia,andeventhoughtherewasaperiodduringthetransfer when your mental contents and capacities were not realized in anyfunctioningorganofthought.9Apersoncouldtravelfromoneplacetoanotherbythemeretransferofpsychologicalinformation—bytelegraph,orintheformof an enormous book, for example. Those advocates of the PsychologicalApproachwhorequirematerialcontinuitywoulddenythis.There is one more complication. It seems doubtful that psychological

continuityalonecouldbesufficientforone tosurvive, for itmightbepossiblefortwodifferentpeopletoinherityourmentalcontentsorcapacitiesatonce.Ifwetransferyourmentalcontentstoanotherbrain,wecanalsotransferthemtotwo brains, and so produce two peoplewhosemental contents are continuouswithyours.Andifwecantransplantyourcerebrumintoanewhead,wecanalsotransplant each of your cerebral hemispheres into a different head, producingtwopeoplewhohaveyourmentalcapacities(moreonthisinChapter3,SectionIII).Ifanyfuturepersonwhohasyourmentalcontentsorcapacitiesisyou,wehaveaproblem,forthereisonlyoneofyou,andonethingcannotbeidenticalwithtwothings.SomanyfriendsofthePsychologicalApproachsaythatsomepast or future person is you just in case she is then uniquely psychologicallycontinuouswithyou—-justincasesheandshealonethenrelatestoyouinthat

way.Wehave seen thatwhat I amcalling thePsychologicalApproach includesa

broadspectrumofviews.Whattheyallhaveincommonistheassumptionthatourpersistencedependsonsomepsychologicalrelation:arelationhavingtodowithmental contentsor capacities.Somesortof continuityofmental features,with or without restrictions about material continuity or uniqueness, is bothnecessaryandsufficientforustosurvive.ImentionthesevariationsnowbecauseIshallhavelittletosayaboutthemin

therestofthebook.Ihavetriedtomakemyargumentsgeneralenoughtoapplyto all versions of thePsychologicalApproach.As a result, I shall often speakrather loosely of that approach as the view that our persistence consists inpsychological continuity.Here the reader is asked to substitutehisorherownfavoriteversionofthePsychologicalApproachformyvaguestatement.

III.TheBiologicalApproach

ThemaincontentionofthisbookisthatthePsychologicalApproachisfalse—orat any rate that it faces serious difficulties that would take many of itsproponents aback. I claim that psychological continuity, with or without therestrictions and specifications discussed in the previous section, is neithernecessarynorsufficientforustosurvive.IargueforthisclaiminChapters4and5. In place of the Psychological Approach I propose a radicallynonpsychologicalaccountofouridentity.WhatittakesforustopersistthroughtimeiswhatIhavecalledbiologicalcontinuity:onesurvivesjustincaseone’spurelyanimalfunctions—metabolism,thecapacitytobreatheandcirculateone’sblood,andthelike—continue.Iwouldputbiologyinplaceofpsychology,andone’sbiologicallifeinplaceofone’smind,indeterminingwhatittakesforustopersist:abiologicalapproachtopersonalidentity.TheBiologicalApproachmakes two claims.10 First, you and I are animals:

members of the speciesHomo sapiens, to be precise. I do not claim that allpeople are human animals, or living organisms of any other species. For all IknowthereareorcouldbeintelligentMartians,gods,angels,demons,trolls,orevenrational,consciouselectroniccomputersmadeofmetalandsilicon.Butallhuman people are animals. We are what Locke called “men”. You are notmerelyintimatelyconnectedinsomewaywithahumananimal.Theclaimisnotthat yourbody is ahumananimal, or that youare “constitutedby” an animal.That livingprimatesitting inyourchair rightnow isyou:youarenumericallyidenticalwithananimal.Thismightseemindisputableoncewehaveaccepted

that we are material objects at all. But it is not so. Legions of materialistphilosophersdeny thatweare identicalwithourbodies, forexample, and it istemptingtothinkthatby‘ourbodies’theymeancertainhumanorganisms.Nowsomeofthosephilosopherssaythat‘mybody’namesamaterialobjectdifferentfrom the animal associated with me, which is consistent with my being ananimal;butmanymaterialistsdenyexplicitlythatweareanimals.11The second claim is more controversial: Psychological continuity is neither

necessary nor sufficient for a human animal to persist through time. I believethat this isevidentwhenwe thinkcarefullyaboutwhat itmeans tobea livingorganism. Recall the Vegetable Case. When you lapse into a persistentvegetativestate,thehumananimalassociatedwithyouappearstosurvive.Thereisstillalivinghumananimalthereevenafteryourpsychologicalfeatureshavebeencompletelyand irrevocablydestroyed;your life-sustainingfunctionswereneverdisrupted.Withitsminddestroyed,thatanimalmightnothavemuchofa“life”.Thereisnothingitislike tobethatanimal.Butitisclearlyabiologicalorganism,aliveinthesamesenseasagoldfishorarosebushisalive.Nordoesitseem that one animal has ceased to exist and been replaced by a new andnumerically different animal. Hence, the animal that survives the loss of itsmental properties is you, if you are an animal, and soyou canpersistwithoutpsychological continuity of any kind. Perhaps we cannot properly call thatvegetatinganimalaperson,sinceithasnoneofthosepsychologicalfeaturesthatdistinguish people from non-people (rationality, the capacity for self-consciousness,orwhathaveyou).Ifso,thatsimplyshowsthatyoucancontinuetoexistwithoutbeingaperson,justasyoucouldcontinuetoexistwithoutbeingaphilosopher,orastudent,orafancieroffastcars.12AsfortheTransplantCase:Whateverhappenstoyouinthatstory,nohuman

animalappearstogettransferredfromoneheadtoanother.Thesurgeonsdonotpare an animal down until only a cerebrum is left, and then attach a newcomplementofpartstothatanimal.Instead,theanimalremainsbehindwhenitscerebrumisremoved.Theresultofremovingthecerebrumfromahumananimalis a living human animalwithout a cerebrum (if the surgeons are careful andthingsgowell).The surgeonsdidnot create that empty-headedanimal. Itwasthere all along, firstwith a cerebrum and thenwithout one. Its life-sustainingfunctionscontinued toanimatea livingorganism throughout theoperation.Asfarastheanimalisconcerned,acerebrumtransplantislikealivertransplant.Soifyouareahumananimal,youdonotgoalongwithyourcerebrumwhenitistransplanted; you simply lose an organ, and with it those psychologicalcapacitiesthatdependedonthatorgan.Youlosethecapacitytothinkandfeel,

just as you would lose the capacity to purify your blood if your liver wereremoved.Someoneelse—someotherhumananimal—getsyour cerebrum, andwith it your personality, your apparent memories, and other psychologicalfeatures.Thus,psychologicalcontinuityisnotsufficientforyoutopersist.Somefuture person could be uniquely psychologically continuouswith you,with asmuch material continuity as even the most cautious advocate of thePsychological Approach could demand, without being you (more on this inChapter5).The claim that human animals do not persist by virtue of psychological

continuityiscloselyconnectedwithanotherclaim—namelythatahumananimalhas thepersistence conditions it hasbyvirtueof being ahumananimal (or ananimalingeneral,oralivingorganism),andnotbyvirtueofbeingapersonorahumanbodyoranythingelse.Ourpersistenceconditionsarethoseforanimalsororganisms of a certain kind. Obviously not all human animals requirepsychological continuity to survive. Human vegetables, human embryos, andanencephalic babies, for example, are human animals that manage to survivewithout having any psychological features at all (see Chapter 4). Thus, nopsychologicalrelationcanbenecessaryforallhumananimalstopersist.Ifthereis one criterion of identity for all human animals, it could not involvepsychological continuity. If you and Iwere animals andyet could not survivewithoutpsychologicalcontinuity,itwouldfollowthatsomehumananimalshadradicallydifferentpersistenceconditionsfromthoseofothers,and thatwehadourpersistenceconditionsnotbyvirtueofbeinghumananimals,butbyvirtueofbeingmembersofsomeotherkind:person,perhaps(moreonthisinChapter2).According to theBiologicalApproach, then,mostphilosophersaremistaken

aboutwhathappenstoyouintheVegetableandTransplantCases.InChapter3,Isuggestareasonwhythismistakehasbeensocommon.ThereIarguethattheBiological Approach can accomodate many of the insights that motivate thePsychologicalApproach.TheBiologicalApproach isnot theview that somephilosophershavecalled

the “physical criterion”. That view says roughly that I shall be someonewhoexiststomorrowjustincasethatpersonhasenoughofmybrainforittobethebrain of a living person (e.g., Parfit 1984, 204;Noonan 1989, 7;Unger 1990,109). That means that I should go along with my cerebrum if it weretransplanted. And if my brain were so badly damaged that its owner was nolonger a person, I should cease to exist, even if my life-sustaining functionscontinued on. The physical criterion is in fact a version of the PsychologicalApproach.MuchslosertotheBiologicalApproachistheviewthatyouandIareidentical

withourbodies,orthatwepersistjustincaseoutbodiescontinuetoexist.Thisview has received far more attention than the Biological Approach, and it isusually considered to be the chief materialist rival to the PsychologicalApproach. In fact, there are important differences between the “BodilyCriterion”,asthisviewisoftencalled,andtheBiologicalApproach.Butthatisacomplicatedmatter,andIshallputitoffuntilChapter6,SectionVI.ThosewhodefendtheBodilyCriterion(ThomsonandWilliams,forexample)typicallyholdthatyouandIareorganismsandthatourpersistenceconditionshavenothingtodo with psychology. For present purposes, then, we can treat the BodilyCriterionasaspecialcaseoftheBiologicalApproach.OnecouldsaythatIammybody,orthatIgowheremybodygoes,butdenythatIamananimal;butthisviewhaslittletorecommendit,andIshallignoreit.The Biological Approach has been strangely neglected in the literature on

personal identity (its few advocates, in addition to Thomson and Williams,includeAyers, Snowdon, and van Inwagen). It is rarely even taken seriously.JohnPollock,forexample,writes:

Historically,therehavebeentwo(allegedly)popularcriteriaofpersonalidentity.Thesimplerofthesetakesittobeanecessary(conceptual)truththatpeoplearetobereidentifiedintermsoftheirbodies.Thiscriterionismuchtalkedabout,butIamunawareofanyrecentphilosopherwhohasendorsedit,andIaminclinedtoregarditasastrawman.Theonlygenuinelypopularkindofcriterionofpersonalidentityisamentalisticone.(Pollock1989,30)

In Harold Noonan’s book surveying the field, to take another example, theBodily Criterion has been dispensedwith by page five, and themore generalBiologicalApproachisnevermentioned.“Forthoughitisundeniablethatinoureverydayexperiencepersonalidentityisconstitutedbybodilyidentity”,Noonanwrites,“itseemsalltooeasytoimaginepossiblecasesinwhichthisisnotso”(1989,3).Somearguethatwecouldnotbeourbodiesonthegroundsthatthoseobjects, unlike ourselves, do not have conversations or write books, and thatone’s body may continue to exist for many years after one has perished, asLenin’sdid.FairornotasacriticismoftheBodilyCriterion,thiscommentdoesnot obviously apply to the view that you and I are animals (but again, seeChapter6).ThePsychologicalApproach,ontheotherhand,isaspopularascanbe.Ithas

been accepted in one version or another by Grice, Hospers, Johnston, Lewis,Mackie, Nagel, Noonan, Nozick, Parfit, Perry, Pollock, Price, Quinton,Rosenberg,Russell,Shoemaker,Strawson,Unger,andWiggins,tomentiononlya fewbignames.13Thebest-knownadvocateof theview is,ofcourse,Locke,whose notorious chapter on identity (Essay, II.xxvii) faces its own special

problems.Beforemovingon to the arguments, Iwant to clearup (or at leastmention)

onepossiblesourceofmisunderstanding.ThenamemostreadilyassociatedwiththeBiologicalApproachisthatofDavidWiggins,foralthoughheoncedeniedthat you and I were organisms, he has arguedmore recently for the oppositeview,aswell ascriticizingLockeanaccounts thatwouldmakeourpersistencesolelyamatterofmemory.However, even the “laterWiggins”, as I read him, stops short of endorsing

what I have called the Biological Approach. Whereas my view is thatpsychological continuity is completely irrelevant, except derivatively, to ourpersistence,Wiggins insists that certain broadlymental capacities—sentience,desire,belief,motion,memoryandothers—arepartofwhatittakesforapersonto remain alive, and so to continue existing (1980, 160, 180; 1976, 168).Although memory does not determine our persistence conditions on its own,Wigginsargues,itis“cruciallyrelevanttoourchoiceofcontinuityprinciplefordeterminingthebiographiesofpersons”(1980,162):

[T]he revised conception of thememory criterionwe have arrived at . . . [is not] redundant in thepresence of some distinct physicalistic criterion. Whether plausibly or implausibly, the memoryconditioninformsandregulatesthecontinuityconditionofpersonalidentity,andholdsitapartfrommerecontinuityofbody,andleavesitsdistinctivemarkonjudgementsfoundedonit.(Wiggins1980,163)

According to what I am calling the Biological Approach, however, there isindeed a “distinct physicalistic criterion” thatmakesmemory irrelevant to ourpersistence,namelycontinuityoflife-sustaining,vegetativefunctions.Wiggins’sview seems to be that onlymy body would survive if I were to lapse into apersistentvegetativestate;Imyself,theanimal,shouldperish.Andalthoughhedeclines topronounceonbrain transplants,Wiggins finds it at least somewhatplausible that psychological continuity could be sufficient for one to persist(1976, 173n.44). Although there is much in Wiggins’s work that I do notunderstand, his view seems to me to be a sophisticated version of thePsychologicalApproach.SimilarremarksapplytoJayRosenberg.“Aperson’sdeathisaneventwhich

brings that person’s history to an end, forwhat a person is, is, so to speak, auniquelycompetentlivingorganism”,hewrites;“wecannotprythenotionofapersonloosefromthenotionofalivingorganism...whichpossessesavarietyofinterestingandspecialabilities,capacities,andcapabilities”(1983,96).Thisand many other things Rosenberg says, including criticism of somepsychologicalaccountsofpersonal identity, seem tome insightfulandcorrect.

Much as I admire his work, though, I cannot accept Rosenberg’s proposedaccountofpersonalidentity,whichisroughlythatonegoeswhereone’sorganofthoughtgoes,forthataccountentailsthatyouandIarenotlivingorganismsatall—apointthatRosenbergseemstobeawareofwhenhesaysthatapersonis“alivingorganismorafunctionallyselectedpartofalivingorganism”(97,myemphasis). Rosenberg, too, ends up endorsing a version of the PsychologicalApproach.

2

Persistence

I.CriteriaofPersonalIdentity

ThePsychologicalApproachisaclaimaboutwhatittakesforapersontoexistattwodifferenttimes:acriterionofpersonalidentity.Itisnoteasytostatethisclaiminaprecisewaythatbothitsdefendersanditsdetractorscanaccept.Partof theproblemhas todowith the ideaof persistence through time ingeneral,which is often a source of confusion. This is the subject of the concludingsection of the chapter. The other problem has to dowithwhat it is to give acriterionof identity forpeople, asopposed to thingsofotherkinds.What is acriterionofpersonalidentity?IunderstandthePsychologicalApproachassayingthis:

Necessarily,foranytimestandt*tandforanyxthatisapersonattandanyythatexistsatt*,x=yifandonlyifx,y,t,andt*standinsomepsychologicalrelationR.

Thatis,anypersonwhoexistsatonetimeisidenticalwithsomethingthatexistsat another time just in case the person is at that time related in somepsychologicalwaytotheotherthingasitisattheothertime.Hereisaspecificinstanceofthatform:

Necessarily,foranyxthatisapersonattandanyythatexistsatt*9x=yifandonlyifxisattpsychologicallycontinuouswithyassheisatt*,andateverytime between t and t* exactly one thing is then psychologically continuouswithyassheisatt*,andexactlyonethingisthenpsychologicallycontinuouswithxassheisatt.

Thisismeanttobeanaccountofwhatouridentitythroughtimeconsistsin,andnotatestormethodforfindingoutwhetherapersonhassurvivedorperished,asthe word ‘criterion’ might suggest (Wiggins 1980, 53). It is a constitutive

criterion,notanepistemicone.ThiswayofstatingthePsychologicalApproachsuggests that theproblemof

personalidentitythroughtimeisthis:

Foranythingthatisapersonatonetime,underwhatpossiblecircumstancesissomething—anything at all—that exists at some other time numericallyidenticalwiththatperson?1

That is the way I understand the question,What does it take for a person topersistthroughtime?Mostphilosophersstatetheproblemdifferently.Theyasksomethinglikethis:

Underwhatpossiblecircumstances is something that isapersonatone timethesamepersonassomethingthatisapersonatanothertime?

There are several reasonswhy someonemayobject to thiswayof putting theproblem.First a quibble. To say that this and that are the same person is usually

understoodbyphilosophersas implying that thisand thatarenumericallyone.But thewords ‘same person’ are not always used in that way. Theremay be“sameness”relationsotherthanstrict,numericalidentity.Thatis, theremaybekindsKsuchthatnumericallydifferentobjectsxandycanbethesameK.Forexample,ClintonisnowthesameelectedofficialasReaganwastenyearsago,even though they are two different men. Many people, especiallynonphilosophers,understand“beingthesameperson”inananalogousway,asakind of resemblance or continuity that neither entails nor is entailed bynumerical identity.According to them, there is no contradiction in saying thatJones, since she became depressed (or since her religious conversion, orwhathave you), is no longer the person she once was, or has become a differentperson,orisnolongerherself.If‘isthesamepersonas’expressedidentityhere,that would be trivially self-contradictory. I shall explore this issue at greaterlengthinthenextchapter.Wecanmakeitclearthatweareaskingaboutnumericalidentity,ratherthan

someother relation, byphrasingour questions in termsof “beingone and thesame” rather than in terms of “being the same person as”. This point wouldhardlybeworthmentioning, though,were itnot fora farmoreseriousmatter.Thisandthatcannotbethesamepersonunlessthisandthatarebothpeople.If‘xisthesamepersonasyisunderstoodintermsofstrict,numericalidentity,itmeans‘xisapersonandyisapersonandx=y’.Thissuggeststhattheproblemofourpersistence through time is theproblemof findingoutwhat it takes for

one of us to be identicalwith someone—someperson—who exists at anothertime. That is in fact how the problem is usually understood. But this way ofputtingitprejudgesanimportantissue,foritcarriestheassumptionthateachofusmustpersistasaperson.This assumption is contentious. ‘Person’maybe awordofmanymeanings,

but philosophers most often use it in a sense that implies having certainpsychological features, such as rationality and the capacity for self-consciousness.2 That is the sense of ‘person’ that figures in statements of thePsychologicalApproach.You and I are peoplewhereas dogs and cats are notbecauseofthepsychologicaldifferencesbetweenyouandme,ontheonehand,anddogs and cats on the other. It is at least arguable that you and Iwere notalwayspeopleinthissense.Embryologiststellusthateachofusstartedoutasatinyembryomadeupofnomorethanafewhundredcells(seeChapter4).Suchathinghasnopsychologicalfeaturesatall,andsoitisnotaperson,atleastnotyet.AndonecouldarguethatyouandIneednotremainpeople—thatonecouldsurvivethepermanentlossofallofone’smentalcapacitiesandcontinuetoexistinapersistentvegetativestate,forexample.Soyoucouldceasetobeaperson,inthissenseoftheterm,withouttherebyceasingtoexist.Theseclaimsmightbe false.Perhaps Iwasneveranembryoor a fetus, and

perhapsitisimpossiblethatIshouldonedaybeahumanvegetable.Mypointisthat these are substantive philosophical claims that should be taken seriously,and not ruled out by theway inwhichwe askwhat it takes for us to persistthroughtime.Wecannotbuildtheclaimthatwhateverisonceapersonmustbea person throughout its career into our statement of the problem of personalidentity.IfwedosoweshalleffectivelyruleoutofcourtanyseriousrivaltothePsychologicalApproach,andtheBiologicalApproachinparticular.BecausetheBiologicalApproachpermits a person tobecomeor tohaveoncebeen anon-person,itwouldhavethewrongformtobeanaccountofpersonalidentityatall.Nor canweavoid thisdifficulty simplyby replacing thewords ‘is the same

person as’ with ‘is numerically identical with’. It is common to talk aboutpersonal identityby asking aboutwhat it takes for apersonwhoexists at onetimetobeidenticalwithapersonwhoexistsatanothertime.Thiswayofputtingtheproblemalsoforeclosesinadvancethequestionwhetherapersoneverwasorwillbeanon-person.Itmaysoundparadoxicaltosaythatapersonmaystillexistbutnolongerbea

person,orthatapersonexistedatatimewhenshewasnotyetaperson.Arewesaying,absurdly, thataperson isnotaperson?No.WhenMarywasborn,shewasaninfant.Nowthatshehasgrownupandbecomeaphilosopher,sheisnolonger an infant. That infant still exists today, although she is no longer an

infant, but an adult instead. The grown-up philosopher before us now onceweighedsixpounds,thoughofcourseshewasnotyetaphilosopheroranadultthen. The claim I want to take seriously (and later defend) is that person isanalogoustoinfantoradultorphilosopher,inthatsomethingmaybeapersonatonetimeandanon-personatanother.Ishallhavemoretosayaboutthisinthenextsection.You may think that my quarrel is merely semantic. To say that there is

personalidentitybetweenxandycanonlybetosaythatxisapersonandyisapersonandxisthesamepersonasy.(Whatelse?)Thentheproblemofpersonalidentity could only be the problem of finding out what it takes for a personpickedoutatonetimetobethesameasapersonpickedoutatanothertime.Ininsisting on asking a broader question I must be either disagreeing with youabout the meaning of the words ‘personal identity’, or simply declining todiscuss personal identity strictly so called and proposing a different probleminstead.3Itistruethattherearetwodifferentquestionswemightaskaboutwhatittakes

forustopersist.Myquestionisabroaderone:

BROAD:Whataretheconditionsunderwhichsomethingthatisapersonatonetimeisidenticalwithanythingatallthatexistsatanothertime?

That is,Whatdoes it take for something that isapersonnow toexistat someothertimeaswell?Butonemightaskanarrowerquestioninstead:

NARROW:Whatare theconditionsunderwhich something that is apersonatonetimeisidenticalwithsomethingthatisapersonatanothertime?

What does it take for something that is a person now to exist as a person atanother time?Bothquestionsareperfectly legitimate ifweunderstand theminthe rightway.Theproblem is that philosophers often ask thenarrowquestionwhentheymeantobeaskingthebroaderone.Butthetwoquestionsmayhaveverydifferentanswers, andananswer to thenarrowquestionmay tellusverylittle about how to answer the broad question. In fact, the narrowquestion byitself is of little interest, and I doubt that any philosopher discussing personalidentity hasmeant to ask it. It is the broad question that philosophers have inmind.We shall see this if we consider a representative answer to the Narrow

Question:

ANSWER:

Foranyxthatisapersonattandanyythatisapersonatt*,x=yifandonlyifyisatt*psychologicallycontinuouswithxasheisatt.

Thisanswertellsusthatifyourcerebrumweretransplanted,producingsomeonewhorememberedyourpastexperiences,thatpersonwouldbeyou,eventhoughhewould not appear to be the same animal as you. SoANSWER rules out theBiological Approach as an answer to the BroadQuestion. But otherwise it issurprisingly uninteresting. Imagine that the transplant operation fails and yourcerebrumissimplydestroyed.Whatwouldhappentoyouthen?ANSWERtellsusonlythatifyousurvive,thennotasaperson.Butitsaysnothingaboutwhetheryou will survive, or in what manner. You might be the brainless humanorganisminwhichyourlife-sustainingfunctionscontinueon;oryoumighthaveceased to exist; or youmight survive in an entirely different form. Likewise,ANSWERtellsusnothingaboutwhetheryousurviveintheVegetableCase.No one who has discussed personal identity and proposed something like

ANSWER intended anything like this. Friends of the Psychological Approachclaim that one ceases to exist if one’smind is destroyed, notmerely that oneceasestobeaperson.ItisnotconsistentwiththeirviewthatImightloseallmymentalfeaturesandthensurvivefortenmoreyearsasahumanvegetable,orasanything else. The Psychological Approach is intended to answer the broaderquestion,notthenarrowerone.Itpurportstotelluswhatittakesforoneofustosurvive (and to have existed at an earlier time) simpliciter, notmerelywhat ittakesforoneofustosurviveasaperson.Ifitisinfactanecessarytruththatwhoeverisapersononcemustbeaperson

throughouther career,NARROW andBROADwillbeequivalent.That iswhy thequestionsareoftenruntogether.However,wemustdistinguishthemifwedon’twanttoassumeattheoutsetthatapersonmustbeapersonaslongassheexists,or (in thevocabulary introduced in thenextsection) thatperson isasubstanceconcept.The reader might suspect that if the Biological Approach is true, ‘personal

identity’ is thewrongname formysubject. If I could startoutor endupas anon-person,isn’titatleastmisleadingtodescribewhatittakesformetopersistastheproblemofpersonalidentity?AmInotsaying,ineffect,thatthereisnosuchthingaspersonalidentity,butonlyanimalidentity?Well,youandIarepeople,andIamaskingaboutouridentity;somytopicis

personal identity in that sense.And Imean to address the question thatmanyphilosophers have discussed under that name. On the other hand, I deny thatthereisanygeneralcriterionofidentityforallandonlypeople.Differentpeoplemayhavecompletelydifferentpersistenceconditions,accordingtowhatkindof

people they are: human animals, organisms of other species, gods, demons,electroniccomputers,orwhathaveyou.OnmyviewthereisnogeneralanswertoBROAD (orNARROW, for thatmatter).According to theBiologicalApproach,because you and I (as opposed to gods or Cartesian egos) are animals, thequestionofouridentityisequivalenttothis:

Underwhatpossiblecircumstancesissomethingthatisahumananimalatonetimethesameanimalasahumananimalthatexistsatanothertime?

Ormoresimply,

Whatdoesittakeforahumananimaltoexistattwodifferenttimes?

Butputtingtheproblemofouridentitythroughtimeinthiswaywouldbejustascontentiousasstatingitintheusualway:

Underwhatpossiblecircumstancesisapersonwhoexistsatonetimethesamepersonassomeonewhoexistsatanothertime?

Inasense,then,thereisnosuchthingaspersonalidentity,anymorethanthereissuchathingasinfantidentityorphilosopheridentity.Wecanaskwhatittakesfor an infant or a philosopher or a person to persist through time; but it is amistake to think that those beings have persistence conditionsas infants or asphilosophers—or,ifIamright,aspeople.

II.SubstanceConcepts

The claim that every person must always be a person follows from a moregeneralprincipleaboutwhatisinvolvedinbeingaperson,onethatdefendersofthe Psychological Approach typically also assume without question. Theyusually assume that personhood is what Wiggins (1967, 7; 1980, 24) calls asubstanceconcept:ThemostfundamentalanswertothequestionWhatamI?isthatIamaperson.Iamalsoanadulthumanbeing,amaterialobject,amemberof the Alpine Club, and many other things. But being a person, it is usuallyassumed,ismoreprivilegedthanallofthese,becauseitdetermineswhatittakesformetopersist.IhavethecriterionofidentitythatIhavebyvirtueofbeingaperson,andnotbyvirtueofbeinganadultoramaterialobjectoramemberoftheAlpineClub,oranyofmyotherproperties.Metaphysicallyspeaking,Iamapersonfirstandeverythingelsesecond.Thisassumptionreliesonageneraltheory,orpartofatheory,ofindividuation

and kinds that most philosophers seem to accept. It is the view thatWigginsstates,inbroadstrokes,likethis:

Ifsomebodyclaimsofsomethingnamedorunnamedthatitmoves,orrunsoriswhite,heisliabletobeasked thequestionbywhichAristotlesought todefine thecategoryofsubstance:What is it thatmoves(orrunsoriswhite...)?Perhapsthemanwhomakestheclaimthatsomethingmovesdoesnotneedtoknowtheanswertothisquestion,andonemayenvisagecircumstancesinwhichhecanknowthat itmoveswithoutknowingwhat the thing is.Yet it seemscertain that, for each compliantof apredicatelike‘moves’,‘runs’or‘white’,thereexistsaknownorunknownnamedornameablekindtowhich the item belongs and by reference to which the ‘what is it’ question could be answered.Everythingthatexistsisathissuch.Ifamanreportsthatthethingthatrunsisthesameasthethingthatiswhite,thenhisjudgementhas

nochanceofbeingtrueunlessatleasttwopreconditionsaresatisfied:(a)thereexistssomeknownorunknownanswertothequestion‘samewhat?’;and(b)thisansweraffordssomeprinciplebywhichentitiesofthisparticularkind—somekindcontainingthingsthataresuchastorunorbewhite—maybetracedthroughspaceandtimeandreidentifiedasoneandthesame.(1980,15)

According to this theory, every particular object falls under some kind orconceptthattellsus,inaspecialsense,whattheobjectis,andnotmerelywhatitdoes or where it is located or some other accidental feature of it. And thatconcept determines persistence conditions that necessarily apply to all (andperhapsonly)thingsofthatkind.Conceptsofthissortaresubstanceconcepts.Although I shall relyon this theory in several places throughout thebook, I

shallnotarguefor it. (It issuchafundamentalclaimthat it ishardtoseehowonecould argue for it in away that couldpersuade anyonewhodoubted it tothinkotherwise.)However, the theoryof substanceconceptsdoesnotby itselftelluswhatsubstanceconceptyouandIfallunder.Theclaimthatpersonisasubstanceconceptentailstwointerestingprinciples.

First, it entails that all people share the same persistence conditions. If theconceptpersondetermineswhatittakesformetosurvive—ifIpersistundertheconditions that Idobyvirtueofbeingaperson—then thatconceptdeterminesthis for all people. Suppose there were two sorts of people, A-people and B-people, that persisted under completely different circumstances. Then the A-peoplewouldhavetheircriterionofidentitybyvirtueofbeingA-people,notbyvirtueofbeingpeople,andlikewisefortheB-people.InthatcaseA-personandB-personwouldbethesubstanceconcepts,andnotperson.Second, it entails that anything that is once a person must be a person

throughoutitscareer;thenotionofaformerpersonoramerelypotentialpersonwould be incoherent. For suppose I am a person now, but was once a non-person.WhenIwasanon-personIcouldnothavehadmypersistenceconditionsbyvirtueofbeingaperson.Buta thingcannot change its criterionof identitypartwaythroughitscareer;whateverittookformetopersistthenmustbewhat

ittakesformetopersistnow(apointIshallreturntoinChapter4).Theremustbesomegeneralconditionsthatenablemetopersistbothasanon-personandasa person. But then there must be some more general kind of thing thatdetermines those persistence conditions, andwhich I thereforemust belong tothroughoutmycareer;mybeingapersonwouldnotdeterminemypersistenceconditions,andsopersonwouldnotbeasubstanceconcept.WecandistinguishsubstanceconceptsfromwhatWigginscallsphasesortals,

orsorts,suchaschildorathleteorphilosopher,whicharekindsthatsomethingcanbelong to temporarily (1967,7;1980,24). Itwouldbeabsurd toask foracriterion of juvenile identity, or to askwhat it takes for an athlete as such topersist through time. There are no persistence conditions that all and onlychildrenhave,forchildrenarenotalwayschildren;theygrowuptobeadults.Tocometobeaphilosopherisnottocomeintoexistencesimpliciter,andtoceasetobeaphilosopherisnotnecessarilytoceasetoexistaltogether.4If this theory of substance concepts is right, and if person is a substance

concept,wecanargueforthePsychologicalApproachlikethis:

Theconceptofapersonisatleastinpartapsychologicalconcept:Somethingisapersonjustincaseithascertainpsychologicalfeatures,suchasrationalityand the capacity for self-awareness. Because people have their persistenceconditions by virtue of being people, we should expect those persistenceconditionstohavesomethingtodowithpsychology.Attheveryleastwecanconcludethatapersoncannotsurviveasavegetableorasthethingthatgetsleftbehindwhenone’scerebrumisremoved,forthosethingsarenotpeople.

Thus, anyone who assumes that person is a substance concept is in effectassumingthePsychologicalApproach.On the other hand, ifperson is not a substance concept, butmerely a phase

sort,theaboveargumentisnomoreconvincingthanthisone:

Somethingisanathletejustincaseithascertainathleticabilitiesandhabits.Thereforewhatittakesforanathletetoexistattwodifferenttimesmusthavesomethingtodowithherathleticfeatures.Attheveryleastwecanconcludethatanathletecannotpersistunlesssheremainsanathlete—unlesssheretainssomeofherathleticabilitiesorhabits.

Ifthisargumentwerevalid,anathletewhoretiredfromsportswouldnotsimplycease tobeanathlete,butwouldcease toexistaltogether. Ihope it isobviousthatthisisnotso.Aparalyzingaccidentoradisablingboutofdepressionmaybringsomeone’scareerasanathletetoanend.Ifthishappenswemightsaythat

shehas“diedasanathlete”,aswesaythatWordsworthdiedasapoetmidwaythrough his life. But there are such things as former athletes and potentialathletes. The argument is invalid because athlete is not a substance concept.Athletes don’t have the criterion of identity that they have by virtue of beingathletes.According to the Biological Approach, person (in the psychological sense

discussedabove)isnotasubstanceconcept,butaphasesortlikeathlete.Theremaybebothformerpeopleandmerelypotentialpeople.Iftherecouldbepeoplewhoaren’tlivingthings(“living”inthebiologicalsense),suchasgodsorangelsorCartesianegos, thendifferentkindsofpeoplemayhavedifferentcriteriaofidentity. And biological people such as you and I persist under the sameconditionsasmanynon-people,suchashumanembryosandhumanvegetables.In fact, it seems likely thatourpersistenceconditionsare thesameas thoseofaardvarksandoystersandotheranimals.Oursubstanceconcept—whatwemostfundamentally are—is not person, but Homo sapiens or animal or livingorganism.I have assumed thatperson is either a substance concept or not a substance

concept, but a phase sort instead. You may suspect that there is a thirdpossibility,namelythattheword‘person’isambiguousandcanbeusedinonewaytoexpressasubstanceconceptandinanotherwayasaphasesortal.5Sothequestion whether person is or is not a substance concept may not have astraightforwardanswer.Ifso,ininsistingthatpersonisnotasubstanceconceptIshould be merely making a verbal point—arguing that the primary sense of‘person’isthephase-sortalsense,forexample,orpointingoutthatadvocatesofthe Psychological Approach have neglected to consider the substance-conceptsenseoftheword.ButtherewouldnotbeanydefinitefactofthematterwhetheryouandIwereonce,ormightbecome,non-people.This suggestion gets us into deepwaters. Suppose there is both a substance

concept person and a phase sort person, and that the English word ‘person’expresses both concepts ambiguously. It seems clear that nothing could be apersoninbothsensesoftheword.Apersoninthephase-sortalsensemustfallunder some substance concept other than person—animal, for example. Thus,shewillhavepersistenceconditionsother than thoseentailedby the substanceconceptperson,andpresumablyincompatiblewiththem.Aphase-sortalpersonwillhavemodalandperhapsalsohistoricalpropertiesthatnosubstance-conceptpersoncouldhave.InwhichsenseofthewordareyouandIpeople,then?Arewepeopleinthe

phase-sortal sense, or people in the substance-concept sense? Ifwe are phase-sortalpeople,thePsychologicalApproachisfalse,foritwouldbepossibleforus

to have once been or to come to be non-people, and thus to survive radicalpsychologicaldiscontinuity.Ifwearepeopleinthesubstance-conceptsense,thePsychological Approach is true. But the mere fact that there exist these twosensesof‘person’doesnotshowthatwhichsortofpersonweareisinanywayaverbalmatter.Wecouldputthepointdifferently.IfthePsychologicalApproachistrue,there

arenopeopleinthephase-sortalsense,evenifthereissuchaphasesort.Infacttherecouldn’tbeanysuchpeople,foriftherewere,therewouldberational,self-consciousmoralagentsofwhomthePsychologicalApproachwasnottrue(seeChapter5,SectionV).Conversely,iftheBiologicalApproachistrue,therearepresumably no people in the substance-concept sense, even if there is such asubstanceconcept.Anditdoesnotseemthatwhetherthereareanybeingsthatfall under the one concept or the other can be settled by analyzing the word‘person’.In thenext section,however, I shall consideranargument for theclaim that

thereisnosubstance-conceptsenseof‘person’.

III.MoversandThinkers

ItiseasytoargueforthePsychologicalApproachfromtheclaimthatpersonisaWigginsiansubstanceconcept.Weneedn’tevenappealtothoughtexperiments.Ifwe have our criterion of identity by virtue of being people, in the sense ofbeing(roughly)rational,self-consciousbeings,thenitseemsthatourpersistenceconditionsmust involve psychology.On the other hand, ifperson (or at leastthinker or some other kind whose members are guaranteed to have someinteresting psychological features) is not a substance concept, it is hard to seehow the Psychological Approach could be true. If we had our persistenceconditions by virtue of being animals, then those conditions could not beessentially psychological ones, formany animals persist through timewithoutpsychologicalcontinuityofanysort.This raises a serious challenge for the PsychologicalApproach, for it is not

clearthatperson(orthinkerorthelike)couldbeasubstanceconcept.RecallthequotationfromWiggins in theprevioussection.Conceptsother thansubstanceconcepts may answer such questions asWhat is it doing?Where is it? Howmuch does it weigh? But only a substance concept can answer the question,Whatis it that isdoingthisandthat, that ishereor there,or thatweighssuch-and-such?The concept of a person, though, in the sense of ‘person’ in which the

PsychologicalApproachpurports togive thepersistenceconditions for all andonly people, does not seem to be the sort of concept that could answer thisquestion.Tosaythatsomethingisapersonistotellussomethingaboutwhatitcando,butnottosaywhatitis.Tosaythatsomethingisapersonistosaythatitcanthinkinacertainway—thatitisrational,thatitisordinarilyconsciousandaware of itself as tracing a path through time and space, that it is morallyaccountablefor itsactions,or the like.But itdoesn’t telluswhat it is thatcanthink in that way.Wemight still ask, Is the thing that can think a biologicalorganism?ACartesianegoorLeibnizianmonad?Anangel?Amachinemadeofmetalandsilicon?What sortof thing is it thathas those specialpsychologicalproperties?Ishalltrytoillustratethispointbymeansofananalogy.Imagine a philosopher who is extremely impressed with our locomotive

capacities.ItsimplyfascinatesherbeyondwordsthatyouandIhavetheabilityto move about under our own steam. Of course many things besides humanbeings can do this as well: tortoises, white blood cells, nuclear submarines,model airplanes. So our imaginary philosopher proposes a “LocomotiveCriterion” of identity, not only for human beings, but for all and only“locomotors”,aswemightcallsuchobjects.A locomotor,shesays,persists ifand only if its capacity for locomotion is preserved—if and only if there is“locomotive continuity”. She thinks that locomotor is a substance concept,whichdetermineswhatittakesforallandonlylocomotorstopersist.Ifaship’sengineisdamagedbeyondrepair,shesays,thatshipceasestoexist,

and the resulting crippled ship (if we can call a thing with no locomotivecapacity a ship) is numerically different from the one that once sailed. If weattachamotortosomethingthatwaspreviouslyunabletomove(arowboat,forexample), andgive it (or rather its successor) locomotivepowers, theoriginal,nonlocomotiveobjectceasestoexistandisreplacedbyalocomotornumericallydifferentfromit—forthelatterobjectwouldhaveadifferentcriterionofidentityfromtheformer.Andifaship’sengineisremovedandinstalledinanewhull,the resulting ship is identicalwith the original ship, for it inherits the originalship’slocomotivecapacity.Ifashiporanairplaneorsomeotherlocomotorhastwo separablemotors or “organs of locomotion”, fission paradoxeswill arise,just as they do for the PsychologicalApproach (owing to the fact that humanbeingshavetwoseparablecerebralhemispheres). In thesameway, ifahumanbeing or any other “locomotive” animal irreversibly loses the function of itslimbs,fins,flagella,orwhatever,itperishes,evenifnoneofitsotherfunctions,including its mental functions, are directly affected. The resulting animal isnumericallydifferent from theoriginalanimal.Thus,StephenHawkingceasedtoexistwhenhisillnessmadeitimpossibleforhimtowalkorcrawlorswim;he

was replaced by a physicist of a different ontological kind (a non-locomotor),withdifferentpersistenceconditions.Perhapsyoucanimagineacase inwhich(speaking loosely) one animal’s locomotive capacity is transferred to anotheranimal;inthatcasetheoriginalanimalwould“follow”thosecapacities.IfabrightundergraduatestudentseriouslyproposedtheLocomotiveCriterion

inmetaphysicsclass,weshouldprobablythinkshewasmakingajoke.Ournextthoughtwouldbethatshehadsomehowfailedtograspthenotionofacriterionofidentity,orperhapsthatshewasextremelyeccentricorworse.Whatissodaftabout the Locomotive Criterion? Compare a barnacle with a crab. Biologistsclassify crabs and barnacles together, for they are close evolutionary cousins,and their physiology is quite similar. But our imaginary philosopher isunimpressed by mere physiological similarity, and insists that crabs andbarnacles(andevennormalcrabsandcrabsthatforsomereasoncannotmove)belong to different substantial kinds: crabs have the Locomotive Criterion ofidentity, whereas barnacles have a different criterion appropriate to sessileobjects.We may object that barnacles—the very same organisms that later attach

themselves permanently to the hulls of ships—canmove about, in their larvalstage.“Contrarytoappearances”,ourphilosopherinsists,“nosessilebarnacleisnumericallythesameasanylocomotivebarnaclelarva.Thelarvaceasestoexistwhenitlosesitslocomotivepowers,andisreplacedbyanumericallydifferent,sessile animal, for a thing cannot change its persistence conditions partwaythroughitscareer”.Now compare our healthy crab with a model airplane. Here we find little

intrinsicsimilarity.Whereasthecrabhasabiochemicalstructureofastronomicalcomplexity,themodelairplanehasarelativelysimpleinternalstructureofpaperandbalsa-woodandglue.While theairplane retains its shapeandstructurebyvirtueoftheintrinsicstabilityofitscomponentmaterials,thecrabmustpreserveits organic structure by constantly taking in new matter and rearranging itaccordingtoacomplexinternalplan;ifitwerenotconstantlyrepairingitself,thecrabwould immediatelycease tobea living thingandbegin todecay.Andsoon.Butourphilosopherisnotimpressedbythesedifferences.Whenitcomestoidentityandpersistence,shesays,theyarealloutweighedbythefactthatcrabsandmodel airplanes are both locomotors. It doesn’t evenmatter that a crab’sway of moving— involving muscles and tendons attached to its exoskeleton,driven by elaborate biochemical machinery—is entirely different from theairplane’swayofmoving.If crabs and battleships somehow did turn out to have the same persistence

conditions,conditionsdifferentfromthoseofbarnaclesandrowboats,weshould

expect this to be so not because the former but not the latter can move bythemselves,butratherbecause,contrarytoallexpectation,crabsandbattleshipsturnedouttohavesomemoresignificantfeatureincommon.Beingabletomoveunder its own power is just not the sort of feature that could determine anobject’s persistence conditions.Locomotor, it seems, could not be a substanceconcept.Supposeyoupointtoacrabandask,Whatisit?Ireplythatitisathingthat

canmove,alocomotor.Youmightstillaskwhatitisthatcanmove.(“Icanseethatit’smoving,butwhatisit?”)Whydoesn’t“It’sathingthatcanmove”,or“It’salocomotor”,answerthequestionWhatisit?Thisisadifficultmatter,butI think part of the answer is that locomotion is a dispositional or functionalproperty thatcanbe realized inawidevarietyof intrinsicstructures.Differentlocomotorsmayhavelittleincommonbesidesthefactthattheyarelocomotors—besides their ability to perform a certain kind of task. A crab and amodelairplanehavelittle intrinsicsimilarity;eventhelocomotivecapacities that theyhave in common are grounded in utterly different internal structures. On theotherhand,manylocomotors,suchascrabs,haveagreatdealincommonwithcertain non-locomotors, such as barnacles. The mere fact that two things arelocomotorsseemstobe,inanimportantsensethatishardtodefine,asuperficialsimilarity,whereasthemerefactthatonethingisalocomotorandanotherisnotisasuperficialdifference.It isameresimilarityordifferenceinoneparticularability,whichneednotreflectanyfurthersimilarityordifference.At least part of the reason for this seems to be the fact that locomotion is a

mere capacity: to say that a thing is a locomotor is merely to say somethingaboutwhatitcando.Moreover,itisacapacitythatisnotcloselyconnectedwithathing’sinternal,structural,orintrinsicfeatures.Locomotor,likecarburetororheat sink, is a functional kind.Anythingwhatever could be a locomotor, or acarburetor,oraheatsink,aslongasitcansomehowmoveunderitsownpower,ormixfuelandairinacertainproportion,orabsorbheat.Thatisatleastpartofthe reason why locomotor is not a substance concept, and why it could notdeterminethepersistenceconditionsforallandonlylocomotors.ThatisatleastpartofthereasonwhytheLocomotiveCriterionissoobviouslyfalse.If this is the right diagnosis of the Locomotive Criterion, the Psychological

Approachfacesasimilarproblem,forpersontooseemstobeafunctionalkindrather than a substance concept.To be a person,we are supposing, is to havecertainmentalproperties;andaccordingtoawidelyacceptedtheory,atanyrate,mental properties are essentially dispositions. For something to be apsychologicalstateorprocessorpropertyofagivenkindisforittohavecertaincausalpowers—forittohavethecapacitytointeractwithsensorystimulations,

bodymovements,andotherpsychologicalstates incertainways.There isnoapriori reason, on that view,why states of a brain should be the only possiblemental states; states of many different sorts of structures—Martian organs,electroniccomputers,Cartesianegos,godsordemons,forexample—mightalsobeabletosupport thought.Thosestructuresneedonlybeinstatesthat interactwiththeirenvironment,movements,andotherinternalstatesoftheobjectintherightways.Hence,Martians,electroniccomputers,gods,andCartesianegos,aswell as human beings, might all be rational, conscious, thinking beings: theymightallbepeople.In that case, to say that something is a person is rather like saying that

somethingisalocomotor.Personhood,likelocomotion,ismerelyacapacityorability of a thing, and different kinds of people may have no more intrinsicsimilarity than do different kinds of locomotors. If anything, human beings,gods, and electronic computers have even less in common than crabs andbattleships have. To say that something is a person—roughly a rational, self-consciousbeing—tellsusevenlessaboutwhatthatthingisthantosaythatitisalocomotor.In fact the analogy between person and locomotor goes further, for the

PsychologicalApproachturnsouttohavemanysurprisingconsequencessimilarto those of the Locomotive Criterion. For example, just as the LocomotiveCriterion entails that a barnacle larva must cease to exist when it loses itslocomotive capacity, and is numerically different from the resulting, sessilebarnacle,thePsychologicalApproachentailsthatahumanorganismmustceasetoexistwhenitlosesitsmentalcapacities,andisnumericallydifferentfromtheresulting “noncognitive” human organism. And just as, on the LocomotiveCriterion, a nonlocomotive object ceases to existwhen amotor or someothersourceof locomotivepower isbuilt into it, thePsychologicalApproachentailsthat an animal that cannot think ceases to exist when it is providedwith thatcapacity,whether by a cerebrum transplant or in the normal course of growthand development. Both theories entail that members of the same biologicalspecies may fall under different substance concepts and have completelydifferent andunrelatedpersistence conditions. (I shall explore thesematters inChapters4and5.)Hence,defendersofthePsychologicalApproachneedtoexplainhowperson

could be a substance concept even though locomotor could not be. TheBiologicalApproach,ontheotherhand,doesnotfacethisproblem.Animal(ororganismorhumananimal)isaparadigmcaseofasubstanceconcept,andsoisan ideal candidate fordetermininga thing’spersistenceconditions.Weshouldexpect an animal to have its persistence conditions by virtue of its being an

animal (or a living organism, or an animal of a particular species), for “ananimal”, unlike “a locomotor” or “a thinker”, is an excellent answer to thequestionwhatsomethingis—whatitisthatcanmoveorthink.Now someone might object to my claim that personhood is a dispositional

property,amerematterofhavingtherightpsychologicalcapacities.Perhapstheconcept person is more like animal and immaterial substance and otherparadigmsubstanceconcepts,andlesslikelocomotor,thanIhaveargued.Itishardtoevaluatethissuggestionwithouthavinganactualproposaltowork

with—a definition of personhood as something other than a dispositional orfunctionalproperty.But it seemsdoubtful that suchan account couldgive thesenseof‘person’thatfiguresintheclaimthatthePsychologicalApproachgivesthe persistence conditions for all and only people. The “people” ofwhich thePsychological Approach purports to be true include you andme, but excludecertainothermembersofourbiologicalspecies:three-month-oldhumanfetuses,anencephalic babies, and human vegetables, for example. And the salientdifferencebetweenanordinary,adulthumanbeingandahumanvegetableisadifferenceinwhat theycando:onecanthinkandactandtheothercannot.Ofcourse, this difference in what they can do is grounded in certain intrinsic,structuraldifferences:thenormaladultcanthinkandactbecauseshehasneuralstructures inside her head that the human vegetable lacks. But those neuralstructuresarenotpartoftheconceptordefinitionofaperson.It’snotthebrainitselfthatmakessomethingaperson,butwhatthebraincando.Ifwebuilttheneuraldifferencebetweenanordinaryhumanbeingandahumanvegetableintoour account of personhood, only beings with human brains could be people;Martians,gods,andelectroniccomputers,nomatterhowrational,intelligent,orself-conscioustheymaybe,couldnotbepeople.Isn’t it good enough if the Psychological Approach applies to all human

people?Whymust it apply to all possible people, including thosewho aren’thumanbeings?Can’twebe lessambitiousandmoreparochial?ButgiventhatthePsychologicalApproachappliestohumanpeople,itwouldbesurprisingifitdidnotapplytonon-humanpeopleaswell.(Eveniftherearen’tinfactanynon-humanpeople,theremighthavebeen;itwouldbesurprisingifthePsychologicalApproach necessarily applied only to human people.) A non-human person—god,Martian,orwhathaveyou—wouldhavethesamereasonsforthinkingthatthePsychologicalApproachappliedtoheraswehaveforthinkingthatitappliestous.Whyshouldshebemistakenaboutherpersistenceconditionswhilewearecorrect about ours? To be sure, some versions of the PsychologicalApproach(Unger’sversion,forexample)saythatonecouldnotsurvivewithoutsomesortof physical continuity, and those versions are clearly not meant to apply to

immaterialpeople,iftherecouldbesuchthings.Butweshouldnotexpectsuchanaccount tobe trueofmaterial peopleunless somegeneralizationof itweretrueof immaterialpeopleaswell.That is, ifyouandIsurvivejust incaseourmental capacities are preserved in a physically continuous way, we shouldexpect any person whatever to survive just in case her mental capacities arepreserved in some analogous way—via some sort of causal continuity, forexample.

IV.“PersonP1atTimet1”

I turn now to a general problem about identity across time that infects manytypicalstatementsoftheproblemofpersonalidentity,aswellasmanyproposedsolutionstoit.Itisarathertechnicalmatter,anditmayneverhaveledanyoneastray. But it involves some interesting and difficult logical andmetaphysicalissuesthatIthinkdeservemoreattentionthantheyhavereceived.Readerswhoareboredbysuchmattersareencouragedtoskipthissection.Theproblemofpersonalidentityistypicallystatedinwordslikethese:

A.xattimetisidenticalwithyattimet*ifandonlyif...,

forallpeoplexandy.Asolutiontotheproblem—acriterionofidentity—wouldbe an appropriate completion of the sentence. How arewe to understand thisformula?Thepositionsofthevariablesxandyencourageustosubstitutenamesofpeopleforthem;soaninstanceofAabovewouldbe

B.TomtodayisidenticalwithTimtomorrowifandonlyif....

But how are we to understand the temporal qualifications ‘today’ and‘tomorrow’? They appear to be adverbs. Adverbs modify predications, andtemporaladverbstelluswhenthepredicateistrueofthesubjectorsubjects.IfwesaythatTimwrotealetterlastweek,thetemporaladverbtellsuswhenTimwrotealetter.IfwesaythatTomwillvisitTedtomorrowthetemporaladverbtellsuswhenTomvisitsTed.Butoursentencehastwotemporaladverbs.DoesthatmeanthatidentityholdsbetweenTomandTimattwodifferenttimes,todayandtomorrow,inthewaythat‘TomwillvisitTedtodayandtomorrow’tellsusthat the relation visiting holds between Tom and Ted at two different times,today and tomorrow? In that case the left-hand side of B would be moreperspicuouslywritten

C.TomandTimareone,bothtodayandtomorrow.

BecauseAhasnopredicatebesides‘isidenticalwith’foranadverbtoapplyto,thisseemstobetheonlypossiblereading.Butthiscannotberight.Thereisnopointinqualifyingapredicationwithan

adverbunlessdifferentadverbscanchangethetruthvalueofthesentence.Thepointofaddingthequalification‘today’tothesentence‘TomvisitsTed’isthattherearetimeswhenitistruethatTomvisitsTedandothertimeswhenitisnottrue (or, if Tom has outstayed his welcome, there might be). But supposesomeonesaid,“Fiveisgreaterthanthreetoday”.Thequalification‘today’addsnothing. It is like saying, “Five is greater than three in Cleveland”. And thepropositionthatTomisTimisratherlikethepropositionthatfiveisgreaterthanthree.ItisnotsometimestrueandsometimesfalsethatTomandTimareone;ifTomandTimareone, that isnecessarily so, and if theyaredifferent theyarenecessarilytwo.Identityisatimelessrelation.Ofcourse,TomandTimdon’talwaysexist.Someonewhosaid,“Tomisthe

same person as Tim” at a time when neither Tom nor Tim exists might beunderstood as saying something false, or at least not strictly true. So thequalifications ‘today’ and ‘tomorrow’ in ‘Tom today is identical with Timtomorrow’ might be there to tell us that Tom and Tim exist both today andtomorrow:

D.TomandTimareidentical,andexisttodayandtomorrow.

Theadverbs inA andBmodify thepredicate ‘exists’ (which, although it doesnot explicitly appear in those sentences,would figure in its “deep structure”),ratherthanthepredicate‘isidenticalwith’.Inthatcaseitwouldbeatbestrathermisleading to use sentences likeA andB to talk about persistence or identitythrough time; in any event, those sentences do not wear their grammaticalstructure on their sleeve. More seriously, it would make no difference if wereversed the temporal adverbs: since ‘Tom exists today and tomorrow’meansthesameas‘Tomexiststomorrowandtoday’,‘TomtodayisidenticalwithTimtomorrow’ would mean the same as ‘Tom tomorrow is identical with Timtoday’.Moreover,identity-statementswithonetemporaladverbwouldbejustasmeaningfulasstatementswithtwo:‘TomisidenticalwithTimtomorrow’wouldmean thatTomandTimare identicalandexist tomorrow.That isnot thewayphilosopherswhotalkaboutpersistencebysaying‘xatt’wanttobeunderstood.Intheclaim

xattisidenticalwithyatt*ifandonlyifxattispsychologicallycontinuouswithyatt*,

we cannot simply reverse the two times, or leave one of them out, withoutchangingtheintendedmeaning.Somephilosophershaveclaimedthat‘today’and‘tomorrow’in‘Tomtodayis

identicalwithTimtomorrow’arenotadverbsmodifyingtheidentitypredicate;rather, they read ‘Tom today’and ‘Tim tomorrow’ascomplexnounphrases.6‘Tomtoday’doesnotdenoteTom,theysay,butthetemporalpartofTomthatoccurs today. ‘Tomtoday’ isanalogous to‘Interstate90 inSpokane’,which(Isuppose)picksoutthepartofInterstate90thatlieswithinthecityofSpokane.Thus,‘Tomtodayis identicalwithTimtomorrow’meansthat the“today-part”ofTom(thetemporalpartofhimthatoccurstoday)isapartofthesamepersonas the“tomorrow-part”ofTim.Thishas theratherunsettlingconsequencethatthepredicate‘isidenticalwith’asitoccursinstatementsofdiachronicidentitydoesnotexpressidentity,butrathertherelationbeingapartofthesameobject(orratherthesamepersonorthesameanimalorwhathaveyou).Ifitexpressedidentity,‘TomtodayisidenticalwithTimtomorrow’wouldbefalseevenifTimandTomwere one, for the today-part of Tom could not be identicalwith thetomorrow-partofTim,occurringastheydoatdifferenttimes.7In any case, this way of analyzing statements of identity through time is

availableonlytothosewhoacceptanontologyoftemporalparts,acontentiousmetaphysic with far-reaching consequences (see Chapter 7). But it contains akerneloftruth:thetemporaladverbsinstatementsofdiachronicidentitydonotmodify the identitypredicate.Rather, theyhelp todetermine therelata of thatpredicate: they are components of complex noun phrases. Our example ‘TomtodayisidenticalwithTimtomorrow’isabadonebecause‘Tom’and‘Tim’arepropernames,anddonotneedthehelpofanytemporalqualificationtopickouttheirreferent(orreferents,asthecasemaybe).Wecannotchangethereferenceof a proper name by tacking on different temporal qualifications. If I refer toTombysaying‘Tom’,Ineednotworrythatthatname,asIusedit,mightreferto someone other than Tom at another time. If I say that Tom will becomepresidentin2012IneednothastentoaddthatImean“Tomtoday”,asifwhatIsaidmightnowpickoutTombutdenotesomeoneelsein2012.Abetterexampleofasentenceexpressingidentitythroughtimewouldbe‘The

saplingweplantedtenyearsagoisthetreethatshadesthegardentoday’.Herewe pick out something via a property it had ten years ago, and we pick outsomethingviaapropertyithastoday,andifthesentenceistruewehavepickedout the same thing twice.Theadverbsmodify thepredicates that figure in thetwo descriptions: they are components of complex noun-phrases. Wephilosophersmightagreetocallthesaplingplantedbackthen‘Tom’,andtocall

the treeshading thegarden today ‘Tim’. In thatcaseweshouldbesaying thatTomisidenticalwithTim.ButtherewouldbenopointinsayingthatTomtenyearsagoisidenticalwithTimtoday;thetemporaladverbsarealreadybuiltintothedefinitionsofthenames‘Tom’and‘Tim’.Ifthisisright,‘xattisidenticalwithyatt*’isnottheschemaforstatements

ofidentitythroughtime.Atanyrateitisnottherightschemaifweinterpretthevariablesintheusualway.Ifwetrytogetaninstanceofitbyputtingsingularterms forx andy and replacing t and t*withnamesof times,wedonotgetastatementof diachronic identity, but something that is bothgrammatically andsemanticallyconfused.Theschemaiscorrectonlyifweread‘xatt’asshortforsomethingquitedifferent,aninstanceofwhichwouldbe‘thecolonelwhowasindictedlastyear’.Amoreperspicuousschemawouldbe‘ThexthatisFattistheythatisGatt*’.Phrases like ‘x at t’ appear not only in statements of diachronic identity but

also in statements of the conditions for identity: in the right-hand side ofsentenceAaboveaswellastheleft.Hereisatypicalexample:

P2att2isthesamepersonasP1att1ifandonlyifP2att2ispsychologicallycontinuouswithP1att1.(Noonan1989,13)

If the temporal adverbs in the left-hand side of this formula (before thebiconditional) are best understood as components of complex definitedescriptions such as ‘the person who ran for office in 1980’, how are we tounderstandthetemporaladverbsontheright-handside?Whatdo‘att1’and‘att2’meanin‘P2att2ispsychologicallycontinuouswithP1att1’?Infacttheirfunctionhereisquitedifferentfromtheonetheyhaveinidentitystatements.Psychologicalcontinuity,unlikeidentity,isafour-placerelationthattakestwo

peopleandtwotimes:tosaythatxandyarepsychologicallycontinuousistosaythatxisatsometimepsychologicallycontinuouswithyassheisatsomeothertime.Thatisbecausepsychologicalcontinuity(ordiscontinuity)isarelationthatholdsor fails toholdbyvirtueof themental statesorcapacities that someonehasatonetimeandthethoughtssomeonehasatsomeothertime.TosaythatIam psychologically continuous with some past person is to say that I havementalfeaturesnowthatrelateinaspecialwaytomentalfeatureshehadthen.A storywillmake this plainer. In 1990 Jane suffered radical andpermanent

amnesia. Or if you think that total amnesia might leave some importantpsychologicalconnectionsintact,imaginethatJanehashercerebrumrearrangedinsomesuitablydisruptiveway.BoththosewhosaythatJanecouldsurvivethisand those who say that she must perish can agree that this is a case ofpsychologicaldiscontinuity.Forsimplicity’ssakeletustakethepointofviewof

thosewho say that Jane survives. According to them, Jane is psychologicallydiscontinuouswithherself.Whatcouldthismean?TodayJanecanrememberthepast four years of her life perfectlywell, and in 1989 she could remember asmuchofherpastasyouandIcan rememberofourpasts.The relevant fact isthatnoneofthementalfeaturesJanehasnowarerelatedintherightwaytoanyof the mental features she had before 1990. That is, Jane is not nowpsychologicallycontinuouswithherselfasshewasbefore1990;however,sheisnowpsychologicallycontinuouswithherselfasshewasayearago,andin1989she was psychologically continuous with herself as she was in 1985. So wecannotleaveoutthetimes.Thus, the clearest and least misleading way of saying that psychological

continuityisnecessaryforapersontopersistissomethinglikethis:

Necessarily,foranyxthatisapersonatt,andanyythatexistsatanothertimet*,x=yonlyifxisattpsychologicallycontinuouswithyassheisatt*.

3

WhyWeNeedNotAcceptthePsychologicalApproach

I.TheTransplantIntuition

Before going on to what I claim to be the metaphysical shortcomings of thePsychologicalApproach,Iwanttosaysomethingabouttheargumentsthathavebeen given in favor of that view. There are two reasons for this. First, anydifficulties thata theoryfaceswillbeseenaslittlemorethanresearchprojectsandopportunities for further refinement if there are believed to be compellingargumentsinfavorofthattheory.AsmypurposeistoattackthePsychologicalApproach, I must try to show that the arguments in support of it need notpersuadeus.Second,agreatmanythoughtfulandintelligentphilosophershaveacceptedthePsychologicalApproach,andifitturnsoutthattheyweremistaken,itwould be gratifying ifwewere able to say something aboutwhat led themastray. I shall try to accomplish both tasks by arguing that the PsychologicalApproach isbased largelyonpracticalconsiderations thatdonotprovideclearsupport for that view, and that may well be compatible with the BiologicalApproach.MostargumentsforthePsychologicalApproacharebasedonstorieslikethis

one:Once there was a prince, called “Prince”, and a cobbler, named “Cobbler”.One day Prince’s cerebrumwas cut out of his head and implanted into thehead of Cobbler, whose own cerebrum had been removed and destroyed tomakeroomforPrince’s.Twohumanbeingsresultedfromthis.Oneofthem,called“Brainy”,hadCobbler’sarms,legs,trunk,andotherparts,butPrince’scerebrum.BrainylookedjustlikeCobbler,buthehadPrince’spersonalityandcharacter,andwasabletorememberasmuchofPrince’spastasPrincecould;and he knew nothing whatever about Cobbler’s past. The other offshoot,“Brainless”, had all of Prince’s parts except for his missing cerebrum.

AlthoughBrainlesscouldwakeandsleep,coughandsneeze,andevenmakereflexmovementswithhisarmsandlegs,hiseyescouldonlystarevacantlyatthe ceiling. He was in roughly the sort of persistent vegetative state thatsometimesresultsfrommassivecerebraldamage.

WhathappenstoPrincewhenwetransplanthiscerebrum?Manyareinclinedtosaythathegoesalongwiththatorganandishimselftransplantedintoanotherhead. Prince survives the transplant as Brainy, the man who ends up withPrince’s cerebrum and all of Prince’s psychological features.AlthoughBrainydoesn’t look like Prince, he thinks and acts like him; and of course BrainybelievesheisPrince.ThefirstthingBrainywillwanttoknowwhenhewakesupiswhyhisbodyissonewandstrangetohim,andwhathappenedtohis“old”body.Brainless,ontheotherhand,maylooklikePrince,buthedoesnotthinkoractlikehim.HehasverylittleofwhatmadePrincePrince.Infact,heisnotapersonatall,ifbeingapersonimplieshavingcertainmentalpowers,suchasacapacity for conscious awareness. If Prince’s cerebrum had not beentransplanted but simply destroyed (wewant to say), thatwould have been theendofhim.Theresultinghumanvegetable,whowouldbejustlikeBrainlessinour transplant story, would not be Prince even then. So we can construct asimpleargumentforthePsychologicalApproach:

1.Prince,inthetransplantstory,isBrainy.2. Therefore, one survives from one time to another if and only if one’smentalcontentsandcapacitiesarepreserved(perhapsgivencertainfurtherconstraints).

IamgoingtocalltheinclinationtosaythatPrincesurvivesthetransplantasBrainytheTransplantIntuition.TheTransplantIntuitionisthehunchorfeeling,thepulltowardssaying,thatonesurvivesinthetransplantstoryastheoffshootwhogetsone’scerebrum.OnecouldalsoargueforthePsychologicalApproachon the basis of the intuition that Prince does not survive the operation asBrainless, and thatCobblerdoesnot survive asBrainy (wemight call this the“Vegetable Intuition”).But I shall focuson theTransplant Intuitionbecause ithasreceivedmoreattention.IfwecanshowthattheTransplantIntuitioncanberesisted,similarconsiderationswillapplytotheVegetableIntuition.This“transplantargument”, inonevariationoranother, isprobably themost

popularreasonforacceptingthePsychologicalApproach.BecauseIaccept theBiologicalApproach, Iamcommitted tosaying that theargument’spremise isfalse:youdon’tgoalongwithyourcerebrumwhenthatorganisremovedfromyourhead;yousimplyloseyourorganofthoughtinthesamewayasyoumight

lose your liver. Prince is not Brainy, but Brainless. But I don’t reject thatpremisebecauseitstrikesmeintuitivelyaswrong.Onthecontrary:IsharetheTransplantIntuitionwithmostofmyreaders.Itseemstometoo,atfirstglance,thatPrincesurvivestheoperationasBrainy.IrejectthisclaimbecauseIbelieveforother reasons thatPrince is a livingorganism, and thatnoorganism in thestoryisfirstcalled‘Prince’andlatercalled‘Brainy’.Thatis,Irejecttheclaimthat Prince is Brainy on theoretical grounds, which I shall lay out in laterchapters.Aswe shall see, defenders of thePsychologicalApproachmust alsoacceptsurprisingclaimsfortheoreticalreasons.SoIwon’tsimplydismisstheTransplantIntuition.Instead,Ishallarguethatit

isbasedonprinciplesthatmayverywellbetrue,butwhichmyownaccount,theBiological Approach, can accommodate. We have the Transplant Intuition, Isuggest, in large part because we think that Prince ought to be prudentiallyconcerned about what happens to Brainy, and not about what happens toBrainless;orbecauseBrainyismorallyresponsibleforPrince’sactionsandnotforCobbler’s;orbecauseeveryonewouldrightlyfeelcompelledtotreatBrainyas if he were Prince; or some combination of these. That is, the TransplantIntuition isbasedonpracticalconcerns thatmaybeperfectlyvalidbut thatdonotnecessarilycoincidewithnumericalidentity.IshallpostponethesepointsuntilSectionIV.First,Ishalldiscussadifference

between my version of the Transplant Case and the one more commonlypresented in the literatureonpersonal identity.ThenIwant toaskwhether theconclusionof the transplantargument really follows from itspremise:whethertheclaimthatBrainyisPrince,notCobbler,entailsthePsychologicalApproach.Asweshallsee,theargumentfromtheTransplantIntuitiontoaviableaccountofouridentityfacesanumberofdifficulties.

II.Whole-BrainTransplants

WhydoItransplantonlythecerebrum,whenatransplantoftheentirebrainisafarmorecommonprocedure inphilosophical thoughtexperiments?Thereasonisthatthewhole-brain-transplantstorydoesnotclearlydistinguishbetweenthePsychological and Biological Approaches. The result of removing andtransplantingyourcerebrum,Ihaveargued,isalivinghumananimalwithoutacerebrum, in which your life-sustaining functions continue on, and a humanbeingwithyourcerebrumandyourpsychologywhoneverthelessdoesn’tseemto be the living animal that was once associatedwith you. Psychological andbiological continuity come apart, and that suits the cerebrum-transplant case

ideallyformypurposes.What happens when one’s entire brain, including the brainstem, is

transplanted?Somehaveargued,onphysiologicalgrounds,thatthiswouldbetoparedownahumananimal toanakedbrainand thenmove it toanotherhead(vanInwagen1990b,172–181).Thethingthesurgeonsremovedfromyourheadwould not be a mere organ, like a heart or a liver, but instead a radicallymutilatedbut(forthetimebeingatleast)livinghumananimal.Atanyrate,thebiologyof thewhole-brain-transplantcase is importantlydifferent fromthatofthecerebrum-transplantcase.Removingyourentirebraindoesnotleavebehindaliving,empty-headedhumananimal,butratherempty-headed,lifelessremains—an empty-headed corpse.Removing an animal’s entire brain either kills theanimal or reduces it to a mere detached brain; it does not simply leave thatanimal without a certain organ.When your entire brain is removed, the vitalfunctionsgoingonintherestofyouimmediatelycease—-justastheywouldifyour entire head were removed. That is because the lower-brain organs thatdirectedthosefunctionsarenolongertheretogiveorders.The“controlcenter”ofone’sautonomicnervoussystemgoesalongwiththebraininthewhole-braintransplant. That iswhy some think that the entire human organismwould getpareddowntoanakedbraininthatcase.Ifthatisright,thenaccordingtotheBiologicalApproachyouwouldgoalong

with your whole brain if that organ were transplanted. So the “Whole-BrainTransplant Intuition”, as opposed to the “Cerebrum-Transplant Intuition”,maybe consistentwith theBiologicalApproach. Thus, Imight have presented theWhole-BrainTransplant Intuition as the central feature ofmost arguments forthe Psychological Approach, and then claimed that although that intuition iscorrect, it does not support the Psychological Approach any more than itsupports the Biological Approach. Nevertheless, the Whole-Brain TransplantIntuitionisrightforthewrongreason.Whydowefeelcompelledtothinkthatthepersonwhoendsupwithyourwholebrainafterthatorganistransplantedisyou? It is most commonly assumed that this is because that person ispsychologicallycontinuouswithyou.Sheisyoubecauseshecanrememberyourlife, has your personality, and so forth; and perhaps also because she hasinheritedthosepsychologicalfeaturesbyvirtueofinheritingfromyoutheorganthatwasmostdirectly responsible for them:yourbrain, and inparticularyourcerebrum.Wearenotinclinedtothinkthatsheisyoubecausesheisbiologicallycontinuouswith you. Ifwewere,we should think that the result of removingyourcerebrumalonewouldbeyouwithoutacerebrum;butthatdoesnotseemtobeacommonintuition.Hence,theWhole-BrainTransplantIntuitionasitisusuallyunderstoodhasthe

same source as the Cerebrum-Transplant Intuition. If it seems to us that onewouldgoalongwithone’swholebrain,thenforthesamereasonitseemstousthat one would go along with one’s cerebrum. Anyone who has the Whole-Brain-TransplantIntuitionwillhavetheCerebrum-TransplantIntuitionaswell,and to the same degree. If so, then it is fair forme to present theCerebrum-TransplantIntuitionasthemainsourceofsupportfortheBiologicalApproach.However, if many philosophers find the Cerebrum-Transplant Intuition lesscompelling than theWhole-Brain-Transplant Intuition, then theyhave erred intaking the latterasstrongsupport for thePsychologicalApproach.Eitherway,strong arguments for the Psychological Approach must be based on theCerebrum-TransplantIntuition,nottheWhole-BrainTransplantIntuition.

III.FissionandHemispherectomy

WhatisitaboutthewayBrainyrelatestoPrinceinourstorythatmakesusthinkthathe isPrince? It seems tobe the fact thatBrainyhasPrince’spsychology:becauseBrainycan rememberPrince’s life andactonPrince’s intentions, andhas inheritedPrince’sconvictionsandquirks,hisability tospeakEnglish, ridehorses, solve crosswordpuzzles, and all the rest of his psychological features.For good measure, those features are continually present throughout theoperation, realized in the organ that is transferred from Prince’s skull toCobbler’s.ButmostfriendsofthePsychologicalApproachconcedethatthisisnotenoughtomakePrinceandBrainyone.Imaginethatthesurgeonswhoremoveyourcerebrumdonotsimplytransplant

itwhole,butinsteadseparateitintoitstwohemispheresbycuttingthebandsofnerves that hold them together (the cerebral commissures), and then implanteach half into its own empty skull. Two different people end up with yourmemories,character,andothermentalfeatures:callthem“Lefty”and“Righty”.TheTransplantIntuition,orsomethingverylikeit,suggeststhatyouareLefty.Italso suggests that you are Righty.Whatever it is that inclines us to say thatPrinceisBrainyalsoinclinesustosaythatyouareLefty,andinclinesustosaythatyouareRighty.IfwefeeltheIntuitionlessstronglyinthiscasethanintheprevious one, that is because the fact that there are two offshoots somehowmakesusuncomfortable.Itstillseemsthatyoumustsomehowhavesurvivedtheoperation;butthereissomethingfishyaboutadoubletransplant.We are right to be suspicious about the “fission” case, for the Transplant

Intuitionleadsusastrayhere.Ifyousurvive,youmustbeeitherLeftyorRightyor some third thing. Suppose you areLefty.Then, sinceLefty andRighty are

twopeople(LeftyisinoneroomandRightyisinanother),youarenotRighty.ButtheTransplantIntuitiontoldusthatyouareRighty,sinceRightyhashalfofyour brain and is psychologically continuous with you. So the TransplantIntuition cannot quite be right. Nor does it seem that there could be anyexplanationforthefactthatyouareLeftyratherthanRighty,foreachisrelatedtoyouinjustthesameway.IfyouwereLeftyandnotRighty,thatwouldbea“brute”,unexplainablefact.Therewouldbenowayofknowingwhichoneyouwere, for each rivalwould be equally convinced that hewas you.This seemsfundamentally opposed to the Transplant Intuition, and to the PsychologicalApproachitself.“ThereistooareasonwhyyoumightbeLeftyratherthanRighty(orRighty

rather than Lefty)”, someonemight argue. “The two cerebral hemispheres arenot exactly alike, but are associated with different cognitive capacities. Forexample, verbal capacities are associated mainly with the left hemisphere,whereastheabilitytorecognizeshapesandpatterns,suchasfaces,isassociatedwiththerighthemisphere.Ifoneofyourhemispheresisdamagedordestroyed,thewayyouareaffectedwilldependonwhichhemisphereitwas.SowhilebothLeftyandRightymaybepsychologicallycontinuouswithyou tosomeextent,the kind and degree of continuity might be quite different. Couldn’t thatdifference make it the case that you were Lefty rather than Righty, or viceversa?”Butthe“divisionoflabor”betweenthecerebralhemispheresisanaccidental

featureof the fissioncase.Thedivision is lessmarked in somepeople than inothers, and there might be people whose hemispheres are completelyequipollent. In any case, this proposal would still contradict the TransplantIntuition,forthereisstillsomeonewhoispsychologicallycontinuouswithyou,andyetnotyoubutsomeoneelseinstead.Ifyoucouldnotbeoneof theoffshoots rather than theother,mightyoube

both? Well, suppose Lefty shaves his head after the operation and Rightydoesn’t.IfyouareLefty,yourheadwillbeshavedthen.IfyouareRighty,yourheadwon’tbeshaved.IfyouareLeftyandyouareRighty,thenitwillbebothtrueandfalsethatyourheadisshaved.Soyoucouldn’tbeboth.Some philosophers claim that both Lefty and Righty existed before the

operation, but were always numerically different (Perry 1972; Lewis 1976a;Noonan1989, 153 f.;Robinson1985).Therewere always “twoof you”, as itwere.Althoughtheremaybegoodtheoreticalreasonsinsupportofthisview,itunderminessomeofourmostfundamentalbeliefsaboutourselves.Itentailsthatthereisnotreallyanysuchpersonasyou,ifthereisfissioninyourfuture.ThereareonlyLeftyandRighty,twopeoplewhoareexactlyalikeineverywayuntil

thesurgeonsseparate them.1ButneitherLeftynorRightyisyou.SupposethataftertheoperationLeftywillvisitBotswanaandRightywillstayhome.Ifyouwere Lefty, then if you said, “I am going to visit Botswana”, youwould saysomethingtrue.Butyoucouldnotsayanythingtruebyutteringthosewords,fortheword‘I’ inyourmouthrefers toRightyaswellas toLefty,andwhile it istrueofLeftythathewillvisitBotswana,thatisnottrueofRighty.Forthesamereason you could not beRighty.And since none of us can be certain thatweshall never be divided in this way at some time in the future, for all anyoneknowsthereisnotreallyanysuchpersonashimself.Itmayseemobviousthatthere is suchapersonas I—that theword ‘I’ inmymouth refers to someonething—but on this proposal it would not be obvious at all. That is hard tobelieve.2YoumayinsistthatwhenLeftyandRightysimultaneouslyutterthesentence

“I shall visit Botswana” before the operation, there are in fact two differentspeechacts.Theword‘I’asLeftyuttersitdoesnotreferambiguouslytoLeftyand toRighty,but refersonly tohimself,Lefty. In that caseLefty’s statementwould be true.Righty’s statementwould of course be false. Lefty andRightywould face an epistemological problem: there would be no way for either ofthemtoknowwhichpersonheis,LeftyorRighty.Moreover,althoughitwouldbecorrectforyoutosay,“ThereissuchapersonasI”,itwouldnotbecorrectfor the rest of us to say that there is such a person as you, forwe should beunabletopickoutanyonepersonuniquelybysaying‘you’.Othershave suggested thatyoumight survive fissionas a spatially scattered

object,withLeftyandRightyasparts(Parfit1984,256;Unger1990,264).Youdon’t become two things.You are not Lefty, and you are notRighty.Rather,Lefty andRightymakeup a third thing,whichweighswhatLefty andRightyweightogether.Thatthird,largerthingisyou:youcometobemadeupoftwospatially separated parts, Lefty and Righty. You have been cut in two, so tospeak, but you still exist, with part of you in Botswana and part of youelsewhere.So ifLeftyshaveshisheadandRightydoesn’t,youwill simplybepartly skin-headed and partly not skin-headed; one of your two headswill beshaved.Thiswouldbeastrangesortofsurvivalindeed.Ifweknowanythingatallabouthowtocountpeople,weknowthataftertheoperationthereareexactlytwopeople,notone,andnotthree.Soyousurvive,onthisproposal,butnotasaperson.Insteadyouareathingmadeupoftwopeople.ButitseemedtobepartoftheTransplantIntuitionthatyousurvivefissionasaperson,notassomethingelse.AndaccordingtothePsychologicalApproachyoucouldnevercometobesomethingotherthanaperson.

Thestandardviewabout thefissioncaseis thatyoudon’tsurviveatall:youare neitherLefty norRighty nor anything else after the operation. The reasonyoudon’tsurviveissimplythattwopeoplearepsychologicallycontinuouswithyou, and not one. If there were only one “candidate”—if only one of yourcerebralhemispheresweretransplantedandtheotherdestroyed,forexample—youwouldsurvive.Whatpreventsyoufromsurvivingastheoffshootwithyourlefthemisphereistheexistenceofanoffshootwithyourrighthemisphere.Soifyouknowthathalfofyourcerebrumisgoingtobetransplanted,andyouwanttosurvive, you ought tomake sure that the other hemisphere is destroyed ratherthantransplanted.Theclaimthatyousurviveonlyifyoustandinsomerelation,such as psychological continuity, to exactly one future or past being issometimes called the “non-branching” or Uniqueness Requirement. It is astartlingclaim,andcertainlynotwhattheTransplantIntuitionledustoexpect.Ifsomefuturepersoncouldhavebothyourpsychologyandabrainthatusedtobeyours(orenoughofabrain tobeaperson)withoutbeingyou,weought towonder whether Brainy is really Prince in the Transplant Case. But no oneaccepts the Uniqueness Requirement because it sounds right. The TransplantIntuitionhasledusintoaquandary,andtheUniquenessRequirementisseenasthebestwayout:itisatheoreticalnecessity.This is more than just a minor technical problem for theories of personal

identity based on theTransplant Intuition, for there are fission cases inwhichoneclearlydoessurvive.Surgeonssometimesremoveacerebralhemisphere—occasionallyeventhe“dominant”hemisphere—fromahumanbeingasadrastictreatment for an otherwise-inoperable tumor. The resulting person may beseverelydebilitated,butcanoftenregainmanylostabilitieslateron.Thereisnoquestion among those who actually confront these cases—doctors, patients,family members, friends—that the person who leaves the hospital with onehemisphereisthepersonwhocheckedinwithtwo.Butifonecouldnotsurvivein the standard “fission” case, it is hard to see how one could survivehemispherectomyeither.When surgeons remove a cerebral hemisphere, they usually throw it into a

bucket labelled“medicalwaste”,or (more likely)send it first to thepathologylabforexamination.Butifcerebraltransplantsarepossible,theymightimplantthat hemisphere into another head, and so produce someone psychologicallycontinuouswith theoriginalpatient.Weshould thenhave twopeople,eachofwhomhadhalfoftheoriginalpatient’scerebrum,alongwithhismemoriesandother psychological features. According to the Uniqueness Requirement, theexistence of two such “competitors” prevents the original person from beingidenticalwitheitherone,foryoucansurviveonlyasthepersonwhoisuniquely

psychologicallycontinuouswithyou.Ifso,hemispherectomywouldkillyou(orat any rate end your existence) if the removed hemisphere were successfullytransplanted.I take this to be obviously false.We can hardly deny that one can survive

hemispherectomy without transplant. Otherwise many surgeons who thoughttheyweresavingtheirpatients’liveswereinfactkillingthem,andmanypeoplewho thought they were congratulating a loved one on a successful surgicalprocedurewereinfactconfrontingsomeonetheyhadnevermetbefore.Idoubtthatanyphilosophicalargumentcouldconvinceusofthat.Simplyremovingonecerebralhemispherefromyourskull(permanently)isnotenoughtokillyou.Butthen how could the surgeons kill you by doing something with that detachedorgan in another room,where onewould think it could not possibly have anyeffect on you? Imaginewaking up after your hemispherectomy operation anddiscoveringthatthedoctorshadkeptyourdetachedcerebralhemisphereviable,andarethinkingaboutatransplant.Yourlawyeristryingtotalkthemoutofiton the grounds that if the transplant “takes”, itwould kill you.Believing thatsomeonecanendyourexistencebytransplantinganorganthatusedtobeyoursisasabsurdasbelievingthatsomeonecankillyoubydrawingapictureofyouandtearingitup.ButIhavenotbeenquitefair.Infact,thestandardviewaboutfissionsuggests

thatonecouldnotsurviveevenordinaryhemispherectomy,withouttransplant—anoperationthatisroutinelyperformedinhospitalsaroundtheworldunderthename of treatment. Recall for a moment the “ordinary” transplant case. Thesurgeonsremovemycerebrumfrommyskull.Itsitsthereasanaked,detachedorganforafewminutesuntil itgetshookedupwith thebloodvessels,nerves,andotherconnectingtissuesofitsnewhome.IfIsurviveastherecipientofthatorgan,thenforawhileIamnothingmorethanadetachedcerebrum.Allofmyotherparts—myarmsandlegs,earsandeyes,andsoforth—havebeencutaway,andtheneworgansthatwillreplacetheoldoneshavenotyetbeenattachedtome.Now,whatwouldhappenifmycerebrumwereremovedfrommyheadbutnever transplanted? Suppose it gets misplaced in the nervous bustle of theoperatingroom,andbythetimeit isfoundagain,somanyofitsneuronshavedied from lackofoxygen that it isno longer suitable for transplant. If I couldsurviveasuccessfultransplant,itseemsthatheretooImustsurviveforawhileasanakedcerebrum.In theonecaseIbecomeadetachedcerebrumuntilnewpartsaregraftedontome; in theotherIbecomeadetachedcerebrumuntilmydeath,whichpresumablytakesplacewhenmybraincellsarenolongercapableof supporting mental activity. If I survive as a detached cerebrum during themiddlepartofasuccessfultransplantoperation,thiscannotbebecauseofwhat

happens later; it cannot be because the transplant is ultimately successful. Asuccessful transplant cannot bring it about retroactively that I existed as adetachedorgan.IfIcansurvivebeingremovedfrommyownhead,thiscanonlybebecausemydetachedcerebrum, then, still realizesmymental capacities,orcontainsmymemories,orthelike(Unger1990,259f.).If this is right, then for a while there are two people psychologically

continuouswithmeinanordinaryhemispherectomy.Thesurgeonsopenupmyskullandcutawayoneofmycerebralhemispheres.Thatorgangetsputaside.But itcouldbe transplanted toproducea thinking,consciousbeing.Sofor thefew minutes during which it is “viable”, that organ is a person. If it is notconscious, it is at least capable of becoming conscious: it would becomeconscious if it were attached to the proper life-support system (a humanorganismwithanemptyskull, forexample).Thus, ifmysurvival requires thattherebeexactlyonepersonwithmymemoriesandotherpsychologicalfeatures,astheordinaryfissioncaseseemstosuggest,thenIcouldnotsurviveordinaryhemispherectomy. I might survive if half of my cerebrum were destroyedwithoutbeingremoved;butIcouldnotsurviveifthatorganwerefirstremovedandthendestroyed.Nodoubttheproblemcouldbesolved.Thereisprobablysomeprinciplethatis

notwhollyimplausible,andwhichpreventsonefromsurvivingintheordinaryfission case while allowing one to survive hemispherectomy (even if theremovedhemisphereistransplanted).Wemightappealtothefactthatoneofthetwooffshootshasmoreofyourparts than theotherhas:whereasoneoffshoothasonlyasinglecerebralhemispherefromyou,theotherhasyourbody—allofyoubutforthatonehemisphere—aswell.In“asymmetrical”fissioncases,onemightargue,thatextradegreeofphysicalcontinuity“breaksthetie”,asitwere,andmakesitthecasethatoneoftheoffshootsbutnottheotherisyou.Nowitisnot immediately clear how this claim could be generalized—how one couldwrite a general criterion of personal identity that incorporates this suggestion.But it couldprobablybedone (see, e.g.,Nozick1981, chap.1).Alternatively,onemightargue that thisconsequence, thathemispherectomywouldendone’sexistence, isnotasrepellentas itsounds, forperishing in thiswaylacksalloftheusualpracticalsignificanceofdeath(moreon this in thenextsection).Mypoint is not that the hemispherectomy paradox is insoluble, but only that it ishardtoderiveacoherentviewofpersonalidentityfromtheTransplantIntuition.Compellingas theTransplant Intuitionmaybe, itdoesnot leadbysimpleandelegantargumentstoanacceptablegeneralprincipleaboutpersistence.

IV.PrudentialConcern

So the Transplant Intuition is no royal road to a plausible theory of personalidentity,butleadsinsteadtotanglesofdifficulties.Forallthat,though,itmaybetherightplacetostart;itmayleadusbyalong,tortuouspathtothetruth.IwanttoargueinsteadthattheTransplantIntuitiondoesnotclearlysupportanyversionof the Psychological Approach, but is based on principles that are consistentwiththeBiologicalApproachaswell.WhattheseprinciplesmightbewillcomeoutwhenweconsidersomeotherargumentsforthePsychologicalApproach.Somephilosophershavearguedfrombrain-transplantstorieslikethis:

You have been diagnosed with cancer in an advanced state, and you havenothing to look forward to but a few months of intense, worsening painfollowed by certain death. Nothing, that is, until a brilliant young surgeonofferstotransplantyourcerebrum,whichisstillfreeofcancer,intotheheadof an accident victim whose own cerebrum is damaged beyond repair. Theoperationisverysafe,sheassuresyou,andinalllikelihoodtheresultwillbesomeonewhosearms,legs,face,andotherpartsaredifferentfromyours,butwhohasyourcerebrumand,mostimportantly,yourmemories,character,andothermentalfeatures.Therestofyou,abrainlessbeingthatcanstillbreathe,digest,anddowhateverahumanbeingcandowithoutbeingconscious,willbecome thepropertyof the localmedical school, andwill likelybeused forexperiments.What would you do? If you are like most people, you would accept the

transplantoffer.Andnotsimplytofurtherthecauseofmedicalscience,butforentirelyselfish reasons.Youwouldanticipateand lookforward to the thingsthatyour“cerebraloffshoot” (callhimorher ‘Frankie’)wouldbeable todoafterhisrecovery,justasifitwereyouwhowouldrecover,leavethehospital,andgetonwithyourlife.IfyouexpectedFrankietobeunhappy,youwouldfear that unhappiness just as if it were your own. Even if you were acompletely selfishperson—the sort of personwhowouldnot lift a finger tosave his ownmother fromunspeakable suffering—youwould go to a lot oftrouble now to ensure that Frankie is treatedwell—asmuch trouble as youwouldtaketoensureyourownwell-being.YouwouldhavethesamespecialconcernforFrankiethatyouhaveforyourself.Ontheotherhand,itwouldbeofnoconcerntoyouwhatthesurgeonsdidwithyourbrainlessremains,aliveor not. Or at any rate this would be of no more concern to you than whathappens to your corpse when you are dead. Ordinary prudence dictates aconcernforFrankie,andfornooneelse.Youwouldcareaboutwhathappens

toFrankiejustasintenselyandforjustthesamereasonsasyouordinarilycareaboutyourownfuture.Andyouwouldnothave that sortofconcern for thebrainlessbeingyouleavebehindtodieslowlyofcancer.Unlessthisattitudeissomehowmisguidedorirrational,itsuggeststhatyou

would survive the operation as Frankie. On the other hand, any theory thatdeniesthatyouwouldbeFrankieentailsthatitwouldbeamistaketoacceptthe transplant operation for selfish reasons. What benefit would a selfishpersonseeindonatinghiscerebrumtosomeoneelse?Ifyouthoughtyouweregoingtobecomeabrainlesshumanvegetable,orceasetoexistoutright,whyshould you care, if you are selfish,whether someone else enjoys the use ofyourcerebrum,orwhether suchaperson ishappyormiserable?Unlessyouthink you would be Frankie, your concern for him could only be like theconcern you would have for a friend or family member; it could not beprudentialconcern,andatrulyselfishpersonwouldnothaveit.ThereforeyouwouldsurvivethetransplantoperationasFrankie.3

Youmightobjectthatprudence,orselfishconcern,isbydefinitionconcernforoneself andnoone else. In that case, to assume thatyour concern forFrankiewould be selfish or prudential concern would be to assume at the outset thatFrankieisyou,whichisjustthepointatissue.ButtheclaimissimplythatyourconcernforFrankie’swell-beingwouldbejustlikeselfishorprudentialconcernineverywayexceptfortherequirementthatFrankiebeyou.Itwouldnotbeliketheconcernyouhaveforfriendsorfamilymembersoranyoneelse.YouwouldhavereasontocareaboutwhathappenedtoFrankieevenifyouwereotherwisecompletely selfish. To be safe, we could call it “quasi-prudence” or “quasi-selfish” concern, by analogy with the “quasi-memory” that figures in somestatementsofthePsychologicalApproach(seeChapter1,Note6).Now it is assumed in the argument that the prudential (or quasi-prudential)

concern that even utterly selfish people have, insofar as it is not based on amistake, isalwaysconcernforoneself,andneverforanyoneelse.Or, toput itdifferently, it is assumed that there are special reasons,or specialmotivations,forconcernaboutoneselfthatcouldneverbereasonsormotivationsforconcernabout anyoneelse, and thatyouwouldorought tobeconcerned forFrankie’swell-beingfor thosereasons. Itassumes that“quasi-prudence” isnothingotherthanordinaryprudence,strictlysocalled.Theargumentsupportstheclaimthatyou are Frankie insofar as the appropriateness of your concern for him isevidencethatheisyou.Your appropriate lack of selfish concern for your brainless offshoot, on the

otherhand,issupposedtoshowthatheisnotyou.(Ifthereisnosuchthingas

the well-being of a human animal without a cerebrum, imagine that a newcerebrumisimplantedintoyourbrainlessremains.)Theassumptionhereisthatrationality requires you always to be concerned about your own future in aspecialway;nothingcouldeverhappentoyouthatwouldmakeitinappropriatefor you to be prudentially concerned about yourself (or that would make itrationalforyounottobeprudentiallyconcernedaboutyourself).These assumptions are plausible. But a number of philosophers reject them

(e.g., Shoemaker 1970a, 284; Parfit 1971, 1984, 215; Perry 1976a; Whiting1986;Korsgaard1989;Martin1991).Iftheyareright,thePrudentialArgumentwouldshownothingaboutpersonalidentity.Wecouldnotderiveanyconclusionaboutwhichfuturebeingonewouldbefrompremisesaboutwhowouldbetheproperobjectofone’sprudentialconcern.Forontheirviewitcouldberationaltobeprudentiallyconcernedforsomeoneotherthanoneself;anditmightnotberational (or at least not rationally required), in some cases, to be prudentiallyconcerned forone’sownwell-being. It isonlyanaccident, logically speaking,that selfish people are always concerned about themselves and never aboutanyoneelse.I shall call the view that prudential concern doesn’t always follow strict

identitytheParfit-ShoemakerThesis,aftertwoofitsearliestadvocates.Onewaytoseetheattractionsofthisviewistorecallthefissionstory.Yourcerebrumisremoved from your head and cut down the middle, whereupon each half isimplantedintoanappropriateemptyskull.Twopeopleendupwithyourmentalfeatures, and they have them because each has a brain that used to be yours.Because one thing cannot be identicalwith two things,we saw, it seems thatneitheroffshootcanbeyou;youhavesimplyperished.Butperishingbyfissionisnotnearlyasbadasdyingintheusualway.Comparethefissioncasewithtwoothers.Inthe“one-sided”case,oneofyourcerebralhemispheresistransplantedand the other is destroyed. In the “no-sided” case, both hemispheres aredestroyed.Whichofthesetwovariantsismostlikethefissioncase?Thefissioncase is like the no-sided case insofar as both of them end your existence.Practicallyspeaking,though,fissionismoreakintotheone-sidedcase.Mostofuswantverybadlynot tohavebothcerebralhemispheresdestroyed.But thereseems to be little reason to prefer having just one of one’s hemispherestransplanted and the other destroyed to having both hemispheres transplanted,eventhough(wearesupposing)thatisthedifferencebetweensurvivingandnotsurviving.Ifanything,havingbothhemispherestransplantedseemspreferabletohaving

only one transplanted and the other destroyed. If we ignore the actual side-effectsofhavingtogetbywithjustonehemisphere,wemayfindfissioneven

betterthanordinarysurvivalwithoutanysurgeryatall:ifyoufelttornbetweentwo attractive but incompatible pursuits—between an academic career, forexample, anddevotingyour life tomountainclimbing—youcannowdoboth.Well,youcan’tdoboth;butsomeonewhoissuitedtocarryoutyourplansandrealizeyouraspirationscandoeach.Itshouldn’tmatterwhethersuchapersonisreallyyou,Parfitargues,as longasheispsychologicallycontinuouswithyou.Each offshoot will take himself to be realizing your long-term goal, for hisactionswillbetheresultofyourplansandwishes.Butforhisknowledgeoftheotheroffshoot,eachwillthinkthatheisyou,anditwillbeforhimjustasifhewere.Notonlycanyourfissionoffshootscarryoutyourplansanddothethingsyou

always wanted to do, according to Parfit and Shoemaker; you will also lookforwardtotheirpleasuresandfeartheirpains,oratleasthavereasontodoso,injustthewaythatyouanticipateyourownpleasuresandpains.Youarewillingtosacrifice a great deal now to ensure their well-being later on. And you arewillingtodothisforthesamereasonsthatjustifysacrificingnowforyourownfuture welfare. Your affective attitude towards your fission upshots is nodifferent (or at least not importantly different) from your affective attitudetowards yourself. And not because you falsely believe that those people areidenticalwithyou.Instead,theyclaimyourconcernbecausetheyarerelatedtoyou in a way that does not entail identity. In the same way, your ordinaryrational concern foryourself in the future is not explainedby the fact that theperson in question is you.You ought to be concerned for yourwelfare in thefutureonlybecause(andonlyif)youwillthenstandinsomerelationotherthanidentity to yourself as you are now: according to Parfit, because you are thenpsychologically continuous with yourself as you are now. But someone otherthanyourselfmightberelatedtoyouinthisway,asthefissioncaseshows.Hence, it may sometimes be rational to care selfishly about somebody one

knows to be numerically different from oneself. If so, the “ordinary” cerebraltransplant might be another such case. Frankie, the person who ends up withyourcerebrum,haswhatittakes,accordingtoParfit,todeserveyourprudentialconcern.Thisissowhetherornotheisyou.Sothesortofconcernyouwouldhave,or rationallyought tohave, forFrankie’swelfaredoesnot at all suggestthatFrankiewouldbeyou;yourattitudetowardshimwouldbethesameevenifhewerenotyou.TheParfit-ShoemakerThesisalsotellsusthatrationalitydoesnot always require prudential concern for oneself. In that case your lack ofconcern about what happens to your brainless offshoot does not support theclaimthatthatanimalisnotyou.Youmayberightnottocarewhathappenstothatbrainlessanimalevenifhewereyou,andyouknewthathewas.Sothefact

thatyouhavereasontobeprudentiallyconcernedforFrankieandnoreasontobe concerned for your brainless offshoot is entirely consistent with theBiological Approach, which says that you are not Frankie but the brainlesshumanvegetable.Thus,itisnotsoclearthattheTransplantIntuitionsupportsthePsychological

Approach.AtleastoneofthereasonswhyweareinclinedtothinkthatBrainy(themanwhoendsupwithPrince’scerebrum)isPrinceseemstobethatPrinceoughttobeprudentiallyconcernedforBrainy,andthatwethinkthatthissortofconcernisalwaysconcernforoneself.Webelievethatonesurvivesifandonlyifone’smentalfeaturesarepreservedbecausethatiswhatittakesforsomeonetobeworthyofourprudentialconcern,andbecauseitisnaturaltosupposethatprudentialconcernalwayscoincideswithidentity.Butifwewerewrongtothinkthatrationalprudentialconcernalwaysimpliesidentity,itoughtnottosurpriseusmuch if Princewere notBrainy, butBrainless, for itwould still be just asappropriate for Prince to feel prudential concern for Brainy, and just asappropriateforhimnottohavesuchconcernforBrainless.4Andweoughtn’ttobesurprisedifCobblersurvivedtheoperationasBrainy,andsimplygotanewcerebrum.Whilewemight ordinarily think that in such a caseCobblerwouldlook forward to having a completely new and different mind, Parfit andShoemakerarguethatwecannotmakethisassumption.Cobblermaynotfeeltheleast concern forBrainy’swelfare after the operation, even knowing fullwellthathe isBrainy.Soonceweadmit thatone’sprudentialconcernneednotbeconcern for oneself, it ought to come as no great surprise if the BiologicalApproachistrue.Andifprudentialconcernisdivorcedfromstrictidentity,otherpracticalconcerns,suchasmoralresponsibility,maynotcoincidewithidentityeither,makingtheBiologicalApproachevenlesssurprising(moreonthislater).So if theParfit-ShoemakerThesiswere true, theBiologicalApproachwould

depart less radically from traditional thinking about personal identity than isordinarilysupposed.On the other hand, theremay indeed be a special kind of concern that it is

rationalformetohaveformyselfandnooneelse.PerhapsthetruthbehindtheParfit-ShoemakerThesisissomethinglikethis.Thereareplentyofreasons,evenreasons that an utterly selfish person might have, for wanting there to besomeoneinthefuturewhoispsychologicallycontinuouswithone,evenifthatperson is not strictly oneself but someone else. If I had such a “Parfitiansuccessor”,hewouldbeinapositiontocarryoutmyprojects,defendmyvalues,fulfilmy obligations, and care for those I love after I am gone.Hewould beeagertotakeupmylife’sworkwhereIleftoff,andhewouldbeabletodoitaswell as I could. That could be very gratifying to me even if I were entirely

selfish.HavingaParfitiansuccessorwouldbelikehavingasonordaughterturnoutjustlikeoneself,withallofone’sprejudicesandideals;andthatisthedreamofmanyaselfishparent.SodyingandbeingreplacedbyaParfitiansuccessorhasmanyadvantagesoversimplydying.Therearemanyreasonstopreferittosurvival inapersistentvegetativestate.Onemayeven find thisprospectmoreattractive than the prospect of living a long and happy life after all of one’smental contents have been permanently erased. (Having one’s cerebrumtransplantedasa“treatment”forlungcancermightnotbeasbadashavingone’scerebrumreplacedwithanewoneasa“treatment”forbraincancer,evenifonewould survive only in the latter case.) If so, Parfit may be right to say thatundergoingfission,orbeingdestroyedandreplacedbyaduplicate,is“aboutasgoodasordinarysurvival”(1984,201).But these are not prudential (or quasi-prudential) concerns. Under some

circumstances we might prefer a vicarious future existence by means of aParfitiansuccessortosurvivingourselves.Still,theremaybenoreasontoregardmy successor’s pains and pleasures in the special way that I regard my ownpainsandpleasures.MyconcernformyParfitiansuccessormaybemorelikethesortofconcernIshouldhaveformysonordaughterthanliketheconcernIhaveformyself.However,IshallnotargueagainsttheParfit-ShoemakerThesis.Letusmove

ontoadifferentsortofargumentforthePsychologicalApproach.

V.MoralResponsibility

It is sometimes claimed that the Psychological Approach follows fromconsiderationsaboutmoral responsibility.AsLockepointedout, ‘person’ is“aforensic term, appropriating actions and their merit.”5 We might take this tomean only that a person is by definition amoral agent, something capable ofansweringforitsactions.(Perhapstoaskwhetheragodoracomputeroraspacealien could be a person is just to askwhether such a being could be amoralagent.)ButthatclaimiscompatiblewithanyplausiblerivaltothePsychologicalApproach. Locke and his followers seem to have had something stronger inmind,namelythatthenotionsofpersonalidentity,psychologicalcontinuity,andmoral responsibility are internally related. Purely biological continuity, on theotherhand,isnotrelatedtomoralresponsibilityinanythingmorethanapurelycontingentway:mymerelybeing thesameanimalas someone isno reason toholdmeaccountableforhisactions,ortoholdhimaccountableformine.Wemightarguelikethis:Who,ifanyone,isaccountableforthethingsPrince

didbeforetheoperation?SupposethatPrince,onhiswaytotheoperatingroom,riskedhis life to savea littlegirl fromdrowning.Whomshould thegirl thankwhenshehasrecovered?ItseemsthatsheshouldthankBrainy,themanwhohasPrince’scerebrumandtherestofCobbler.IfBrainyisresponsibleforanythingthatwasdonebefore theoperation,he is responsible for the thingsPrincedid.We certainly cannot hold him accountable for Cobbler’s actions. Brainyremembers(orat least“quasi-remembers”)doing the thingsPrincedid,andhehas Prince’s character. He has Prince’s sins on his conscience. Brainy feelsresponsible for Prince’s actions. But we couldn’t very well hold Brainyaccountableforthingsheneverdid.Notbecausenooneiseveraccountableforanyoneelse’sactions.Parentsareresponsibleforthethingstheiryoungchildrendo;militaryofficersareaccountable, tosomedegreeatleast,fortheactionsofsubordinates under their command.But in cases like these there is anunequalrelationship:IcanbemadeaccountableforyouractionsonlyifIamyourlegalguardian,orifyouareactingonmyorders,orthelike.NothinglikethisappliestoPrinceandBrainy.Theyareequals,andneitherisaccountabletoanyoneelse.BrainycanbeheldtoaccountforPrince’sactionsonlyifheisPrince.Therefore,BrainyisPrince,supportingthePsychologicalApproach.On the other hand (the argument goes), if Brainy were Cobbler, as the

Biological Approach tells us—if Cobbler survived the operation with a newcerebrumandanewmind—thenBrainyought tobe responsible forCobbler’sactions.Ofcourse,oneisn’talwaysresponsibleforeverythingonedoes.Theremaybeexcuses.ImaynotberesponsibleforsomethingIdidatatimewhenIwas not morally competent—for example, when I was unable to grasp theconsequencesofwhatIwasdoing,orwhenIwasinsaneorhypnotizedorunderthe influence of a powerful mind-altering drug. And even if I was morallycompetent when I did something, I may not be responsible for it if I am notmorallycompetentnow.Butnoneof theseexcusesapplyin thecaseofBrainyandCobbler.Cobbler,

we are supposing, was perfectly normal in every way up to the time of theoperation, and we may assume that Brainy, despite his resemblance toFrankenstein’smonster,isacompetentmoralagentaswell.ThereisthefactthatBrainycannotrememberthethingswearesupposinghedid(underthenameofCobbler)beforetheoperation.Butifitreallywashewhodidthosethings,thisfactwouldnotexcusehimofresponsibilityforthem.Oneisnotexoneratedforone’s crimes simply because one has forgotten them. If onewere accountableonly for what one could remember doing, the criminals of the twenty-fifthcenturywould be able to escape responsibility for their crimes by having therelevantmemoriesselectivelyerasedbyoneofthemarvellousgadgetsthatwill

no doubt be invented by then. So there is no reason to excuse Brainy fromresponsibilityforthethingsCobblerdidbeforetheoperation,giventhatBrainyis Cobbler. But obviously Brainy is no more responsible for those actions ofCobbler’sthanyouareresponsibleforthethingsIdidlastweek.Therefore(theargument concludes),Brainy couldnot beCobbler.Onemight goon to arguethat thereasonwhyBrainy isnotCobbler isbecausehe isnotpsychologicallycontinuous with Cobbler as he was before the transplant, supporting thePsychological Approach. But evenwithoutmaking that further claim, we cantaketheargumenttohaverefutedtheBiologicalApproach,accordingtowhichBrainyisCobbler.Now if theParfit-ShoemakerThesis is correct, theseargumentsoughtnot to

persuade us. It says that Brainy is the proper object of Prince’s prudentialconcern,whetherBrainyandPrinceareonepersonortwo.Ifso,itseemsthatweought to hold Brainy responsible for Prince’s actions, even if Brainy is notPrince. That thesis also suggests that it may be rational for Cobbler to beunconcerned, before the operation, about what happens to Brainy afterwards,evenifhebelievesthathewillbeBrainy.InthatcaseitwouldseemamistaketoholdBrainyaccountable,aftertheoperation,forthethingsCobblerdidbeforeheentered the hospital, even ifBrainy andCobbler are one.This is not a formalconsequenceoftheParfit-ShoemakerThesis.However,onecouldatleastmakea plausible case for supposing that anyone who is not a fit subject of one’sprudential concern could not be accountable for one’s actions. But howpersuasivearetheargumentsfrommoralaccountabilityiftheParfit-ShoemakerThesisisfalse?Thefirstlineofargumenthadtwopremises.First,Brainyisresponsibleforthe

things Prince did. Second, one can be held responsible only for one’s ownactions,andneverforsomeoneelse’s(exceptinspecialcaseslikethatofparentsand their children,whicharenot relevanthere).Takenby itself, eachof theseclaims is plausible. But their conjunction is problematic. Why is Brainyresponsible forPrince’s actions?Well,Brainy can apparently remember doingthosethings,andhehasthecharacterthatPrincehadwhenPrincedidthem;hefeels responsible for them. In short,Brainy is psychologically continuouswithPrince as hewaswhenhedid the things inquestion (saving the little girl, forexample). Itwould seem thatweholdBrainy accountable forPrince’s actionsbecauseweacceptacertaingeneralprincipleaboutwhoisaccountableforwhatactions: Someone is now responsible for an earlier action if he is nowpsychologically continuous with the agent as he was when he performed theaction (in the absence of the usual excuses). But this principle is inconsistentwiththeclaimthatoneisaccountableonlyforone’sownactions.

Suppose the operation fails and Prince dies, with his cerebrum, on theoperating table. Afterwards, however, some hospital technicians manage toassemble a perfect duplicate of Prince as hewas shortly before the operation,when an exhaustive series of measurements were taken, using yet anothermarvellousmachine.Theduplicatecanapparently rememberchecking into thehospital and entering the scanning machine, but not having his head shaved,meetingtheanaesthetist,orhavingtheneedleputintohisarm.TheduplicateisobviouslynotPrince.HedidnotevenbegintoexistuntilseveraldaysorweeksafterPrince’sdemise.(AtleastIhopethisisobvious.IftheduplicateisPrince,andPrinceisneveranythingotherthanamaterialobject,thenPrinceceasedtoexist for a while and then came into existence once again, this timemade ofcompletelynewatoms. IfPrincecancome intobeingoncemoreevenafterhehasdiedandhisremainshavebeenburnt,thenpresumablyanymaterialobjectthatwasoncedestroyedcan,inprinciple,bemadetoexistoncemore.Thisdoesnot seem to be a coherent position.) Nevertheless, it does not seem whollyinappropriate to hold the duplicate accountable for Prince’s actions. Theduplicate,andnooneelse,willownuptoPrince’sactionsandfeelresponsiblefor them. In any case, ifBrainy is accountable forPrince’s acts because he ispsychologically continuous with Prince, then Prince’s duplicate will beaccountableforPrince’sactions,andtheargument’ssecondpremiseisfalse:onecanberesponsibleforsomeoneelse’sactions.Todefendtheargument,onewouldhavetofindaplausiblereasonforholding

BrainyresponsibleforPrince’sactionsinthetransplantcasethatwasnotalsoareason for holding Prince’s duplicate accountable for those actions in theduplicationstory.ThemostattractivereasonIcanthinkofforsayingthisisthatBrainy is accountable for Prince’s actions because he is Prince, whereas theduplicateisnotaccountableforthoseactionsbecauseheisnotPrince.6Butanyappealtothatclaimwouldbetoassumethepointatissue.Althoughitmaybetrue that Brainy is accountable for Prince’s actions because he is Prince, thistruthwouldbeofnouseinarguingfortheclaimthatBrainyisPrince.Let’sturnnowtothesecondargument.Wemightsummarizeitlikethis:

1.Someoneisnowresponsibleforsomethinghedidearlierifandonlyifheismorallycompetentnowandhewasmorallycompetentatthatearliertime.

2. Brainy is morally competent now and Cobbler was morally competentwhenhedidtheactionsinquestion.

3. Thus, if Brainy were Cobbler, he would now be responsible for thingsCobblerdidbeforetheoperation.

4. But Brainy is not now responsible for anything Cobbler did before the

operation.5.ThereforeBrainyisnotCobbler.

That Brainy and Cobbler are morally competent throughout was part of thestory,andIamwilling toconcede thatBrainy isnot responsible forCobbler’spastactions.Iamgoingtoarguethatthefirstpremiseoftheargument,thoughplausible,isnotcompelling,andIshallofferinitsplaceaweakerprinciplethatseemstomeatleastasattractive,butwhich,ifsubstitutedforthefirstpremise,wouldmaketheargumentinvalid.Try to imagine a counterexample to Premise 1: someone who is not now

responsibleforsomethinghedidearlier,even thoughhewasresponsiblefor itthenandheisgenerallymorallycompetentnow.Arethereanysuchcases?Wemight try something like this. At age forty-five, something goes wrong withMary’s brain and causes retrograde amnesia. Suddenly she cannot recallanythingthathappenedduringthefirstfortyyearsofherlife.Theearliestthingshecanrememberdoingiscelebratingherfortiethbirthday.Theselostmemoriesare notmerely inaccessible, but gonewithout a trace.As a result, she doesn’tremember cheating on her income taxes at age thirty-five. Nor does sherememberthinkinglongandhardaboutwhetheritwasjustifiedandherchancesof getting caught, or her final decision, brought on by pressing debts, to gothroughwithit.Andshehascompletelyforgottenallof theevents thatshapedher character and, as we say, “made her the person she was” then. Is Maryresponsible, now, for what she did ten years ago? If she is not responsible,Premise 1 is false and the argument collapses. If she is responsible (and I aminclinedtothinkthatsheis),weoughttoaskwhy.HowisMary’srelationtoheractions of ten years agodifferent fromBrainy’s relation to the thingsCobblerdid?Ithinktheansweristhat,althoughneitherMarynorBrainycanremembertheactions inquestion,Mary ispsychologicallycontinuouswithherselfasshewasthen,whereasBrainyisnotpsychologicallycontinuouswithCobblerashewas then. Although Mary doesn’t remember cheating on her taxes, sheremembersatimewhensherememberedit.Moreover,Mary’spresentcharacterand other mental features evolved in the usual way, more or less, from themental features she had ten years ago. Brainy, however, got all his mentalfeatures from Prince, not from Cobbler. That is whyMary is responsible forthingsshedoesnotrememberdoing,andwhyBrainyisnotresponsibleforwhatCobblerdid.Ifthisisright,wecanargueagainstPremise1onlybyfindingacaseinwhich

someone is no longer psychologically continuous with herself as she was atsome earlier time, for that is the only way, other than for reasons of moral

incompetence and the other “usual” excuses, that one can be absolved ofresponsibilityforsomethingonedid.Arethereanysuchcases?Well,IthinkthestoryofBrainy andCobbler is such a case:Brainy is not now responsible forwhathedidbeforetheoperation(whenhewasknownasCobbler),becauseheisnotnowpsychologicallycontinuouswithhimselfashewasthen.FriendsofthePsychologicalApproach,ofcourse,deny that this ispossible,becauseon theirview someone inCobbler’s position couldnot endup likeBrainy.Thedebateseemstohavereachedastalemate:wecannotdecidewhetherPremise1istrueuntil we know whether someone could survive complete psychologicaldiscontinuity—whethersomeonepersoncouldstartoutwithonecerebrumandend up with a different one, with completely different mental contents, forexample.Andthatisjustthepointatissue.Theargumentisinconclusive.There is one more point to make. The Biological Approach seems to be

incompatiblewithPremise1. (It is incompatiblewithPremise1unlesswecanholdBrainyaccountableforthethingsCobblerdidbeforetheoperation.)Ihaveargued that Premise 1 is exactly as plausible as the denial of the BiologicalApproach. But this is so only if the Biological Approach is compatible withsomeother acceptableprinciple aboutwho is accountable forwhichactions—somethingtoreplacePremise1.IfwecouldnotreplacePremise1withanotherequally plausible principle, thatwould be a reason to accept that premise andreject theBiologicalApproach.Fortunately,wehavealreadyseen that there issuchaprinciple:

1*.Someoneisnowresponsibleforsomethinghedidearlierifandonlyifheismorallycompetentnowandhewasmorallycompetentat thatearliertime,andheisnowpsychologicallycontinuouswithhimselfashewasthen.

1*explainswhyBrainyisnotresponsibleforthethingsCobblerdidbeforethetransplantoperation,evenifBrainyisCobbler.ButunliketheoriginalPremise1,1*doesnotsupportanyargumentagainsttheBiologicalApproach(oratleastnone that I can think of). If we put personal identity out of our minds for amoment, I thinkweshall find1*,asaprincipleaboutmoralaccountability,atleastasplausibleasPremise1.Ifso,theargumentbasedonPremise1neednotpersuadeusthatthePsychologicalApproachistrue.

VI.TheTreatmentArgument

Iturnnowtosomethingsimilartothemoralargument,butwhichisinterestingenough to deserve a separate discussion. Return once more to the Transplant

Case.Someonemightarguelikethis:

SupposePrince’smother—Queen—visits thehospitalafter theoperationandasks to see her son. To which of the twomen should the nurses take her?ShouldtheytakehertoseeBrainless,wholooksjustlikePrinceusedtolookbuthasnotraceofPrince’smentalfeatures?Shewouldn’tgetmuchoutofthatvisit.EvenifweimaginethatBrainlesshasbeengivenanewcerebrumsothatheisconsciousandabletoreceivevisitors,heisn’tgoingtorecognizeQueen,andhewilldenythatsheishismother.ItwouldbemoreappropriatetotakeQueentoseeBrainy.HeistheonewhothinksheisPrince,andwhocanrecallPrince’spast.HeistheonewhowillrecognizeQueenashismother.Infactitwould be difficult to convinceBrainy that hewas notPrince, or thatQueenwasnothismother.ItwouldbeunjusttobothpartiesifthehospitalofficialsdeniedQueentherighttovisitBrainyonthegroundsthatsheisnotrelatedtohim.(Ontheotherhand,wemightbeabletoimagineQueensaying,withasigh,

“BrainytalksandactslikePrince,buthe’snotthesonIbore.TakemebacktoBrainless!”Nodoubt itwouldallbequiteashock forher,and foreveryoneelse.ButafterawhileshewouldgetusedtoBrainy’sappearanceandcometoseehimasherson.)Now consider Prince’s wife, Princess. Is she married to Brainy, or to

Brainless(orisshenowawidow)?Ifshehasanythingtosayaboutthematter,shewill consider herselfmarried to Brainy, at least after she has recoveredfromthenovelty.ThesamegoesforPrince’sfriends.Brainy,obviously,isthemantheyknow,andthemanwhoknowsthem.PromisestheymadetoPrinceoughttobekepttoBrainy(whoelse?).EveryonewillfeelcompelledtotreatBrainyasifhewerePrince,andtheywillberighttodoso.Inthesameway,BrainyoughttobeconsideredtheownerofPrince’sproperty,tobegiventhecustodyofPrince’schildren,and togetPrince’shospitalbill. In short, thosepeoplewhoareactuallyinvolvedinthetransplantcasewillfinditimpossibleto doubt that Brainy is Prince. Their conviction is also morally andpragmatically justified: it is best for everyone, includingBrainy, if everyonebelievesthatBrainyisPrince.ThissupportstheclaimthatBrainyisPrince.On the other hand, if Cobbler, not Prince, were Brainy (as the Biological

Approachwouldhaveit),BrainywouldbemarriedtoCobbler’swife,andnotto Princess. For it would be Brainy, that is, Cobbler, withwhomCobbler’swife once exchanged hermarriage vows.But that is absurd, forBrainy andCobbler’swifearecompletestrangers.Worse,Brainythinksheismarriedtosomeone else; in fact he can remember in great detail years of marriage to

Princess. If all three—Brainy, Princess, and Cobbler’s wife—were broughttogether to sort thematterout, itwould soonbecomeclearwhoought tobeconsidered married to whom. And the same goes for Prince’s children andfriends,andforanyoneelsewhoknewhim.WecanmakethisespeciallyvividifweimaginethatPrinceandCobblerwereverydifferent,asinLocke’sstory.The Biological Approach would turn the Transplant Case into a grotesquecomedyoferrors.ThuswecanconcludethatBrainycouldnotbeCobbler.7

Iclaimthattheseargumentsareexactlyasconvincingasthemoralargumentsdiscussedintheprevioussection.Thefirststrandofargumentisfoundedontwopremises.First,everyonewouldtreatBrainyasPrince,andtheywouldberight,practically speaking, todo so.This is a complexmatter, but let us concede it.Second,wheneveritisnaturalandpragmaticallyjustifiedtotreatsomeoneasifhewereacertainperson,thenheisthatperson.Thisprincipleisjustasplausibleas the corresponding claim that one can be heldmorally accountable only forone’s own actions, and it is questionable for the same reasons. Suppose thatSmith is annihilated in his sleep by a malicious demon. An hour later abenevolent demon takes pity on Smith’s loved ones and creates a perfectduplicateofSmithashewasjustbeforehisdemise,whomhethensecretsintoSmith’s bed. The duplicate, of course, would not be Smith; but he would beconvinced that he was, and everyone, including Smith’s wife, children, andclosestfriends,wouldfeelcompelledtotreattheduplicateasifhewereSmith.And itwould be just as appropriate for them to do so as itwould be to treatBrainyasifhewerePrinceinthetransplantstory.Todefendtheargument,onewouldhave to find a plausible reason for treatingBrainy as if hewerePrincethatwas not also a reason for treating Smith’s duplicate as if hewere Smith,without making the moot assumption that Brainy is Prince. This task iscomparabletothatoffindingareasonforholdingBrainymorallyresponsibleforPrince’sactions that isnotalsoa reasonforholdingSmith’sduplicatemorallyresponsibleforSmith’sactions.8Inthesecondstrandoftheargumentitwasassumedthatnoonewouldbeable

totreatBrainyasifhewereCobbler,andnooneoughtto.Anditwasassumedthatwheneveritisneithernaturalnorpragmaticallyjustifiedtotreatsomeoneasifhewereacertainperson,thenheisnotthatperson.Thatis,nothingcouldeverhappen to you that would make it right and natural for everyone involved,includingyourselfandyourclosestfriends,totreatyouasifyouweresomeoneelse.Isthistrue?Thatwouldseemtodependonwhetheritispossibleforyoutoloseforeverallofyourmemories,yourcharacter,andotherpsychologicaltraits,and acquire completely new ones. If this could happen—if you could survive

completepsychologicaldiscontinuity—weshouldhaveacaseinwhicheveryonewould find itnaturaland right to treatyouas ifyouweresomeoneelse.Yourspouse would not consider him-or herself married to you, nor would youconsideryourselfmarriedtothatperson;yourfriendswouldnolongerknowyouandyouwouldnotknowthem;andsoon.Oratanyratethiswouldbesoif itwouldbenaturalandrightnottotreatBrainyasCobblerinthetransplantcase.Butwhetheritispossibletoloseone’smemoriesandcharacterandacquirenewonescompletelyunrelated to theold, so that everyonewouldbepragmaticallyjustified in treatingyouas if youwere someoneelse, is just thepoint at issuebetweenthePsychologicalApproachandtheBiologicalApproach.ForsomeonewhoholdstheBiologicalApproach,itisperfectlyreasonabletosupposethatonemight appropriately treat someone as if hewere a different person, and so todeny the argument’smajor premise. Thus, any justification of the argument’spremiseswould have to involve thePsychologicalApproach itself, and so theargumentisinconclusive.

VII.SamePerson

If there is a common thread running through these arguments—the prudentialargument, themoral argument, and the treatment argument—it is the practicalimportance of personal identity. We have reasons for identifying andreidentifyingpeople,reasonsthataresoimportantthatitishardtoimaginewhatitwouldbe likenot tohave them.It ishard to imaginenothavinganyspecialreason to be concerned about one’s own future that is not a reason to beconcerned about anyone else’s; it is hard to imagine not holding peopleaccountableforwhattheyhavedone.Whatwoulditbelikeifwehadnoreasontoseekoutthesamepeopleagainandagain,ifmeetingsomeoneagainwerenodifferent frommeetingsomeonefor the first time, if strangerswere treated thesameasfriendsandrelatives?Toimaginethisistoimagineaworldwithoutloveor friendshipor respect:aworldwithout interpersonal relationships.Perhaps itwouldbeaworldwithoutpeople.Ordinarilythesepracticalconcernscoincidewithabsolute,numericalidentity.

Butwhenwethinkaboutunusualorimaginarycases,itseemsthatthismaynotalwaysbeso.Reflectiononthesecasessuggeststhatrationalitymaynotalwaysrequirethatonebeprudentiallyconcernedforoneself,andthattheproperobjectofone’sprudentialconcernmightsometimesbesomeoneelse. It suggests thatonemightsometimesbeaccountableforsomeoneelse’sactionsratherthanforone’sown.Anditsuggeststhatitissometimescorrecttotreatsomeoneasifhe

were someone else. If so, the Biological Approach can accommodate thesepracticalconcerns.Supposeforamoment(perhaps implausibly) that the threekindsofpractical

concern we have discussed—prudential concern, moral responsibility, and“coherent social treatment”—always go together. That is, suppose that it isrationaltobeprudentiallyconcernedforsomeoneifandonlyif(intheabsenceoftheusualexcuses)thatpersonisthenaccountableforyouractions,andifandonlyifitwouldbenaturalandrighttotreatthatpersonasifshewereyou.Thenwecoulddefinea relationcalled“being the samepersonas” in the followingway:

xisattimetthesamepersonasyisatalatertimet*ifandonlyifxoughttobeprudentiallyconcerned,att,fory’swell-beingatt*;andyisresponsible,att*,forwhatxdoesatt;anditisnaturalandrightatt*totreatyasifshewerex.

It is at least arguable that this relation (if there is such a relation) does notnecessarilycoincidewithabsoluteidentity.Inthatcasewecandefineasenseof“beingaparticularperson”asasortofroleorofficethatahumanorganism(oranyotherappropriateobject)mightfillataparticular time.Inunusualcases,asinglehumanbeingsuchasyouorImightbeoneparticularpersonatonetime,in this sense of ‘person’, and another particular person later on. Imight oncehavebeenormightlaterbecomeadifferentpersonfromtheoneIamnow.Ifmycerebrum is damaged or destroyed, Imay no longer be a person at all; Imaysurvivewithoutbeingthesamepersonasanyone.Andtwonumericallydifferenthumanbeingsmightbethesameperson,thoughperhapsnotatonce.Thatmightbe thecase ifyouweredestroyedandreplacedbyaperfectduplicate:perhapstheduplicatewouldbethesamepersonasyouwithoutbeingyou.ThisismeanttobeanalogoustothesenseinwhichClintonisnowthesameelectedofficialasReaganwastenyearsago,eventhoughClintonisnotReagan.Andhalfadozenyears ago (when he was governor) Clinton himself was not the same electedofficialasheisnow.Whenheleavesoffice,Clintonwillprobablynolongerbean elected official at all, and so he will not be the same elected official asanyone.SupposeIsuddenlyloseagreatdealofmemory,andthatthelossisabsolutely

permanent. I come to have a character, values, and goals that are completelydifferentfromtheonesIhavenow.Iacquiredifferentfriends,differenthabits,adifferentsenseofwhoIam.Nota traceofmyformerpersonalityremains.Asfar asmy “personal” attributes are concerned, I become as different from the

wayIoncewasasIamfromyou.Ifthisalterationisdramaticenough,itmightbebestforthepeoplewhoknowandlovemenowtotreatmethenasifIweresomeoneelse.Perhapsmyfriendswouldnolongerhaveanyreasontoassociatewithme,andmycurrentspouseoughtnolongertoconsiderherselfmarriedtome.PerhapsitwouldbeunjusttoholdmeaccountableforthethingsIdidbeforethechange;Imightnolongerbetheappropriatesubjectofpromisesmadetomenow.IfIknewthatthisweregoingtohappentome,itmightevenberationalforme not to have any special concern, now, for myself as I shall be after thechange.Facedwith this sortof thing,manypeople feelanalmost irresistibleurge to

saythatIshouldnolongerbethepersonasIoncewas,orthatIshouldhaveadifferent identity. (“I wouldn’t be me anymore”.) If these words express acoherent thought, they seem to imply that the result of complete, irreversibleamnesiaorthelikewouldbealteration,notextinction.Icouldn’tbeadifferentperson from the one I was before losing my memories unless I existed bothbeforeandaftertheloss.Whenpeopletalkthisway(“Iwouldn’tbemyselfanylonger if I changed in that way”), they are often taken to be expressing theirsupportfor theclaimthatonecannotsurvivewithoutpsychologicalcontinuity.Butwhattheyactuallysayseemstoimplythatonewouldstillexistafterone’smindchangedprofoundly,butthatonewouldbeadifferentperson.The language of personal identity is often used in this way, especially by

nonphilosophers. The Encyclopedia of Psychology, for example, definespersonal identity as “a sense of sameness or continuity of self despiteenvironmental changes and individual growth” (Corsini 1994, 2: 203). Thatimplies nothing about numerical identity or persistence. Thisway of speakingalso figures indiscussionsof religious conversion: “Forweknow that ouroldself was crucified with [Christ] so that the body of sin might be renderedpowerless”(Rom.6:6);“Therefore,ifanyoneisinChrist,heisanewcreation;theoldhasgone,thenewhascome”(2Cor.5:17);“SucharadicalchangetakesplaceinaChristianastobecomparabletoacreation”(Hastings1919,10:640).CertainlyChristiansdon’tbelieve thatoneceases toexistand is replacedbyanumericallydifferentpersonwhenoneconverts.Hereisanexamplefromacontemporarynovel:

Lookingatherself,shewonderedwhatshewouldbe like ifhernosegrewamillimeteraday.Howlongwouldittakebeforeherfacebegantolooklikesomeoneelse’s?AndifvariouspartsofherbodybegantogrowandshrinkandTerezanolongerlookedlikeherself,wouldshestillbeherself,wouldshe still be Tereza?Of course. Even if Terezawere completely unlike Tereza, her soul inside herwouldbe the sameand lookon inamazement atwhatwashappening toherbody. (Kundera1984,139)

WouldTerezastillbeherselfifherappearancechangedtoomuch?Ifthiswereaquestionaboutnumericalidentity,theanswerwouldbetrivial:nothingcaneverbesomethingotherthanitself.Youdon’tneedtokeepthesamesoulinordernotto become someone numerically different from what you once were. Maybewhat Tereza means to ask is whether she would still exist at all if her bodychanged toomuch. (Coming to be and passing away are notorious sources ofconfusion.)Butheractualwordsimplythatshewouldstillbethereinanycase,andthatthequestionisaboutwhatstatussheherselfwouldhave:Wouldshestillbethepersonsheoncewas?Wouldshestillbesimilar, incertainways, to thewayshewasearlier?Wouldshestill feel thesamewayaboutherself, insomespecial, personal sense? These are important questions, but they are notquestionsaboutpersistence.Tosaythatsomeonehasbecomeadifferentperson,on this understanding of the words ‘same person’, is simply to say that sheherselfunderwentaspecialsortofprofoundpsychological(ormoralorspiritualorother)alteration.Thisaccountofthe“practicalsense”ofbeingthesamepersonwillneedsome

refinement,ofcourse.Thethreerelationsofpracticalconcernthatwentintoitsdefinitionmaynotcoincideinallpossiblecases.Perhapsthefitobjectofone’sprudential concern (one’s “Parfitian successor”) is not always accountable forone’sactions;perhapsonemaybe“morally identical”, touseLeibniz’sphrase(1982, 233), with some future personwho is not one’s Parfitian successor. Itmight be possible for someone to be one’s “social successor” without beingaccountableforone’sactions;andsoon.Theremayalsobeadditionalrelationsofpracticalconcernassociatedwithpersonalidentitybesidesthethreewehavediscussed.Itwouldbemorerealistictosupposethatseveraldifferentpracticallyimportantrelationsdeservetobecalled“beingthesameperson”—thatbeingthesamepersonsometimesmeansonethingandsometimesmeansanother.Nor havewe said verymuch about the formal properties of this relation, or

theserelations.It ishardtoseehowtwopeoplecouldbe“thesameperson”atonce. However, in the traditional fission case it seems that each of the twooffshoots is the same person as the one fromwhom the cerebral hemisphereswere taken. If so, being the sameperson is not a transitive relation.That is, ImightnowbethesamepersonasLeftyislateron,andalsothesamepersonasRighty is then, even though Lefty is not the same person, then, as Righty is.While this may be surprising, it is not obviously a problem. Being the samepersonisamoralorpracticalrelation,andthereisnoreasontoexpectittohavethe same formal features as identity strictly so called.We already know thatbeing the same person requires temporal qualification, as identity does not. Icannot simplybe the samepersonas someonewithoutqualification, anymore

than Clinton can be the same elected official as Reagan timelessly, withoutqualification.Icanonlybeatsometimethesamepersonassomeoneisatsometime.Mostimportantly,perhaps,wehavenotsaidwhatittakesforsomeonetobe,

atonetime,thesamepersonassomeoneisatanothertime.Formallyspeaking,we have not given the satisfaction conditions for the relation being the sameperson. Presumably the answerwill have something to dowith psychologicalcontinuity: roughly speaking,x is now the samepersonasy is lateron just incase y is then psychologically continuous with x as she is now. But this is adifficultquestion.Ultimatelyitisforethiciststotelluswhenprudentialconcernis rational,whensomeonecanbeheldaccountable forwhichpastactions,andwho deserves to be treated as whom. These are not metaphysical questionsbecause,beingthesameperson,aswemightsay,isnotametaphysicalrelation.Mypointinintroducingapracticalsenseof‘sameperson’isnottolaunchan

inquiry into values, but to contrast it with personal identity in the numericalsense.Usingthepracticalsenseof‘sameperson’,wecandescribethetransplantcase inaplausibleway that isconsistentwith theBiologicalApproach:WhilePrincesurvivestheoperationasBrainless,PrinceandBrainlessarenotthesameperson.Princeisnotthesamepersonaftertheoperationashewasbefore.ItisBrainywho, after the operation, is the person that Princewas before it, eventhough Brainy and Prince are two different beings. And although Brainy isnumerically identical with Cobbler, he is not the same person, after theoperation,asCobblerwasbeforeit.Iamnowgoing tomakeaboldconjecture:The fact thatBrainy is thesame

personaftertheoperationasPrincewasbeforeit,inthispracticalsenseof‘sameperson’, is the main source of the Transplant Intuition. (And the fact thatBrainless is not the same person as Prince, and that Brainy is not the samepersonasCobbler,isthesourceoftheVegetableIntuition.)Atanyrate,thatisthe truth behind the Transplant Intuition. And a very important truth it is; toanyone but a metaphysician it is more important than the truth about who isnumericallyidenticalwithwhom.Of course, the Transplant Intuition may not be based entirely on the

questionable assumption that the relations of practical concern we havediscussed always coincide with numerical identity. I have attributed to theadvocatesofthePsychologicalApproachanargumentlikethis:

1. Brainy, in the transplant story, is “the same person as” Prince in thepracticalsenseofthosewords.

2.Apersonxis“thesamepersonas”apersonyinthissenseifandonlyifx

andyarenumericallyidentical.3.ThereforePrinceisBrainy,contrarytotheBiologicalApproach.

Icriticizedthisargumentbytryingtocastdoubtonitssecondpremise.Butnodoubt some philosophers look at the Transplant Case and are convincedstraightaway that Prince survives as Brainy and not as Brainless, withoutappealingtoanyintermediatepremiseaboutrelationsofpracticalconcern.Theyargue from 1 to 3 directly. To them I can only explain why I think that theconclusion,3,isfalse,andhopethatmyargumentsagainstthatconclusionwillconvincethemthattheyaremistaken.Thatisthetopicofthenexttwochapters.

VIII.PracticalConsequencesoftheBiologicalApproach

In criticizing the most common arguments for the Psychological Approach, Ihavetriedtodivorcenumericalidentityfromthoserelationsofpracticalconcernthataretraditionallythoughttogoalongwithouridentity:whoseactionsweareaccountable for, how we ought to be treated over time, and (perhaps) whodeserves our prudential concern. So I seem to be saying that personal identityhas no practical importance whatever, except insofar as it often accidentallycoincideswithsomeotherrelation,suchaspsychologicalcontinuity.Onemightwonder whether I have not deprived personal identity of all of its practicalinterest. But wasn’t that just what gave the problem of personal identity itsfascination? Now it no longer seems to matter. Whether the BiologicalApproach,thePsychologicalApproach,orsomeotheraccountofournumericalidentityistruenolongerseemstohaveanyimportanceoutsideofmetaphysics.Ithinkitisanexaggerationtosaythatwhatittakesforustopersistthrough

timehasnoethicalorotherpracticalconsequenceswhatever.Itriedtoarguethatthe relations of practical concern that typically go along with our identitythroughtimearecloselyconnectedwithpsychologicalcontinuity.Ifthatisright,then the Biological Approach does have an interesting ethical consequence,namely that those practical relations are not necessarily connected withnumericalidentity.Imightbemorallyaccountableforsomethingthatsomeoneelse did, and not accountable for things that I did, even if I am morallycompetent now and I was morally competent then. That is because, on theBiological Approach, I might be psychologically continuous with some pastperson other thanmyself; and Imight not be psychologically continuouswithmyselfasIwasatsomepasttime.Indivorcingouridentityfrompsychologicalcontinuity,theBiologicalApproachwouldentailthattheserelationsofpracticalconcernareevenlessreliablyconnectedwithnumericalidentitythanParfitand

Shoemakerhaveargued.On the other hand,my arguments and those of Parfit and Shoemakermight

have failed: moral responsibility and the other practical relations might beessentially tied to numerical identity. Perhaps prudential concern for someoneother than oneself, or lack of prudential concern for oneself, could never berational.Maybeonecouldneverberesponsibleforanyoneelse’sactions,andisalwaysresponsibleforone’sown(asidefromtheusualexcuses).Inthatcasetheconsequences the Biological Approach has for ethics would be even moresurprising, for it would entail that those practical relations did not coincidereliablywithpsychologicalcontinuity.IcouldberesponsibleforsomethingIdidatanearliertimeevenifIamnolongerpsychologicallycontinuouswithmyselfas I was then—even if 1 now have a different cerebrum, for example. And Imightfailtoberesponsibleforactionsdonebysomeonewhohadmybrainandmypsychology,whichIcanrememberandfeelresponsiblefor.The traditionalviewof thematter is that these relationsofpractical concern

coincide both with numerical identity and with psychological continuity. Youareresponsibleforsomethingjustincaseyoudiditandyouarepsychologicallycontinuous with yourself as you were then (the usual excuses aside). If theBiological Approach is true, we cannot have it both ways. We can tie thesepractical relations topsychologicalcontinuity,orwecan tie themtonumericalidentity;wecannottiethemtoboth.TheBiologicalApproachalsobearsonsomereligiousdoctrines.Onthatview,

youareananimal,andananimalceases toexistwhen itdies—when itsvitalfunctions cease and its tissues decay beyond the point where they can bereanimated.Soexistenceafterdeathseemstoberuledout.Oncebiologicaldeathhasoccurred,notevenGodcancallyouback intobeing,at least if Iamrightaboutwhat it takesforananimal topersist throughtime(butseevanInwagen1978forasuggestionabouthowresurrectionmightbepossibleevenifyouareessentially an animal).Sinceyoucouldneverbecomeanythingbut an animal,youcouldbeimmortalonlyifitispossibleforthelife-sustainingfunctionsofabiologicalorganismtocontinueforever.Of course, there might still be “Parfitian resurrection”: if God created a

heavenlybeingwhohadyourpersonalityandcouldapparentlyrememberyourlife, such a beingmight deserve your prudential concern, even if he couldn’tstrictly be you. Perhaps having a Parfitian successor inHeaven is as good asbeingthereyourself.Butthatisunlikelytobeofmuchcomforttothereligious,eveniftheyaccepttheParfit-ShoemakerThesis,forademoncouldalsocreateabeingpsychologicallycontinuouswithyouandthrowhimintotheburninglake.IfhavingaParfitiansuccessorinHeavenisbliss,havingaParfitiansuccessorin

Hellwould be just as bad as undergoing eternal torment yourself. So perhapsGodcouldgiveyouwhatyouwantonlybypreventinganyoneelsefromcreatingsomeonewithyourapparentmemories.The Christian and Hindu doctrine of the divine incarnation also appears

incompatiblewiththeBiologicalApproach.Foragodtobecomeahumanbeinglikeyouandme,onthatapproach,hewouldhavetobecomeabiologicalanimal.Butifanimalisasubstanceconcept,nothingcouldbeananimalatonetimeandanon-animalatanothertime.Thus,agodcouldbeamanonlyifhewasalwaysaman,alwaysaflesh-and-bloodmemberofthespeciesHomosapiens.Nogodcouldbecomeaman,strictlyspeaking.(Once again, there might still be “Parfitian incarnation”: even if Jesus is

numerically different from God and began to exist shortly after he wasconceived, hemight still be the fit subject of God’s prudential concern. Thatmightbeenoughtosatisfysometheologians.)On some versions of the Psychological Approach, on the other hand,

resurrection,reincarnation,anddivineincarnationarenotparticularlymysterious(at leastnotphilosophicallymysterious).Foryou toexist afteryourbiologicaldeath, on that view, there need only be someone whose mental contents andcapacities are causally related to yours in the rightway. If after your death ababyisbornwithreliablememoriesofyourlife,shemightliterallybeyou.Andif a certain man, and no one else, is in a position to remember the pastexperiencesofagod,thenheisthatgod,onsomeviews.But I won’t speculate any further on theological matters. I turn now tomy

argumentsagainstthePsychologicalApproach.

4

WasIEveraFetus?

I.TheFetusProblem

I turn now to my arguments against the Psychological Approach. The mainthemeoftheseargumentsistherelationbetweenhumanpeople—youandme—andhumananimals.ThePsychologicalApproachdoesnotappeartobetrueofthose animals: no psychological relation appears to be either necessary orsufficient for ahumananimal topersist.Butyouand Iare humananimals, atleastifwearematerialobjectsatall.Orifwearenotanimals,someaccountisneededofthewayeachhumanpersonrelatestotheanimalintimatelyconnectedwithher.Inthischapterweshallconsideraspecialcaseofthisgeneralproblem.Both biological science and folk wisdom seem to tell us that each human

person was once a fetus. Each one of us spent several months inside ourmother’swombbeforebeingborn. Ifallgoeswell,ahealthyhumanfetuswillbecomeanadulthumanperson,suchasyouorI.ButthisfactmakestroubleforthePsychologicalApproach.The problem is that a human fetus less than about sixmonths old does not

haveanyinterestingpsychologicalfeatures.Ahumanembryodoesnotbegintoacquire even the rudiments of a cerebrum until at least six weeks afterfertilization(McLaren1986,15),andthecerebrumisnotcapableoffunctioningasanorganofthoughtandsensationforanotherfourmonthsormoreafterthat.Oratleastthatiswhatmostembryologiststellus,andIsupposetheyoughttoknow.Iftheyareright,youcouldnotnowberelatedtoafive-month-oldhumanfetus inanypsychologicalway.Yourmentalcontentsandcapacitiescouldnotbecontinuouswiththoseofabeingwithnomentalcontentsorcapacitiesatall.According to the Psychological Approach, however, some sort of

psychologicalrelationisnecessaryforustopersistthroughtime.IshallexistatsomefuturetimeonlyifIcanthenremembersomepresentexperienceofmine,orifIamthenconnectedwithmyselfasIamnowbyanoverlappingchainofmemories, or of psychological connections of some other sort. At best, I can

surviveonlyifcertainofmymostbasicmentalcapacitiesremainintact.Andinthesameway,IexistedatsometimeinthepastonlyifIamnowrelatedinthatsamewaytomyselfasIwasthen:onlyifmycurrentpsychologicalcontentsorcapacities are connected in a continuous way with the ones I had then. AsMichaelLockwoodwrites,

JustasIshallliveonlyaslongastherelevantpartofmybrainremainsessentiallyintact,soIcameinto existence only when the appropriate part or parts of my brain came into existence, or moreprecisely,reachedtheappropriatestageofdevelopmenttosustainmyidentityasahumanbeing,withthecapacityforconsciousness.WhenIcameintoexistenceisaquestionofhowfarbacktherelevantneurophysiologicalcontinuitycanbetraced.(1985,23)

JustasIcouldnotloseallofmymentalcontentsandcapacitiesandstillsurvive,IcouldnothaveexistedatsomepasttimewhenIhadnosuchmentalfeatures.Thus,Icouldnothavebeenahumanembryoorfetus(oratleastafetusintheearlierstagesofitsdevelopment,beforetherelevantpsychologicalfeaturesareinplace).AccordingtothePsychologicalApproach,nothingcouldbeafetusatone timeandaperson lateron.Nopersonwasevera fetus, andno fetuseverbecomesaperson.Recall theVegetableCase:Your cerebrum isdestroyed,butyour autonomic

nervoussystemremainsintact,sothatyourvitalfunctionscontinueonwithoutinterruption.Theresultisahumanorganismthatisaliveinthebiologicalsense:it spontaneously breathes, circulates its blood, digests its food, grows, repairsdamage to itself, fights off infection, and in many cases even coughs andswallowsandmakesotherreflexmovements.Allofyourpsychologicalfeatures,however,havebeenirrevocablydestroyed.Theresultinghumanvegetableisnotawareofitssurroundingsandcannotfeelanything.Thereisnomentallifethereatall.AccordingtothePsychologicalApproach,thatmustbetheendofyou,forthevegetableisnotrelatedtoyouintherightpsychologicalway.Youcouldnotsurviveasavegetable;thevegetatinganimalcouldnotbeyou.Notonlydoesthevegetablelackmentalstatesthatareconnectedintherightwaywithyours,butitseemstohavenomentalpropertiesatall,oratleastnoneofthesortthathavetobe present if you are to survive. There cannot be psychological continuitybetweenyouand amindlessbeing.But then the same thingmustpreventyoufrom ever having been a fetus: in both cases there is utter psychologicaldiscontinuity.Fora five-month-oldhuman fetushasnomorementalcontentsorcapacities

than a human vegetable has.1 The reason is that the cerebrum cannot supportthoughtorawarenessuntilitsneuronscancommunicatewithoneanother.Thistakesplacewhentheygetconnectedtogetherwithsynapses,roughlytwenty-five

to thirty-twoweeks after fertilization.Before that time the cerebrum is simplynot yet “wired up”, and there is no capacity for conscious awareness orreasoning.Asonepairofscientistsputit,“Beforesynapsesareformed,thefetalbrain is just acollectionofnervecells.The fetus is incapableofawarenessorvolition” (Morowitz and Trefil 1992, 116). The cerebral cortex “comes intoexistenceasafunctionalentity”betweentwenty-fiveandthirty-twoweeksafterfertilization(119).ContinuousEEGpatternsarenotobserveduntilaboutthirtyweeks(Flower1985,246).Before this timeit isunlikely that thefetus isevenminimally sentient.Pain, surelyoneof themostprimitive statesof awareness,does not seem to be possible until the cerebrum gets hooked up with thethalamus at mid-gestation (247). The embryologist Clifford Grobstein writes,“The available facts speak against the presence of an imaginable state ofsentiencepriortotwentyweeks[afterfertilization]andforaperiodofuncertainduration beyond—in all likelihood to at least thirty weeks, when corticalmaturationandconnectivitynoticeablyrise”(1988,130;seealso54ff.).Infact thePsychologicalApproach,asmostof itsproponentsstate it,entails

thatnoneofuswaseverasix-month-oldinfanteither.Itisnotlikelythatyouareconnected by a chain of overlappingmemories or the like to a six-month-oldinfant;thechild’sbrainsimplylacksthecapacitytorememberorintendmuchofanything. And those who say that we persist just in case our basic mentalcapacities are preserved usuallymean those capacities that distinguish peoplefromnon-people.OnThomasNagel’sview,forexample,IsurviveaslongasIretainthecapacityforconsciousexperienceandmyabilitytoreidentifymyselfviamemory(1986,41).UngersaysroughlythatIsurviveaslongasmycapacityfor reasoning and consciousness is preserved (1989, 109, 144).2 Probably noinfantacquiresthosecapacitiesuntilmorethanayearafterbirth.AccordingtoPiaget,clear signsof intentionalorgoal-directedbehaviorappear four toeightmonths after birth, and infants do not acquire the capacity for symbolicrepresentation—reasoning—until one and a half to two years (Young 1971,279).ManypsychologistsnowthinkthatPiaget’stimetableisabitlateformostchildren(Donaldson1987);stillitseemsclearthatyoucouldnothavecomeintoexistenceuntilatleastayearafteryourbirth,ifrationalityisessentialtoyou.Now someone might claim that we need retain only quite primitive mental

capacities inorder topersist, thekindsofmentalcapacities thatevennewborninfantshave.3Inthatcaseyoucouldpresumablysurvivethelossofallofyourmentalcontentstoday,andevenyourcapacityforrationalityandself-awareness.Youcouldsurvivetheseverestdementia,reducingyoutothementallevelofanewborn infant. Although this does not seem to be a popular view, it is still

technically a version of the Psychological Approach. But because I want toargueagainstallaccountsofpersonalidentitybasedonpsychology,andallsuchaccounts appear to be inconsistent with my having once been a fetus, I shallconcentrateonthatquestionandleaveasidethematterofwhetherIwaseveraninfant.Mostofthesameconsiderationswillapplyineithercase.AdvocatesofthePsychologicalApproachmighttryeitheroftwostrategiesfor

dealingwiththe“fetusproblem”.Thefirstistoplaytheproblemdown:itmightcome as a surprise to learn that none of us was ever a fetus, but that is aconsequencethatwecanlivewith,ameretechnicalpoint.Thesecondstrategyistoarguethat, inspiteofappearances,thePsychologicalApproachisconsistentwith our havingonce been fetuses.Though surviving the loss of thosementalcapacities that one already has is clearly incompatible with the PsychologicalApproach, why should that view prevent one from having lacked mentalcapacitiesinthefirstplace?Isn’tthePsychologicalApproachaviewaboutwhatsortofthingIcouldsurvivenow,onceIamrationalandconscious?Evenifnofuture being could be me without having my mind, why couldn’t some pastbeingwithoutamindbeme?Andifthatwon’tsolvetheproblem,thereisstillone important difference between the fetus and the vegetable that we mightappealto:whileneithercanthinkorfeelorrememberanything,thefetus,unlikethe vegetable, canacquire those capacities. So in a sense the fetus does havemental capacities, namely the capacity to become conscious and rational. I dostand in somepsychological relation to a certain human fetus that I could notstandintoanyhumanvegetable.Hence,Imighthavebeenafetusafterall,evenifthePsychologicalApproachistrue.

II.PlayingtheProblemDown

On the face of it, those who accept the Psychological Approach, as mostphilosophersapparentlydo,arecommittedtothesurprisingpositionthatnothingiseverfirstafetusandlateraperson.Thiswouldbesurprisingenoughwereitnotthatmostphilosophersalsoappeartosaytheopposite.Indebatesaboutthemoralstatusoftheunborn,allpartiesusuallyagreethatahumanfetusisatleastapotentialperson,inthesensethatitmightlaterbeaperson.Hereisatypicalquotation:

Itisobviouslytruethatthenormalfetusisatleastapotentialperson:itisanentitywhichwill,barringabnormal circumstances or intervention, develop into something incontestably a person. The onlyquestioniswhatmoralclaimuponusthisgivesit.(Glover1977,122)

Ethicistsassumethatitispossibleforsomethingtobeanunthinkingfetusatone

timeandapersonlateron;eachpersonwasonceafetus.Thisassumptionenjoysthesamenear-unanimousassentas thePsychologicalApproach itself.Yet fewethicists argue against the Psychological Approach, and few friends of thePsychological Approach claim that debates about abortion, infanticide, or thelike are otiose on the grounds that a fetus or infant is not even a potentialperson.4Howcouldthisbe?Perhaps they haven’t noticed the conflict.This is not as flippant as itmight

sound,foraswesawinChapter2,personalidentityusuallygetsdiscussedinaway that prevents one from askingwhether any personwas once a fetus.Theusualquestioniswhenapersonpickedoutatonetimeisidenticalwithapersonpickedoutatanothertime,orwhensomeonewhoexistsnowisthesamepersonassomeonewhoexistsearlieror later. If this is therightwaytoaskaboutouridentitythroughtime,thenwhetherIwasonceafetusisnotaproperquestion.On the common assumption that being a person means having certain fairlysophisticatedmentalcapacitiessuchasrationalityorself-consciousness,afetusisnotaperson(atleastnotyet).Becausenofetuscouldbethesamepersonasanyone,whetheranyonewaseverafetusorwhetheranyfetusislaterapersonisnotaquestionabout“personal”identityatall,evenifitisaquestionaboutouridentity. Thus, the fetus problem may have been overlooked simply becausephilosophershave inquiredaboutpersonal identity inway thatprevented themfromseeingit,encouragedbyanentrenchedtheory.On the other hand, some friends of the PsychologicalApproachmight have

thoughtaboutthe“fetusproblem”,butsimplynotseenitasaproblem,oratanyrate not as a very serious problem. They might defend their view in thefollowingway:

Our view entails that you did not come into the world as a microscopicembryo, but rather as a well-developed fetus six months or more afterconception(ormorelikelyasaninfantayearorsoafterbirth).Whilethatmaysoundat first likeareductioof thePsychologicalApproach, there isnothingabsurdaboutthisconsequenceifweunderstanditcorrectly.Whenwelearnedatmother’sknee thateachofusspent timeinside thewombbeforewewereborn,orthathumanfetusesandinfantsdevelopintoandbecomeadulthumanbeings,perhapswedidnotlearnthateachofusisnumericallyidenticalwithafetusoraninfant,butonlythatafetusorinfant,asitdevelops,givesrisetoorproducesaperson.Thereisnothingabsurdinsayingthatthesparksbecameaconflagration, or that Slovakia and the Czech Republic were once a singlecountry;itwouldcertainlybewrongtotakethisasimplyingthatonethingisnumerically identical with more than one thing. This shows that there is a

senseinwhichonethingcan“become”somethingnumericallydifferentfromit, and a sense inwhich one thing can “once have been” another.The samegoes for the claim that a fetus is a potential person. A wooden house is apotentialpileofashes;butthatdoesn’timplythatanyonethingcouldbefirsta house and later a pile of ashes. Thus, even if none of us is numericallyidenticalwithafetus,andevenifnofetusisevernumericallyidenticalwithaperson—evenifnoonethingiseverfirstafetusandlateraperson—itisnotclearthatthisconflictswithanythingestablishedbyscience,orwithanythingthat every enlightened person believes. It is still true that a fetus “developsinto” and “becomes” a person in the weak sense that there is a continuousprocessofself-directedgrowththatbeginswithafetusandendswithaperson.Why suppose that our mothers and our biology teachers meant to tell usanythingmorethanthat?

Nowtheremightbea loosesenseof“becoming”andof“havingoncebeen”accordingtowhichanF’sbecomingaG,oraG’shavingoncebeenanF,doesnot imply that anyone thing is first anF and later aG, but only that anF insomesenseengendersaG.But this loose sensedoesnotappear tobe theonethatfiguresinfolkwisdomabouthowwecametobe.Iwasonceachild.Thisdoesnotmeanmerely thatsomechildengenderedme. Itmeans thatsomeonething—I—was first a child and later an adult. If your five-year-old daughterfindsherbabybrotherdisgusting,andyouremindherthatshe,too,wasonceaninfant, youdonotmeanmerely that she developed froman infant.Youmeanthatsheherself,notsomeother thing,onceweighed tenpounds,nursedathermother’s breast, cried at night, and did everything else that babies do. In thesameway,whenyou learn thatyouweren’tbroughtbya stork,you learn thatyouwere once a fetus in just the sense that youwere once a toddler, later anadolescent,andsoon.Atanyrate,theredoesnotappeartobeanydeeplogicaldifferencebetweensaying, in theordinarycourseof life, thatyouwereonceatoddleroranadolescentandsaying,intheordinarycourseoflife,thatyouwereonceafetus.Thesamegoesforembryology.IfitisabiologicalfactthatIwasonceafetus,

it isalsoabiologicalfactthatIoncelivedinsidemymother’swomb,weighedlessthanapound,andhadgillslits.AndthatIoncehadgillslitscertainlyentailsthattherewasoncesomethingwithgillslitsandthatIamnumericallyidenticalwiththatthing.Atleastanyonewhowoulddenythishasgotsomeexplainingtodo.Sofolkwisdomandmodernembryologyseemtotellusquiteplainlythateach

ofuswasonceafetus, in thesenseofbeingnumerically identicalwithone. It

wouldbesurprisingindeedifthisturnedouttobefalse.Butweneedn’trestourcasethatwewereoncefetusesonlinguisticevidence.

Theclaimthatnothingiseverfirstafetusandlaterapersonalsofacesseriousphilosophicalproblems.Suppose I came intobeingsixor sevenmonthsafter Iwasconceived,when

the normal course of fetal development produced the first mental capacitiesworthyofthename—orayearormoreaftermybirth,whenthenormalcourseof infantile development produced those mental capacities that distinguishpeoplefromnon-people,suchasrationalityandself-consciousness.Supposethatthe fetusmymother bore during that time (and perhaps the infantmymothernursed) isnumericallydifferentfromme.Whatbecameof thatfetusor infant?WhathappenedtoitwhenIcameintoexistence?Isitstillwithus?Thecurrentproposalmakes just one thing certain: that fetus did not come to be a person.Nothingstartedoutcomposedofonlyafewdozencells,begantoacquireitsfirstcrudepsychologicalfeaturesseveralmonthsintoitslife,grewbiggerandbigger,andfinallywentintophilosophy.Atsomepoint,orduringsomevagueperiod—perhapssomesixorsevenmonthsafterthefetuswasconceived,perhapslater—ayounghumanpersonorthinkingbeingappears.Thatpersonorthinkingbeingwasnotpreviouslyanon-person,butonlythenbeginstoexist.Whathappenstotheoriginalfetusthen?Therearetwopossibilities.Oneisthatthefetusceasestoexistandisreplacedbyaperson.Theotheris that thefetuscontinuestoexist,butnevercomestobeaperson;instead,itsimplycomestoshareitsmatterwithapersonnumericallydifferentfromit.Neither option is easy to believe. According to the first, it is logically

impossible for a human fetus to come to be a normal, adult humanbeing: thefetus necessarily ceases to exist as soon as its nervous system has developedenoughtomakethoughtpossible.Nothingstartsoutweighinglessthananounceandgrowsuntilitweighs150pounds.Eachhumanfetus(orinfant)mustperishin the act of bringing forth a human being. This would be one of the mostremarkablefacts inallofnaturalhistory—assuming,atanyrate, thatembryosandneonatesofothermammalspeciesmanagetosurvivetoadulthood.Why,weshould want to know, should a fetus perish simply because, in the course ofcarryingouttheprogramencodedinitsgenes,it(orratheritssuccessor)cametobeable to think?This isnot the sortof thing that typicallycausesdeath.Thatonenecessarilyperishes ifone losesone’sability to thinkmaybe false,butatleast we can understand why someonemight think that it was the case. Thatsomethingshouldperishbyvirtueofgainingthatabilityisabsurd.Thesecondoptionisthatahumanfetusdoessurvivethenormaldevelopment

of its nervous system and grows into an adult human animal, just as we all

thought.Butdespitethatdevelopmentitnevercomestobeaperson.Nohumanfetus ever comes to be one of us, the beings to whom the PsychologicalApproachapplies.Rather,atacertainpointinafetus’sdevelopmenttheatomsthatmake itupbegin tocomposesomethingelseaswell, a secondbeing;andthatthingistheperson.You,theperson,nowshareyourspaceandyourmatterwithahumananimal,anditistheanimal,notyou,thatstartedoutasafetus.(Atleast I assume that the thing that used to be a fetus is now an animal; itwascertainly an animalwhen itwas a fetus.) That animal is numerically differentfromyoubecauseitbegantoexistbeforeyoudid,andbecauseithasdifferentdispositionalpropertiesfromyours:youcouldnotsurvivewithoutpsychologicalcontinuity, but the animal accompanying you manifestly can—or at least itcould,anddid,atonetime.Althoughwearematerialbeingsmadeoffleshandblood,onthisproposal,we

are not human animals: we are not members of the species Homo sapiens.Apparentlywearenotorganismsatall,inspiteofappearances—eventhoughwearealiveandarecomposedentirelyoflivingtissuesarrangedinjustthewaythatthetissuesofalivinghumanorganismarearranged.Not,atanyrate,unlesstwohumananimalscouldbecomposedofthesamematteratthesametime;buteventhosewhobelieve that two thingscanoccupy thesameplaceat thesame timedenythatthisispossiblefortwothingsofthesamekind.5(Whatcouldmakeitthecasethattherewerejusttwoorganismsthere,andnotsomeothernumber?)This is not an plausible position.Not onlywould there be non-animals that

werejustlikeanimalsexceptfortheirhistoriesandtheirpersistenceconditions,namelyhumanpeople;therewouldalsobenon-peoplethatwerejustlikepeopleexcept for their persistence conditions, namely human animals. Consider theanimal that you now share your matter with, on this proposal—the one thatstartedout as a fetus.That animalwould seem tobe rational and conscious ifyouarerationalandconscious;atanyrateitsbrainandcentralnervoussystem,its sensory stimulations, and itsbehavior arenodifferent fromyours.Yet it isnotaperson, for thePsychologicalApproachdoesnotapply to it.Butdoesn’ttheanimal think (wrongly) that it isaperson?Andhowdoyouknowthatyouaren’tmakingthesamemistake?Howdoyouknowthatyouaren’t theanimalratherthantheperson?Youmightsuggestthatwhatstartedoutasafetus,andthatmayoutlivemeas

avegetable,isonlymybody.6Andourbodies,unlikeourselves,arenotrationalor conscious; they do not write books or have conversations. It may beproblematic to claim that each of us coincides spatially with an animalnumericallydifferentfromus;butisn’titaphilosophicalcommonplacethatwe

aredistinctfromourbodies?But calling the thing that startedout as a fetus ‘mybody’doesn’t solve any

problems. Why isn’t my body—assuming that those words pick out somematerialobject—ananimal?Itwouldcertainlysatisfyall thebiologicalcriteriaforbeingananimal.Itisobviouslyalive.Sounlesstherecanbetwoanimalsinthesameplaceatonce,mybeingdifferentfrommybodymeansthatIamnotananimal—even though I too am biologically no different from an animal. Andwhyisn’tmybodyrationalorintelligent?Whatcouldpreventsomethingwhosebrain,movements,andsurroundingswereexactlylikeminefrombeingrationalorconscious?But I shallpostponefurtherdiscussionof thesemattersuntil thenextchapter.Thus,theclaimthatnoneofuswaseverafetusfacesseriousproblems.Letus

see whether the defenders of the Psychological Approach can avoid thisconsequence.

III.Future-DirectedIdentityandDisjunctiveCriteria

YoumightthinkitunfairofmetosaddlethePsychologicalApproachwiththefetusproblem.Ifthatviewistheclaimthatsomesortofpsychologicalrelationisnecessary and sufficient for us to persist through time, then it entails that nopersonwaseverafetus,forifIwasafetusIpersistedwithoutanypsychologyatall. But that (onemight argue) is not theway its proponents state the theory.TheyunderstandthePsychologicalApproachasaviewaboutwhatittakesforapersonpickedoutatonetimetobeidenticalwithapersonpickedoutatanothertime.Asafetusisnotaperson,whysupposethatthattheoryentailsanythingatallaboutwhetherapersoncouldhavebeenafetus?Thiswon’t get us very far. Since the PsychologicalApproach says that one

couldn’t loseallofone’smentalcontentsandcapacitiesandsurvive, it entailsthat no person could ever be a human vegetable or a corpse. So it does haveconsequencesaboutwhetherapersonpickedoutatonetimecouldbeidenticalwithanon-personpickedoutatanothertime(seeChapter2,SectionI).ButevenifthePsychologicalApproachentailsthatonecouldneverbecomea

non-person, itmightnotbesoclear that itpreventsone fromstartingout asanon-person. Because I am a person now, onemight suggest, I cannot exist atsomefuturetimeunlessmymentalfeaturesarepreserved.ButwhycouldInothave existed at some past time even if I had no mental features at all then?PerhapsthePsychologicalApproachwasnevermeanttobeaclaimaboutwhatittakesforapersontohaveexistedinthepast,butonlyaboutwhatittakesfora

persontosurviveintothefuture.ThisisPeterUnger’sview.Hewrites,

ThepersonXnowisoneandthesameasthepersonYatsometimeinthefutureif,andonlyif,fromthepresent realizerofX’spsychologynow to thephysical realizerofY’spsychologyat that futuretime, there is sufficiently continuous physical realization of enough central enough aspects of X’spresentpsychology.(1990,140f.)7

Unger(5f.)claimsthathisviewpermitsmetohaveexistedatsometimeinthepast—as a fetus, for example—without now bearing any interestingpsychologicalrelationtomyselfasIwasthen,butpreventsmefromsurvivingthe lossofmybasicmentalcapacitiesonceIhave them.It isa future-directedcriteriononly.Thismaybewellandgood;butsofartheproposalisimportantlyincomplete.

IfIwasonceafetus,Imanagedtosurvivethenwithoutanypsychologyatall,physicallyrealizedornot.SoUnger’scriterioncannotbethewholestoryaboutmyidentity,oreventhewholestoryaboutmysurvival intothefuture.Evenifthecriterionappliestomenow,itdidnotapplytomewhenIwasafetus.Asitbegins, “thepersonX . . .”, presumably itwas never intended to apply tomethen; Unger is concerned with personal identity in the strict sense of what ittakesforonetosurviveonceonehasbecomeaperson.Thatiswhatmakeshisaccountincomplete,evenasafuture-directedcriterionofidentity.Howmightitbecompleted?YoumightsuggestthatUnger’scriterionsimplywentintoeffectafewmonths

oryearsintomycareer,whenIbecamerationalandself-conscious,whilebeforethat time some other criterion of identity—presumably one that requires only“purely animal” continuity—was in force. The “personal” criterion of identityreplaces the “fetal” criterion when one becomes a person, much as newlegislationmaysupersedeanoldlaw.Soperhapsafetusthatexistsnowandhasnomentalfeaturesatallexistsatalatertimeifandonlyifsomethingatthatlatertimeisbiologicallycontinuouswiththatfetus(the“fetal”criterionofidentity).Once that fetus becomes a person, though, it exists at a later time only if itspsychologyispreserved(Unger’s“personal”criterion).Thisclearlywillnotdo.Supposeacertain fetus,Mary,grows intoaperson.

Latershelapsesintoapersistentvegetativestate.TheresultinghumanvegetableisthenbiologicallycontinuouswiththefetusthatMaryoncewas—thatis,withMaryherself.Ourproposal, though, tellsus thatMary the fetus isnumericallyidentical with any future being that is biologically continuous with it. So thefetus is the human vegetable, and Mary has survived her traumatic accident.Unger’s “personal” criterion, though, entails thatMary cannot survive such a

thing.The lesson tobe learned is that thepersistenceconditions thatapplied tome

when I was a fetus must still apply to me now, when I am a person; andwhateverpersistenceconditionsapplytomenowmusthaveappliedtomewhenI was a fetus or an embryo, if I ever was one. A thing cannot exchange itscriterion of identity part way through its career for a new and incompatiblecriterion.Mypersistencethroughtimecannotconsistinonethingatonestageinmy career and consist in something else later on.Whatever is necessary andsufficient forme to persist at the beginning ofmy careermust continue to benecessary and sufficient for me to persist, on pain of contradiction. If InecessarilypersistifandonlyifF,itcannotlaterbethecasethatIpersistifandonly if G, whereG could obtain withoutF’s obtaining. If physically realizedcontinuityofmybasicmentalcapacities isnecessaryformetosurvivenow,itmustbenecessaryformetosurvive throughoutmycareer.Soit isnoteasytoseehowUnger’saccountcouldbeconsistentwithmyhavingoncebeenafetus.The difficulty arose because Unger’s proposal seemed to make something

necessary for me to persist that could not have obtained when I was a fetus,namelypsychologicalcontinuityofsomesort.Butwecouldavoidthisproblemwitha technical trick.Thereisawayofsaying,withoutcontradiction, thatmypersistence consists first in narrowly biological continuity until I become aperson (roughly, until I become rational and self-conscious), after whichbiological continuity becomes irrelevant and only psychological continuitycounts. We can avoid the problem of assigning different and incompatiblepersistenceconditionstoathingatdifferenttimesbybuildingthoseconditionsinto different disjuncts of a single, unitary criterion, each ofwhich applies indifferent circumstances. Unger’s “personal” criterion would turn out to be aspecial case of a more general account that applies to one throughout one’scareer,evenbeforeonehasbecomeaperson.HereisanexampleofwhatIhaveinmind(myapologiestothereader,butI

don’tknowhowtomakeitanysimpler):

TRICK

Ifxisahumanbeingatatimet,thenforanyythatexistsatalatertimet*,x=yifandonlyif

1.yisatt*psychologicallycontinuouswithxasheisatt;or2. x isnotapersonat tandy isnotapersonat t*andx isat tbiologically

continuouswithyasheisatt*,andnothingthatisapersonbetweentandt*isthenbiologicallycontinuouswithxasheisatt;or

3.xisnotapersonattandyisapersonatt*,andthereisatimet’betweentandt*atwhichthereisapersonzwhoisthenbiologicallycontinuouswithx, and nothing is a person biologically continuous with x at any timebetweentandt’,andyisatt*psychologicallycontinuouswithzasheisatt’.8

The first disjunct of the formula is Unger’s criterion, somewhat simplified; ittellsuswhatittakesforonetosurviveonceonehasbecomeaperson.Thisisthepart that prevents anyone from surviving as a human vegetable, and whichenablesonetogoalongwithone’scerebruminatransplantoperation,onceoneis rational and conscious. The second disjunct applies to the period of one’scareerbeforeonebecameaperson: the“fetal”criterion. Itpermitsanembryo,fetus,orinfanttosurvivewithoutpsychologicalcontinuity,aslongasithasnotyet become a person. Clause 3 deals with the transition from non-person toperson: it tells us which future person an unthinking fetus or infant will be.Roughly, a fetus is identical with any future person who is psychologicallycontinuouswithhim,thefetus,ashewaswhenhefirstbecameaperson.(Thinkof t’ as the time when you became a person. You were then biologicallycontinuous with a certain past fetus or infant and psychologically continuouswithacertainfutureperson.Thatpastfetusandthatfuturepersonarethenone.)ThisispresumablythesortofthingUngerhadinmind.SomethinglikeTRICK

iswhat thosefriendsof thePsychologicalApproachwhothinktheywereoncefetusesmustaccept.One potential difficulty for TRICK is that the transition from non-person to

personmightbegradualratherthanabrupt.ItseemsquitelikelythatthereweretimeswhenIwasneitherdefinitelyapersonnordefinitelyanon-person,anditisnotclearwhat,accordingtoTRICK,ittookformetopersistthen.Onemightalsocomplainthatifsomethingcouldhaveirreduciblydisjunctive

persistence conditions, Wiggins’s theory of substance concepts would bereducedtotriviality.Ifourpersistenceconditionsareirreduciblydisjunctive,andif everything must fall under some substance concept, then some substanceconcepts, such as ours, will determine irreducibly disjunctive persistenceconditions.But in that case, youmight think, the result of disjoining any twosubstanceconceptswouldbeasubstanceconceptitself.IfXandYaresubstanceconcepts, we could form the concept X or Y, whose associated persistenceconditionswouldbe,“isanXandhasthepersistenceconditionsforXsorisaYandhas the persistence conditions forYs”. Since that concept,XorY,would

determine its own unique criterion of identity, it too would be a substanceconcept.So ifdogandshrubaresubstanceconcepts,dogorshrubwouldbeasubstance concept as well. Thing would end up being a substance concept,namely the disjunction of all other substance concepts. But “It’s a dog or ashrub”(or,“It’sathing”)cannotbethewholeanswertothequestionWhatisit?;itdoesn’ttelluswhatsomethingmostfundamentallyis.Thus,itseemsthatdogorshrub,oringeneralXorY,cannotbeasubstanceconcept;andthinkingupanondisjunctive name for that concept won’t make it into one. Hence, nosubstance concept can be associated with irreducibly disjunctive persistenceconditions.SomuchtheworseforWiggins’stheoryofsubstanceconcepts,youmightsay,

andyoumayproposeanalternative to that theory.Oryoumightobject to thecomparisonbetweenTRICKandsuchdisjunctiveconceptsasdogorshrub (andsuch high-level concepts as thing). Obviously dog or shrub couldn’t be asubstanceconcept(if therearesubstanceconceptsatall),becausethedisjunctsthatoccur in itsassociatedpersistenceconditionsapply tocompletelydifferentthings.Nothingcanbebothadogandashrub,oradogatonetimeandashrubat another.But it is one thing for a criterion of identity to have disjuncts thateachapplytodiscreteclassesofobjects;itisanotherforthosedisjunctstoapplytothesameobjectatdifferentstagesof itscareer.Somethingcanbeafetusatone time and a person at another, even if nothing can be both at once; so theconcept fetus or person (or whatever you want to call the concept associatedwithTRICK)doestelluswhatyouandImostfundamentallyare.Iwon’ttrytoresolvethisdisputehere.WeshallhavemoretosayaboutTRICK

andsimilarproposalslateron.

IV.Second-OrderCapacities

Let us turn now to a second strategy formaking the Psychological Approachconsistent with our having once been fetuses. I argued that this could not bedonebecauseafetus,atleastbeforethesixthorseventhmonthafterfertilization,could not stand in any psychological relation to you or me, as it has nopsychological features at all then. But someone might argue that a fetus orembryo does have psychological features, namely certain mental capacities.Therearetwodifferentsensesinwhichsomethingmighthavethecapacitytodosomething.Inonesense,someonehasthecapacitytoswim(forexample)ifshehas learned how to swim and is not paralyzed, unconscious, or otherwisehandicapped. If you put her in thewater, she can swim.Wemight call this a

“first-ordercapacity”.Butthereisalsoasenseinwhichevensomeonewhohasnotlearnedhowtoswimhasthecapacitytoswimifshecouldlearnhowtodoit.Inthissenseallhumanbeingswhoaren’tsomehowphysicallydisabledhavethecapacity to swim. Butterflies, on the other hand, do not have the capacity toswim. They simply aren’t built for swimming. Someone has a “second-ordercapacity”toswimifshecouldacquireafirst-ordercapacitytoswim.Now there isone sense inwhichahumanembryoor fetus lacksanymental

capacities, in particular the capacity for rationality and self-consciousness. Afive-month-old fetus cannot think or feel or remember because the neuralstructuresneededtocarryoutthoseactivitiesarenotyetinplace.Butthefetuscan become rational and self-conscious. It has the second-order capacity toacquire the first-order capacity to think and reason.Hence, there is a sense inwhich ordinary human fetuses, but not armchairs or oysters, have mentalcapacities,andinparticularthosementalcapacitiesthatdistinguishpeoplefromnon-people.Eveniftheyhavenofirst-ordermentalcapacities,theyhavesecond-ordermentalcapacities.AccordingtothePsychologicalApproach,wecannotsurviveunlesscertainof

our mental capacities are preserved. Which capacities? Suppose our second-ordermentalcapacitiesaregoodenough.Thatwouldallowmetohavepersistedasanunthinkingfetus.ThereisaninterestingpsychologicalrelationthatIstandintoacertainfetus,forthementalfeaturesIhavenowarerelateduniquelyinaspecial causal way to the (second-order) mental capacities that that fetus hadwhen it lived inside my mother’s womb. On the other hand, I could not berelated in that way to a human vegetable, for the vegetable, unlike the fetus,lacksthesecond-ordercapacitytobecomeconsciousandrational.Sowemightproposesomethinglikethis:

COMPROMISE

Foranyxthatisapersonattandanyythatexistsatt*,x=yifandonlyifyhasatt*thesecond-ordercapacitytobecomerationalandself-consciousintheordinary course of development; and that capacity is causally continuous, inthe appropriate sense and to a sufficient degree, with the psychologicalfeaturesthatxhasatt.

Could defenders of the Psychological Approach solve the “fetus problem” insomethinglikethisway?COMPROMISE is supposed to be a version of the Psychological Approach

because it says that Imust stand insomepsychological relation tomyselfas IwasorshallbeateveryothertimewhenIexist.Herethewords‘psychologicalrelation’mustbeunderstoodliberally.Whatsortofpsychologicalrelationcouldonestandintosomethingthathasno(first-order)psychologicalfeaturesatall?In what sense of ‘psychological continuity’ am I psychologically continuouswithatinyhumanembryothatlooksmorelikeacorncobthanahumanbeing?This is not the sort of psychological relation that most friends of thePsychologicalApproachhadinmind.Infact,thePsychologicalApproachthreatenstobecometrivialifCOMPROMISE

countsasaversionofit,foritwouldbeconsistentwithjustaboutanytheoryofpersonalidentity.OntheBiologicalApproach,forexample,onecouldsurviveasavegetableafterthedestructionofone’scerebrum.Butevenahumanvegetablehas psychological capacities in a sense, for it could become rational andconscious if a healthy new cerebrum were implanted into its head. Just as ahumanembryohasthesecond-ordercapacitytobecomerationalandconsciousintheordinarycourseofdevelopment,ahumanvegetablehasthesecond-ordercapacity to become rational and conscious if the right surgical measures aretaken.Soeven theBiologicalApproach requires thatcertainofone’s (second-order)mentalcapacitiesbepreservedifoneistosurvive.Thus,COMPROMISEisapsychologicalaccountofpersonal identityonlyinthesensethat theBiologicalApproachisapsychologicalaccount.Nowmanyof thephilosophers Ihavediscussedarenone toohappy tohave

their view called a psychological approach to personal identity. Unger, forexample, argues against what he calls the “psychological approach”, andclassifies his own view as a “physically based” theory. He emphasizes thedistinctionbetweenaccountsofourpersistenceintermsofcontinuityofmentalcontents alone, such as Shoemaker’s view, and accounts that require physicalcontinuityaswell.SomuchtheworseforwhatIhavecalledthePsychologicalApproach,whichthrowsbothapproachesintothesamepot.COMPROMISEisstillanalternativetotheBiologicalApproach.Still, COMPROMISE is hardly the sort of view that the philosophers I have

discussed had in mind. As things are, human brain tissue does not have thecapacity to regenerate itself after being damaged or destroyed; once someonelapses into a persistent vegetative state due to massive cerebral damage, norecoveryispossible.Butperhapsthingsmighthavebeenotherwise.Supposeaseverely damagedor even a surgically removed cerebrumcould regenerate, insomethinglikethewaythatastarfishcangrowanewarmafteroneisdetached.(The information sufficient for growing a cerebrum is still present in thechromosomesofeveryhumancell;theyneedonlybeactivatedbybeingputinto

the right surroundings.) If that is possible, then according toCOMPROMISE onemightsurvivethedestructionofone’smentalcapacitiesandcontinuetoexistasa human vegetable, for even after your cerebrum is destroyed, the resultinganimalwouldhavethesamesecond-ordermentalcapacitiesas thefetushas: itcould,inthenormalcourseofitsdevelopment,becomerationalandconscious.Moreover,itwouldnotbeclearthatyoucouldsurviveacerebrumtransplant,forboththerecipientofthatorganandtheempty-headedanimalleftbehindwouldhavesecond-ordermentalcapacitiesthatwererelatedintheappropriatewaytoyours.The“ordinary”cerebrumtransplantwouldbeafissioncaseliketheoneinwhicheachhalfofyourcerebrumisimplantedintoadifferenthead.Soitisfarfrom clear that COMPROMISE can accommodate the sorts of considerations thatmotivatedthePsychologicalApproachinthefirstplace.Nodoubt thesedefectscouldberemediedbyaddingfurtherqualifications to

COMPROMISE,perhapssomethingalongthelinesofTRICKintheprevioussection.To my mind, though, it is a mistake to look for an account of our identityaccording towhichwewere once fetuses but could never become vegetables.Thinkaboutwhyitwaswrongtosaythatnoonewaseverafetus.Ifyouwereneverafetus, thenthefetusyourmotherboreceasedtoexistwhenitsnervoussystemmadecertainmentalcapacitiespossible,andanewanddifferentbeing—you—tookitsplace.Butitdoesnotseemtobethecasethatananimalperishesandisreplacedbyanumericallydifferentanimalsimplybecauseofachangeinitsmentalcapacities. Instead, thesameanimalfirst lacksandthenacquires theabilitytothink.Alternatively,perhapsthefetusyourmotherboredidnotceasetoexistwhenyoucame intobeing,but simplycame to share its spaceand itsmatter with you. But that seemed to entail that there are two thinking beingsinsideyourskin,apersonandananimal.If these are good reasons for thinking that you were once a fetus, they are

equallygoodreasonsforthinkingthatyoumightonedaybeahumanvegetable.Supposeonecouldnotsurviveasavegetable.Thensomeonewholapsedintoapersistent vegetative state would cease to exist. Although it cannot think orremember or feel anything, though, the resulting being is also a living humananimal. It canbreathe, circulate itsblood, regulate its internal temperatureandrateofmetabolism,digestitsfood,fightoffinfection,growandrepairdamagetoitself,andsoon,withoutanyoutsidehelp.Wheredidthatanimalcomefrom,ifit isn’t you? Either it came into beingwhen you perished, or it was there allalong,sharingitsspaceanditsmatterwithyouuntilyouceasedtoexist.Butitdoesnotseemtobethecasethatthatananimalperishesandgetsreplacedbyanumericallydifferentanimalsimplybecauseofachangeinitsmentalcapacities.Rather,thesameanimalfirsthasandlaterlacksthecapacitytothink.Andthere

are not two numerically different beings inside your skin, a person and ananimal.Thus,itseemsthatifIwasonceafetus,thenImightonedaybeavegetable.

Startingoutasa fetusandendingupasavegetableare twosidesof the samephilosophicalcoin.ButIshallhavemoretosayaboutthesemattersinthenextchapter.

V.WhenDidIBegin?

WhatdoestheBiologicalApproachhavetosayaboutthefetusproblem?Whendowecomeintobeing?OntheBiologicalApproach,whatittakesforustosurviveremainsthesame

throughout our careers: like other animals, we persist as long as our life-sustaining functions remain intact.One survives, at any point in one’s career,just in caseone’s circulation, respiration,metabolism, and the like continue tofunction,oraslongasthoseactivitieshavenotirreversiblycometoahalt,oraslongasone’scapacity todirectandregulate thosefunctionsisnotdestroyed.Ishallhavemoretosayaboutthisinthenexttwochapters.Therelevantpointforpresent purposes is that these vegetative functions do not require any mentalactivityormentalcapacities(oratleastnotany“first-order”mentalcapacities).A human vegetable that can be kept alivewith a feeding tube is still a livinghumananimal,eventhoughitnolongerhasanymentalfunctions.Afour-week-oldhumanembryoisalsoalivinghumananimal: ithasitsownDNA,itsownclosedcirculatorysystem,itsownbloodtype, itsownimmunesystem,andtheprimitivebeginningsofitsownnervoussystem.9IstartedoutasanunthinkingembryoandImayendupasahumanvegetable—aslongasmylife-sustainingfunctionscontinue.Thereisno“fetusproblem”fortheBiologicalApproach.Ahumanfetusorinfantdoesnotperishwhenitbecomesabletothink(unlessthatprocess somehow interrupts its vital functions), nor is there any reason to saythat it becomescoincidentwith a thinkingbeingnumericallydifferent from it.Thefetusorinfantsimplycomestobeaperson.SomefinditstrangetosaythatIwasonceanunthinkingembryo(Engelhardt

1974,219ff.).‘I’isapersonalpronoun,theypointout,andcallingsomethingbya personal pronoun, unlesswe are speaking loosely, aswe dowith ships andpets, implies that it is a person, that is, a rational, self-conscious being. Theembryoisnotan“I”,butan“it”.Sowecannotsensiblyaskwhoafetusis,sincethat is toaskwhichperson it is,anda fetus isnotaperson.Andfor thesamereason(onemightthink)itisabsurdtosaythatImightonedaybeavegetable.

Butevenifwegrantthatpersonalpronounscannotproperlybeappliedtonon-people, this accident of grammar couldhardly entail ametaphysical or factualclaim aboutwhen a human being begins or ceases to exist. Theremight be alanguage with no such distinction between personal and impersonal pronounsandinterrogatives,andspeakersofsuchalanguagecouldaskandsaywhatwesupposedly cannot. The problem of how to talk about the way I was or maycometobewhennotapersonisnomoreseriousthantheproblemofhowtotalkaboutsomeonewhohashadorisplanningasex-changeoperation.Whenamanhas such an operation,we refer to him afterwards as ‘she’, and talk about thethingsshedidwhenshewasaman.Whilethismaybegrammaticallyawkward,itishardlyreasontothinkthatitisimpossibletochangeone’sgender.Andwhatgoesfor‘he’and‘she’,Ithink,goesfor‘I’and‘it’aswell.Whendoesonebegin?Idonotmeanwhenhumanlifebegins,orwhetheran

embryoorfetusisahumanbeing.MyquestioniswhenyouandIbegantoexist.DoestheBiologicalApproachentailthatwebegantoexistatconception?Thatyouwereonceafertilizedovum?Thatisdoubtful.Youbegantoexistwhenthehuman animal that you are came into being. But that organismwas probablyneverafertilizedovum.Tobesure,thefertilizedeggisabiologicalorganism.Itisanorganismbecauseeverylivingcell(perhapswithafewexceptions,suchasredbloodcells,whichhavenonucleusandnoDNA)isanorganism.Butwhenthefertilizedeggcleavesintotwo,thenfour,theneightcells,embryologiststellus, it does not become a two-celled, a four-celled, and then an eight-celledorganism.Thosecellsadhere togetheronly loosely,andtheirgrowthandotheractivitiesarenotcoordinatedinthewaythattheactivitiesofanorganism’scellsarecoordinated.Untiltheendofthesecondweekafterfertilization,thecellsareallalike,or totipotent: theydonothavespecialized tasks,andeachcanbe theancestorofanykindofhumancell.Mostofthosecellsinfactdevelopintotheplacenta andother supporting structures andnot into the embryoproper.Eachfunctionsindependentlyoftheothers,metabolizinganddividingatisownrate.If you separated the cells into two clumps, you would end up with identicaltwins; and if you put the separated cells back together—before they begin tospecialize,atanyrate—onlyonehumanbeingwillresult. Infact, thecellscanberearrangedarbitrarilywithoutaffectingtheeventualoutcome(Diamond1975,312).Althoughthezygotehasitsownuniquegenotype,thatgenotypedoesnotdirectitsdevelopmentintheearlystages;thatisdoneinsteadbybitsofmaternalRNA(Ford1988,113,118;Diamond1975,310).Thezygotedoesnotbegintoabsorbnutrientsfromitsenvironmentorgrowinmassuntilafter implantation;untilabouttheendofthethirdweek,whentheembryonicheartbeginstobeat,thecellsarecompletelydependentontheinternalreservesthatwerepresentin

theoriginalovum.Why suppose that the loosely adhering cells of the zygotemakeup a single

multicellular organism? Not simply because they are stuck together, for youcan’tgettwolivingorganismstomakeupalargerorganismsimplybycausingthemtoadheretooneanother.Nordoesthefactthatasingleorganismtypicallydevelopsfromthosecellsentail that theymakeupamulticellularorganism.Ahumanorganismdevelopsfromaparticularspermandegg;butthosetwocellsdidnotmakeupanorganismbeforetheycametogether.Manyembryologistsbelievethatagenuinehumanembryo—themulticellular

organismthatlaterbecomesafetus,aninfant,andanadult—comesintobeingaboutsixteendaysafter fertilization,when thecells thatdevelop into the fetus(asopposedtotheplacenta)becomespecializedandbegintogrowandfunctioninacoordinatedmanner.Theydevelopbilateralsymmetryaroundthe“primitivestreak”, the ancestor of the spinal cord. At this point, twinning is no longerpossible: cutting away half the cells would not result in two smaller livingembryos, but would simply cause death. “Prior to this stage,” writes NormanFord,inhisfascinatingbookonthesubject,

we do not have a living individual human body, but a mass of preprogrammed loosely organizeddevelopingcellsandheterogeneoustissuesuntil their‘clock’mechanismsbecomesynchronizedandtriggered toharmoniouslyorganize,differentiateandgrowasheterogeneouspartsofasinglewholehumanorganism.(1988,175)10

Onlyatthispointdowewehaveamulticellularorganismandnotmerelyamassoflivingcellsstucktogether.According to theBiologicalApproach,youare theorganismthatcomes into

being then; so if we have done our embryology correctly, you began to existroughly fourteen to seventeen days after conception. This is a purely factualmatter, tobesettledempirically.There isnothingsubjective,on theBiologicalApproach, about the question when you and I came into being. It is not anethicalquestion,butascientificone.11TheremaynotbeaprecisepointatwhichIcameintobeing,butonlyavagueperiod;butthatdoesnotmakethequestionanymore subjective or less factual.When the animal that you are acquires acertainmoral status is a different issue, not to be confused with the questionwhen the animal came into being. And of course facts about psychologicalcontinuity and about the embryo’s or the fetus’s mental capacities arecompletelyirrelevant.Thispositionmaysoundparadoxical.Isaidthatthefertilizedovum,likeother

cells, isa livingorganism,but that it isnot thehumanorganism thatdevelopsfromitandgrowsintoafetus,aninfant,andanadult.Whatsortoforganismis

that fertilized ovum, then? Is it a human organism numerically different fromyou,theanimalwhodevelopedfromit?Didyourparentshaveasonordaughterwho lived just a few hours before it divided and died?Mustwe say that in asense you are your parents’ grandchild? And if the fertilized ovum is not ahumanorganism,whatspeciesdoesitbelongto?These questions are sophistical. If I am right in assuming (as biologists

typicallydo)thatlivingcells,includingthosethatarepartsoflargerorganisms,are themselvesorganisms, thequestionwhatspeciessuchanorganismbelongstoisotiose.Acellthatispartofyourcatisinasenseafelineorganism,butitisnotacat.Likewise,thecellsthatmakeyouupnoware“human”organisms(asopposed to feline ones), but they are not human beings,Homo sapiens. Thefertilizedovumisahumanorganismin theformersense.Conversely, if it isamistaketothinkthateverycellisalivingorganism,thenitisnotclearthatthefertilizedovumisalivingorganism.Some readers may suspect that the Biological Approach faces its own

analogue of the “fetus problem”.12According to that view, Imust be a livingorganismthroughoutmycareer.13Themulticellularzygoteor“pre-embryo”thatresults when the fertilized ovum divides, however, does not seem to be anorganism;nomulticellularanimal ispresentuntil the“primitivestreak” forms,some twoweeks later.Thus, Iwasneverazygote. If so,whathappens to thatmulticellularnon-organismwhenagenuinehumanorganism—youorI—comestobe?Therewouldseemtobetwopossibilities:eitherthezygoteceasestoexistand is replacedbyanumericallydifferentbeing, theanimal;or it continues toexist but comes to share its space and its matter with an animal numericallydifferentfromit.Butneitheroptionisacceptable.Obviouslyazygotedoesnotcease to exist simply because its cells, in the normal course of theirdevelopment, come to be integrated in such a way as to compose a livingorganism.And the cells of the embryoproper don’tmakeup twonumericallydifferentbeings,oneofwhichcameintobeingtwoweeksafterfertilizationandtheotherofwhichexistedbeforethen.Forassumingthatbothobjectssurvivedtoadulthood,wouldn’t theybothcometoberationalandconscious?Wouldn’tthatmean,absurdly,thatthereweretwopeoplesittinginmychair,writingthisbook?(HowcouldIknowwhichoneIwas?)Thus,theBiologicalApproachhasno more attractive solution to the fetus problem than the PsychologicalApproachhas.However,weneednotsupposethatthereisanyonepersistingobject,beitan

organismor anything else, that is first a fertilizedovumcomposedof a singlecell,andlaterconsistsoftwocells,thenfour,andsoforth.Bywayofanalogy,

when an amoeba divides into two cells, it does not become a two-celled,spatiallyscatteredobject.Itceasestoexistandisreplacedbytwodifferentcells.Atanyratethatseemstobethemostreasonablethingtosayaboutthematter.Youmightthinkthatsomesinglematerialobjectmustsurvivethechangefromone cell to two because there is spatio-temporal continuity. But the samereasoning would entail that the fertilized ovum existed before fertilization aswell, and was composed of an unfertilized egg and a sperm, for the egg andsperm are also spatio-temporally continuous with the resulting fertilized egg.Thatwouldmean thatyouand Iandeveryother livingorganismexisted fromthebeginningoflifeonearth.You might suggest that the fertilized ovum must persist as a multicellular

zygote, an embryo, a fetus, and finally as a child because those stages are alllinkedbyasingle,continuousprocessofgrowthanddevelopment (aside fromthosedescendantsof thezygote thatbecome theplacentaandothersupportingstructures).14A living thing,organismornot,doesn’t cease toexist simplybygrowinganddevelopinginitscharacteristicway.But inasensethereisalsoacontinuous process of growth and development when an amoeba grows anddivides into two, four, and then eight daughter amoebas; and yet the originalamoebadoesnotbecomeaneight-celledobject.There isnot, so to speak,anysingle process of growth and development that encompasses all of the eightresultingamoebas;eachdaughtercelldevelopsincompleteindependenceoftheothers.But precisely the same is true for the fertilized ovum and its daughtercells; that is why embryologists deny that the ovum becomes a two-celledorganismwhenitdivides.Thereisagreatdealmoretobesaidabouttheidentityoflivingorganisms.I

shall have more to say about the matter in the next two chapters; but manyquestionswillremainunanswered.

5

ArePeopleAnimals?

I.HumanPeopleorHumanAnimals?

IturnnowtothemostfundamentalproblemfacingthePsychologicalApproach:Ifweacceptthatview,itseemsthatwemustdenythatwearehumananimals.Notonlyarewenotessentiallyanimals;wearenotlivingorganismsatall,evencontingently.WecanseethisifweconsiderthetwopuzzlecasessetoutinChapter1.Inthe

first story, you lapse into a persistent vegetative state, in which yourmind isdestroyedbutthosevegetativefunctionsthatkeepyoualivecontinue.Accordingto the Psychological Approach, that is the end of you. But no human animalceasestoexistwhenthishappens.“Your”humananimal—theoneyoupointtowhenyoupoint toyourself—continues to liveandbreathe; it simply loses itspsychological features. Even if you never in fact lapse into a persistentvegetative state, you could do so, and if that happened, your human animalwouldoutliveyou.Andifyouandtheanimalcouldcomeapart,youcouldnotbetheanimal:athingcannotoutliveitself.Fromthisitfollowsthatyouarenotananimal.Forthereisonlyonehumananimalsittinginyourchairandwearingyourshoesrightnow,nottwo,andthatanimal,beingabletooutliveyou,isnotyou.In the second story,we transplant your cerebrum fromone head to another.

Butwe don’t transfer anyanimal from one head to anotherwhenwe do this.Rather,wetransplantanorganfromoneanimal toanother.Thehumananimalassociated with you stays behind when your cerebrum is removed. You,however, go along with your cerebrum, according to the PsychologicalApproach.Evenifyouinfactnevergetseparatedfromyouranimal,youcouldbeseparated.Soyoucouldnotbethatanimal:athinganditselfcannotgotheirseparateways.I want to argue that since you and I are human animals, the Psychological

Approachmustbefalse.TodothisIneedtodefendtwoclaims.First,Ineedto

arguethatwereallyareanimals.Thisisthetaskofthenextfoursections.ThenImust try to show that thePsychologicalApproachcouldnotbe trueofhumananimals—thatnopsychologicalrelationisnecessaryandsufficientforahumananimaltopersistthroughtime.Thatis,Imustarguethatahumananimalreallydoessurvivewhenit lapses intoapersistentvegetativestate;or thatnohumananimal is transferred from one head to another when your cerebrum istransplanted.ThismoredifficultprojectistakenupinSectionsVItoVIII.

II.Appearances

IsaidIwouldarguethatyouandIareanimals.Thismightseemastrangethingtoarguefor,givenourassumptionthatyouandIarematerialobjects.Wherearewe going to find premises that are evenmore obviously true than thatwe areanimalsifwearematerialobjectsatall?Wecanunderstandhowsomeonemightdenythatwearenotanimalsbyrejectingmaterialism.Manyphilosophershaveargued that we are not material objects of any kind, but immaterial souls, orabstract objects akin to computer programs, or the like; or thatwe essentiallyhavesomeimmaterialpart.Butonceitisconcededthatwearematerialbeingsofsomesort,itseemsquiteobviouswhatsortofmaterialbeingsweare:wearelivinganimals.Tobespecific,ouropposablethumbs,forward-facingeyes,andevolutionary history make it clear that we are primates, along with apes,monkeys,andlemurs.Anymaterialistcouldeasilypersuadehimselfthatheisananimal by examining himself in a mirror—or, if need be, by having himselfexaminedmorethoroughlybyacompetentzoologist.Chisholmhaswritten:

[I]nourtheoreticalthinking,weshouldbeguidedbythosepropositionswepresupposeinourordinaryactivity. They are propositions we have a right to believe. Or, somewhat more exactly, they arepropositionswhich should be regarded as innocent, epistemically, until there is positive reason forthinkingthemguilty.(1977,169)

And thatwe aremembers of the speciesHomo sapiens is certainly somethingthat we ordinarily assume when we are not doing philosophy. Anyone whoclaims to be a materialist but at the same time insists that you and I are notanimals, or holds a theory of personal identity inconsistent with our beinganimals,hasgotsomeexplainingtodo.ButthefriendsofthePsychologicalApproachhaveasubtlereplytothis.They

willconcedethatweareanimals,andobviouslyso.Theywillevenagreethatnoanimal is transferred from one head to another when your cerebrum istransplanted, and that no animal ceases to exist when you become a humanvegetable. Nevertheless, they claim, the Psychological Approach is consistent

withthefactthatweareanimals:

Theclaimthateachhumanpersonisananimal(thereplygoes)isambiguous.The source of the ambiguity is the harmless-looking word is: we mustdistinguishthe“isofidentity”fromthe“isofconstitution”.Ofcourseyouareananimal.Butinsofarasthisisanundeniableempiricalfact,itdoesnotentailthatyouarenumericallyidenticalwithanyanimal.Rather(asShoemakerputsit),“aperson‘is’ananimal,notinthesenseofbeingidenticaltoone,butinthesenseofsharingitsmatterwithone.”1Whenyoulookinamirroryouseeananimal.Itiseasytobelievethatyouandthatanimalareoneandthesame,andthatisindeedthewayitappears.Thatisbecauseyouareconnectedwiththatanimalinaparticularlyintimateway:youandtheanimalaremadeoftheverysameatomsandoccupyexactlythesameregionofspace.Butwhenweattend to that animal’s modal and dispositional properties (and perhaps itshistorical features aswell, aswe saw in the previous chapter), and comparethem with your own, we see that the animal must be numerically differentfromyou.Humanpeopleappear tobeidenticalwithhumananimalsbecausetherelationofcompletespatialandmaterialcoincidenceiseasilymistakenforidentity.Sothereisnothingabsurd(saythefriendsofthePsychologicalApproach)in

denyingthatyouarenumericallyidenticalwithanyanimal;tosaysoismerelyto takeoneside inanarcanemetaphysicaldispute. Ifyouwant toclaimthatyou are an animal in the sense of beingnumerically identicalwith one, youwillneedaphilosophicalargumentforthatclaim.Ifyouwanttosaythatweareobviouslyandverifiablyanimals,youcanestablishthatwe“are”animalsonly in the sense that we stand to those animals in some relation that isempirically indistinguishable from identity—forexample, thatweeach shareallofourmatterwithananimal.

ThisreplyisanalogoustoamovethatCartesiandualistshavebeenmakingforcenturies.Considerasimple-mindedargumentagainstDescartes:

Youcan’tdenythatyouweighatleast150pounds.(Steponthescalesandseefor yourself if you don’t believe it.) But only a material object can haveweight.Thereforeyoumustbeamaterialobjectandnotanimmaterialsoul.

Cartesianshaveareadyreply:

Iconcede that Iweigh150pounds,and thatonlyamaterialobjectcanhaveweight.ButthatdoesnotimplythatIamnumericallyidenticalwithanything

thatweighs150pounds.ItmerelyentailsthatIamintimatelyconnectedwithsome150-poundobject.Whatmakesittruetosay,intheordinarybusinessoflife,thatIweigh150poundsisthefactthatmybodyweighs150pounds.Tothink otherwise is to confuse the property ofweighing 150 poundswith thesuperficially similar property of having a body that weighs 150 pounds.Comparethetruckdriverwhosaysattheweighstation,“Iweigh35tons.”Shemeans,ofcourse,thatsheisdrivingatruckthatweighs35tons.IfyouwanttoestablishempiricallythatIweigh150pounds(bysettingmeonthescale,say),youcanshowonlythatIweigh150poundsinthesenseofstandinginsomerelation empirically indistinguishable from identity with something of thatweight.IfyouwanttoshowthatIhavethepropertyofweighing150poundsinthestrictandliteralsense—thatIhavethatpropertyinthewaythatIhavethe property of thinking, for example—you will need a philosophicalargument.

If thisreplyissound,Cartesiandualismisnotabsurdonitsface; itdoesnotconflictwithanythingthatnosanepersoncoulddeny.Itisevenconsistentwiththeordinary,nonphilosophicalclaimthatyouandIareanimals.Inthatcase,wecanconcedethatthesameistruefortheviewthatyouandIarematerialobjectsbut not animals. Nevertheless, Cartesian dualism faces problems that areimmune to solutions from the philosophy of language. No matter what ourordinary, nonphilosophical claims about ourselves mean or entail, the dualistmust confront anumberof seriousmetaphysical challenges; and shewillhavetroublesquaringherviewwithcontemporaryscience.Thesameholds,Ibelieve,forthe“anti-animalist”claim.

III.Coincidence

NoadvocateofthePsychologicalApproachisgoingtodenythattherearesuchthings ashumananimals.Thus, theviewunder consideration is that there is ahuman animal sitting in your chair and wearing your clothes right now. Itoccupies the same region of space that you occupy; it has the same size andshape, thesamemass, thesamechemicalcompositionandcellularstructureasyouhave.That is because that animal ismadeof the samematter as you are,arrangedinthesameway.Yetthatanimalisnotyou,foritwouldoutliveyouifit became a human vegetable. You and the animal are numerically differentbecauseyouhavedifferentpersistenceconditions.This view faces a general metaphysical difficulty.2 You and the animal are

nowmadeupofthesameatoms,arrangedinthesameway.Thiswouldappear

to make you and the animal exactly alike: you are, now at least, perfectduplicatesofoneanother.Thisraisesanapparentlyunanswerablequestion:Howcanwe destroy just one of two qualitatively identical objects by applying thesameforces tobothof them?That is,whydoes thedestructionofyourmentalcontents or capacities destroy you but not the human animal connected withyou?Andwhydoesdestroyingallofyoubutyourcerebrumdestroytheanimalbutnotyou?Whatisitabouttheanimalthatenablesittosurvivesuchathing,and what is it about you that prevents you from surviving it? What is thedifference between you and the animal that gives it different persistenceconditionsfromyours?Youmaythinkthattheanimalsurvivestheadventureinquestionwhileyoudo

not because the animal is an animal and you are a person; and being able tosurvive the loss of all mental features is part of the nature of animals, whilebeingunabletodosoispartofthenatureofpeople.Thatis,theanimalsurvivesand thepersondoesnotbecauseeachhasadifferentcriterionof identity.Thismightbeaperfectlygoodwaytoexplainwhysomeparticularanimalsurvived,and some particular person did not survive, on some particular occasion: thisparticular animal survived brain damage today because it had the capacity tosurviveit,andthatparticularpersondidn’tsurvivetheverysamebraindamagebecauseitlackedthatcapacity.Butthatleavesuswonderingwhytheanimalcansurvivethatadventureandwhythepersoncannot.Whatgivesthepersonandhercoincident humananimal thesedifferent capacities or dispositions?Wecannotanswerthisquestionbyappealingtothedifferencebetweenpeopleandanimalsandthefactthatthepersonisapersonandtheanimalisananimal.Forallthatmakesoneofthetwothingsinquestionapersonandtheotherananimalisthisdispositional difference; the only difference between you and the animal ismodalordispositional.Tobesure,youandtheanimalmighthavedifferenthistories,aswesawinthe

previouschapter.Youmighthavecome intoexistence severalmonthsorevenyearsaftertheanimalassociatedwithyoudid,perhapswhentheanimalbecamerational.But themere fact that two thingswereoncedifferentcannotby itselfexplainwhy one of them can now survive an adventure that the other cannotsurvive.Inanycase,thehistoricaldifferencebetweenthepersonandtheanimalisanaccidentalfeatureofthesituationswehavebeenimagining.Youandyouranimalwouldhavedifferentpersistence conditions even if yourhistorieswerethe same—if you had been created fully grown, for example, rather thandevelopingfromafetusliketherestofus.Wecanillustratetheproblemwithathoughtexperiment.Imagineawondrous

machine with the power to make a perfect duplicate of any material object.

Whenyouputsomethingintothe“in”boxofthemachineandpressthebutton,themachine“scans”theobject,recordingtheprecisestateandlocationofeveryatom,andthensendsthisinformationtothe“out”box,whereitgathersfromitsstockofrawmaterialsthesamenumberofatomsofthesamekindsandarrangestheminpreciselythewaythattheoriginalobject’satomsarearranged.Whenthemachinehasdoneitsworkthereappearsinthe“out”boxanobjectthat,thoughnumerically different from the original, is exactly similar to it in all of itsmomentary, physical properties, and in those properties that are fixed by itsphysicalproperties.Nowimaginethatyoucrawlintothe“in”boxoftheduplicatingmachineand

press the button.What should we expect to find in the “out” box?Well, weshould find atoms exactly like the ones that composed you a moment ago,arrangedinjustthewaythatyouratomswerearrangedthen.Letussupposethatthoseatomswouldcomposetwodifferentthings,apersonandlivingorganism.(Iftheydidn’t,weshouldwonderwhyyouratomscomposebothapersonandanorganism.)Whichiswhich?Theanimal,youwillsay,istheonethatcansurviveasavegetable,andthepersonistheonewhocannot.Butwhatdidthemachinedotogivethosetwoobjectsdifferentpersistenceconditions?Itmusthavedonesomethingmorethansimplyarrangeatoms,forthearrangementofatomsisthesame in both objects (their being the very same atoms). If the machine didnothingbeyondarrangingatoms,thesamecausesactinginthesamewaywouldhaveproducedboth theperson and the animal, and therewouldbenothing toaccountfortheirdifference—forthefactthatonebutnottheothercansurvivethedestructionofitscerebrum,forexample.Andwhatfeaturesoftwomaterialobjectsotherthanthenatureandarrangementoftheatomstheyarecomposedofcould account for such a difference? You may insist that an object’sdispositional and modal properties are not fixed by its internal, structuralfeatures,andthattwoobjectscomposedofthesameatomsarrangedinthesamewaycanverywelldifferintheirdispositions.Thatmaybe;buthowwouldourduplicating machine bestow these different dispositions on the two objects?Whatwould it have to do beyond just arranging atoms?Andwhat shouldweexpecttofindinthe“out”boxofthemachineifitdidnothingbeyondarrangingatoms?I doubt that there is any satisfactory answer to these questions. I think we

oughttoconcludethatthecurrentproposal—thatyouandIarematerialobjectsbut not animals—is incoherent.Many readers, though,will find this argumentunpersuasive, for the notion that twomaterial objects can be composedof thevery same atoms and occupy the same space at once is a widely acceptedphilosophical dogma.3 Thus, let us consider some possible strategies for

defending the view that people and human animals materially and spatiallycoincideagainsttheargumentgivenabove.Iclaimedthattheonlydifferencebetweenyouandyourhumananimal,onthe

current proposal, is the difference in what it takes for you and the animal topersist through time, leaving themysteryofhow thosedispositionalpropertiescouldvarywithoutanydifferenceintheunderlyingphysicalproperties.Butthatmayhavebeenoverlyhasty.Youmighttrytoarguethatthepersonhasallsortsof psychological and other properties that her coincident human animal lacks.Youcanhaveconversations,balanceyourcheckbook,hopeforbetterweather;but the human animal connected with you cannot do any of those things. Sothere are many differences between you and the animal to account for yourdifferentpersistenceconditions.Butwhyisn’tthatanimalrationalorintelligent?Whydoesn’titspeakEnglish,

performactionsforwhichitismorallyaccountable,andingeneralhaveallthesamepsychologicalandbehavioralpropertiesthatyouhave?Itsbrainisexactlylike yours, and it is connectedwith itsmovements and the stimulations of itssensoryorgans in the sameway as yours are.Your thoughts are states of thatanimal, justas theyarestatesofyou.Evenyoursurroundingsare thesame. Ifthat animalwere not rational or conscious,we should have to conclude that abeing’s neural states, behavioral dispositions, and surroundings were notsufficient to fix itspsychologicalproperties,orevensufficient toensure thatabeinghasanypsychologicalfeaturesatall,foryourhumanorganismwouldbeexactly like you in those respects but lack any thought or consciousnesswhatever.TypicalmembersofthespeciesHomosapienscertainlyappeartobeintelligent language-users, an appearance confirmed by a number of well-establishedsciences.Anyonewhowoulddenythismustbepreparedtoproposeatheoryofintentionalitythatcouldaccountforit.Psychological and behavioral features are emergent properties, you might

suggest,differentfromathing’spurelyphysicalproperties;sowhyshoulditbesosurprisingifphysicallysimilarthings—humanpeopleandhumananimals,forexample—have different psychological features, and thus different persistenceconditions?This is a red herring. Emergent properties must emerge out of something;

thingscannothavedifferentemergentpropertiesunlessthereissomeunderlyingintrinsic difference between those things. Fragility is a dispositional propertythatemergesoutofa thing’snondispositional,microstructural features; so twoobjects with the same microstructure must be either both fragile or bothnonfragile. In the same way, there are no underlying, nonpsychologicaldifferencesbetweenyouandyourhumananimal—nor anydifferences inyour

surroundings—thatcouldaccountfordifferentemergentproperties.You might try to argue that animals belong to the wrong “category” to be

rational or conscious. The human animal associatedwithme is justmy body,andalthoughImightwritealettertoyou,mybodycannotwritealettertoyourbody. But why not, if ‘my body’ is the name of a material object that isphysically indistinguishable fromme?Whateverwemay end up saying aboutthe notion of a category mistake, it is hard to see how this could prevent amaterial object from being rational or intelligent if it has the same physicalproperties(andthesamesurroundings)assomerational,intelligentbeing.Inmyopinion,thereasonwhy‘mybodywrotealettertoyourbody’soundsabsurdisnotthat‘mybody’isthenameforsomematerialobjectdevoidofpsychologicalfeatures,but that thosewordsareused tocallattention tomy“brute”physicalproperties,andawayfrommymentalfeatures.Soitmaybeliterallytruethatmybody wrote a letter to your body; but this way of putting it has a false ormisleadingconversationalimplicature.ButmoreonthisinChapter6.Some have tried to account for the difference between human people and

humananimalsbysayingthattheanimal“constitutes”theperson(e.g.,Johnston1987a, 76, 78). The animal could outlive the person in away that the personcouldnotoutlivetheanimal.Analterationoftheanimalnotinvolvinganylossof its parts (braindamage, for example)would entail andexplain theperson’sdestruction(Doepke1982).Moregenerally,thepropertiesoftheanimalexplainthe properties of the person in away that the properties of the person do notexplain the properties of the animal. So although the animal constitutes theperson,thepersondoesnotconstitutetheanimal—animportantdifference.This reply is unhelpful for two reasons. First, the animal’s constituting the

persondoesnotalterthefactthatthepersonandtheanimalarenowcomposedof the same atoms arranged in the same way, and thus are perfect intrinsicduplicates of one another. The constitution relation is just as problematic ascoincidenceitself.Ifitismysterioushowoneoftwophysicallyidenticalobjectscouldsurvivesomethingthattheothercouldnotsurvive,itisjustasmysterioushowoneofthemcouldconstitutetheother.Second, the mystery of how the animal could outlive the person is not a

mystery about coincident objects per se.4 It is a problem about how any twomaterial objects,whether or not they share theirmatter, can be exact physicalduplicatesofoneanotherandyethavedifferentpersistenceconditions.And iftherearecoincidentobjects, therearealsoqualitatively identicalnoncoincidentobjects with different persistence conditions, neither of which constitutes theother.Supposeoncemore thatweuseour fantasticmachine tomakeaperfectduplicate of you—a person intrinsically exactly like you, but made of

numerically different atoms andoccupying a different regionof space. (Leaveasidethequestionofwhetherandhowthemachinealsomakesananimalexactlylikeyouranimal.)Thatpersonisaperfectintrinsicduplicateoftheanimalnowcoincidentwith you.On the current proposal, that personmust have differentpersistence conditions from those of your animal, just as you and that animalhave different persistence conditions. But even if the fact that your animalconstitutesyoucanexplainwhyyouanditcansurvivedifferentthings,itcannotexplainwhy that animal and the duplicate person can survive different things,foryouranimaldoesnotconstitutethatperson.

IV.Personhood

Thismaybe just somuchadoaboutnothing.Perhapswecanunderstandhowtwoperfectphysicalduplicatesofoneanothercouldhavedifferentpersistenceconditions.Butevenifthedifficultiesaboutcoincidentobjectsingeneralcanberesolved, themorespecificdoctrine thatyouandIarematerialobjectsbutnotanimalsfacesitsownspecialproblems.Itisnotconsistentwithanyacceptableaccountofwhatapersonis.Thispointissoimportantthatafewremarksaboutthenotionofpersonhoodareinorder.Whatisaperson?Whatisitaboutyouandmethatmakesuspeople,andwhat

is it about oysters and overshoes that makes them non-people? Because ourconcern iswhat it takes forhumanpeople topersist through time, theremightnotbe anyneed to address thisquestion. It is clear enough that you and I arepeople, and we don’t in practice havemuch trouble telling people from non-people.As ‘person’ inEnglishcanmeanmany things,What is aperson?maynotevenbeaquestioningoodstanding.ButthePsychologicalApproachgivesthis question a clear sense, for it purports to give conditions under which allpeopleandonlypeoplepersistthroughtime.Oratanyratethatisthewayitisusuallyunderstood.Ifthatviewistrue,thenthereisaclassofbeingsthatcanbedistinguished fromotherbeingsby their persistence conditions: people, in thissenseoftheword,arejustthosebeingsofwhichthePsychologicalApproachisorpurportstobetrue.Inwhatsenseof‘person’isthePsychologicalApproachmeanttotelluswhat

ittakesforapersontopersist?Itisoftenassumedthatpersonhoodissomesortofpsychologicalconcept.Cabbagesaren’tpeoplebecausetheydon’thavemindsatall,andalthoughchimpanzeesanddolphinscertainlyhaveminds,asfarasweknow their mental powers aren’t sophisticated enough for them to count aspeople.ThiswasLocke’sview:

[W]emust considerwhatPerson stands for;which, I think, is a thinking intelligentBeing, thathasreasonandreflection,andcanconsideritselfasitself,thesamethinkingthingindifferenttimesandplaces;whichitdoesonlybythatconsciousness,whichisinseparablefromthinking,andasitseemstomeessentialtoit.(EssayII.xxvii§9)

WemayquibbleaboutLocke’sclaimthatthinkingentailsconsciousness,butwegettheidea:apersonisarationalbeingcapableofthought,consciousness,andacertainkindof self-awareness that involves thinkingof itself as tracing apaththroughtimeandspace.Many contemporarywriters followLocke here. Frankfurt, for example, says

that what is essential to being a person is having “second-order volitions”:desirestobemotivatedbyotherdesiresthantheonesthatinfactmotivateone(1971). I might want to be motivated to finish my work because of theenjoymentIgetoutofit,ratherthanbythefearofwhatmayhappenifIleaveitundone,forexample.Itisthecapacitytowantsuchthings,togetherwithallthatnecessarilygoesalongwithit,thatmakesyouandmepeople.Inasimilarspirit,Swinburneproposesthathavingsecond-orderdesires,togetherwiththecapacitytouselanguageforcommunicationandthought,theabilitytothinkaboutthingsbeyond observation, such as invisible particles, and the ability tomakemoraljudgmentsare jointlysufficient forpersonhood,and thathavingat leastoneofthese features is essential (1977, 101 ; other Lockean accounts includeLockwood1985,10;andNoonan1989,10).WemightcallthissortofviewtheLockeanAccountofpersonhood(although

Aristotlemayhavehad the idea first). It soundsplausible enough.The idea isthatpersonhood isacomplexpsychologicalproperty: thedifferencebetweenapersonandanon-personisadifferenceinpsychologicalcapacities.Somethingisaperson just incase it is smartenough, in the rightway, tobeone.Nodoubttherewillbeborderlinecases—someofwhichcanbefoundinanystatehospital—but the same is trueof almost anyuseful concept. If it is not possible for arobottobeaperson,thatisnotbecausearobotisanartifactorbecauseitisnotaliving organism (or at at least not just because of that), but because no robotcould have rationality, or self-consciousness, or second-order desires, or freewill,orsomeotherpsychologicalfeaturethattheLockeanAccountrequires.Some Lockeans include being a moral agent in their list of person-making

features. I shall suppose for simplicity’s sake that this too is a psychologicalproperty.Thatmaynot quite be true; but itwould seem to be primarily one’spsychologicalfeaturesthatmakeoneamoralagent.InthatcaseitisroughlytheconceptofarationalbeingthatLocke’sdefinitionpicksout.(Ontheotherhand,youmightclaimthatpersonhoodisnothingmorethanamoralstatusbestowedonsomething:see,e.g.,Rosenberg1983,116.ThisisnotaLockeanaccountof

personhood;moreover, thePsychologicalApproachcouldhardlybe trueofalland only people in this sense of the term, for we don’t bestow persistenceconditionsonthings.)ToavoidhavingtolistallthepropertiesthatgointooneoranotherversionoftheLockeanAccount,Ishallabbreviateitastheviewthatapersonisbydefinitionarational,self-consciousbeing.The Lockean Account of personhood seems to agree pretty well with our

ordinaryunderstandingoftheword‘person’.Itmakespersonhoodasignificantproperty, for the difference between being rational and self-conscious and notbeingthatwayisasalientandimportantdifference.Anditentailsanumberofhighly attractive general principles about people. For example, the LockeanAccount entails that you and I, with our psychological features, are people.Moreover, this isobviously so;our statusaspeople is innowayepistemicallyproblematic.Itisnotsomethingwecouldbemistakenabout,foritisascertainasanythingiscertainthatyouandIarerational,self-consciousmoralagents.ThisisaprinciplethatfriendsofthePsychologicalApproachseemtoaccept.

TheyassumethatifthePsychologicalApproachistrue,thenitisobviouslytrueofyouandme.Ifwecouldeasilybewrongaboutwhetherwewerepeople,wecould just as easily be wrong in thinking that the Psychological Approachappliestous,evenifitistrue.Butnooneworriesaboutthis.The Lockean Account also seems to entail that being a person is a

nonrelationalproperty (at least ifbeing rationalandconsciousand the likearenonrelationalproperties).Tosaythatpersonhoodisanonrelationalpropertyistosaythatanythingwiththesamenonrelationalpropertiesassomepersonisalsoaperson. Think of the duplicating machine discussed earlier. The claim thatpersonhood is not a relational property entails that if I am a person and amaterialobject,andyouputmeintothe“in”boxoftheduplicatingmachine,thething that appears in the “out” boxwill also be a person.Therewill bemanydifferences between my duplicate and me. I have lived for more than thirtyyears,andtheduplicatecameintobeingjustnow;Iamhere,andtheduplicateisover there.Butwedifferonly inour relationalproperties,bywhich Imean toincludeourhistoriesandourfutures.Ifpersonhoodisanonrelationalproperty,no such difference could prevent my duplicate from being a person. Myduplicate couldnot fail tobe apersonbecausehewasnotbornofwoman,orbecauseheneverlearnedalanguagebuthadone“builtinto”himwhenhecameintobeing,orbecausetherestofusrefusedtogranthimtherightsortofsocialormoral status. Ifhe isnot aperson, this canonlybebecause theduplicatingmachine somehow malfunctioned, and failed to give him consciousness orrationalityorfreewillorsomeothercrucialpsychologicalattribute.IftheLockeanAccountistrue,itfollowsaswellthatnothingcouldfailtobea

person just because of itsmodal or dispositional properties.A being thatwasrational,self-conscious,andhadwhateverfurtherfeaturestheLockeanAccountrequires—abeingwithmentalproperties just likeyours,say—couldnotfail tobeapersonjustbecauseitcouldsurviveasavegetable,orbecauseitwouldnotgoalongwith itscerebrum if thatorganwere transplanted. If therecouldbearational,self-consciousbeingwhosepersistenceconditionswerenotthoseofthePsychologicalApproach, theneither thePsychologicalApproachwouldnotbetrue of all people (in which case it would be false), or the being in questionwouldnotbeaperson(inwhichcasetheLockeanAccountwouldbefalse).TheConjunction of the Psychological Approach and the Lockean Account, then,entails that every rational, self-conscious being must persist through time byvirtueofpsychologicalcontinuity.Nosuchbeingcouldsurviveasavegetable,orfailtogoalongwithitscerebrumwhenthatorganistransplanted.Thisconnectswiththeepistemicpointmentionedpreviously.IfIcouldfailto

beapersonjustbyhavingthewrongrelationalormodalproperties,thenIcouldeasily be wrong about whether I am a person, for I cannot discover byintrospectionwhatmymodaland relationalpropertiesare. Imayhaveno ideawhetherIcouldsurviveasavegetable.Ifitwereeasyforustoknowthistherewouldbe no controversyover personal identity.Moreover, ifwe set aside thepossibilitythatImightbethoroughlydeceivedaboutmyownmentallife—ifweassumethatIcouldnotsincerelybelieve thatIwasrationalandself-consciousunlessIreallywererationalandself-conscious—thenitseemsthattheonlywayIcouldbemistakenaboutwhetherIwasapersonis ifbeingapersonrequiresthatonehavecertainrelationalormodalpropertiesinadditiontobeingrationaland self-conscious; and if it is possible for something to be rational and self-consciouswithouthavingthoserelationalormodalfeatures.

V.WhyWeAreAnimals

BynowitwillbeevidentthatthereisserioustensionbetweenthePsychologicalApproach and the Lockean Account of personhood. Whereas the LockeanAccounttellsusthatanybeingwiththerightpsychologicalfeaturesisaperson,the PsychologicalApproach tells us that only those beings that have both therightpsychologicalfeaturesand therightpersistenceconditionsarepeople.Onthe Psychological Approach, a rational, conscious being with the wrongpersistenceconditionswouldnotbeaperson.ButifyouandIarenotanimals,therewouldseemtobeplentyofbeingswiththerightpsychologicalfeaturestobepeoplebutthewrongpersistenceconditions,namelyhumananimals.Human

animalsarepeopleaccordingtotheLockeanAccount;andyetthePsychologicalApproach is not true of them, for they can survive without any sort ofpsychological continuity. Thus, friends of the Psychological Approach mustreject theLockeanAccount of personhood.Alternatively, if they concede thatyou and I are animals, they must argue that, despite appearances, a humananimal does get transferred from one head to another when the cerebrum istransplanted,andthatnohumananimalcansurviveasavegetable.But we cannot save the Psychological Approach by giving up the Lockean

Account of personhood. If you and I are not animals, and the PsychologicalApproach is therefore inconsistent with the Lockean Account, the result isdisaster.Tobeginwith,we shouldbeunable to knowwhetherwe are people.Becausethehumananimalconnectedwithyouisaperfectduplicateofyou,itisconsciousandintelligentifyouareconsciousandintelligent.Whatevermakesitthecasethatyouthinkandactrationallywouldseemtomakeitthecasethattheanimalthinksandactsrationallyaswell.TheanimalspeaksEnglish,oratleastalanguagehomophonicallyindistinguishablefromEnglish.Soifyoucanrefertoyourselfbysaying‘I’,theanimaltooshouldbeabletorefertoitselfbysayingthatword.Howcoulditsmerelyhavingthewrongpersistenceconditions,whichisall thatmakes theanimaldifferent fromyou,prevent it from thinkingaboutand referring to itself? If you believe you are a person, the animal connectedwithyouthinksitisapersonaswell.Itthinkssoforthesamereasonsthatyouthinkso; ithas thesameevidenceasyouhave. (Moreover, therelevantbelief-formingprocessesarethesamefortheanimalandforyourself.)Itismistaken,however,foritisnotaperson.Butifitissoeasytobelievethatoneisapersonandbewrong,howdoyou

knowyouaren’tmistakenaboutthis?Howdoyouknowyou’renottheanimalrather than the person?Why believe that yours is the “personal” criterion ofidentity rather than the “organic” criterion? There would seem to be an evenchance,andnoevidencecoulddecidethematter.AhumananimalwillfindtheargumentsforthePsychologicalApproachjustasconvincinginhiscaseaswefindtheminours.Believingthatoneisapersonwouldbelikebelievingthatafaircoin tossed randomlywillcomeupheads—except thatweareall stronglyinclinedtothinkthatwearepeople.Butthisinclinationisnomorereliablethantheinclinationtothinkthattossedcoinswillcomeupheads:itiswronghalfthetime.Andifwecannotknowwhetherwearepeople,wecannotknowwhetherthePsychologicalApproachistrueofus.Youmighttrytoavoidthisproblembysuggestingthatourpersonalpronouns

andproper names always refer ambiguously to at least twodifferent beings, apersonandananimal.5However,asentencewhosesubject refersambiguously

canbetrueonlyifitspredicateistrueofalloratleastmostofthereferentsofitssubject.IfeachtimeItrytorefertomyselfIalsorefertoananimal,whateverIsayaboutmyselfcanbetrueonlyifitistrueofthatanimalaswell.Inthatcase,althoughIcouldsaytrulythatIweigh150pounds,itwouldnotbetruethatIama person, or that I could not survive as a vegetable.The latter two statementswouldhavenotruthvalue(oranintermediatevalue),forthepredicatewouldbetrueofonlyoneof theobjectsambiguouslydenotedandfalseofanother.Andthe statements ‘I could survive as a vegetable’ and ‘I aman animal andnot aperson’would not be false.Theywould have the same truth value as ‘I am aperson’(anintermediatevalueornoneatall).Althoughthismaybeacoherentposition,itcontradictsthePsychologicalApproach,foraccordingtothatviewitisfalsethatIcouldsurviveasavegetable.Youmight suggest that the sentence ‘I amaperson’ inmymouthexpresses

twodifferent statements, one to the effect that the person is a person, and theothertotheeffectthattheotherthingthere,theanimal,isaperson,andtheotherto the effect that the other thing there, the animal, is a person. One of thesestatements is true, and the other is false. But this leaves the epistemologicalproblem:How do I knowwhether I’mmaking the true statement or the falseone?Ifthehumananimalsassociatedwithusarenotpeople,thenthepossessionof

such properties as intelligence, rationality, self-consciousness, and moralresponsibility is no evidence that something is a person— or at least it is nobetter evidence for that claim than the fact that a coin has been tossed isevidence that the coin will come up heads. This makes personhood anuninteresting and unimportant property. There would be little reason to carewhetheronewasaperson.Certainlybeingapersonwouldnothaveanygreatmoralsignificance.Thosehumananimalsthatarenotpeoplewoulddeservethesamemoralstatusthatgenuinepeoplehave.ThePsychologicalApproachwouldturn out to be a disappointment, for it would apply, rather arbitrarily, to onlyabouthalfofthe“qualifiedcandidates”,thatis,therational,self-consciousmoralagents—the“people”intheLockeansense.Thisisallperfectlyabsurd.Humananimalscouldnotfailtobepeoplesimply

becausethePsychologicalApproachdoesnotapplytothem,atleastnotinanyinterestingsenseof ‘person’.Therecouldnotbenon-peoplewhowereexactlylikepeoplebutfor theirpersistenceconditions.6 If thePsychologicalApproachis true, it could not be the case that half of those beings who, on carefulreflection, come to believe that that theory is true of them are mistaken.Wecould not fail to be people; andwe could not fail to be justified in believingourselvestobepeople.ThePsychologicalApproachistenableonlyifitcanbe

made compatiblewith theLockeanAccount of personhood—only if it appliesacrosstheboardtopeopleinasenseof‘person’thatisbothmorallysignificantand epistemically salient and unproblematic.And thiswill be the case only ifhumananimalsarehumanpeople—that is,only ifyouandIareanimals ifwearematerialobjectsatall.Friends of the Psychological Approach might counter that the Lockean

Accountseemsattractiveonlybecauseofanequivocation.Thereisonesenseof‘person’accordingtowhichanyrational,self-consciousmoralagentisaperson;inthissensenothingcouldfailtobeapersonmerelybecauseofitshistoricalormodalproperties.Itisthissenseof‘person’thattheLockeanAccountcaptures.ThePsychologicalApproachisatheoryaboutpeopleinadifferentsenseoftheterm. People in that sense are rational beings who persist by virtue ofpsychologicalcontinuity.Whyshouldn’ttheEnglishword‘person’simplyhavetwosenses,the“Lockean”senseandthe“identity”sense?While this may be true, it doesn’t help matters much. The Psychological

Approachseemedtobeaninterestingandattractiveprincipleinpartbecausewethoughtittoldussomethingaboutsomesalientclassofthings:rationalbeings.We assumed that we were talking about people in some important andinterestingsenseoftheterm—somethingliketheLockeansense.Ifit turnsoutinsteadtobetrueonlyofpeopleinthe“identity”sense,thenthePsychologicalApproach is a theory about an unintuitive, gerrymandered class that includessome rational beings but excludesmany other beings that are just as rational,conscious, and morally responsible, and we shall rightly feel cheated. Whatwouldbethepointofatheorylikethat?Thus, unless we can explain how ordinary human animals could fail to be

rational or conscious or morally responsible (as well as how two physicallyindistinguishable material objects can have different persistence conditions) itseemsthatwemustadmitthatyouandIareanimalsifwearematerialobjectsatall.Butisthatreallytheonlyalternative?Ithasmorethanoncebeensuggestedto

methatImightbea“functionalanimal”ratherthanjustaplainanimal,wherefunctionality implieshavingcertainpsychologicalcapacities.Theidea is thatahuman vegetable is an animal but not a functional animal; its brain is not afunctioningbrain.BecauseIamafunctionalanimal,Icouldnotbecomeanon-functional one, and must therefore cease to exist when this animal stopsfunctioning.Forthesamereason,Iwasneverafetus,foralthoughafetusisananimal, it isnotyeta functionalone.Whathappens tomewhenmycerebrumgetstransplanted,onthisview,islessclear.IsupposetheessentiallyfunctionalentitythatIamgetstransplantedalongwiththatorgan(inwhichcaseIamnot

essentially a functionalanimal, since a detached cerebrum is not an animal ofanysort).Butwhat sortof thing isa functionalanimal, ifnot simplyananimal that is

“functioning”?Whentheanimalceasestofunction,whysupposethatanythingceasestoexist, if theanimal itself isstill there?Supposeyourcar isunreliableand runs only half the time. Is there a two-ton, metal-and-glass object withwheels,called“thefunctioningcar”,whichnecessarilyceasestoexistwhenthecar stops running? Isn’t there just one material object there, which has theproperty of being functional half the time and the property of being non-functional otherwise? And even if something does cease to exist when theanimal(orthecar)stopsfunctioning,howisthisproposalanydifferentfromtheonewehavealreadyconsidered,accordingtowhichthesamemattermakesuptwodifferentmaterialobjectsatonce,oneofwhichcanoutlivetheother?Perhaps what my well-meaning friends meant to say is that we are

straightforwardlyanimals,butthatahumananimalceasestoexistwhenitceasesto “function”—that is, when it loses those mental capacities that make it aperson.AtanyratethatistheonlyintelligiblepositionthatIcanmakeoutofthe“functionalanimal”proposal.Soletusturntothisview.

VI.PsychologicalPersistenceConditionsforAnimals?

ItlooksasthoughyouandIreallyareanimals.ForthehumananimalthatIpointtowhen Ipoint tomyself isaperson in theLockeansense—and therearenottwopeoplehere.AndIamclearlyaperson.Thus,Iamthatanimal.Couldn’tthePsychologicalApproachsomehowaccommodatethisfact?Does

it really entail that you and I are not animals?Couldn’t some animals—thosethat are rational and self-conscious, say—persist just in case their mentalcontents or capacities are preserved? Couldn’t something still be at once aperson and an animal, as some have thought?7 Given the problems thePsychologicalApproachfacesiftheanswertothesequestionsisno,thisoptiondeservesseriousconsideration.It isclear, tobeginwith, that thePsychologicalApproachcouldnotapplyto

all animals. Many animals—oysters, for example—manage to persist withouthaving any psychological capacities at all. So the proposalmust be that someanimals,suchasyouandI,haveradicallydifferentpersistenceconditionsfromthoseofotheranimals.WhichanimalsmightthePsychologicalApproachapplyto? Perhaps it applies to all animals that have any mental features at all,including dogs and pigeons and fish. Your favorite horse, then, could be

transferred from one head to another by means of a cerebrum transplant (asUngerbelieves:1990,6).Inthatcaseweshouldhaveourpersistenceconditionsnot by virtue of being people, but by virtue of being thinkers, for thoseconditionsaresharedbymanythinkersthataren’tpeople.“Criterionofthinkeridentity” would be a more appropriate name for our goal than “criterion ofpersonal identity”,Alternatively, thePsychologicalApproachmightapplyonlytopeopleintheLockeansense—rationalbeings—whileorangutansandtherestof our evolutionary cousins would have some purely biological criterion ofidentity.Eitherway, different animalswouldhave completelydifferent andunrelated

persistenceconditions,andthusneitheranimalnorlivingorganismcouldnotbeasubstanceconcept in theWigginsiansensediscussed inChapter2.A thing’sbeing an animal would not determine its persistence conditions. You and Ishould have the persistence conditions that we have, not by virtue of beinganimals, but by virtue of being people or thinking beings. According to thestandardtheoryofsubstanceconcepts,thismeansthatnoanimalwouldhaveitspersistenceconditionsbyvirtueofbeingananimal.JustasyouandIarepeople(or thinkers) first and animals second, as it were, an oyster would be, well,something first and an animal second.What substance concept could stand tooysterasperson(orthinker)standstohumananimalisaquestionthatfriendsofthePsychologicalApproachwouldhavetoanswer.Coulditbe,onthisview,thatoursubstanceconceptwasnotpersonoranimal

but the more specific concept human animal (and that an oyster’s substanceconceptwasoyster)? No. In fact, the PsychologicalApproach could not evenapplytoallhumananimals.Forsomehumananimals,atsometimes,managetopersist without having any psychological features at all. As we saw in thepreviouschapter,afive-month-oldfetusisnotapersonintheLockeansense,foritisnotrationalorself-conscious;itishardlycapableofanymentalstatemoresophisticatedthanpain.Itlacksthementalcontentsandcapacitiesthatmustbepreserved, on the Psychological Approach, for you andme to survive. And amonth-oldhumanembryohasnopsychologyatall.Yettheseareclearlyhumananimals.Anencephalicbabiesandhumanvegetablesarehumananimalsthatcanlive foryearswithout aworkingcerebrum.Notonlydo they lack amind,butthey do not even have the capacity to develop amind. Thatmeans that somehuman organisms would have radically different persistence conditions fromthoseofothers.Thus, human organism could not be a substance concept; a human animal

wouldnothavethepersistenceconditionsthatithasbyvirtueofbeingahumananimal,butbyvirtueofbeingaperson,forexample,orathinker,or,inthecase

ofhumananimals thatareneitherpeoplenor thinkers,somethingelseentirely.(You might propose an irreducibly disjunctive criterion of identity, with apsychological disjunct that applies to human people and a nonpsychologicaldisjunctthatappliestothosehumananimalsthatarenotpeople.Butthatwouldnot make human organism a substance concept, any more than the fact thatanything whatever could be said to fall under the disjunction of all possiblepersistenceconditionsentailsthatthingorobjectisasubstanceconcept.)This means that friends of the Psychological Approach must reject the

traditional,WigginsianaccountofsubstanceconceptsiftheyclaimthatyouandIareanimals.Foronthattraditionalviewitisnaturalkindsthatarebestsuitedto be substance concepts; and animal and human organism are surely naturalkinds.However,thisisahighlytheoreticalpoint.MaybeWiggins’stheoryneedsmorework;ormaybeanimalisnotanaturalkindafterall.Atanyrate,Idon’twanttorestmuchweightonthematter.However, the current proposal faces more obvious difficulties. It would

requireustoredescribeourpuzzlecasesinanovelandabsurdway.

VII.DeathandCeasingtoBe

RecalltheVegetableCase:Yourcerebrumisseverelyandirreversiblydamagedso that all of your higher cognitive functions, including rationality and thecapacityforconsciousawareness,are irretrievably lost,whileyour lowerbrainremains intact and continues to direct your life-sustaining functions withoutinterruption.According to the PsychologicalApproach, you could not survivesuchanadventure.Theresultinghumanvegetableisnotyou,forithasinheritednoneofyourpsychologicalfeatures.Nowletussupposethatyouareahumananimal.Presumablyyouaretheonly

humananimalpresentat thebeginningof thestory (otherwiseweshouldhavethesameproblemsaswegotbysaying thatyouarenotananimal).Then thathumananimal ceases to existwhen itsmental capacities aredestroyed (on thePsychologicalApproach)—eventhoughthosebiologicalfunctionsthatmakeitaliving organism, including breathing, circulation, digestion, and metabolism,continuewithoutinterruption,andeventhoughtheresultofthechangeisclearlya livinghumanorganism. In theVegetableCase, then,onehumanorganism—you—ceases to existwhen itsmental capacities aredestroyed, and is instantlyreplacedbyanumericallydifferenthumanorganism.Thiswould be startling news.We are being told that a living organism has

ceased to exist, even though its vital functionshavenotbeendisrupted in any

way,and its cells andorganscontinue to functionasbeforeand tocomposealiving organism. No death in the biological sense has occurred. There is nobreakdown of living organization. No once-living tissues begin to decay. Nolifelesscorpseisleftbehind.Tobesure,thetissuesofthedamagedcerebrumaredestroyed,andtheymaybegintodecay;butthesamewouldhappenifanyotherorgan or limb (a kidney, say) were damaged or destroyed, and that need notcausedeath.8Now I have said that the destruction of a human animal’smental capacities

neednotdisruptitslife-sustaining,organicfunctionsinanyway,fortheresultofthat loss may be something that is still clearly a living organism. But whichbiological functions are life-sustaining? The animal’s mental functions havecertainlybeendisrupted.Mightnotthosefunctionsbelife-sustainingaswell,inthesensethatahumananimalcannotsurvivewithoutthem?Whyincludeonlysuch nonpsychological features as metabolism and respiration among ananimal’slife-sustainingfunctions?By“life-sustaining” functions Imean those that sustain life in thebiological

sense:theyarethosefunctionsthatkeepanorganismaliveinthesenseinwhichnotonlyhumanbeings,butalsocockroachesandcabbages,arealive.Therearecertainfeaturesthatdistinguishbiologicalorganismsfromnon-livingthings(seeChapter 6).All living organismsmetabolize, for example: they take in energyand nutrients from their environment, use them to build complex livingstructures,andthenexpeltheremainsinaless-orderedform.Thatispartofwhatmakessomethingalivingorganism.These“life-giving”features—theonesthatmakeyouandanyotherorganismalivingthing—arepreservedintheVegetableCase.A living human organism is present throughout the story; themetabolicandrelatedfunctionsthatunitethosecellsandatomsintoalivinghumananimalcontinue toworkwithout interruption. Granted, the animal’smental functionsaredestroyed;butsomethingcanbealivinganimalwithouthavinganymentalfunctions.Thus,intheVegetableCase,alivingorganismisdestroyedandreplacedbya

similarlivingorganismwithoutanydisruptionofthoseactivitiesthatmakeitaliving thing—that is, even though nothing dies in the biological sense. Ingeneral,we can conclude that an animal (or at any rate a human animal) thatloses its mental capacities ceases to exist and is replaced by a similar butnumerically different animal. Although some human animals are rational andconsciousandothersarenot,noonehumananimalcanberationalandconsciousatonetimeandfailtoberationalandconsciousatanothertime.Althoughsomehuman animals are vegetables, no human animal canbecome a vegetable if itdidn’tstartoutasone.(Andaswesawinthepreviouschapter,nohumananimal

canstartoutasanunthinkingembryoandlaterbecomerationalandconscious.)This isnot thewayanyphysiologistwoulddescribe theVegetableCase.No

matterwhatyourviewsmaybeaboutpersonal identity, thecontinuityof life-sustaining, biological functions throughout the story makes it at least verynatural to suppose thata singleanimal ispresent throughout, andsimply losescertain capacities as the result of injury or trauma. The animal undergoes aprofoundalteration.Itlosesagreatdeal,andbecomesseverelydebilitated.Butitdoesnotceasetoexist,andnonewanimalcomesintobeingtoreplaceit.I say this as if it were obvious. But isn’t there a lively debate over the

definition of death?While some say that one should be considered dead onlywhenone’s entirebrainhas irreversibly shutdown,others argue that ahumanbeing should be declared dead as soon as her higher cognitive centers aredestroyed.Aren’tthesereasonablepeoplewhohavecometotheconclusionthatahumananimalceasestoexistwhenitlapsesintoapersistentvegetativestate?Herewemustbecareful.Ourquestioniswhetherahumananimalthatlosesits

cognitive capacities is still present or has ceased to exist, and whether theresulting, irreversibly noncognitive animal is the animal that lost its mentalpowers,orratheranew,numericallydifferentanimal.Whenpeople,particularlymedicalethicists,askwhethertheoriginalanimalisdeadoralive,theyusuallyhaveadifferentquestion inmind.Noonedoubts that thevegetativeanimal isaliveinthebiologicalsense,inthewaythatanoysterisalive.Theyaretypicallyasking about the ethical status of the human vegetable. They have in mindcertainurgent,practicalquestionsaboutwhatweoughttodowithsuchbeings:Doesthehospitalhaveanobligationtokeepthehumanvegetablealive,atgreatcost,bycontinuingtofeedit?Ormayweconsiderit tohaveforfeiteditslegalandmoralrights,andremoveitsorgansfortransplant?Doesanyofwhatmakesour existence valuable remain for the vegetable?9 These are important anddifficultquestions.Buttheyarenotthequestionwhetherthehumanvegetableinthe story is or is not numerically identical with the original human animal.Someonemightagreethatahumanvegetableshouldbeconsidered“dead”inthelegalandethicalsense,withoutdenyingthat it is thevery livingorganismthatwasoncefully“alive”inthesamesense.Youmight try tomake this consequence—that an animal can cease to exist

without dying in the biological sense—more palatable by comparing it withanotherfamouspuzzle.Whenanamoebadivides,itseemsthatitmustceasetoexist.(Clearlythereareexactlytwoamoebasafterthedivision,andtheoriginalamoeba cannot be identical with both. And nothing could make the originalamoeba identicalwithoneof itsdaughtersbutnot theother, for its relation toeach is the same. Neither does the amoeba become something other than an

amoeba by dividing. Hence, it must perish.) But when an amoeba divides,nothing happens that looksmuch like death.Nothing begins to decay, and nocorpse results. So we know that an organism can cease to exist withoutinterruption of its vital functions, and without leaving behind any lifelessremains—withoutdying,asitwere.Andifthiscanhappenincelldivision,whynotintheVegetableCaseaswell?Butcelldivision isaspecialcase.Profoundchanges takeplacewithinacell

whenitdivides.Whilethe“plans”(thechromosomes)arebeingcopied,theflowof chemically coded instructions to the rest of the cell is interrupted and itsenzymesystemsmustfunctionwithoutrenewal(Young1971,302).Thenucleussplitsintwo,andthecell’sorganellesarrangethemselvessymmetricallyaroundan internal axis; thebiological event thatwemight call the cell’s life loses itsintegrityanddividesintotwoindependentstreams.Itseemsappropriatetocallthiseventthebirthoftwoneworganismsandthedemiseoftheoriginalcell.10Idon’tmean to imply that thisdescription isentirelyunproblematic,or thatcelldivisionisnotmetaphysicallyinterestingandmysterious.Butitseemstobethebest description of the case.Nothing like this happenswhen a human being’smentalcapacitiesaredestroyedbycerebraldamageanditlapsesintoapersistentvegetativestate.Mostoftheinternalworkingsofahumananimalcontinuetogoonjustasbefore;theyarenotdisruptedinthewaythatacell’sinternalworkingsare disrupted when the cell divides. Cerebral damage does not disrupt ananimal’sintegrityasanorganisminthewaythatcellularfissiondoes.But letusmoveon to theTransplantCase.There thecurrentproposal—that

you and I are human animals individuated psychologically— has even moresurprisingconsequencesthanithasintheVegetableCase.Yourcerebrumiscutoutofyourheadandimplantedintoanother,resultingin

someone who is uniquely psychologically continuous with you, with enoughphysical continuity to satisfy even the most cautious advocate of thePsychologicalApproach.AccordingtothePsychologicalApproach,thatpersonisyou.What the surgeonsdo,on thatview, ispareyoudown to a two-poundmass of yellowish and pinkish tissue by cutting away, all at once, all of yournonessentialparts.Abitlatertheygraftafullcomplementofreplacementpartsontoyou.Nowletussupposethatyouareananimal.Inthatcasethesurgeonshavenot

transplanted an organ fromone animal to another.Rather, they have pared ananimaldowntoanakedcerebrumandlaterattachedafullcomplementofotherhumanpartstoit.Theyhavetransferredananimalfromoneheadtoanother.Butadetachedcerebrumisnotananimal,ora livingorganismofanyother

sort.Itisnomorealivingorganismthanafreshlyseveredarmisanorganism.If

the cerebrumappears to be anorganism, that is because it consists entirely oflivingtissue;infact, it ismadeupoftinyorganisms,its individualcells.Ifweexamine the detached cerebrum closely, though, we see that it bears littleresemblance to a living animal; it is not an animal because its parts do notcoordinate their activities in theway that the parts of an organism coordinatetheirs. Its cells don’t work together as a self-sustaining unit. Theymay worktogetherinsomeotherway—toproducethought,forexample—buttheydonotwork together in the biological way that the parts of an organismmust worktogether (see Chapter 6). Warm-blooded animals like ourselves control theirinternaltemperature,forexample,bychangingtherateoftheirmetabolismandby constricting or dilating the blood vessels near their surface in response totheir surroundings. The concentration of their blood and other fluids isconstantlymonitoredandadjusted.Andsoon. (Astudentofphysiologycouldexpandthelistindefinitely.)Noneofthisistrueofaseveredarmoradetachedcerebrum.Thereasonisnotjustthatmanylife-sustainingorgans—heart,lungs,digestive tract, and just about everything else—have been removed from thecerebrum, but also that those organs that once coordinated the life-sustainingfunctionsthatwentoninthearmorcerebrumhavebeencutaway.Likeakidneyawaitingtransplant,wemaykeepthecerebrum“alive”bycarefulhandlingonlyinthesenseofkeepingitscellsindividuallyalive,orinthesenseofpreventingitfromdecayingbeyondthepointwhereitcouldresumeitsproperfunctionafterbeingtransplanted.Norcouldwemakethedetachedcerebrum,orkidneyorarm,intoanorganismbyputtingitintoavatandpumpingoxygenatedbloodthroughit, or byproviding anyother life-support systems.Not just anymassof livingtissueisanorganism.If you think a detached cerebrum is an organism—because it can support

thought,perhaps—thenpresumablyadetachedliverisalsoanorganism,forinasuitableartificialenvironmentitcanperformitscharacteristicfunctionaswellasthedetachedcerebrumcan.Inthatcaseweoughttowonderwhathappenstoananimalwhenitsliverisremoved.Theresultwouldbetwoanimals,thedetachedliverandtheanimalwithaholewhereitsliverusedtobe.Which,ifany,istheoriginal animal?Youmight argue that the latter is the original animal, on thegroundsthatitretainsthatanimal’smentalcapacities,andmentalcapacitiesaremoreimportanttoananimal’ssurvivalthanblood-purifyingcapacities.Butwhathappensifweremovetheliverfromananimalthathasnomentalcapacities—ananencephalicbabyorahumanvegetable,forexample?Ontheotherhand,thethingleftbehindafteryourcerebrumisremovedmay

well be a living animal. If the surgeons are careful to leave its brainstem andmidbrain organs intact, its circulation, breathing, digestion, and other vital

functions may continue without interruption. It will be very like the humanvegetable that resultswhen one’s cerebrum is severely damaged or destroyed.Notonlyisthatbrainlessthingalivinghumananimal;itsorganicfunctionsarecontinuouswithyours:yourmetabolismandotherlife-sustainingfunctionshavecontinued onwithout interruption and are now the life-sustaining functions ofthebrainlessanimal.Ifwesetasidepersonalidentityforamomentandthinkaboutwhathappensto

theanimalsinvolvedintheTransplantCase,thenaturalthingtosayisthatthereareexactlytwohumananimalsinthestory,andthatanorgan—yourcerebrum—gets transferred from one of them to the other. One animal starts out with acerebrumandendsupwithnone,andanotheranimalstartsoutwithnocerebrumandthenacquiresone(orratherstartsoutwithacerebrum,thenhasitremovedanddoeswithoutforawhile,andfinallygetsanewcerebruminplaceoftheoldone).Asfarasanimal identity isconcerned, transplantingacerebrumought tobe like transplanting a liver.Many philosophers, including some advocates ofthePsychologicalApproach,describethebiologyoftheTransplantCaseinjustthis way. (John Perry, for example, writes, “By ‘human being’ I shall meanmerely ‘live human body’. It is a purely biological notion. Thus, in a ‘braintransplant’operation,thesamehumanbeingacquiresanewsetofmemoriesandpersonality,whateverwemaysayaboutthepersonsinvolved”.)11But if thePsychologicalApproach is true, and ifyouand Iareanimals, this

description cannot be right. There are not two animals in the story, but four.Whathappensisthis.Westartwithonehumananimal,Alpha.(Ifyoulike,youcanimaginethatAlphaisyou;butkeepinmindthestipulationthatAlphabeananimal.)Alphagetspareddownuntilnothingisleftofitbutanakedcerebrum,at which point it ceases to be a living organism at all. Alpha’s biologicalfunctionscontinuewithoutinterruptiontoanimatetheresultingbrainlesshumanorganism, Beta. But Beta is not Alpha, for Alpha is now a naked cerebrum.Rather,BetacameintoexistencewhenAlpha’scerebrumwasremoved—-justasdestroying your cerebrum produced a new human organism in the VegetableCase.Beta never had a cerebrum (and, aswe shall see in amoment, it couldneveracquireone).SotheresultofremovingAlpha’scerebrumisthecreationofabrand-newhumanorganism,Beta.Alpha,nowanakedcerebrum,isthenimplantedintothehalf-emptyskullofa

thirdlivinghumananimal,Gamma.(IfGammawerenotalive,theresultofthetransplantwouldnotbealivinganimalwithAlpha’smemories;youcan’tmakean empty-headed corpse into a living thing by implanting a cerebrum into it.)Alpha now becomes a living organism once more by taking over the vitalfunctionsofits“host”,Gamma,whichimmediatelyceasestoexist(eventhough

its vital functions are not disrupted). Gamma must perish, for Alpha hasassimilatedallofGamma’smatter, and therecannotbe twohumananimals inthesameplaceatonce.NowGamma’sskullwasnotalwaysempty,butoncecontainedacerebrumof

itsown.ButGammaitselfneverhadacerebrum.Theremusthavebeenafourthanimal,Delta,whose cerebrumwas removed from its head tomake room forAlpha’scerebrum.Delta,ofcourse,wentalongwith itscerebrumwhen itwasremoved, just as Alpha went along with its cerebrum when that organ wasremovedfromAlpha’sskull.Gammais thenewanimal thatwascreatedwhenDeltagotreducedtoacerebrum,justasBetawascreatedwhenthesamethinghappenedtoAlpha.GiventheassumptionthatthePsychologicalApproachistrueandthatyouand

Iarehumananimals,nootherdescriptionoftheTransplantCaseispossible.From this descriptionwe can learn a number of surprising things about the

identity of human organisms. First, you can destroy a human animal bydestroyingitscerebrum,inspiteofthefactthatthisorganhaslittleornothingtodo with the regulation of the animal’s life-sustaining functions. For if wedestroyedyourcerebrumafterremovingitfromyourhead,youwouldceasetoexist—eventhoughyourlife-sustainingfunctionscontinuedoninyourbrainlessremains.Second, it is possible to destroy a human animal that lacks a functioning

cerebrumby implanting such anorgan into it—andnot because this operationwould disrupt the animal’s life-sustaining functions, but simply because thatorgan carries with it those mental capacities associated with personhood. Forwhenweimplantaworkingcerebrumintoahumanorganism,wedonotmerelytransplantanorgan;we transplantaperson into thatemptyhead.Andbecausethat transplanted person then immediately becomes a human organism oncemorebymakingall thepartsof thebrainlessanimalpartsof itself,noroomisleft,ontologicallyspeaking,fortheoriginal,empty-headedanimal.ThatiswhyBeta, the empty-headed animal created when your cerebrum is removed, canneveracquireanewcerebrum:Betawouldceasetoexistifsuchanorganwereprovided.Betaisessentiallydecerebrate—oratanyrate,giventhatBetalacksaworkingcerebrum(andsofailstobeaperson)atonetime,Betacouldnothaveaworkingcerebrumatanyothertime.Third,bringingananimal’slife-sustainingfunctionstoanendandproducinga

lifeless corpse—what the vulgar call “death”—need not kill the animal; theanimalmay continue to exist and remain alive. For instead of separating yourcerebrumfromtherestofyou,thesurgeonsmightsimplydestroyallofyoubutyour cerebrum. In that case your circulation, respiration, metabolism, and so

forth, would cease, and the organs that coordinated those functions and thosethat carried them out would be destroyed. The result would be the lifelessremains of an animal.Nevertheless, no animalwould cease to existwhen thishappens,norwouldanyanimalcometobeacorpse.Instead,theanimal—you—would survive the adventure and simply come to be something other than ananimal,namelyanakedbuttransplantablecerebrum(whichmaylaterbecomealivinganimaloncemore).The cerebrum, on this view, turns out to be an organwith peculiar powers.

There is no other organ whose destruction entails the demise of the wholeanimal, irrespectiveof its effects on the animal’s life-sustaining functions; nordoesananimalnecessarilyperishifanyotherorganisimplantedintoit.Noristhereanyotherorganthatcanpreserveananimal’sexistencewithouteverbeinganorganism itself.Noanimalwouldgoalongwith its stomachor liver if thatorganwere transplantedintoanotherabdomen.Thecerebrumhas thesespecialpowers because it is anorgan of thought, and because it carrieswith it all ormostofananimal’spsychologicalcontentsandcapacities.Thus,theconclusionswehavereachedabout the identityofhumananimalsneedhavenothing todowiththecerebrumperse.Normusttheyberestrictedtohumananimals.BecausethePsychologicalApproachissupposedtobeanecessarytruthaboutallpeople,analogousclaimswillholdfornon-humanthinkingbeingsaswell.Thus, we can generalize still further: If we separate an animal’s organ of

thoughtfromtherestoftheanimal(orforthatmatteranyorganism),thatanimalceases to be an organism and becomes a mere detached organ, while a newanimal is instantly created and takes over the original animal’s life-sustainingfunctions. That new animal necessarily perishes if an organ of thought isimplanted into it to produce a thinking animal. An animal can survive theirreversibledisruptionofitslife-sustainingfunctions—itsbiologicaldeath—ifitsorganofthoughtispreserved(althoughitbecomessomethingotherthanalivingorganismwhenthishappens).Finally,ananimalnecessarilyperishesifitsorganofthoughtisdestroyed,orifthatorganlosesitscapacitytofunctionasanorganof thought, even if no death in the biological sense occurs.At any rate, theseprincipleswillbetrueiftheorganofthoughtinquestionisonewhoseassociatedmental powers can make something a person; friends of the PsychologicalApproachmay differ aboutwhether it is also true for such organs as a dog’scerebrum.The same lessons, or many of them, can be learned from any account of

personal identity that involves psychology, or at least any theory that wouldmake some sort of psychological continuity either necessary or sufficient forsomeonetosurvive.Ifanypsychologicalrelationisnecessaryforonetosurvive,

onecouldnotsurvivein theVegetableCase,andthefirstsetof lessons,abouthowwecandestroyananimalwithoutdisruptingitsvitalfunctions,willapply.Ifanypsychologicalrelationissufficientforonetosurvive,thenonegoesalongwithone’scerebrumintheTransplantCase,andthesecondsetoflessonsapply:the lesson about how we can bring an animal’s vital functions to a halt andproducealifelesscorpse(orevenapileofashes)withoutdestroyingtheanimal,andtheoneabouthowabrainlesshumananimalmustceasetoexistifprovidedwithaworkingcerebrum.This isallperfectlyabsurd.Atany rate, ifwe thinkabout thepersistenceof

human animals and other intelligent organisms in this way, we shall departsignificantly from the concept of a living organism that today’s life sciencesoperatewith.Consider thebiologicalconceptofdeath.Although theremaybesomedisagreementaboutexactlywhatdeathcomesto(aswesawearlier),mostbiologistswouldagreethatithassomethingtodowiththeirreversiblecessationof those metabolic and other activities that distinguish living organisms fromnon-living things.Roughly,anorganismdieswhenits life-sustainingfunctionsceaseandcannotberestarted,orwhenitscapacitytoregulatethosefunctionsisdestroyed.But on the present proposal,whether a living organism survives orperisheshasnothingtodowithwhetheritdiesinthisbiologicalsense.Deathisneither necessary nor sufficient, in general, for a living organism to cease toexist.Youmayreplythatthisisnothingnew.Manypeoplebelievethatanorganism

continuestoexistafteritsdeath,asacorpse.Sodeathisnotobviouslysufficientforthedemiseofalivingorganism.Fairenough.(Althoughonemightwonderwhatthepersistenceconditionsfororganismsmightbeiftheydon’tinvolvethenotionoflife.Whatdoesittaketogetridofanorganism,ifnotdeath?)Butthepresent proposal is that an organismmight not only continue to exist after itsdeath,but that itmightcontinue tofunction, ifnotnecessarilyasanorganism,thenatleastasathinkingbeing.

VIII.ACounterattack

FriendsofthePsychologicalApproach,then,arefacedwithachoice.TheycandescribethebiologyoftheTransplantandVegetableCasesintheusualway,andthus deny that you and I are living organisms. In that case the PsychologicalApproach will be true of people in a non-Lockean sense of ‘person’ that ismorallyinsignificantandepistemicallyproblematic,anditwillfailtobetrueofmany beings that are psychologically just like people. Alternatively, they can

concedethatyouandIareorganismsbutdenythatthepersistenceconditionsofsuchorganismshaveanydirectconnectionwith thebiologicalconceptsof lifeanddeath.Nowsomeonemightarguethatthissecondoption—divorcingthepersistence

ofhumanorganismsfromthebiologicalnotionsoflifeanddeath—isnotasbadas it sounds, and in fact is no worse than what follows from the BiologicalApproach:

Admittedly (someone might say), this novel account of what it takes for ahumananimaltopersistmightsoundstrangeatfirst.Butyou,theproponentoftheBiologicalApproach,mustsaysomethingjustassurprising.Onyourview,apersonmayceasetoexisteventhoughthosementalfunctionsthatmakeherapersonarenotdisrupted.Supposeyourcerebrumistransplantedandtherestof you is destroyed. According to the Biological Approach, the resultingperson is not you, but someone else; for you, the animal, were left behindwhen your cerebrumwas removed. But yourmental life was not disrupted.Mostofyourotherpsychologicalfeaturesremainintact; theremightevenbefull consciousness throughout the operation (although this seems to requirethat thecerebrumbeattachedtothelowerbrain).Soapersonperisheswhenher biological functions cease—producing a brand-new person who inheritsthemindoftheoriginalperson.Isn’t this justashardtobelieveastheclaimthat ananimal ceases to existwhen itspsychological functions cease, and isreplaced by a new animal without any disruption of its life-sustainingfunctions?Moreover, onyourviewwe cannot destroy aperson simplybydestroying

thosepsychologicalfeaturesthatmakeheraperson,forintheVegetableCasethepersonsimplycarriesonexistingasanon-person.Worse,wecandestroyapersonbymerelygraftingsomenewpartsontoher,withoutanydisruptioninhermental life. Suppose your cerebrum is removed and destroyed.You aresupposedtosurvivethis, thoughnotasaperson(at leastnot inanyLockeansenseof‘person’).Letusconcedethatyoudo.Laterwetakeacerebrumfromsomeone else and implant it into your empty cranial cavity. Thus you, aperson,mightceasetobeapersonforatimeandlaterbecomeapersononcemore,withapsychologycompletelyunrelatedtothemindyouformerlyhad.But that’s not all.That detached cerebrum, before it got put into your head,waspresumablyaperson.Forallweknowitmayevenhavebeenconscious,though of course unaware of its surroundings. At any rate, philosophersusuallyassume thatabrainkept“alive” inavatmightbeaperson,andyouhavegivenusnoreasontodoubtthat;andifabraininavatcanbeaperson,

whynotacerebruminacoolerawaitingtransplant?Nowwhathappenstothatpersonwhenshegetsputintoyourhead?Onyourview,itseemsthatshemustcease toexist, forotherwise therewouldbe twopeople in the sameplaceatonce:you,withyournewcerebrum,and thepersonwhojusthadyourarms,legs, and other parts grafted onto her. Thus, according to the BiologicalApproach, a personmight cease to exist simply by virtue of having a lot ofhumanpartsattachedtoher—withouttheleastdisruptionofhermentallife.Isthisanyhardertobelievethanthatananimalmightceasetobeananimal

for a while and later become an animal one more, while its vital functionscontinuewithout interruptionas thevital functionsofanumericallydifferentanimal? Or that a decerebrate animal would necessarily perish if it weresupplied with a cerebrum, without any disruption of its life-sustainingfunctions?ForeveryapparentlyabsurdconsequenceofthePsychologicalApproach(on

theassumption thatweareanimals), theBiologicalApproachhasanequallyabsurdconsequence.Bothviews faceparallel difficulties.The score is even.Therealquestioniswhetherpersonoranimalisasubstanceconcept:whetherwe are essentially people or essentially animals, and whether we have ourpersistenceconditionsbyvirtueofbeingpeopleorwhetherwehavethembyvirtueofbeinganimals.ToestablishtheBiologicalApproachyoumustarguethat we are essentially animals and only accidentally people. But you havedonenothingtoshowthat.

This is a powerful objection, and it represents perhaps the most promisingstrategy for defending the Psychological Approach against the challengesbroughtinthischapterandinthepreviousone.Ihavereliedontheassumptionthat animal, or at any rate human animal, is a natural kind and therefore asubstanceconcept,andthatanyanimalhasthepersistenceconditionsthatithasby virtue of being an animal, or by virtue of being an animal of a particularbiologicalspecies,suchasahumananimal.ButIhavenotofferedanydefenseofthatclaim.Whatseemsthemorelikelysubstanceconcept:animal,orperson?Whatiseasiertobelieve:thatsomethingstartsoutwithoutbeingabletothink,thenacquiresthatcapacity,andstilllaterceasestobeabletothink,andbecomesanon-thinker oncemore?Or that something starts out as a biologically livingthing, then ceases to be biologically alive—not simply by having its life-sustaining functions interrupted, but by losing the capacity for life—and latercomes tobealiveoncemore? I find ithard tounderstandhow lifecouldbeatemporallyaccidentalattributeofsomething,howalivingorganismcouldcometobeanon-organism.Ontheotherhand,Ihavenotroubleunderstandinghow

thought could be a temporally accidental attribute.But I do not know how toargueforthatconviction.I have pointed out that physiologists who discuss the medical and ethical

implications of persistent vegetative state typically assume that the debilitatedhumananimalinquestionistheveryanimalthatwasoncehealthyandnormal,and that the embryo developing in itsmother’swomb is the very animal thatmay later be a child and an adult. But that is hardly a powerful argument.PerhapsthosephysiologistswouldquestionthatassumptioniftheyrealizedthatitwasincompatiblewiththePsychologicalApproach.IhavepointedoutthattakingthePsychologicalApproachtobetrueofhuman

animalswouldbearadicaldeparturefromtheusualwayofthinkingaboutlivingorganisms.Butperhaps thosewho think in theusualwaywould stop thinkingthat way if they realized that it was inconsistent with the PsychologicalApproach.AndyoumightarguethattakingtheBiologicalApproachtobetrueofhumanpeoplewouldbe a radicaldeparture from theusualwayof thinkingaboutpeople.Icanonlyoffersomesuggestions.AdvocatesoftheBiologicalApproachmust

denythatperson isanaturalkind—atleast ifWiggins isright inclaimingthatnatural kinds are also substance concepts—for that view entails thatperson isnotasubstanceconceptanddoesnotdeterminethepersistenceconditionsforthethings that fall under it. Although this may not be one of themost attractivefeaturesof theBiologicalApproach, it isperhaps somethingwecan livewith.Manyphilosophershavedeniedforotherreasons thatperson isanaturalkind,andIgavesomereasonsofmyowninChapter2,SectionIII.AdvocatesofthePsychological Approach, on the other hand, must deny that living organism,animal,andHomosapiensarenaturalkinds,fortheyarenotsubstanceconcepts:notallorganisms,orallanimals,orevenallhumananimalshavethepersistenceconditionslaiddownbythePsychologicalApproach,astheexistenceofhumanvegetablesandanencephalicbabiesshows.Thatseemshardertoaccept.AtleastI knowof nophilosopherwhohas ever argued explicitly, for any reason, thatanimalisnotanaturalkind.There is also this consideration. If not all animals have the same or even

similarpersistenceconditions,weoughttowonderwhatittakesfornonrationalor non-thinking animals—those animals that aren’t also people—to persistthroughtime.Whatdoesittakeforanoystertopersist,forexample?Wemighthavethoughtthatanoysterpersistsjustaslongasthosebiologicalfunctionsthatkeepitalivecarryon—aslongasitcontinuestometabolize,breathe,digest,andso forth, or as long as it remains capable of doing those things (itmight stopbreathingordigestingforabriefperiod,butwouldcontinuetoexistuntilitwas

revived,oruntil lackofoxygenornutrientsbroughtonitsdeath).Butnowwearetoldthatthisisnot,ingeneral,enoughforananimaltosurvive.Itisneithernecessarynorsufficient,astheTransplantandVegetableCasesshow.Sowhat does it take for an oyster to survive, and how arewe to find out?

Might there be some relation other than continuity of life-sustaining functionsthatfiguresinthepersistenceofanoysteraspsychologicalcontinuityfiguresinthe persistence of some human animals? If a thinking organism continues toexistifitsorganofthoughtcontinuestofunction,andwouldgoalongwiththatorganifitwereimplantedintoadifferentorganism,mighttherebesomeotherorganthatplaysasimilarroleforsomenon-thinkingorganisms?Inanycase,theproponentsofthePsychologicalApproach(iftheythinkthatweareanimals)arelikelytohaveahardtimesayingmuchaboutthepersistenceconditionsforthoseanimals to which the Psychological Approach does not apply. The BiologicalApproach,ontheotherhand,canprovideaunifiedaccountofthepersistenceofalllivingorganisms.Butthatisthesubjectofthenextchapter.

6

TheBiologicalApproach

I.FurtherQuestions

TheBiologicalApproachistheviewthatyouandIarehumananimals,andthatnosortofpsychologicalcontinuityiseithernecessaryorsufficientforahumananimaltopersistthroughtime.AlthoughIhavearguedforthisclaimatlength,Ihavehadrather little tosayabout justwhat thetheoryentails.In thischapterIwill try to answer some of the hard questions theBiologicalApproach raises:Whichbeings is thephrase ‘youand I’meant to include?Does theBiologicalApproachentailthatwearemereanimals?Whatisananimal,ormoregenerallyalivingorganism?Andwhatdoesittakeforananimaltopersistthroughtime?What is the relation between you and I and our bodies, on the BiologicalApproach,andhowdoes thataccountcomparewith themore familiar“BodilyCriterion’?Aswe have seen, the Biological Approach does not say that all people are

humananimals.Theremaybepeopleofotherbiologicalspecies, like theonesthatpopulate science fiction.Theremaybewholly immaterialpeople, like theones that populate religiouswritings: gods or angels or demons orwhat haveyou.ForallIknowthereareorcouldbeCartesianegosorLeibnizianmonads.Iwould not even venture to claim that all material people must be biologicalorganisms.Perhapsacerebruminavatcouldcountasaperson;butitwouldnotbe a livingorganism. Itmight evenbepossible to build a thing that is just asrational, conscious, and free as you and I out of nuts and bolts, orwires anddiodes. (The electronic digital computer is only fifty years old.Who can saywhattheengineersofthefuturewillbeabletoproduceiftechnologycontinuestoprogress at itspresent rate for another ten thousandyears?)Thepersistenceconditionsof suchpeoplewouldobviouslyhavenothing todowithbiologicalcontinuity.Whether or not there could be such non-animal people, you and I, who are

animals,couldnotbecomegodsorCartesianegosordigitalcomputers. Itmay

bepossibletoreplaceallofyourparts,includingyourbrain,graduallyandpieceby piece,with inorganic prostheses in such away that yourmental capacitieswerepreservedthroughout(Unger1990,107f.).Theresultwouldbeawhollynon-biological person—with rationality, consciousness, free will, the works—whowasbothpsychologicallyandmateriallycontinuouswithyou.Nevertheless,accordingtotheBiologicalApproachthatbeingwouldnotbeyou,foryouareabiologicalorganism,andnoorganismcouldcometobeanon-organism(orsoIshallargue).TojustwhichpeopleistheBiologicalApproachmeanttoapply,ifitdoesnot

necessarilyapplytoallpeople?Toallpeoplewhoarehumananimals,wemightanswer.Butthatthreatenstobetrivial:aCartesiandualistoranadvocateofthePsychologicalApproachmightacceptit,andsimplydenythatthereareanysuchpeople. “If therewere peoplewhowerehumananimals,” theymight say, “theBiologicalApproachwouldapplytothem.ButneitheryounorInoranyotherpersonisananimal.”IclaimthattheBiologicalApproachistrueofyouandmeandallofourauntsandunclesandcousinsandfriends:allhumanpeople.Butwhichpeople arehumanpeople? If they are just thosepeoplewho arehumanorganisms,thesameproblemarisesoncemore.Consider thehumananimal thatwepoint towhenwepoint toyou:ahuman

person is anyonewho relates to a human animal in thewayyou relate to thatanimal.Thisdefinitionpicksout theclassofpeople Iwant to talkabout—youandme and everyone we know—nomatter what our ultimate nature and ourpersistence conditions might be. These are the beings who, according to thedualist, are immaterial thinking substances somehow housed within humanorganisms,who, according to thePsychologicalApproach,persistbyvirtueofpsychologicalcontinuity,andwho,accordingtome,arehumananimalswhosepersistenceconditionshavenothingtodowithpsychology.IhavesaidthatforallIknowtherecouldbe“non-human”peopleofwhomthe

Biological Approach was not true—gods, for example—who persisted not byvirtueofbiological continuitybutbyvirtueof someverydifferent relation. Inthatcase,mighttherealsobepeopleofwhomthePsychologicalApproachwastrue?Could thePsychologicalApproach be true—if not for us human people,then for peopleof someother kind?Or is itnecessarily false?Could there besomething that necessarily persisted just in case its psychological contents orcapacitieswerepreserved?Thisisaninterestingquestion.Lockethoughtthatanimmaterialthinkingsubstancecouldloseitspsychologicalcontents,andthatonesuchsubstancecouldbepsychologicallycontinuouswithanotherone;andmanylatter-day dualists, such as Swinburne, seem to agree. That suggests thatsubstance dualism is not compatible with the Psychological Approach. But I

wouldn’t put much money on this claim; I have no idea what an immaterialsubstance could and could not survive. Nor have I any idea what sorts ofalterationsagodoranangelor,forthatmatter,aconscious,intelligentcomputercouldsurvive.SoIshallsetthisquestionaside.TheBiologicalApproachisnottheviewthatyouandIareidenticalwithour

bodies, or that we persist if and only if our bodies persist. But the relationbetween theBiologicalApproach and the “BodilyCriterion” is a complicatedmatter,andIshallputitoffuntilSectionV.(Wehavealreadyseen,inChapter1, Section III, that the so-called physical criterion is in fact a version of thePsychologicalApproach.)Somephilosophersassociatewith theBiologicalApproachtheviewthatyou

and I have only physical properties, whatever exactly that may mean. TheBiological Approach is intended to be compatible with a “dual-aspect” or“property-dualist” theoryofmind,according towhichpsychologicalpropertiesareinsomesensenon-physicalproperties.Ifit ispossibleforanythingtohavebothphysicalpropertiessuchasmassandpsychologicalpropertiessuchasbeingneurotic,thisissurelypossibleforhumanorganisms.Thus,Idonotunderstandclaimslikethisone:

Persons are emergent entities in the benign sense that, possessing the properties of linguisticcompetence, other rule-following abilities, and other attributes presupposing such abilities, theypossess properties essentially lacking in purely physical bodies and in mere biological organisms.(Margolis1978,22)

I seeno reason tobelieve thatbiologicalorganismsare“merely biological”or“purely physical” things that do not and could not have such properties aslinguistic competence—unless the claim is that nomaterial object could havesuchproperties.If thosewhosaythatyouandIarenot“just”organismsmeanby this simply that we have properties that are in some important sense notbiologicalorphysicalisticproperties,suchasbeingfamousorwiseorforgiven,then theirviewiscompatiblewithmine.But if theymean thatyouandIhaveparts that arenotpartsof any livingorganism, theymust reject theBiologicalApproach.

II.Organisms

What isanorganism?Ultimately it is thebusinessofbiologists toanswer thisquestion: it is roughly the same project as explaining the nature of life. Theyhavehadagreatdealtosayaboutthematter.1Anumberofinterestingfeaturesdistinguishbacteria,earthworms,rosebushes,goldfish,humanbeings,andother

living organisms from non-living things. Some of these are features that weshouldexpectanylivingcreaturetohave, includingextraterrestrial lifeandtheartificialorganismswemightonedaybeabletocreateinthelaboratory.

Metabolism

Livingorganismshaveadynamicstability: theyretaintheircharacteristicformandstructuredespiteaconstantand rapidexchangeofmatter andenergywiththeir surroundings. In this respect a living thing is analogous to a flame or afountain.Atthemicroscopiclevelandbelow,anorganismisthesiteoffreneticactivity.Infivedaysyourliverexchangesabouthalfofitsmatter.Matterdoesnot flow through all living tissues so quickly, but the rate of exchange isastonishingly high. For example, a shrewmust eat three times its ownweighteachdayordieofstarvation;andabacteriumsynthesizes“asizablefraction”ofits total mass every ten minutes, with each individual enzyme turning out ahundredproteinmoleculespersecond(Sagan1990,986).In fact, the stability of living things depends on this constant exchange;

withoutittheelaborateinternalstructuresnecessaryfortheorganismtoremainalivewould soon break down. Themachinery thatmakes the organism run ismadeupofextremelycomplexorganicmolecules.If thosemoleculeswerenotconstantly being repaired or replaced with new ones, random thermal motionwould soon alter their structure; and almost any such change would preventthosemolecules fromdoing their job in theorganism’smetabolism.Withoutaregularsupplyofenergyandmolecularrawmaterials(food),alivingthinggoesout likea light,unless it can shutdown itsmetabolismandgo intoadormantstate,assomebacteriacan.

Teleology

Thedynamicstabilityofanorganismisunlikethatofaflameinthattheflowofmatter and energy through anorganism is subject to a complex set of internalcontrols.Whereasthesize,shape,temperature,chemicalcomposition,andotherpropertiesofa flamedependentirelyupon its surroundings (theavailabilityoffuel andoxygen, theambient temperature,wind, etc.), the size, shape, internalstructure and chemical composition, temperature, and movements of anorganism, though influenced by its surroundings, are to an important extentgovernedfromwithin.Organismsareself-directedandself-organizedinawaythatotherdissipativestructuresarenot.Anorganismadjustsitsactivitiestotakeadvantageofthechangingconditions

in its surroundings. When the ambient temperature drops, a warm-bloodedanimal’smetabolismincreasesandbloodflowisdirectedawayfromitssurfacetoconserveheat.Whenabacteriumfindsitselfinthepresenceofachemicalitusesasfood,itmaybegintosynthesizeanenzymethatenablesittoassimilatethatchemical;whentheconcentrationoffooddecreases,theenzyme-synthesisisswitchedoff.There isnosimple,mechanical relationshipbetween theambienttemperature and the internal temperature of a warm-blooded organism, orbetweentheconcentrationofsugarinabacterium’senvironmentandtherateatwhichitabsorbsthatchemical.Ineachcasetheorganismregisterschangesinitssurroundings and adjusts its activities in a way that increases its chances ofattainingitsgoal:obtainingasmuchfoodaspossibleormaintainingaconstantinteriortemperature.Thepartsofanorganism,likethoseofafinewatch,areconnectedtogetherin

suchawaythateachhasarole toplayinenablingtheorganismtoachieveitsends—survival and reproduction. No part can fulfil its function without theothers; the entire structure will collapse—the organism will die and decay—unlessallornearlyallofitspartsdowhattheyaresupposedtodo.2

OrganizedComplexity

The goal-directed nature of living things is grounded in an underlyingbiochemical structure of unimaginable complexity. A typical human beingconsistsof1014cells,eachofwhichcontainssome1012bitsofinformation,theequivalentofahundredmillionencyclopediapages(Sagan1990,987).Eventheverysimplest living thingsare impressivelycomplex. Imaginebuildingascalemodelofanordinarybacterium,usingbeads to representatoms. If a thousandworkers each stuck two beads together every five seconds, eight hours a day,fivedaysaweek,theywouldcompletetheproject(whichwouldfillacathedral)inaboutthirty-fiveyears—andthatisassumingthatthewatermolecules,whichmakeup70percentofthewhole,comepreassembledfromthefactory(Cairns-Smith1985,19).AsBlakesaid,“tocreatealittlefloweristhelabourofages”,atleastforus.Thebacteriumitselfdoesthejobinhalfanhour.Butthecomplexityofahumanbeingorofanyotherorganismisnotsimplya

matter of having a vast number of parts.We are complex in a way inwhichmarblestatuesofhumanbeingsarenot.Ourpartsarearrangedinanextremelydelicate and highly improbableway. If the atoms thatmake youup (there areabout1028 of them,giveor takea fewgazillion)werearranged in almost anyotherway, theywouldnotcomposea living thing.Anorganismiscomplex insomethinglikethewaythat thetextofabookiscomplex.Abookconsistsof,say,500,000charactersdrawnfromastockofaboutahundredupper-andlower-caseletters,numerals,spaces,andpunctuationmarks.Needlesstosay,thevastmajorityofstringsof500,000characterschosenatrandomarenotbookswrittenin English or any other language. Richard Dawkins has calculated that thechancesofhittinguponeventhebriefShakespeareanphrase“methinksitislikea weasel” by choosing twenty-eight characters at random (leaving asidepunctuation and cases) is about one in 1040 (1986, 47). But the degree ofcomplexitywefindinlivingorganismsisclosertothatofanentirelibrarythantothatofasinglesentence.Infact,theanalogywiththebookgoesfurther.Eachlivingorganismcontains

within it a sort of plan. This plan contains the organism’s “basic operatinginstructions”. As we have seen, an organism’s molecular parts, beingthermodynamically delicate, must be constantly repaired or replaced. Thechemicalmachinerythatdoesthishasto“know”whatmoleculestoreplaceandhow to produce them. To find out, it consults the plan (which is itself inchemical form and in need of constant repair). The plan also contains

instructions for the organism’s growth and development. As we have seen,organismsdon’t simplygrow larger inproportion to the resourcesavailable tothem, as fires do. They grow (and sometimes shrink) in a controlled, self-directedway, and theymaychange in form inaway thathas little todowiththeirsurroundings,aswhenacaterpillarturnsintoabutterfly,orwhenahumanembryostopslookinglikeafishandbeginstogrowarmsandlegs.Finally,theplancontainsinstructionsforbuildinganeworganismofthesamekind,andsomakesreproductionpossible.Theplan thateach terrestrialorganism(ormoreaccuratelyeachcell)carries

withinitselfismadeofDNA(inmostcases),anditcarriesitsinformationintheformofamolecularcodeorlanguage.ADNAmoleculeisachaincomposedofsmallermoleculesofseveralkinds,anditfunctionslikeaverylonglineoftext(it is amillion times longer than it iswide).The smallermoleculeswork likeletters,anditistheirarrangementthatinstructsthecell’schemicalmachinerytogrow,repairitself,takeinfood,expelwaste,andreproduceinitscharacteristicway. This “genetic code” is like a language insofar as the correspondencebetweensequencesofDNA“letters”and thechemicalprocessescarriedout inresponse to them is arbitrary, and could have been different. If the chemicalmachinerythat“reads”theDNAstrandhadbeendifferent,thesamesequenceof“letters” would have caused different chemical processes within the cell; thatsequencemighthavehadadifferentbiochemicalmeaning,justasthesequenceof Roman letters c-a-t might have meant “dog” instead of “cat” in English.Although there may be organisms without DNA (or its cousin, RNA), somebiologiststhinkthataninternalplanofsomesort,writteninanarbitrarycode,isessentialtolivingthings(Monod1971,77f.).Someconsideritessentialtoalivingorganismthatitbecapableofevolution

by natural selection (e.g.,Maynard Smith 1986, 7).NowDarwinian evolutionmaybe the only explanation for theorigin of organized complexity (Dawkins1986,chap.11);butitisnotcleartomethatthisisanecessaryfeatureofeverypossible individual organism. It at least appears possible for an organism toreproduceitselfwithcompleteaccuracy(amutationrateofzero),inwhichcasetherewould be no fortuitous variations for natural selection towork on.Or ifthat is toomuch to ask, an organismmight be such that any geneticmutationlikely to takeplacewithin abillionyearswouldnot result inviableoffspring,making evolution impossible on anything like the time scale of the actualuniverse.Amutationratethatwastoohighwouldhavethesameeffect.Evenifsuchorganismscouldneverariseinnature,wemightbeabletocookthemupinthelaboratory.However that may be, it seems reasonable to say that a living organism is

anythingthathasthese“life-giving”features—metabolism,teleology,organizedcomplexity—and whatever further properties necessarily go along with them,such as self-directed growth and development, an internal genetic plan, lowinternalentropy,andperhapsthecapacityforevolutionbynaturalselection.The reader may wonder whether this account distinguishes genuine living

organismsfrommerehunksof livingtissue—detachedorgansandproperpartsoflivingorganisms,forexample.Supposeweremoveoneofyourkidneysandkeep it “alive” by pumping nutrients through it. Doesn’t that detached organexhibitmetabolism,teleology,andorganizedcomplexity?Ifso,thoseconditionsarenotsufficientforsomethingtobealivingorganism,forthekidneyisnotananimal,oranorganismofanyothersort.If the kidney has many of the features that living organisms have, that is

because it is entirely made up of living organisms: its individual cells. Theymetabolize,and theyaremadeupofparts thatwork togetherasaunit tokeepthecellalive.However,thisisnottrueofthedetachedkidney.Theactivitiesofthekidney’spartsarenotcoordinatedinawaythattendstokeepthekidneyasawholealive;thekidneygetsitsteleologicalpropertiesfromthewayitrelatestoa human organism. One biologist defines an organism as “a complexmacromolecular system that behaves as a unit and is capable of replicationthrough a conversion of materials and energies derived from its environmentthrough a self-controlled interface or boundary” (Grobstein 1964, 61). Thekidney, unlike yourself, does not behave as a unit, and has no self-controlledboundary—at leastnotas longas it isdetachedfromyouoranyotheranimal.ButIshallhavemoretosayaboutthesemattersbelow.

III.TheIdentityofOrganisms

What does it take for an organism, or at any rate a human animal, to persistthroughtime?ConsiderTimandTom,whoareordinaryhumanorganismsuntilthedaytheywanderintoaphilosophicalthoughtexperiment.ThephilosopherscutoffTim’srightarmandgraftitontotheplacewhereTom’srightarmusedtobe, andarrange things so thatTom’smetabolismassimilates thenewpart (thearm does not decay, is not attacked by Tom’s immune system, etc.). Is theresulting human organism— the onemade up of Tim’s right arm and Tom’s“right-arm-complement”—Tim or Tom? Or is it some third animal? It isobvious,Ithink,thattheresultinganimalisTom.Youdonotdestroyananimalsimply by cutting off an arm (though this might cause death indirectly: theanimalmightbleedtodeathorgetgangreneasaresultoftheamputation).Nor

dowepareananimaldowntoamerearmbyseparatingthatarmfromtherestoftheanimal.Whenyoucutoffananimal’sarm,thatanimalsurvivesasthearm-complement, not as the detached arm. Neither does the animal become aspatially scattered object, consisting of a detached arm and a detached “arm-complement”.Butwhy?ThereasonwhytheresultinganimalinourstoryisTom,youmight

think, is that thatanimalgotnearlyallofof itsorgans,cells, and tissues fromTom;moreover,thoseorgans,cells,andtissuescontinuetobearrangedinmuchthe sameway as they were arrangedwhen theywere parts or constituents ofTom.Tim’scontribution ispaltrybycomparison.Thissuggests thatananimalpersists just incasemostof itsorgansorcellsor tissuesorwhathaveyouarepreserved, at least in the short run (perhaps an animal could survive thereplacement ofmost of its organs, cells, etc., if those replacements tookplacegradually over a long period). If any animal is cut in two and both parts areprevented from “dying” and decaying, the suggestion goes, it survives as thelargerofthetwoseparatedparts.Now imagine that insteadof cuttingoffTim’s arm,wecutoff his head and

graftitontotheplacewhereTom’sheadusedtobe.Istheresultinganimal,withTim’sheadandTom’s“head-complement”,TimorTom?(RememberthatTimandTomaretheorganismsinthestory;nevermindwhathappenstothepeopleinvolved,whomightbenumericallydifferentfromtheorganisms.IfitdistractsyouinthepresentcontexttothinkthatTimandTommightbepeople,imaginethat they are both in a persistent vegetative state.)What happens to a humananimalifyouseparateitsheadfromtherestofitandattacheachresultingbittoa life-support system? Does the animal get reduced to a mere severed head?Does it lose its head in theway that itmight lose an arm?Does it become aspatially scattered object, composed of a detached head and a detached head-complement?Ordoestheanimalceasetoexistaltogether?Aheadhasaboutthesamenumberofcellsandthesameamountoftissueasanarm,soifananimalsurvives when most of its cells or tissues are preserved, the resulting animaloughttobeTom.CuttingawayTom’sheadoughttobejustlikecuttingawayhisrightarm: ineachcaseweremove5or10percentofTom’s tissuesandmakehim ten pounds lighter. In each case Tom should survive as the larger of theresultingpieces.Butthisisnotaplausibleaccountofwhatittakesforanorganismtopersist.

Biology tellsus that the result of cuttingawayaman’shead isnot aheadlessliving organism, but a mere heap of flesh, a headless corpse (van Inwagen1990b,173ff.).Thatheap iscomposed, for the timebeing,of livingcells;butthosecellsareunabletocoordinatetheiractivitiesinthewaythatthepartsofa

livingorganismcoordinatetheirs.Theydon’tfunctiontogetherasaunit.Allofanorganism’slife-sustainingfunctionsceaseimmediatelywhenyouremove(oratanyratedestroy) itshead.Wemightclose thewoundandpumpair into thelungs with a respirator. If we are lucky, that may cause the heart to go onbeating;otherwiseweshouldhave tostimulate theheartmuscleelectricallyaswell. This would be a good way to preserve the organs of Tom’s head-complement for transplant; but it would not cause those cells and organs tocompose a living animal. Its vital organswouldnot functionunless theywereconstantly stimulated fromwithout. The headless objectwould not be able toregulate its internal temperatureor the rateof itsmetabolism.Foodwouldnotmovethroughthedigestivetract,andtheglandswouldnotproducetheirusualsecretions.Therewouldbenoswallowingorcoughingreflex;asaresult,fluidwould tend to accumulate in the lungs. That is because the organs that oncedirected those activities—the pons, medulla oblongata, and hypothalamus,among others—are missing. Tom’s detached head-complement is no more alivingorganismthanhisseveredarmisanorganism.Tobelieveotherwiseistothinkthatjustanyconnectedaggregateoflivingtissueisanorganism,includingakidneyawaitingtransplantorahumanpyramidatthecircus.WhataboutTim’sdetachedhead?IsitanymorealivingorganismthanTom’s

detachedhead-complement?Infact,itseemslikelythattheheadwouldbehaveasalivingorganismifitwereattachedtoalife-supportsystem.Theheadwouldbe able to regulate itsmetabolic rate andwake-sleep cycle. Itwould retain itsmuscletone(evenifnoconsciousnesswerepresent).Itspupilswouldopenandcloseaccordingtotheamountoflighthittingtheretina,andthelensoftheeyewould focus. And so on. That is because the organs that control Tim’sautonomicnervoussystemanddirecthisvitalfunctionsarepresentandintactinhis detached head. Of course, the head lacks many vital organs and cannotremainalivewithoutanelaboratelife-supportsystem.Thereisnotasmuchfortheautonomicnervoussystemtodoasthereordinarilyis,formanyoftheorganswhoseactivitiesitwouldotherwisedirectaremissing.Butthatneednotpreventtheheadfrombeingalivinganimal.Ifweremovedyourkidneysyouwouldlackvitalorgans,andyouwouldnotbeable tosurvivewithoutadialysismachine.Butthatwouldnotkillyou,norwoulditmakeyouintosomethingotherthanalivingorganism.Youwouldbecomeadebilitatedhumananimal.Tim’sdetachedheadisafarmoreseverelydebilitatedanimal.Withoutaheart-lungmachineitcan remain alive for only a few minutes (until it dies of oxygen starvation),whereasyoucouldremainalivewithoutkidneysforafewdays(untilyoudieofbloodpoisoning).Nevertheless,theheadseemstobealivingorganismbecauseitretainsthecapacitytocoordinateitsvitalfunctions.3

Thismay soundparadoxical.Tim’s detachedhead is a debilitatedbut livinganimal, I say,even though itcannot remainalive formore thana fewminuteswithout a heart-lung machine. Why don’t I say the same thing about Tom’sdetachedhead-complement?Tobesure,wecan’tmakethatheadlessthinglookmuchlikealivinganimalsimplybypumpingairintoitslungsandstimulatingtheheartmuscle.TherestofTom’svegetativefunctionsstillwouldn’twork.Butsupposeweattachedan“artificialbrainstem”toTom’sheadlessremains—asortofcomputerthattakesoverthebrainstem’sjobofcoordinatingtheactivitiesofthe circulatory and respiratory, digestive, and immune systems, receiving,processing, and sending out chemical and electrical signals from the variousremaining organs, in such a way that those organs function just as they didbeforetheheadwasremoved.Wouldn’tTom’sheadlessremainsthenbealivingorganism?4Itwouldbeadebilitatedlivingorganism,ofcourse,foritwouldnotbeabletokeepitselfalivewithoutartificialhelp.ButthenthesameistrueforTim’s detached head, and for many living human beings who cannot survivewithout a respirator, pacemaker, dialysis machine, mechanical heart, or whathave you.Why aren’t both things, Tim’s detached head and Tom’s detachedhead-complement,livingbutmachine-dependentanimals?Partofwhatmakessomethinga livingorganism, Isuggest, is itscapacity to

coordinate and regulate its metabolic and other vital functions.5 A livingorganismmaybepreventedfromcarryingoutthosefunctions.Imightbeunabletodigestmy foodbecauseofablockage inmy intestine; Imightbeunable topurifymybloodbecausemyliverorkidneysaredamaged;Imightbeunabletodraw air into my lungs because my windpipe is clogged, or because mydiaphragm muscles are paralyzed. In that case I could not survive for longwithout some sort of outside intervention. The instructions thatmy brainstemsendsouttotherestofmyorgansmaynotarriveattheirintendeddestinations,or they may not have the effects they are designed to have (“intended” and“designed” by evolution, not consciously). Nevertheless, the control andcoordinationmechanismsareintact.Tom’sheadless remains,however, lack thecapacity to coordinate anddirect

their vital functions—and not simply because the instructions don’t arrive orcan’tbecarriedout,butbecausetheorgansthatproducedthoseinstructionsaremissing. Consider a political analogy: a state in which all lines ofcommunication—radio,television,telegraph,andsoforth—arecut,orinwhichthe police, roadbuilders, and other people who ordinarily carry out on thegovernment’sinstructionsgoonstrike,mightbeastateincrisis,paralyzed.Butastateinwhichallpeoplecapableofleadershiphavesuddenlybeenkilledisno

stateatall.Considerwhatwouldhappenifweturnedofftheartificiallife-supportsystems

ineachcase. Ifweswitchedoff theheart-lungmachine that thedetachedheadneeds to survive, the head would behave like a dying organism. It wouldcontinuetoregulateitsinternalmetabolicactivitiesinitscharacteristicwayuntilthe“controlcenters”shutdownowingtolackofoxygen.Afterafewminutes,death,withitscharacteristicsymptoms—lackofcoordinatedactivity,decay,andsoforth—wouldoccur.Ifweshutoffthe“artificialbrainstem”thatweattachedtoTom’sheadlessremains,however,allsignsoflifewouldceaseimmediately.Heartbeat, respiration, and digestion would stop cold. All muscle tone wouldvanish. And so on. Without artificial help, the head-complement could notbehavelikealivinganimalevenforamoment.Tom’s headless remains are much like Tim’s detached arm. By pumping

oxygenated blood through the arm and stimulating the severed nerve endsartificially and so on, we could produce the appearance of life; but for itssurroundings,thearmwouldbenodifferentfromanarmthatwasattachedtotherestof ahumanbeing. Ifwe removed the life-support system, this appearancewouldinstantlycease.Buttheseveredarmisnotalivingorganism,foralthoughitmaybemadeupoflivingcells,itdoesnotitselfhavetheabilitytocoordinatetheactivitiesofthosecellsinthewaythatischaracteristicoflivingorganisms.Tom’sheadlessremainsarenotanorganismforthesamereason.But isn’tTom’shead-complement alive as long as the artificial brainstem is

attached?Ifthoseheadlessremainsbythemselvesareunabletocoordinatetheirvital activities in the right way, might not those remains together with theartificialbrainstemmakeupagenuinelivinganimal?Thisisadifficultquestion.Iaminclinedtoanswerlikethis:Itisnotclearthat

an organism could have an inorganic object larger than amolecule, such as astainless-steelhiporapacemakeroranartificialbrainstem,asapart. Imaginethatyourkidneysstopworking,sothatyoucannotliveformorethanafewdayswithoutattachingyourselftoadialysismachine.Still,themachinethatyoucan’tlivewithoutisneverliterallyapartofyou(orapartofyourbody,ifyouprefer).Whynot?Because it isnotcaughtup inyourmetabolism.Themachinedidn’tgrowaccordingto theplanencodedinyourgenes.If itbreaksdown,someonehastorepairitwithascrewdriverandsolderingiron;unlikeagenuineorgan,itdoesnothealorformscartissue.Themachinedoesnotassimilatenutrientsfromyourbloodstream,andthechemicals thatmakeituparenotaccessible toyourmetabolisminthewaythatthoseofyourbonesandothertissuesare.Ifyouareanemic,forexample,yourmetabolismcannotutilizetheironthatcertainpartsofthemachinearemadeof.Thestabilityorhomeostasisofthesystemcomposed

partlyoflivingtissueandpartlyofmetalorwhateverisnotdynamicinthewaythatalivingorganism’sstabilityisdynamic.Itmakesnodifferencewhetherthemachineisinsideyourskin(vanInwagen

1990b,94 ff.).TheJezailbulletDr.Watsoncarriedaround insidehisshoulderwasneverapartofhim.Strictlyspeaking,itwasapartofhisenvironment.Wecannotaddpartstoananimalbyimplantingrocksintoitsabdominalcavity.AndwhatgoesforyourdialysismachineandWatson’sbulletgoesfor theartificialbrainstem as well. It is not caught up in themetabolic processes going on inTom’sheadlessremains;soitisnomoreapartofanylivingorganismthanyourdialysismachineisapartofalivingorganism.Thus,thereisnoanimalmadeupof Tom’s headless remains together with some mechanical or electroniccontraption.6

IV.Lives

Allofthissuggeststhatananimal,orforthatmatteranyorganism,persistsjustincaseitscapacitytodirectthosevitalfunctionsthatkeepitbiologicallyaliveisnot disrupted. We could make this into a general account of the identity ofanimalsalongsomethingliketheselines:

Ifxisananimalattandyexistsatt*,x=yifandonlyifthevitalfunctionsthatyhasatt*arecausallycontinuousintheappropriatewaywiththosethatxhasatt.

Presumablythiswillbethecaseonlyifyisananimalatt*;thus,anythingthatisan animal at one time will always be an animal. Of course, which causalconnections are “appropriate” is amoot point. But then just about any theoryabout the persistence of concrete objects will face an analogous question.According to the Psychological Approach, for example, my currentpsychologicalfeaturesmustbecausallyrelatedinsomeappropriatewaytothosethat I have at every other time at which I exist. Phrases like “psychologicalcontinuity”or“biologicalcontinuity”onlycoverupthisproblem.Thisproposalentailsthatananimalnecessarilyceasestoexistwhenitdies.In

thatcasethereisnosuchthingasadeadanimal,strictlysocalled.Wemaycallsomethinglyingbythesideoftheroadadeadanimal,butstrictlyspeakingwhatis lying there are only the lifeless remains of an animal that no longer exists.Thatadeadanimalshouldnotbeananimalmaysoundabsurd.Butthenaghosttownisnotatown,adrylakeisnotalake,atinsoldierisnotasoldier,andadeadpersonisnotaperson.

This is reminiscent of Locke’s account of the identity of organisms. Hedescribed the difference between a living organism and a mere aggregate ofliving tissue bymeans of the concept of a life. In a loose sense of the term,perhaps,athing’slifeissimplyitscareer,thesumofeverythingitdoesandallthat happens to it throughout its existence.Everythinghas a life in this sense.Somekindsofobjects, though—roughlymembersofnaturalkinds—havelivesin a more interesting sense, in that they do not merely undergo changes, butdevelopinamannercharacteristicofthingsofthatkind.Forexample,wemayspeakofthelifeofastar,fromits“birth”inacollapsingcloudofhotgastoits“decay” into a white dwarf and its “death” when there is no longer enoughenergy left to radiate light, or when it has cooled to the temperature of itssurroundings.ButLocke’sconceptofalifeisaspecificallybiologicalone,andhasessentiallytodowiththespecialwayinwhichlivingorganismsinteractwiththeirsurroundings.Theindividualbiologicallifeofaparticularlivingorganismis a special kind of event, roughly the sum of the metabolic activities theorganism’spartsarecaughtupin.Alifeisasortofstormofparticlesinconstantmotion.(Stormstooareevents:

they are extended in time, begin and end, have earlier and later parts.)A lifedraws in new particles and energy from its surroundings, imposes itscharacteristic form of activity on those particles, and later expels them. Butunlikemeteorological storms, lives are self-directing, or self-organizing. Theiractivitiesareconstrainedbyelaborateinternalcontrols.Oneresultofthisisthata life retains its formandstructure fora remarkably long time,comparedwiththerateatwhichmatter flows through it.Another result is thata lifehasa farmoredefiniteboundarywith its surroundings thanameteorological stormhas.Lives are well-individuated events: there is usually a definite answer to thequestionwhetheragivenparticleisorisnotcaughtupinaparticularlife.Lives are easy to count: inmost cases there is a clear difference between a

situationthatcontainsonelifeandasituationthatcontainstwo.Thatisbecauseofthenatureoftheactivitiesthatalifeenforcesupontheparticlescaughtupinit.Likeanarmyoratotalitarianstate,alifeimposes“totalobedience”uponthematerialswhoseactivitiesconstituteit.Whenalifedrawsamoleculeintoitself,itbreaksthatmoleculeintosmallerpiecesandreassemblesthemaccordingtoitsneeds.Afterextractingsuchchemicalenergyfromthemasitcan,itexpelstheirremainsinalessorderedform.Thus,aparticlecannotparticipateintwolivesatonce,anymorethanonecanserveintwoarmiesatonce;andtwolivescannotoverlap.Unless,thatis,oneofthelivesissubordinatetotheother.Eachofyourcellshasalifeofitsown,withaninternalplanandawell-definedboundary.Thelife of an individual cell can be a part of the life of amulticellular organism

becausethedemandsthatthosetwolivesimposearecompatible.Youcanserveintwoarmiesatonceifoneofthemisadivisionoftheother.Every organism has a life, and it is hard to see how there could be a life

withouttherebeinganorganismwhoselifeitwas.Andanorganismcannotbeanimated by two lives, at least not at once. This suggests that organisms andlivesmightalwaysmatchuponetoone,inwhichcasewecangiveacriterionofidentityfororganismsintermsoflives.ThatwasLocke’sproposal:

WemustthereforeconsiderwhereinanOakdiffersfromaMassofMatter,andthatseemstometobein this; that the one is only the Cohesion of Particles ofMatter any how united, the other such adispositionofthemasconstitutesthepartsofanOak;andsuchanOrganizationofthoseparts,asisfittoreceive,anddistributenourishment,soastocontinue,andframetheWood,Bark,andLeaves,etc.,of an Oak, in which consists the Vegetable Life. That being then one Plant, which has such anOrganization ofParts in one coherentBody, partaking of oneCommonLife, it continues to be thesamePlant,aslongasitpartakesofthesameLife,thoughthatLifebecommunicatedtonewParticlesofMattervitallyunitedtothelivingPlant,inalikecontinuedOrganization,conformabletothatsortofPlants.7

Whatgoesforplants,onLocke’sview,goesforalllivingorganisms,including“men”,humananimals:anorganismpersists just incase themetabolicprocessthat is its individual biological life continues to impose its characteristicorganizationonnewparticles.Hence,wemightfollowLocke(andvanInwagen)andproposethiscriterionof

identityfororganisms:

Foranyorganismxandanyy,x=yifandonlyifx’slifeisy’slife.

ThisAccountraisesseveraltechnicalpoints.First: A life is the life of a given organism just in case all the parts of the

organismarecaughtupinthatlife,andeverythingcaughtupinthatlifeisapartof the organism. The objects that compose the organism are the ones whoseactivitiesconstituteitslife.8Second:Notjustanyself-directing,homeodynamic,biologicaleventisalife.

Alifemustcontrastwithitssurroundings.Thisisnotmeanttobeanempiricalclaimfrombiology,butpartoftheconceptofalife.Perhapstheactivitiesofallthe atoms inmyupperhalf constitute abiological event.That eventwouldberatherlikealife.Butitisnotalifebecauseithasnonaturallowerboundary;itslowerboundaryisentirelyarbitrary.Considerananalogy.Ahurricanehasvaguebutnon-arbitraryboundaries.Vague,becausetherearesomegasmolecules,dustmotes, droplets of water, etc., that are neither definitely caught up in thehurricanenordefinitelynot caughtup in it.Non-arbitrarybecausemost things

areeitherdefinitelycaughtupinthehurricaneordefinitelynotcaughtupinit,andtheactivitiesof thosethingsdiffer inasalientandrelevantway.Althoughthehurricane’sboundaryisfuzzy,itiseasyenoughtoseeroughlywhereitis;itisn’t drawn arbitrarily, like a political boundary. Now consider an arbitrarysubsetof themolecules caughtup in thehurricane: allof those in itsnorthernhalf, say.Do the activities of thosemoleculesmakeup a smaller hurricane oftheir own? There is a sense of ‘hurricane’ in which they do not, for theboundariesofthatsmallerevent(ifthereissuchaneventatall)arearbitrary;itdoes not contrast with its surroundings. That event is not “maximal” or self-contained in the right way to be a hurricane. This is not simply a relationalfeature of the event, a matter of how it is situated in space. The hurricane’snorthernhalf isnotcausally self-contained in theway that theentirehurricaneis; the two events interactwith their surroundings in very differentways.Thesameistrueoflives.Yourtheoryofeventsmaytellyouthateveryregionofspaceorspacetime(or

atanyrateeveryregionwheresomethingisgoingon)isthesiteofatleastoneevent.Thenyouwillsaythateverypartofthehurricaneisastormyeventofitsown,ormorepreciselythateverysubregionofthelargestregionthatisaclearcandidateforbeingthehurricane’slocationcontainsitsownsuchevent.Ifso,itcouldhardlybethecasethatjustoneofthoseeventswasahurricane,fornooneofthemismorehurricane-likethanalltherest.Strictlyspeaking,then,theremaybenosucheventasthehurricane.Inthesameway,perhapsnoeventwillbethelife of a particular organism, for a great many events may be equally goodcandidates for being that organism’s life. But this need not undermine theLockeanprogramofidentifyingorganismsbytheirlives.Wehavetermsthatatleastappeartorefertoindividualeventssuchasstorms,floods,fires,andlives.Therearemanytruthsthatwecanexpressbysayingsuchthingsas,“Thisisthepoint thewaterreachedin thefloodof‘68”,or,“HurricaneAndrewismovingtowardsthecoastofFloridaatfortymilesperhour”,whetherornotexpressionssuch as ‘the floodof ’68’ or ‘HurricaneAndrew’manage to refer uniquely tosomeoneevent.MypointisthatanorganismhasjustonelifeinthesamesenseasHurricaneAndrewwasjustonestorm.Third:SinceIhavenotgivenanindependentcriterionofidentityforlives,you

may wonder whether giving persistence conditions for organisms in terms oflivesisatallhelpfulorinformative.Isaythatapastorfuturebeingisyoujustincase ithasyourbiological life;but is thereanyway to findoutwhether someanimal’s life is your lifewithout first knowingwhether that animal is you? Ifnot,thecurrentproposalwouldbenobetterthanthisone:apersonxpickedoutatonetimeandsomethingypickedoutatanothertimeareidenticaljustincasex

andy are legallyentitled tobear the samepassport.While thismaybe true, itdoesn’ttellusanythingabouthowtoindividuatepeople,becauseanyevidencefortheclaimthatxandyareentitledtothesamepassportwouldhavetoinvolvethe claim that x is y. If youwanted to find out whether x was y, itmight behelpfultocheckwhetherthereispsychologicalcontinuitybetweenxandy,foryoucouldknowthelatterwithoutknowingtheformer.Butitwouldn’tbeofanyhelptocheckwhetherxandyareentitledtothesamepassport,foryoucouldn’tknowthatwithoutalreadyknowingwhetherxwasy.It may be hard to say exactly what is wrong with the “same-passport”

criterion,butthereisclearlysomethingwrongwithit.Isthe“same-life”criterionany better off? The general question seems to be whether there can be anyevidence for the claim that events picked out at different times are the sameeventthatdidnotinvolve,insomeunspecifiedbutdirectway,theclaimthatthesubstancescomposedoftheitemscaughtupintheeventswereone.Ithinktheanswertothisquestionisclearlyyes.Forexample,wecanoftenknowwhetherthestormthathitCubayesterdayandthestormthatbroughtfloodstoAlabamatodayarethesamestormordifferentones;andourabilitytoknowthisdoesn’tinvolveanyjudgmentsaboutthepersistenceofmaterialobjects.Wedon’tfirstneed to find out whether the material object composed of all and only thoseparticles caught up in the Cuban storm is the same as, or different from, thematerial object composedof thoseparticles caught up in theAlabaman storm.Theremaynot evenbe any suchmaterial objects.Therewill behard casesofcourse,where it isn’t clearwhetherwehave twodifferent storms or the samestormagain,orwhetherastormisstillgoingonorhasceased.Thatisbecausestorms(unlikelives)arenotespeciallypreciseorwell-individuatedevents.Butthat problem does not arise out of an inability to distinguish stormymaterialsubstances.Whyshouldn’tthesamebetrueforlives?Ifso,wecanidentifyandreidentify

liveswithoutfirstidentifyingandreidentifyingtheorganismstheyanimate,andthe“same-life”criterionwillbeusefulandinformative.

V.BrainstemReplacementsandOtherDifficulties

Some readers sympathetic with the Biological Approach have objected tomyaccountoftheidentityofhumananimals.Ihavesuggestedthatyourbrainstem,as the organ that is chiefly responsible for directing your life-sustainingfunctions,isessentialtoyou,forwithoutitthereisnoLockeanlifeandnolivinghumanorganismatall.Butwouldn’ttheBiologicalApproachbeeasiertoaccept

without that claim? Imagine that surgeons destroy your brainstem andimmediately replace itwith a perfect duplicate. The resultwould be a humanbeingwhowasbothpsychologicallyandbiologicallyexactlylikeyou,exceptforthescars.Isn’titevidentthathewouldbeyou,andhencethatyoucouldsurvivethe replacement of your brainstem? And not only because he would bepsychologicallycontinuouswithyou,withplentyofphysicalcontinuitythrownin for goodmeasure.He also seems to be the same animal as you. It doesn’tseem that we necessarily kill an animal by destroying and replacing itsbrainstem. The same Lockean life seems to continuewithout interruption.Nolifelesscorpseresults.Doesn’tthisshowthatmyaccountofwhatittakesforananimaltopersistiswrong?Evenifremovingyourcerebrumwouldsimplyleaveyouwithanemptyhead,andeven ifyoucouldsurviveasahumanvegetable,isn’titevidentthatyourbrainstemisnotessentialtoyou?I don’t find this so evident.Despite appearances, it does not seem to be the

casethatyourbiologicallifecontinueswithoutinterruptionwhenyourbrainstemisdestroyedandreplaced.Assoonasyourbrainstemisdestroyed,youlosethecapacity todirectyourvitalfunctions.Yourindividualcellsandorganscannolongerworktogetherasaunitinthemannercharacteristicofalivingorganism.Whatwehaveisacorpsethatmerelyappearstobealivebecauseitissofreshlydead,andnota livinganimal.Thisperiodof“metabolicanarchy”might seeminsignificant because it is so brief. (How could just a few seconds orminutesmatter?) But suppose Descartes’ evil genius annihilates you and replaces youwithaperfectduplicateathousandthofasecondlater.Heretootheinterruptionofyourbiologicallifeisbrief—sobrief,infact,thatnoonewouldsuspectthatanythingoutof theordinaryhadhappened.Nevertheless,whathappensduringthatthousandthofasecondisenoughtobringyourexistencetoanend.Isuggestthatyoucannotsurvivebrainstemreplacement for thesamereasonyoucannotsurviveannihilationandreplacementbyaperfectduplicate.Youmight find this analogymisleading.Nomatter how quickly the demon

works,allofyourvitalfunctions(aswellasyourmentallife)willbedisrupted,ifonlybriefly.Butsupposethesurgeonsreplaceyourbrainstemsoswiftlythatneitheryourvitalfunctionsnoryourmentallifehasachancetoreactbeforetheneworganisinplace;orweasktheevilgeniustoleavetherestofyoualoneandannihilate and replace only your brainstem, all in a thousandth of a second.Surely there would be no disruption of your biological life then? Everything,exceptthebrainstem,wouldcarryonexactlyasbefore,continuingtofunctioninthesamebeautifullyharmoniousway.IfImustdenythatyoucouldsurvivethis,surelythatamountstoareductioadabsurdumofmyview.But even here, for that thousandth of a second during which you have no

brainstem,thereisnothingtodirectyourlife-sustainingfunctions.Evenifthosefunctions—heartbeat, respiration, digestion, and so forth— continue in theinterval, your capacity to direct them is destroyed. So for a thousandth of asecondthereisnoself-directingeventthatcoordinatestheactivitiesofyourpartsintheuniquewaythatbiologicallivesdo.Forathousandthofasecondthereisnolivingorganismthere,butonlyacorpsesofreshthatitsheartisstillbeating.Butitwouldnotcontinuebeatingforlongunlessthebrainstemisreplaced.Themerefactthatmanysignsoflifecontinueduringthatbriefperioddoesnotshowthat a living organism is still present.Many of an organism’s individual cellsmaycontinuetofunctionlongaftertheorganismasawholeisdead;thatiswhatmakesorgantransplantspossible.But now imagine that your brainstem is replaced by an inorganic substitute

gradually, bit by bit, rather than all at once. The rest of you is left intact.Alternatively, if you feel more comfortable with traditional philosophicalthought experiments, you can imagine that you are gradually reduced to acerebrum in a vat.This time there is never a periodwhenyour life-sustainingfunctionsareleftwithoutanorgantocoordinatethem,orwhenyourcerebrumisnotarousedandactivatedinthenormalwaybythebrainstem.Asaresult,thereneedbenointerruptioninconsciousnessthroughouttheoperation(supposethesurgeonsuseonlyalocalanaesthetic).The result would be a rational, conscious being with your mind. Isn’t it

obviousthatyouwouldbethatbeing?Myview,however,entailsthatyoucouldnot survive this; despite appearances, the resulting being would not be you.Worse,thatresultingpersonwouldnotevenbeahumanbeing,atleastifbeingahuman being implies being a human animal. For somethingwith an inorganicbrainstem, I argued, could not be an animal at all. Either that being is one ofthose people that aren’t living organisms, along with gods and angels andrationalelectroniccomputers,towhomtheBiologicalApproachdoesnotapply;or there isno thinkingbeing thereatall,butonly thoughtsandsensations thatarenotthethoughtsofanyone.Isn’tthisanabsurdresult?ThereislittlethatIcansayinreplytothis.ItissimilartotheTransplantCase.

There too itmay seem as if the resulting person,who has your cerebrum andyour psychology, must be you. But he cannot be you if you are a livingorganism, for the animal associated with you did not get transplanted, butremainedbehindinstead.Heretoo,intheartificial-brainstem(orcerebrum-in-a-vat) case, the human animal associated with you does not come to have anartificialbrainstem(orcome tobeacerebruminavat).The resultingbeing isnot an animal at all; nor does the original animal cease to be an animal andbecome an object of some other kind. Rather, it perishes when its original

brainstem is destroyed (whichmay be a gradual process), for that destroys itsabilitytocoordinateitslife-sustainingfunctions.Thisisaconsequenceofwhatseemstometobethebestaccountoftheidentityoflivingorganisms.Thus,ifyouareanorganism,itfollowsthatyoucouldnotsurviveasacerebruminavat,or in any otherwaywithout a brainstem. If youwant to insist that you couldsurvive such a thing, youmust either deny that you are a living organism, orcome upwith an alternative account of what it takes for an animal to persistthroughtime.

VI.TheBodilyCriterion

The Biological Approach is not what some philosophers call “the BodilyCriterion”.ThatviewsaysthatIpersistifandonlyifmybodydoes:

Ifxisapersonattimetandyexistsatt*,x=yifandonlyifthethingthatisx’sbodyattisy’sbodyatt*.

ThisisusuallyheldinconjunctionwiththethesisthatIammybody;butthetwoclaimsaredifferent.Someonemightbelievethatshewasnecessarilythatpastorfuturebeingwhosebodyisherbody,butatthesametimeinsistthatsheherselfwasnot thatbodybutsomethingelse—althoughIcannot imaginewhyanyonewouldholdthatcombinationofviews.NorisitobviousthatmybeingidenticalwithmybodyentailstheBodilyCriterion.Manyphilosophersbelievethat‘mybody’ names an object that stands in a certain causal relation tome: it is theobjectthatIcanmoveandfeelinsomeespeciallydirectway,forexample(seebelow).Inthatcase,evenifIamtheobjectthatisnowmybody,Imayonedaycease to stand in that relation tomyself andcome to stand in it to someotherobject. That is, I might lose the ability to move and feel myself directly andacquiretheabilitytomoveandfeelsomeotherobjectinthatway,andthuscometohaveabodynumericallydifferentfromtheobjectthatismybodynow.Thus,theBodilyCriterionmightbefalseevenifIamidenticalwiththethingthat isnowmybody.TheBiologicalApproach,however,neitheraffirmsnordeniesthatpeopleare

identicalwiththeirbodies,orthatIamidenticalwiththatpastorfuturepersonwhosebody ismybody. It saysnothingatall abouthumanbodies, a fact thatwillnodoubthavepuzzledmany readers.Fewphilosophers seem tobeawarethattheBiologicalApproachandtheBodilyCriterionaredifferentviews.Theyassume that the Bodily Criterion is the chief materialist rival to thePsychologicalApproach.

What is the difference between the Biological Approach and the BodilyCriterion? Isn’t the Biological Approachmeant to be a version of the BodilyCriterion, a refinement of that view?How do you and I relate to our bodies,accordingtotheBiologicalApproach?Thatishardtosay,foritisnotatallclearjust what view the Bodily Criterion is meant to be. The problem lies in thenotionofahumanbody.9Supposepeopleareidenticalwiththeirbodies.Whatwouldthattellusabout

personalidentity?PresumablyitentailsthatIamamaterialobjectofsomesort(somethingcalled“mybody”),andthatwhatittakesformetosurviveiswhatittakes for thatobject tosurvive.Butwhatdoes it take formybody tosurvive?When do someone picked out at one time and someone picked out at anothertimehavethesamebody?Whathappenstomybodywhenyoucutoffmyarm,for example?Doesmybodyget a bit smaller and ten pounds lighter?Does itbecomeaspatiallyscatteredobject?Doesitmakeadifferenceifyoucutoffmyheadinsteadofmyarm?Some philosophers apparently have clear intuitions on this matter. It is

supposedtobeobviousthatmybodywouldsimplybecomeheadlessifmyheadwereseparatedfromtherestofme.Pollockisevenmoreprecise:“Thetimewillnodoubtcomewhenwecankeepapersonalivebyreplacingasmuchasthree-fourths of his body by mechanical contrivances (keeping at least his centralnervous system intact).When we have done that, he will no longer have thesamebody”(1989,36).Othersassertconfidentlythatone’sbodyceasestoexistand is replacedbyanumericallydifferentonewhenall itsparticleshavebeenrenewed in thecourseofone’smetabolism,orwhenallormostofone’scellshave died and been replaced by new ones: Owen Flanagan, for example,calculates that a person has seven different bodies, on average, during hislifetime(Flanagan1984,17;seealsoTaylor1992,127).Ifanyof this isright,we can conclude that the Bodily Criterion is inconsistent with the BiologicalApproach, for a human organism does not become headless when its head isremoved,anditisabiologicalcommonplacethatalivingorganismcansurvivethecompleteturnoveroftheatomsthatmakeitup.ButIhavenoideawhetherthesepronouncementsare right, and Idon’tknowhow to findout.Certainly Idon’t find ithelpful, in thinkingaboutwhat it takes formybody topersist, toreflectontheconceptof“mybody”thatIhavebyvirtueofbeingacompetentspeakerofEnglish.Norisitclearhowtheseclaimsaboutparticularcasescouldbe generalized. So it is not clearwhat the BodilyCriterion tells us about ourpersistence conditions, except presumably that the Psychological Approach isfalse.Nowitmightbeamistake toaskwhat it takesforahumanbodyassuch to

persist through time.Theremightnotbe anypersistence conditions associatedwith the concepthuman body. Perhaps thewords ‘human body’ getwhatevermeaning they have from such phrases as ‘my body’ and ‘your body’, so thatsomethingisahumanbodyonlybyvirtueofbeingsomeone’sbody—bybeingrelated inacertainway tosomeperson (or someother thing, if thingsbesidespeoplehavebodies).Beingahumanbodymightbelikebeinganuncle:tobeanuncle is tobesomeone’suncle.Soanobjectmightbeoneperson’sbodyforawhile, and then someone else’s body, and still later, perhaps, cease to be ahuman body at all by ceasing to be related to anyone in the rightway,whilecontinuing toexist.Orat least theconceptofahumanbodydoesnot rule thisout, even if the Bodily Criterion does. If so, human body is not a substanceconcept:yourbodyhasitspersistenceconditionsnotbyvirtueofbeingahumanbody, or by virtue of being your body, but because it falls under some othersubstance concept, such as organism—just as an uncle does not have hispersistenceconditionsbyvirtueofbeinganuncle,orbyvirtueofbeingtheuncleofanyparticularperson,butbyvirtueofbeingapersonorahumananimalorwhat have you.A human body that is an organismmight have quite differentpersistence conditions from those of a human body that is partly or whollyinorganic, ifsuchthingscanbehumanbodies,because theyare thingsofsuchdifferentkinds.In that case the question is what makes something someone’s body. It is

surprisinglydifficult to say.Themostcommonview is thatone’sbody is thatmaterial object that one can feel andmove in some especially directway:mybody is “the vehicle of my agency in the world and my knowledge of theworld”.10Ihaveadirect,proprioceptiveawarenessofmybodyanditsparts,butnotofanyotherobject.Allofmyknowledgeoftheworld(exceptperhapswhatIcanfigureoutapriori)comestomethroughmybody.Conversely,mybodyanditspartsaretheonlythingsIcanmove“justlikethat”,withoutintendingtomoveanythingelse:“Icallminetheonlybodyinwhich,forinstance,mymerelywillingtoraiseanarmdoes,innormalcircumstances,causemyarmtorise”(C.J.Ducasse,quotedinChisholm1976,35).SomybodyisroughlythatmaterialobjectthatIcanbeawareofwithoutbeingawareofanythingelse(exceptpartsofit),andthatIcanmoveintentionallywithoutintendingtomoveanythingelse(exceptpartsofit).IshallcallthistheCartesianAccountofthemeaningof‘mybody’.Sensiblethoughitmaysound,thisaccountfacesseriousdifficulties.Suppose

themotor nerves leaving your cerebellumwere somehow hooked upwith themuscles of one human organism,while your incoming sensory nerves carriedinformation fromadifferentorganism. In thatcase thevehicleofyouragency

and the vehicle of your awareness of the world would be entirely differentthings.Which thingwould then be your body?Youmay say that our humbleconceptofone’sbodyissimplynotuptosuchastrain:theconceptbreaksdown,andthequestionismeaningless.(Butthestorymaynotbecoherent.Itmaynotbepossibletomoveanarminacertainwaysimplybywillingtomoveitinthatway, without having some proprioceptive feedback from the arm: perhapsnothingcouldbeavehicleofyouragencyunlessitwerealsoavehicleofyourawareness.Anditmaybethatnoproprioceptiveorothersensoryawarenessofalimboranythingelseispossiblewithoutsomemotorcontrolof that limb.It isprobably more than mere coincidence that proprioception and motor controlalwaysseemtobepresentorabsenttogetherinactualmedicalcases.)As it stands, however, theCartesianAccount is not adequate even in actual

cases.Unlesswehaveaverysparseontologyofmaterialobjects,nothingwillbethevehicleofmyagencyintheworld,fortherearemanythingsthatIcanmovebymerelywillingtomovethem,andwithoutintendingtomoveanythingelse.Icanmovemyrightfootdirectly—itisavehicleofmyagencyintheworld—butmyrightfootisnotmybody.(Myrightfootisnotabody—ahumanbody—thatIcanmovedirectly,youmayobject.Butwhatmakessomethingahumanbodyispartofthepointatissue.)Similarremarksapplytothenotionofthevehicleofmyknowledgeoftheworld.Wemightsaythatmybodyisthelargestmaterialobject that I can move just by willing to move it. That would rule out thepossibility thatmy foot ismy body, for although I canmovemy foot just bywillingtodoso,itispartofalargerobjectthatIcanalsomoveinthatway.Butconsider the mereological sum of this human organism and the pencil in myhand.Iftherereallyissuchanobject,surelyIcanmoveitsimplybywillingtomove it? When I will to move my pencil, or the hand holding it, themereologicalsumofmeandthepencilmoves.Ifso,thereisnolargestmaterialobjectthatIcanmovedirectly;orifthereis,itisnotanythingwewouldcallmybody.Whyismypencilnotpartofmybody?BecauseIcannotmoveitbysimply

willing to move it, you will say: I can move my pencil only by willing orintendingtomovemyhand,orsomeotherorganicpartofmybody.Thisisnotobviouslytrue.Whenyoudrawapictureyouintendtomovethepencil.Doyoudo this by intending to move your hand? You might, if drawing were anunfamiliar activity and you had to proceed very deliberately, or if you wererecovering froman injuryand found itdifficult tomoveyourhand in thewaythat youwant it tomove.But suppose drawing comes naturally, and you canmoveyourhandwithout any special effort.Your attention ison thepencil, ormorelikelyonthepicturetakingshapeorthethingbeingdrawn;inanycaseitis

notonyourhand.Youprobablydon’teventhinkaboutyourhandasyoudraw.Imagine trying tostateyour intention todrawthepetalofaflower in termsofmovements of your hand, in such a way that someone who had never drawnbeforebutwhowasverydextrous—aBalinesedancer,say—couldimitateyou.Probablyyour handmoves in all sorts ofways that you aren’t even aware of.(Suppose you are shown a close-up video tape of your hand takenwhile youweredrawingtheflower.Youmightbesurprisedatsomeofthemovementsyoumadeandclaimthatyoudidnotintendthem.Ifthiswerenotso,teachingpeopletodancewouldbefareasier.)YoumightsuggestthatwhileIcanmovemyhandwithoutmovingthepencil,

I cannotmove the pencil withoutmovingmy hand or some other part ofmybody,andthatiswhatmarksoffmybodyfromtherestoftheworld.Thedevil’sadvocatewouldsaythatmyabilitytomovemyhandwithoutmovingmypencilbutnotviceversaisduemerelytothefactthatmyhand,butnotthepencil, isattachedtome.Ifapencilwerepermanentlyattachedtomyhand,Ishouldnotbeabletomovemyhandwithoutmovingthepencil.Butapartofmybodymustbe connectedwithme in amore intimateway thanmere physical attachment.Youcan’tmakemybodylargerbygluingthingstome.Acluemightlieinthefactthatalthoughyoucoulddetachthepencilwithoutdiminishingmycapacityforagency,thisisnotsoformyhand—atleastifitisingoodworkingorder.Amputees with prosthetic limbs are an interesting case for the Cartesian

Account.Ifwhatmakessomethingapartofone’sbodyissomehowamatterofone’sproprioceptiveawarenessofitandone’sabilitytomoveitinsomedirectway, it is a serious question whether some prosthetic limbs count as parts ofpeople’sbodies.Infact,therelationshipbetweenanamputeeandherprosthesisisoften farmorecomplexand intimate thanmostofuswould imagine.Manyamputeeshavesensationsof thesamesortas theywouldhave if theirmissingpartswere still intact: “phantom limbs”. It seems that amputeesoftenperceivetheir prosthetic limbs as if theywere parts of themselves by associating themwithaphantom,so that theyhavemuch thesameproprioceptiveawarenessaswehaveofournaturallimbs:theycan“feel”theorientationofthelimb“fromtheinside”.TheneurologistOliverSackswrites,

Allamputees,andallwhoworkwiththem,knowthataphantomlimbisessentialifanartificiallimbistobeused.Dr.MichaelKremerwrites:“Itsvaluetotheamputeeisenormous.Iamquitecertainthatnoamputeewithanartificial lower limbcanwalkon it satisfactorilyuntil thebody-image, inotherwords thephantom, is incorporated into it.” . . .Onesuchpatient,undermycare,describeshowhemust“wakeup”hisphantominthemornings:firstheflexesthethigh-stumptowardshim,andthenheslaps it sharply—”like a baby’s bottom”—several times. On the fifth or sixth slap the phantomsuddenlyshootsforth,rekindled,fulgurated,bytheperipheralstimulus.Onlythencanheputonhisprosthesisandwalk.(1987b,67)

Dowediminishtheamputee’scapacityforagencybydetachinghisprosthesis?Ishisconnectionwiththatdeviceintimateenoughforittocountashisbody?Ifso,thensomepeople’sbodiesaremadepartlyofmetalandplastic;andsincenoliving organism is made partly of metal or plastic, that would mean that noteveryone’sbodyisananimal,andtheclaimthatpeopleareidenticalwiththeirbodieswouldbedifferentfromtheclaimthatpeopleareanimals.Limbsthatarenumbandparalyzedraiseananalogousquestion.Aparaplegic

mustmovehislegsinthesamewayasyouandImovepiecesofcordwood:bypickingthemupwithhisarmsandheavingthem.Andhecangetknowledgeoftheworldthroughhislegsonlyinthewaythatablindpersongetsknowledgeoftheworldthroughhercane.Thosewhohavelostproprioceptiveawarenessofalimboften feel emotionally alienated from it, anddonot regard it as apartoftheirbody.Sackscallsthem“internalamputees”(1984,75).Hewrites:

Ifoneisgivenaspinalanaestheticthatbringstoahaltneuraltrafficinthelowerhalfofthebody,onecannot feel merely that this is paralysed and senseless; one feels that it is wholly, impossibly,“nonexistent”,thatonehasbeencutinhalf,andthatthelowerhalfisabsolutelymissing—notinthefamiliar sense of being somewhere, elsewhere, but in the uncanny sense of not-being, or beingnowhere....havingabody,havinganything,dependsonone’snerves.(1987a,564)

Butaparaplegic’slegsareclearlypartsoftheanimalassociatedwithhim;theyarecaughtupinhisbiologicallife.Ifaparalyzedlimbisnotpartofone’sbody,then some people have bodies that are smaller than the human animalsassociatedwiththem.However,letussetthesemattersasideandsupposeforthesakeofargument

that there is some sense in which I can move my pencil only indirectly, bymovingmy hand or some other part ofmy body in amore directway. Thus,pencils,hammers,walkingsticks,andthelikearenotpartsofourbodies,ontheCartesianAccount. (Whetherprosthetic andparalyzed limbsarepartsofone’sbodymaysimplybeindeterminate.)Inthatcaseweoughttowonderwhatmakesmyspleenapartofmybody,forIcannotmoveitdirectlyanymorethanIcanmovemypencildirectly.HadInotbeentold,IshouldneverhaveknownthatIhadaspleen.Icanmovemyspleenonlybywillingtomovesomethingelse—mytorso,say,orthisentirelivingthing.Considertheobjectcomposedofallofmybonesandmuscles (if there is suchanobject). If there isany largest thingthatIcanmoveinsomeparticularlydirectsense, itought tobe that thing(my“structural body”, we might call it); I can move my internal organs only bymovingmy structural body.At any rate I can think of no interesting sense inwhichIcanmovemyspleenbutnotmypencilmerelybywillingtodoso.Forthatmatter I havenoproprioceptive awareness ofmy spleen either; and some

organs even lack pain receptors. So the proposed account seems to entail thatfew,ifany,ofmyinternalorgansarepartsofmybody:mybodyismystructuralbody. If there is no such object as that, there are no human bodies.Withoutfurther refinements, then, theCartesianAccount does not capture the ordinaryconceptofone’sbody.We could solve this problem by defining ‘my body’ as the largest living

organismthatIcanmoveandfeelwithoutmovingorfeelinganythingbutpartsofthatorganism.11Butitdoesnotseemtobepartoftheconceptofone’sbodythatitmustbealivingorganism;inanycase,thosewhobelievethat‘mybody’isthenameofacertainkindofobjectdonotclaimthatitisfalsebydefinitionthat advances inmedical technologymay one day enable us to have partly orwhollyinorganicbodies.Perhaps“theobjectthatIcanmoveandfeeldirectly”isaredherring,andwe

oughttolookforacompletelydifferentstoryaboutwhatmakessomethingmybody.Michael Tye has proposed such an account.He applies to ‘my body’ atechnique that is ordinarily used to define theoretical terms (Lewis 1970).According toTye,mybody is thatmaterial object that is thebearer of all thephysical and spatio-temporal properties truly predicable of me in ordinarylanguage.12Whenwearen’tdoingmetaphysics,wesaytrulythatBillClintonisa tallmanwholives inWashington.IfClintonisamaterialobject, this isalsotrue strictly speaking. But if Clinton is a Cartesian ego or an abstract objectanalogous to a computer program, as some philosophers have thought, thenstrictlyspeakinghemayhavenosizeorspatiallocationatall,andwhenintheordinary business of lifewe imply otherwise,we are speaking loosely. Eitherway,someobjectreallyistallandinWashington,andhasalltheotherphysicaland spatio-temporal properties we ordinarily attribute to Clinton. That objectTyedefinesasClinton’sbody.Tye’singeniousdefinitionavoidstheproblemsfacingtheCartesianAccount.

Inmostcasesitseemsfairlyeasytofindoutwhichobjectisone’sbodyonTye’saccount;andiftherearedifficulties—withartificiallimbs,forexample—wecansimplychalkthemuptothevaguenessinherentintheconceptofone’sbody.ButTye’s account is not compatiblewith theway thewords ‘my body’ are

oftenused indiscussionsofpersonal identity.Adefinitionof ‘mybody’oughtnottoruleoutanysubstantiveclaimsaboutpeopleandtheirbodies.Itoughttobesomethingthatboththosewhosaythatpeoplearetheirbodiesandthosewhoreject that claim can accept; otherwise it wouldn’t define the sort of objectwhose properties are in dispute. But consider the view, so popular amongphilosophers,thatIamamaterialobjectnumericallydifferentfrommybody.On

thatview,mybodyandIhaveexactlythesamemomentaryspatio-temporalandphysical properties.We have the same height, weight, shape, orientation, andlocation. That means that there are two bearers of the spatio-temporal andphysicalpropertiestrulypredicableofmeinordinarylanguage.Noonethingismybody.Ifmybodymustbethebearerofthoseproperties,thennothingismybody,justasnothingisthelargegiraffeinBotswana.Alternatively,ifanythingthatisabearerofthosepropertiesisabodyofmine,

thenInowhaveatleasttwobodies:Imyself,andsomethingthatisjustlikemeexceptperhapsthatitdoesn’tthinkorfeeloract,andmayoutlivemewhenIdie.Eitherway, thismakesnonsenseoutof theclaim thatmybody isnumericallydifferentfromme.NorcoulditbetruethatmybodyoutlivedmewhenIdied,forIshouldhaveeithernobodyatall,ortwobodies,onlyoneofwhichcouldoutliveme.TheclaimthatI leavemybodybehindandacquireanewoneinabrain transplantwouldalsobefalsebydefinition.Atbest Icould leaveoneofmybodiesbehindandreplaceitwithanewone.Thus, Tye’s account seems inadequate as well. If nothing better is

forthcoming,then,itisnotatallclearjustwhattheBodilyCriterionismeanttosayaboutpersonalidentity.Thenotionofahumanbodyisnotclearenoughtobeofmuchuseindiscussingwhatittakesforustopersist.TheBodilyCriterionisnotfalse,butmeaningless;oratbestitsmeaningisnotclearenoughtoenableustojudgewhetheritistrueorfalse,orwhetheritisconsistentorinconsistentwith the Biological Approach. If you insist on calling the human organismassociatedwithme“mybody”, I shallnotobject—as longasyoudon’t try toderiveanyphilosophicalconclusionsfromthefactthatthatanimalismybody,orahumanbody.Thereisnoharmincallingthatanimal“mybody”aslongaswedon’thavesomethingliketheBodilyCriterioninmind.Theanimalstillhasitspersistenceconditionsbyvirtueofbeingananimalandnotbyvirtueofbeinga human body; and whether it is my body or someone else’s or no one’s iscompletelyirrelevanttomattersofpersonalidentity.Butinfactthereisnoneedto use the words ‘my body’ at all in discussing personal identity. I think thenotion of a human body is best left out of philosophy, or at least out ofdiscussionsofpersonalidentity.“Youmay choose not to formulate your theory in terms of human bodies,”

someonemight object, “but that doesn’t solve the problem of how you and Irelatetoourbodies.Youcan’tmakebodiesgoawaybysimplyignoringthem.”But Iamnot ignoringanything. Iclaim that if“mybody” is supposed tobeamaterialobjectotherthanmyself,thishumananimal,thenthereisnosuchthingasmy body; and I have arguments for that.We haveme, the person; andwehave the animal (whether or not they are the same). Thatmuch everyone can

agreeon.Whysupposethatthereissomethingcalled“mybody”aswell?Itiscommonlyheldthatourbodiescontinuetoexistafterwedie,unlessone’s

deathisunusuallyviolent.ThebodiesofsomeoftheEgyptianpharaohscanbeseeninmuseumstothisday,eventhoughboththepharaohsthemselvesandthehumananimals associatedwith themhave long sinceceased toexist (Wiggins1976, 151; 1980, 164; Chisholm 1977, 171). Others find it obvious that ourbodies do not think or act: “There is something absurd—so unnatural that theupshotissimplyfalsity—inthepropositionthatpeople’sbodiesplaychess,talksense,knowarithmetic,or evenplaygamesor sitdown” (Wiggins1976,152;seealsoWiggins1980,163f.).Thesearephilosophicalcommonplaces,eachofwhichseems toentail that ‘mybody’ is thenameofanobject that isdifferentbothfrommeandfromthehumananimalassociatedwithme.Mustweacceptthem?Consider the first argument. Why suppose that there is some 150-pound

material object that continues to exist when I die? You might think that Icontinue to exist after my death, as a corpse; but that would not support theclaimthatthereissomethingcalledmybodythatisnumericallydifferentfromme.Formybodytooutliveme,theremustbesomethingthatisverymuchlikemeuntilIceasetoexist,and(presumably)acorpseafterwards.Onereasonwhyphilosophers often believe in such an object is that we call corpses “bodies”:“JohnBrown’sbodyliesa-mould’ringinthegrave,”wesay.Butthisisamerelinguisticaccident.Notall languageshaveaword thatmeansboth“body”and“corpse”: for example, neither of the German words for “body” (Körper andLeib)appliestocorpses(Leichen).Sothislendsatbestonlyweaksupporttothemetaphysicalclaimthatmybodyissomethingthatcansurvivemydemise.Thesamegoesfor thephilosophers’ termofart‘livehumanbody’,whichsuggeststhatbeingaliveisanaccidentalattributeofhumanbodies.But there is spatio-temporal continuitybetweenapersonand the corpse that

resultswhenshedies,youmay insist.Doesn’t that show that someoneobjectcontinues to exist through death, and is first living and then dead? I thinkWigginshasshownthat there isnosuch thingasspatio-temporalcontinuity ingeneral,butonlyspatio-temporalcontinuity relative toaconcept.Consider theTransplantCaseoncemore: both thepersonwhoendsupwithyour cerebrumandtheanimalthatendsupwithanemptyheadarespatio-temporallycontinuouswith you in someway.Butwhether you end up as the former or as the latteroffshoot(orneither)dependsonwhatsubstanceconceptyoufallunder—person,animal,orsomethingelse—andwhatpersistenceconditionsareassociatedwiththatsubstanceconcept.Whetherthereisanythingatallthatwasfirstanordinaryhuman being (or at any rate very like a human being) and later a brainless

vegetable in the Transplant Case depends on whether there is a substanceconcept whose associated persistence conditions are satisfied in thattransformation.Thatis,itdependsonwhetherthereisakindofmaterialobjectthatcansurvivethatsortofchange.Themerefactthatthereisspatio-temporalcontinuityof somesortdoesnotguarantee thatanymaterial substancepersiststhroughthechange.Consideranotherexample: Imagine thatDescartes’demonrearrangesyouratomsuntiltheycomposeapig(notasuperintelligentpigwithyour psychology, but an ordinary pig). The pig is in some sense spatio-temporally continuous with you. But there is no obvious reason to think thatanything larger than an atomsurvived the change. If you think thepig’sbodywouldhave tobe thevery thing thatwasonceyourbody, suppose thedemonuses your atoms to make seven piglets. Although there is spatio-temporalcontinuity of a sort between you and each piglet, none of the piglets existedbeforethedemondidhiswork.So the mere fact that your corpse is spatio-temporally continuous with you

doesnotshowthatitexistedbeforeyouperished.Forthattobethecase,theremust be a special sort of continuity between you, or rather something nowcoincidentwith you, and the corpse.Why think that there is any such specialcontinuity?The changes that go on in an animalwhen it dies are really quitedramatic. All of that frenetic, highly organized, and extremely complexbiochemical activity that was going on throughout the organism comes to arathersuddenend,andthechemicalmachinerybeginsimmediatelytodecay.Ifit looks like there isn’tall thatmuchdifferencebetweena livinganimalandafresh corpse, that is because the most striking changes take place at themicroscopiclevelandbelow.Thinkofitthisway:Ifthereissuchathingasyourbody,itmustceasetoexistatsomepoint(orduringsomevagueperiod)betweennowandamillionyears fromnow,when therewillbenothing leftofyoubutdust. Themost salient andmost dramatic change that takes place during thathistorywouldseemtobeyourdeath.Everythingthathappensbetweendeathanddust(assumingthatyourremainsrestpeacefully)isonlyslow,gradualdecay.Sowhateverobjects theremaybe thatyouratomsnowcompose, it isplausible tosuppose that they cease to exist no later than your death.There is no obviousreasontosupposethatany150-poundobjectpersiststhroughthatchange.What about the other argument, that my body must be different from me

becausebodiescan’tthinkorfeeloract?Well,if‘mybody’reallyisthenameofa150-poundmaterialobjectthatisnowmadeupofthesameatomsthatmakemeup,whycan’t thatobject think? Itsbrain is in thesamestateasmine,andmediatesbetweenitssensory inputsanditsmovements inexactly thewaythatmy brain does. What could explain the fact that I am perfectly rational and

consciouswhilesomematerialobjectthatisphysicallyexactlylikeme,withthesame environment, has no psychological features at all?What could possiblyprevent that thing from using its highly developed central nervous system tothinkandfeelandact?Thatmybodycannotthinkoractissupposedtofollowfromtheabsurdityof

sayingthingslike,“Mybodyreadanovellastweek,”or“Jones’sbodywrotealettertoSmith’sbody”.Butwecanadmitthat thereissomethingabsurdaboutthesestatementswithouttakingthattoimplythat‘mybody’isthenameofsomeobjectthatisjustlikemeexceptthatitcan’treadorwritelettersordoanyother“personal”things.Supposethephrase‘mybody’isn’tareferringexpressionatall,butadeviceusedtocallattentiontomy“bodily”features:roughlythosethatI have no voluntary control over andwhich are not psychologically guided—something like Strawson’s “M-predicates”.13 (The rough-and-ready distinctionbetween“bodily”and“personal”attributesisexpressedinthephrase“soundofbodyandmind”.)Thus,sayingthatmybodyplayedagameofchessyesterdayisto say, absurdly, that I played a game of chess unconsciously, or withoutthinking or having any voluntary control over what I was doing. It is absurdbecauseitimpliesthatplayingchessisa“purelybodily”featureorM-predicate,likedigestingone’sfoodorbeinglowonselenium.Alternatively,itmaybethat‘mybody’referstome,ortothishumananimal,

in which case it would be literally true that my body has conversations andwritesbooks.Butreferringtomyselfas‘mybody’ratherthanas‘I’carriesthepragmatic implication that the property I go on to ascribe tomyself is a non-psychological, “bodily”one.Byanalogy, itmaybe literally true that a certainbookisajumbleofwords;buttocallitthatistoimplythatitconsistsofwordsthrowntogetheratrandom,oratanyrate that it isbadlywritten.Itmaysoundabsurd to say that this jumbleofwords is clearlywrittenandwell argued,butthatmaybeliterallytrueandonlyexpressedinamisleadingway.The semantics of “body talk” is of course more complex than this, but the

accountsketchedhereisatleastabeginning.

7

Alternatives

I.AreThereAnyPeople?

That completes my defense of the claim that psychology is not relevant topersonalidentity.Whatfollowsisasortofappendix,addressedtoamatterthatisrelevanttotheforegoingdiscussions,butwhichseemedtoocomplexandtooperipheraltoincludethere.In the Introduction I mentioned three substantive metaphysical claims (in

addition to the assumption of materialism) that I said I was going to assumewithoutargumentbecausewithout thoseassumptionsmyproject couldnotgetofftheground.Theassumptionswerethattherereallyarepeople(whoreallydopersist through time), that identity is not concept-relative, and that you and Iendure through time rather than being extended in time. I said that theseassumptionshad tobe true if thereare tobeanymetaphysicalquestionsaboutpersonalidentity,andthatwithoutthemallsuchquestionsaremerelylinguisticones.NowisthetimetoexplainwhatImeantbythatandwhyitisso.Iftherearenopeople,therearenometaphysicalproblemsaboutpeople.The

“eliminativist”, as we might call someone who holds this view, solves theproblemofpersonalidentityinthewaythattheatheistresolvestheproblemofthe Trinity, and that the nominalist dealswith the paradoxes of set theory. Inclaiming that there are no people, the eliminativist is not merely saying thatnothing, you and I included, deserves to be called a person. If someone’sdefinitionof‘person’entailedthatyouandIweren’tpeople,wemightwonderwhether thatdefinitionwas right,orhowsomeonecouldbemoreconfident inanydefinitionthanshewasinherownstatusasaperson;butthedisputewouldbe about the meaning of a word. Eliminativism, however, is not merely alinguistic claim. It is the view that there areno rational, conscious beings: nosuchbeingsasyouandI.Thatmeansthattherearenohumananimalsorhumanbrains,forifthereweresuchthings,someofthemwouldbeyouandIandourfriends and relatives. Or at least they would be beings capable of wondering

whatit takesforthemtokeeponexisting,andtheeliminativistpositionwouldagainboildowntothemerelylinguisticclaimthatthoserationalbeingsforsomereasondon’tdeservetobecalledpeople.Thiscure for theproblemsofpersonal identitymayseemfarworse than the

disease.Aretheproblemsreallysointractablethatallwecandoisthrowupourhands and conclude that there couldn’t be any people? For that matter, howcouldtheeliminativistmakeherpositioncoherent?Isn’tanyonewhodeniesherownexistenceboundtobemistaken?Didn’tDescartesshowthatnomatterwhatelse one might be mistaken about, one cannot deny, on pain of pragmaticinconsistency,thatsomeoneismistaken?Yet the list of those philosophers who have denied their own existence

includessuchpastmastersasSpinoza,Hume,andRussell1;andIampreparedtotake it seriously.Considerananalogy.Nominalists,whodeny theexistenceofabstractobjects,don’tusuallygoontosaythatmathematiciansaremistakentothink that there are any prime numbers, even though prime numbers, if theyexisted, would be abstract objects. At least they do not say that thosemathematicians aremistaken in theway inwhich someonewho believes thatthere are fairies or unicorns is mistaken. The belief that there are fairies orunicornsisliabletoleadoneastrayintheordinarybusinessoflife.Butbelievingthat there are prime numbers isn’t going to lead anyone astray unless one isdoingmetaphysics,eveniftherearen’treallyanynumbers.Thebeliefthatthereareprimenumbershassome importantcognitivevirtue,even if it isn’t strictlytrue.It isatmosta“harmless”mistake.Certainlyoneisbetteroffbelievinginprimenumbers thanbelieving thatnonumber isevenlydivisibleonlyby itselfandone.Thatwouldbe averydifferent sort ofmistake.Theeliminativist cansaysomethinganalogous.Toput thepointsomewhatparadoxically, thosewhobelieveinpeoplearenotmistaken.Oratleasttheyarenotmakingamistakethatisgoingtoleadthemastrayaslongastheyaren’tdoingmetaphysics.Believinginpeople isatmosta“harmless”mistake.Thebelief that therearepeoplehassome cognitive virtue, even if there aren’t, strictly speaking, any people.Certainlyitisbettertobelievethattherearepeoplethantobelievethatnooneisgoingtotakeanynoticeifwedon’tpayourbills.So far, so good. But it is one thing to say that believing in people is not a

mistake, or at least not a mistake akin to believing in unicorns; it is anothermattertoshowhowthisiscompatiblewitheliminativism.Howcantheordinary,nonphilosophical belief that some people are taller than others, to take anordinary example, be true, or at most “harmlessly” mistaken, if there aren’treallyanypeople?Whatmakesbelieving inpeopledifferent frombelieving inunicorns?

Theusualwayofansweringchallenges like this is to try toparaphrase thosesentences that appear to be about people (or numbers orwhat have you) intosentences that do not entail that there are people (numbers, etc.), but whichnevertheless say more or less the same thing as the original sentences. Theparaphraseisasentencethatcanbestrictlyandliterallytrueeveniftherearen’tanypeople.Itismeanttotelluswhatmakestheoriginalsentencetrue,oratleastnot misleading in nonphilosophical contexts. Whether we can say that theoriginalsentenceistrue,orwhetherwemustsaythatitisstrictlyfalsebutonly“harmlessly”so,willdependonhowclosetheparaphrasecomestocapturingthemeaningoftheoriginalsentence.Whatisit,then,thatmakesthesentence“Somepeoplearetallerthanothers”

true(oronly“harmlessly”false)?Thatdependsonwhattheeliminativistthinksthere is—what phenomena are responsible for the appearance that there arepeople.Supposethereareonlyelementaryparticles—thingswithoutparts—anditisthewayinwhichthoseparticlesarearrangedthatmakesitappearasiftherewerepeople.Someparticlesarearranged“anthropomorphically”(physiologistscould tellusmoreabout justwhat thisarrangement is andhow itdiffers fromother “zoological” arrangements). But particles arranged in that way don’tcompose anything: there is never any larger object that has those particles asparts.Ifthatisthereasonwhytherearenopeople,thenpresumablytherearenoother familiar composite objects either: particles arranged “tablewise” don’tcompose tables, for example, and “table-talk” is only a loose way of talkingaboutparticlesarrangedinthatway.Onthistheorywecouldgivethefollowingparaphraseof“Somepeoplearetallerthanothers”:

Thereareparticlesarrangedanthropomorphically,andthereareotherparticles,different from the first, also arranged anthropomorphically, such that thelengthwise extension of the former particles is greater than the lengthwiseextensionofthelatterparticles.

This paraphrase at least comes fairly close to saying the same thing as theoriginalsentence,anditdoesnotappear toentail that thereareanypeople.Sothe eliminativist can say that it is the truth expressed by the paraphrase thatmakes the ordinary, nonphilosophical claim that some people are taller thanotherstrue(orappropriate).What has this got to dowith personal identity?Well, the eliminativist may

wanttosaythatsomestatementsaboutpersonalidentityaretrue,oratleastnotmisleading.Thus,wecantrytofindparaphrasesforthosestatementsthatcanbestrictlytrueeventhoughtherearenopeople.Butwhatrelationsamongparticles

arrangedanthropomorphicallyatdifferenttimesmakeittrue(orappropriate)tosaythatasinglepersonexistsattwodifferenttimes?Thatiswheretheproblemof personal identity comes in. Those who accept the Psychological Approachwill answer this question differently from those who accept the BiologicalApproach, for example. Here are two possible paraphrases of the sentence“SomebodyinthisroomwasinParislastyear”:2

Thereareparticlesarrangedanthropomorphicallyinthisroomandtherewereparticles arranged anthropomorphically in Paris last year, and the formerparticlesarenowassociatedwithpsychologicalfeaturesandthelatterparticleswereassociatedwithpsychologicalfeatureswhentheywereinParislastyear,andtheformerfeaturesarecausallycontinuous, in theappropriateway,withthelatterfeatures.

Thereareparticlesarrangedanthropomorphicallyinthisroomandtherewereparticles arranged anthropomorphically in Paris last year, and there is abiologicallifesuchthattheformerparticlesarecaughtupinthatlifenowandthelatterparticleswerecaughtupinthatlifewhentheywereinParislastyear.

These two paraphrases embody quite different truth (or appropriateness)conditions for statements aboutpersonal identity.ThePsychologicalApproachwillbetruejustincasesomethinglikethefirstparaphraseisthecorrectone;theBiological Approach will be true just in case something like the secondparaphrase is correct.Which is the case depends onwhich paraphrase reflectsmost closely themeaningof theoriginal sentence.And that is not amatter ofmetaphysics,butamatterof themeaningofour language.Themetaphysics isthesameonbothviews:therearereallyonlyparticlesrelatedtooneanotherincertain ways. Thus, what it takes for you and me to persist through time isultimatelyalinguisticquestion,notametaphysicalone.One needn’t deny that particles “arranged anthropomorphically” compose

anything to enjoy the advantages of the eliminativist view. Indeed, there aregood reasons not to accept that view, for although it may be easy enough toexplainhowalotofparticlescouldcooperatetoinstantiateapropertylikebeingsix feet talleven thoughno individualparticlehas thatproperty, it is farmoredifficult togive suchanaccountofpsychologicalproperties.Tryparaphrasingthe sentence “Some people believe in ghosts” (or “Some people think they’rebetterthanothers”)intoaformthatdoesnotinvolvequantificationoverthinkingbeings.Wemight try, “There are particles arranged anthropomorphically, andsomeofthoseparticlesarejointlyassociatedwiththebeliefinghosts”.Butwhat

is it for particles to be “associatedwith” a belief?And how could there be abeliefatalliftherearenobelievingsubjects?Amore promising alternativemight be to admit that appropriately arranged

particles composepeople, but deny that suchbeingspersist, or remainpeople,long enough to getmixed up in any of the cases that figure in discussions ofpersonalidentity.(Youmaydoubtthatsuchshort-livedthingscouldbegenuinepeople;butthepointisthattheyareobjectsmomentarilyindistinguishablefrompeople,andarguablythesubjectsofcertainpsychologicalstates.)Anumberofphilosophers find it hard to understand how a singlematerial object could becomposed of different parts at different times, or in different counterfactualsituations. They think that an object’s parts are essential to it. But if humanbeingspersisted through time, theywouldbeconstantlygainingnewpartsandlosingold ones, owing to their biologicalmetabolism.Soon their view, oftencalled “mereological essentialism”, human people do not persist through time.You are not the same person as the one who started reading this sentence amoment ago, for that personhas already expelled a numberof carbondioxidemolecules.Whathappened to thatperson?Thatdependsonwhathappens toamaterialobjectwhenitspartsbecomeseparatedfromoneanother.(Mereologicalessentialismpersedoesnottellusanythingaboutwhatittakesforanobjecttopersistthroughtime,savethatitmustcontinuetohaveexactlythesameparts.)Ifa thingceasestoexistwhenitspartsareseparated, thenthepersonwhobeganreading this sentence amoment ago has nowperished. If a thing continues toexist and simplybecomes spatially scatteredwhen itspartsget separated, thenthe being who bore your name a moment ago is now no longer a connectedobject (and presumably no longer a person, although that could be disputed).Soon, in fact, itwill be a rather rarefied objectwith its parts scatteredwidelythroughoutthebiosphere.On this proposal, it is rarely if ever strictly true to say that someone has

persisted through time.Nevertheless, somesuchstatementsmayexpress truthswhen they are made in the ordinary business of life. At any rate, there issomethingmoreappropriateor lessmisleadingabout theclaimthatIhavemetsomepeoplemore thanonce thanabout theclaim that someofmyfriendsaremorethanninehundredyearsold.Hereagainwecantrytocapturethistruthorappropriateness byparaphrasingordinary statements about personal identity intermsoftherelations—biologicalorpsychological,dependingonyourtheory—between the things that really are people (or human organisms, etc.)momentarily.3 So as before,which account of personal identity is correctwilldepend onwhat sort of paraphrase—one involving biological relations or oneinvolvingpsychologicalrelations—comesclosesttothemeaningofourordinary

statementsaboutpersistence;andthusitisalinguisticratherthanametaphysicalquestion.WecanillustratethisbyapplyingittooneofthepuzzlecasesfromChapter1.

Jones lapses into a persistent vegetative state: Does she still exist? Is theresultinghumanvegetableJones,orsomethingelse?Sincenothingisreallyfirstahealthypersonandlateravegetable,onthe“no-persistence”view,theanswerto the question depends on what sort of “feigned identity” the language ofpersonalidentityisgroundedin.Wehavethesentence

ThebeingwhowasahealthypersonatnoononTuesdayisahumanvegetableatnoononWednesday.

Wemightsuggesttwoparaphrases:

ThethingthatwasahumanvegetableforamomentatnoononWednesdayispsychologically continuous with the thing that was a healthy person for amomentatnoononTuesday.

The thing thatwasahumanvegetable for amoment atnoononWednesdayhas the same biological life as the thing that was a healthy person for amomentatnoononTuesday.

The first paraphrase is false; the second is true. If something like the firstparaphrasecomesclosesttocapturingthemeaningoftheoriginalsentence,thatoriginal sentencewillbestraightforwardly false,andweshallbecorrect (oratmost “harmlessly” mistaken) to suppose that one cannot survive as a humanvegetable. If thesecondparaphrase isbetter, then theoriginal sentencewillbetrue (or at most “harmlessly” false), and we are right to think that one cansurviveasahumanvegetable.Sowhetherpsychologicalcontinuityisnecessaryforustopersistthroughtimedependsonthelinguisticfactofwhichofthetwoparaphrasesbestapproximatesthemeaningofourordinarylanguage.

II.RelativeIdentity

Similar remarks apply to the two other metaphysical doctrines, the view thatidentityisconcept-relativeandtheontologyoftemporalparts.Suppose that this thing isbothapersonandananimal,and that that thing is

alsobothapersonandananimal.Thenaccordingtotherelative-identitythesis,althoughwecanaskwhetherthisthingandthatthingarethesameperson,orthesame animal, we cannot ask whether this thing and that thing are just plain

numerically identical, without qualification. In general, from the fact that thisthing and that thing are the same F, we cannot infer that this and that arenumericallyone;andfromthefactthattheyarenotthesameGwecannotinferthat theyarenumericallydifferent.Moreover, thisandthatmaybe thesameFbutnotthesameG,eventhoughbothareGs(see,e.g.,Geach1967).It follows that there is no such relation as absolute, unqualified numerical

identity.Iftherewere,thenthefactthatthisthingandthatthingarenotthesameGwouldentailthattheywerenumericallydifferent.ForthisthingisthesameGasitself,andthusifitisnotthesameGasthatthing,ithasapropertythatthatthing lacks, namely being the sameG as this thing.ByLeibniz’sLaw it thenfollows that this thing and that thing are numerically different. Because therelative-identitytheoristrejectsthatconclusion,shemustdenythatthereissucha relation as “absolute” numerical identity.To askwhether this thing and thatthing are the same without qualification, she will say, is like asking whetherOhio is to the left of Pennsylvaniawithout qualification.We can askwhetherOhioistotheleftofPennsylvaniafromaparticularorientation(fromthesouth,say);butthereisnosuchrelationasbeingtotheleftofsimpliciter.Andwecanaskwhether this and that are the sameF or the sameG, but there is no suchrelationasbeingthesamesimpliciter,andthusnosuchquestionaswhethertheyareabsolutelytwoorone.If there is no such relation as strict, “classical” identity, questions about our

persistencethroughtimearenotquestionsaboutstrict identity,butaboutsomesameness relation or another.Which sameness relation? Supposewe ask oncemorewhether Jones still exists after lapsing into a persistent vegetative state.(Analogousconsiderationsapplytothequestionwhetheryouwereeverafetusoranembryo.)TheresultinghumanvegetableispresumablythesameanimalasJones,butitcouldhardlybethesameperson,asitseemsnottobeapersonatall.Whichrelationareweaskingabout,samepersonorsameanimal?Thisisalinguisticquestion,notametaphysicalone.YoumayarguethatbecauseJones’is a “personal” name, correlated with the personal pronoun ‘she’, we areprobablyaskingwhetherthevegetableisthesamepersonasJones,andnotthesame animal (or the samemass of matter or anything else). So whether it iscorrecttosaythatJonessurviveswilldependonthissemanticpoint.Toputthepointanotherway,whetheritistruetosaythatJoneshassurvived

as a vegetable will depend on which relative-identity relation figures in thereferenceof thenameJones’.Ordinarily,singularreference is takento involveabsoluteidentity:anamesuchasJones’denotesacertainbeingandnothingelse.Thatis,itdenotesallandonlythosethingsthatarenumericallyidenticalwithaparticularperson.Thiscannotbethecaseifthereisnosuchrelationasabsolute

identity.Ifidentityisrelativetokindsorconcepts,referencetoowillhavetoberelative to kinds in an analogous way. Presumably the sentence “Jones hassurvived”willbetrueifJones’denotesthosebeingsthatarethesameanimalasthewomanbaptizedJones’andfalse if thenamedenotes thosebeings thatarethesamepersonasthatwoman.Consider amore difficult case: Tim andTom exchange cerebrums.Call the

onewhoendsupwithTim’scerebrumandtherestofTom‘Timbrain’,andcallthe one who gets Tom’s cerebrum and the rest of Tim ‘Tombrain’. Whatbecomes of Tim? Does he survive as Timbrain or as Tombrain? Who isTimbrain—TimorTom?Hereallfourcharactersarepeople,sowecannotruleoutanyanswer to thesequestionsonthegroundsthatweare talkingabout thesamepersonrelationandoneoftherelataisnotaperson.Theissueiswhetherwearetalkingaboutabiologicalrelationorapsychologicalone(orsomethirdpossibility) when we ask whether Tim is Timbrain. For Timbrain ispsychologicallycontinuouswithTim,butnotbiologicallycontinuouswithhim.There are plenty of psychologically based sameness relations and plenty ofbiologicallybasedsamenessrelationsthatwemightappealto,andthequestioniswhichsuchrelationfiguresinaproperanalysisofsentenceslike‘TimbrainisTim’or‘TimsurvivesasTombrain’.Thisisofcoursealinguisticmatterandnotametaphysicalone.Allpartiestothedebatemayagreeaboutthemetaphysics—which sameness relations hold between the four characters in the story andwhich do not hold. If they still disagree about who is who, this can only bedisagreementaboutwhichsuchrelationwemeanwhenwetalkthelanguageofidentity.Now this way of resolving (or dissolving) problems about personal identity

involvescertaincomplications.Allareasofphilosophy,logic,andrelatedfieldsthatdealwithnumericalidentitywillhavetoberethoughtifthereturnsouttobenosuchrelationasidentity.Wehavealreadyseenthatreferencewillhavetoberelativizedtokindsorconcepts(formoreonthismatter,seevanInwagen1988).The same goes forde remodality.On the orthodox view, to say that ImighthavebeensixfeettallistosaythatinsomepossibleworldIamsixfeettall.Butwithout absolute identitywe cannot saywhether aworld containsmewithoutqualification.AgivenworldmightcontainsomethingthatisthesamepersonasIamandsomethingthatisthesamelumpoffleshasIam,thingsthatareneitherthesamepersonnorthesamelumpoffleshaseachother.WecannotsaywhichpossiblestateofaffairsisoneinwhichIamsixfeettalluntilwehavespecifieda sameness relation. So the relative-identity theorist (like the four-dimensionalist,asweshallsee)iscommittedtotheviewthatmodalpredicatessuchas‘couldhavebeensixfeettall’areambiguousandmayexpressdifferent

propertiesindifferentcontexts.Settheoryisanotherexampleofanestablishedbodyofdoctrinethatwillneed

revisionifthereisnosuchrelationasabsoluteidentity.Logicianstellusthatsetsare identical when they have the same members. But suppose that Tim andTimbrainarethesamepersonbutnotthesameanimal.ArethesetconsistingofTimandthesetconsistingofTimandTimbrainthesameset?Ifweaskwhetherthey have the same members, we shall get a different answer depending onwhetherwecomparetheirmembersbythesamepersonorbythesameanimalrelation.Forthesamereason,wecannotsaywhetherthesetconsistingofTimandTimbrainhasonememberortwo.

III.TemporalParts

Ontheontologyoftemporalparts,youandIandotherconcretematerialobjectsdonotstrictlyendure throughtime,bybeingwhollypresentatdifferent times,butareinsteadextendedintimebybeingmadeupoftemporalpartsthat“occur”at different times (Quine 1953; Heller 1990, chap. 1; Lewis 1976a; Noonan1989,122ff.).Likeanevent,youfillupanintervaloftimewithearlierandlaterparts.Youarestretchedacrosstimeinsomethinglikethewaythatahighwayisstretchedoutinspace.Muchasonlyapartofthehighwayispresentatanypointalongitslength,onlyapartofyouispresentatanyonetimeduringyourcareer.To say that you have a certain property at a particular time is to say that thetemporalpartofyou that “occurs”at that timehas thatproperty timelessly (atleasta“momentary”propertysuchasbeingsixfeettall;propertiesthatittakessome time to have, such as reading a novel or climbing amountain, are a bitmoredifficult).Togettheresultthatquestionsaboutouridentityarelinguisticquestions,we

needafurtherassumption:thateverymatter-filledregionofspacetimecontainsanobject.Foreveryportionofyourcareer(bywhichImeanasortofeventorprocess that includes everything you do or that happens to you), there is aconcrete, flesh-and-bloodobject thatwalksand talks (orwhatever),andwhosetemporalextentmatchesthatofthecorrespondingpartofyourcareer.Thereisatemporalpartofyouthatcorrespondstoyourchildhood,forexample,extendingfromyourbirthuntil,say,youreighteenthbirthday.Thereisalsoanobjectmadeupofyourfirsthalfandmysecondhalf,andonemadeupofmyupperhalfandyourlowerhalf.Thedoctrine thatmaterialobjects are temporallyextendeddoesnotby itself

entailthateverymatter-filledspacetimeregioncontainsanobject,andyoumight

wonder whether the “four-dimensionalist” really needs to say so. As far as Iknow,allfour-dimensionalistsdoacceptthisfurtherclaim,andforgoodreason:nearly all of the philosophicalwork that the temporal-parts ontology is put torequiresit(seebelow).SowasIeverafetus?Considerthattemporalpartofmethatbeginsnowand

isextendedfortenseconds.Call it“mycurrentpart”.Giventhateverymatter-filledspacetimeregioncontainsanobject,mycurrentpartwillbeapartofanobjectwhose earliest parts are fetus-parts. In fact, therewill be a greatmanyobjectsthatincludebothadultpartsthatarepsychologicallycontinuouswithmycurrentpartandfetalpartsthatarebiologicallycontinuouswithmycurrentpart.But to avoidneedless complication, consider just those thathavenoparts thatarenot eitherpsychologicallyorbiologically continuouswithmycurrent part,andwhichhavenotemporalgapsoranyotheroddfeatures.Isaythattherearemanysuchobjectsbecauseforanyfour-dimensionalobjectthatis,asitwere,acandidateforbeingme,thereisanotherobjectjustlikethatonebutafractionofasecondlongerorshorterthanit,which(owingtothefactthatonedoesn’tcomeintoorpassout of existence instantaneously) is an equallygoodcandidate forbeingme.Mycurrentpartisalsoapartofmanyobjectsthathavenofetalparts,andthepartsofwhichareallpsychologicallycontinuouswithmycurrentpart.Thus, thereare candidates forbeingme that include fetalparts andcandidatesforbeingmethatdon’tincludefetalparts.WhichcandidateamI?Thatdependson which of the many candidates—one with or one without fetal parts—thename‘Olson’,andtheword‘I’asspokenbymycurrentpart,denotes.Hence,itisalinguisticquestion.Thesamegoesforanyadventurethatmightleavemyidentityinquestion.If

mycerebrumgetstransplanted,therewillbemanyobjectscomposedentirelyofperson-parts psychologically continuous with my current part, including partsthathavemycerebrumandtherestofsomeotherhumananimal;andtherewillbemanyobjectscomposedentirelyofhuman-animal-partsthatarebiologicallycontinuous with my current part, including parts that lack a cerebrum. Whathappenstomewhenmycerebrumistransplanteddependsonwhethermyself-referring‘I’picksoutoneoftheformerobjectsoroneofthelatter(orneither).BoththosewhosaythatIgoalongwithmycerebruminatransplantandthosewhosaythatIstaybehindcanagreeabouttheontologyofthesituation:theycanagree that my current part is a part of many objects that go along with mycerebrum, and a part of many objects that stay behind when that organ isremoved. They disagree only on the semantic question of what object is theproper referent of the name ‘Olson’, or theword ‘I’ as uttered bymy currentpart.

Somephilosophers talk the languageof temporalpartswithoutaccepting theontological claim that you and I really are extended in time (Perry 1975, 10;Shoemaker1984,75,90).Whilethereisnothingwrongwiththisaslongasitisunderstood correctly, it does not make questions about personal identity intolinguisticquestions,asthegenuineontologyoftemporalpartsdoes.Aswesawin Chapter 2, it is difficult to talk about identity through time and diachronicrelationslikepsychologicalcontinuitywithoutsayingthingslike,“Apersonxatt is identical with a person y at i* if and only if x at t is psychologicallycontinuous with); at t*”, an ungrammatical sentence with uncertain logicalstructure. One strategy for avoiding this awkward problem is to talk about“person-stages”:“Anearlierperson-stagexandalaterperson-stageybelongtothesamepersonifandonly ify ispsychologicallycontinuouswithx—i.e., ifycontainsapsychologicalstatethatiscausallyrelated,inanappropriateway,toastatecontainedinx.”If“person-stages”arepartsor“temporalslices”ofpeople,thiswayoftalkingcommitsustotheontologyoftemporalparts.Butifwecallpartsofsomeone’scareerorhistory(notasubstance,butasortoflongeventorprocess) “person-stages”, we can enjoy some of the benefits of that way oftalkingwithoutsayingthatyouandIareourselvestemporallyextended.However,thelanguageofperson-stages,harmlessthoughitmaybe,doesnot

byitselfprovideuswithasolutiontoanysubstantivequestionsaboutpersonalidentity. Recall the case of Tim and Tom,who exchange cerebrums. (Letmesidestepthequestionofwhetherone’scareermighthavestageswhenoneisnotstrictly a person, which it might sound awkward to call “person-stages”.)SomeonemightsaythatTimgoesalongwithhiscerebrumratherthanwithhisother parts because those postoperative person-stages that include Tim’scerebrum are psychologically continuous with Tim’s preoperative stages,whereasthosepostoperativestagesthatincludeTom’scerebrumandtherestofTimarenotpsychologicallycontinuouswithTim’spreoperativestages.ButthisdescriptionoftheproblemprovidesnoreasontothinkthatwhathappenstoTimisinanywayalinguisticmatter.ForittobealinguisticquestionwhetherTimgoesalongwithhiscerebrumorstaysbehindwithhisotherparts,theremustbetwo material objects, one of which goes along with Tim’s cerebrum and theother ofwhich stays behind. In that case,what happens toTim is amatter ofwhichobjectweusethename‘Tim’topickout.Andalthoughtheontologyoftemporalpartsentailsthattherearetwosuchbeings(farmorethantwo,infact),thelanguageoftemporalpartsbyitselfhasnosuchimplication.Youmayinsistthat there are two such careers or histories— one history that follows Tim’scerebrumandonethatfollowstherestofhim.Perhapsanyperson-ororganism-stageswhatevermakeupsuchahistory.Butwecannotassumewithoutfurther

argument that every such “person-history” is the history of a person, or of amaterial substanceof anyother sort.Thosewho talk the languageof temporalparts, without accepting the metaphysical claim that people are composed ofarbitrary temporal parts,must solve the problemof personal identity by doingmetaphysics,notsemantics.Like the relative-identity thesis, the ontology of temporal parts also has

complications having to do with suchmatters as de re modality and singularreference (Lewis 1968, 1971; Noonan 1989, 145 ff.; van Inwagen 1990a).SupposeIamneverinfactinvolvedinanyadventurethatleavesmyidentityinquestion.Evenso,wemightaskwhetherIshouldsurviveifIweresounluckyasto lapseintoapersistentvegetativestate.Hereadvocatesof theBiologicalandPsychological Approaches appear to agree about which object I am (leavingaside the fetus problem), but to disagree about that thing’s modal properties.This sounds like a substantive metaphysical dispute rather than a merelylinguistic one. But on the ontology of temporal parts, what sort of thing onecould survive in counterfactual situations is also determined by our language.That ontology requires a counterpart-theoretic account of de re modality, ormoregenerallyan“Abelardian”accountaccording towhichpredicatessuchas‘could survive as a vegetable’ express different properties in differentcircumstancesofuse (Noonan1993). Iwon’tbother toexplainwhy this is so,but itseemstobegenerallyaccepted.According tocounterpart theory(to takethebest-knownaccountofthissort),tosaythatIcouldsurviveasavegetableistosaythatsomepossibleworldcontainsacounterpartofmethatsurvivesasavegetable.TosaythatIcouldnotsurviveasavegetableistosaythatnoworldcontainsacounterpartofmethatsurvivesasavegetable.Acounterpartofmeissomethingthatresemblesmeincertainrespects,andwhichrespectsofsimilaritymake something a counterpart of me is up to us, as speakers about de remodality, to decide. So whether it is true to say that I could survive as avegetable is roughlyamatterofwhetherwearewilling to talkas if Icould—whether we are willing to take as counterparts of me beings that survive asvegetables.Presumably we employ different counterpart relations in different

circumstances. It seems to be true that a human animal can survive as avegetable;and italsoseems tobe true,at least tomanyofus, that Icouldnotsurvive as a vegetable, even though I am a human animal. With counterparttheorywe can have it bothways.Whenwe say that thishumananimal couldsurvive as a vegetable, we mean that some world contains an “animal”counterpart of it—something that resembles it in biological respects—thatsurvivesasavegetable.WhenwesaythatIcouldnotsurviveasavegetable,we

mean that no world contains a “personal” counterpart of me—something thatresembles me in its “personal” or psychological respects—who survives as avegetable. If both claims are true (as many advocates of the PsychologicalApproachwouldmaintain),and if Iamthishumananimal, thatshows that thepredicate ‘could survive as a vegetable’ expresses different properties indifferentcircumstances.Thereisnosuchpropertyastheabilitytosurviveasavegetable without qualification, only the ability to survive such a thing quapersonandtheabilitytosurviveitquaanimal.(Ofcourse,anyonewhoactuallydoeslapseintoapersistentvegetativestateandtherebyceasestoexistmustbenumericallydifferentfromthehumananimalthatoutlivesher.)Another complication arises from the sheer multitude of objects that the

ontologyof temporalpartsprovidesuswith.Nomatterwhat the truth isaboutpersonalidentity,therewillalwaysbeavastnumberoffour-dimensionalobjectsthatareallexcellentcandidatesforbeingme,owingtothefactthateverymatter-filled region of spacetime contains its own material object. If you think thatsomeparticularobjectisme,consideroneoftheobjectsjustlikethatonebutafraction of a second shorter or longer, or containing one atommore or less atsomepointduring its life. If Iamarational,consciousEnglishspeaker,surelythat being is too; and if I am able to refer tomyself by saying ‘I’, that beingought tobeable to refer tohimself in thatwayaswell.Each time I say ‘I’, alegionofsimilarbeingsalsosay‘I’.WhichoneamI?ItseemsthatIcouldn’tbeanyofthem.IamthebeingIpick

outbysaying ‘I’. (Whoelse?)But Ican’tpickoutanyonebeing in thatway.EachtimeIsay‘I’,Iambiguouslydenoteavasthostofbeingstoosimilartooneanotherforanylinguisticconventiontodistinguish.SothereisnosuchpersonasI. There are, rather, many such people as I. There are far too many rationalbeingsforanyofthemtobeyouorI.Alternatively,ifIcouldsomehowpickoutjustonebeingbysaying‘I’,andthesameoneoneachoccasionofutterance,Icouldneverknowwhichperson—whichofthemanycandidatesforbeingme—Iwas.4Four-dimensionalistsmaytrytobringthisconsequenceintolinewithpopular

opinion by proposing a deviant semantics for English. People are sometimesalone, they say, and this book was not written by a committee, because we“count”allthecandidatesforbeingmeasone(Lewis1976a).Thatis,alloftherational beings that havemy current part as a part (except for gerrymanderedbeings such as the one composed of my first half and your second half) arecountedasone,andarereferredtointhesingular.Soitistruetosay,whenoneisnotdoingmetaphysics,thatthereissuchapersonasI,forwepretendthatallof the beings picked out by that utterance are the same being. Nevertheless,

singular reference strictly so called, both to ourselves and to other materialobjects,willnotbepossible.TheontologyoftemporalpartsisalsoincompatiblewiththeLockeanAccount

ofpersonhooddiscussedinChapter5.Thatistheviewthattobeapersonistohavecertainpsychologicalfeatures,suchasrationalityandthecapacityforself-awareness.Theontologyoftemporalpartstellsusthattherearemanyrational,self-conscious beings that are not people. Take my earlier half, for example.Accordingtotheontologyoftemporalpartsthereisanobjectcomposedofjustthosetemporalpartsofmethatoccurbeforethemidpointofmycareer(ormorelikelymanysuchobjects,since thisdescription isvague).Thatbeing is justasrationaland justasconsciousasIam; infact,assumingthatmylife isnotyethalfover, thatbeing isnowpsychologically indistinguishablefromme,formycurrentpartisalsoapartofhim.Butmostfour-dimensionalistswoulddenythatmyearlierhalfwasaperson.CertainlythePsychologicalApproachentailsthatheisnotaperson,sincehewillceasetoexistmidwaythroughmycareerwithoutany sort of psychological discontinuity—that is, even though many latertemporal parts ofme are psychologically continuouswith him.Assuming thatmyearlierhalf is capableof referring to and thinkingabouthimself, hemight(andpresumablydoes)mistakenlythinkthatheisaperson.Someofthesedifficultiescouldbeavoidedbydenyingthateverymatter-filled

spacetimeregioncontainsanobject.Perhapstherearen’tvastnumbersofbeingswho are all equally good candidates for being me and better than any othercandidates;perhapsthereareno“propertemporalsegments”ofme,suchasmyearlier half. Perhapsmy current part is a part of only one rational, consciousbeing. But in that case the four-dimensionalist has no linguistic solution toproblems of personal identity. Suppose you and I trade cerebrums next year:Willyousurviveasthepersonwithmycerebrumandtherestofyou,orasthepersonwithyourcerebrumandtherestofme?Ormightyounotsurviveatall?Thefour-dimensionalist’ssolutiontothispuzzleassumedthatyourcurrentpartwas a part of at least three objects: one that has future parts consisting ofmycerebrum and the rest of you, one that has future parts consisting of yourcerebrumandtherestofme,andonethatdoesnotextendbeyondtheoperation.What happens to you, then, depends on which of those beings we use thepronoun‘you’topickout.Butifyourcurrentpartisapartofonlyonerationalbeing,weareleftwiththequestionofwhathappenstothatbeingwhenyouandI trade cerebrums. Advocates of the Psychological Approach say that it goesalongwithyour cerebrum; friendsof theBiologicalApproach say that it goesalongwithyourbrainlessremains;othersmaysaysomethingstilldifferent.Andthisseemstobeagenuinemetaphysicaldispute,andnotadisagreementabout

language. Similar remarks apply to any other puzzle about personal identity,suchasthefetusproblemandtheVegetableCase.Withoutalargestockoffour-dimensional objects to feed into the semantic machinery, the temporal-partsontologydoesn’tdomuchphilosophicalwork.5I have presented these views—eliminativism, relative identity, and the

ontology of temporal parts—as alternatives to the way I see the problem ofpersonal identity. It is not my purpose to criticize them here. Even if thedifficulties I mentioned briefly are not just technical problems requiringtechnical solutions, but symptoms of deep incoherence, developing thoseobjectionswouldbeadifferentprojectfrommine.BydrawingoutsomeoftheproblematicconsequencesofthoseviewsIdonotmeantosuggestthattheyaretherefore false or implausible, but only to give the reader some idea of whatthoseviews involve.Onecannot simply accept the relativityof identityor theontologyoftemporalpartsandbedonewithmetaphysicalproblems,evenifthatgetsoneoutofmanyofthemetaphysicalproblemsofpersonalidentity.Suchadecision commits one to a metaphysic with far-reaching and surprisingconsequences.At best one can trade in the problem of personal identity for anew batch of philosophical problems: how there can be thought (and inparticular the difference between my thoughts and yours) without thinkingbeings; how we can get by without identity or de re modality; howmaterialobjectscouldbetemporallyextended;andhowtodealwiththe“problemofthemany”,forexample.Therearenoeasysolutions.

Notes

NotestoChapter11. Cranford and Smith 1979, 204; Cranford 1988, 28. See alsoBrock 1993, 147; Culver andGert

1982,Chap. 10; Stickel 1979;Walker 1985, xiii, 13. Persistent vegetative state is defined as “a state ofextremelyseverebraindamageinwhichthepatientdemonstratesnobehavioralresponsewhatsoever,eventhoughheappearsawake”(CranfordandSmith1979,203).

2.Cranford 1988, 30.TheAmericanAcademyofNeurology has stated officially that patients in apersistentvegetativestateareincapableofsuffering(31).Althoughtheycansometimesgrimaceorreactinotherwaystonoxiousstimuli,thisappearstobeareflexgroundedinthebrainstem.

3.Thetransplantstoryissciencefiction,anditislegitimatetoaskwhetherthecaseasdescribedisinanysensepossible.Puccetti(1969),Snowdon(1991,114–117),andWilkes(1988,37)havearguedindetailthat whole-brain transplants, in which not only the cerebrum but also the lower brain is removed, aretheoreticallypossible,andIknowofnoadditionalproblemsthatmightariseforacerebrumtransplant.

4.Lockwood1985,11.Ayers,ontheotherhand,whoisalsoscientificallyeducated,believesnotonlythatyoucouldsurvivethedestructionofyourmind,butalsothatyoumaycontinuetoexistasacorpseevenafteryourvegetativefunctionsshutdown(1990,224;seealsovanInwagen1980,295).

5.Somephilosophersuse the term‘psychologicalcontinuity’ topickout thisrelation(orsomethinglikeit),whichholdsbyvirtueofone’smentalcontents(e.g.,Parfit1984,206).Iusethetermmorebroadly.For simplicity I shall also pretend that psychological continuity is a symmetric relation: if x is at tpsychologicallycontinuouswithyassheisatt*,thenyisatt*psychologicallycontinuouswithxassheisatt.Itwouldbeasimplebutsomewhattediousexercisetoeliminatethispretension.

6. Itmay be part of the definition of ‘memory’ that I can remember (“from the inside”) a certainexperienceonlyif thatexperiencehappenedtome,ratherthansomeoneelse.Thatwouldmakeit truebydefinitionthatIamsomepastpersonifInowremembersomethingthathappenedtohimthen,andevenopponents of the Psychological Approach could accept this. In that case, what is needed to state thePsychologicalApproach isa relation that is just likememory,except that itdoesnot implybydefinitionthatonecanrememberonlyone’sownexperiences:callit“quasi-memory”.Roughly,anapparentmemoryofmineisaquasi-memoryofsomepastexperiencejustincasetheapparentmemorywascausedbythatexperience inanappropriateway,away thatneednot imply that Ihad thatexperience. (SeeShoemaker1970a,1984,chap.4;Noonan1989,chap.8;andmanyothersources.)Foraninterestingvariationonthetraditionalaccountofcontinuityofmentalcontents,seeSchechtman1994.

7.Korsakoff’ssyndromehaseffectsonlyslightlylessdrasticthanthis.ForafascinatingaccountseeSacks1987b,sections2and12.SeealsoPerry1976b,421,andvanInwagen1990b,183.

8. 1990, 116. (Unger later qualifies this formula somewhat, 147–52.) Gert, Johnston, Lockwood,Mackie,Nagel,Rosenberg,andWigginshavegivensimilaraccounts(seebelowforreferences).

9.Forexample,Shoemaker1984,108ff.;Hick1990,122f.;Davies1982,125f.;Lewis1976b.10.AsSnowdon(1991,111)haspointedout.11.Wiggins,forexample,oncewrote:

Wearenot identicalwithourbodies. . . .Theconceptwhichbelongs tophysiological science ishumanorganism,humanbody, orwhatever.Wecan imagine such thingsbeing replenishedwithsparehands,sparekidneysandwithsparebrains.Therepairneednotpreservecharacter-continuityormemory-continuity.Butifthisisthephysicalisticwayoflookingattheindividuationofpersonsthenthewayofphysicalismiswrong.(1967,57f.)

SeealsoJohnston1987,64;Lockwood1985,11;Lowe1991b,106;Shoemaker1984,113.EvenChisholmwrites,“Itislogicallypossiblethat,whentheperson’sbodydies,thenthepersondoesnotceasetobe.Anditislogicallypossiblethatthepersonceasestobebeforehisbodydies”(1977,171).Whatevermayhappen

tothehumananimalassociatedwithmewhenmybodydies,itcertainlycontinuestoexistuntilmybodydies.Thus,theanimalcouldoutliveme,andsoisnumericallydifferentfromme.

12.Ethicistscommonlyassumethatapatientinapersistentvegetativestateistheverybeingthatwasoncerationalandconscious.Brody,forexample,saysthatoneis“alivebutnotaperson”afterlapsingintoapersistentvegetativestate(1988,36).Itakethistoimplythatonecanceasetobeapersonbutstillexist.

13.Grice1941;Hospers1967,410–414;Johnston1987,1989a;Lewis1976a;Mackie1976,202f.;T.Nagel1986,40;Noonan1989,especially13;Nozick1981,chap.1;Parfit1971;1984,207;Perry1972;Pollock1989,chap.2;Price1972,104f.and1973,27;Quinton1962;Rosenberg1983,92ff.,223;Russell1967, 73; Shoemaker 1970a and 1984, 90; Strawson 1992; Unger 1990, chap. 5; Wiggins 1976, 168,173n.44and1980,160,162,163.SeealsoAgichandJones1986,273;Aune1985,93;Brennan1988,275,336;Carruthers1986,194ff.;Gert1971,477f.;GreenandWikler1980;Hamlyn1984,206–211;Lizza1993; Lockwood 1985, 19; MacIntosh 1974; Puccetti 1969; J. Robinson 1988; Schechtman 1994; andWikler1988.

NotestoChapter21.Somereadershavedoubtedthatwecanunderstandthisformula.Wecanaskwhethersomeperson,

oranimal,orwhathaveyou,thatexistsatonetimeisidenticalwiththepersonwhoexistsattheothertime,theysay;butwecannotaskthisaboutjustanything,withoutqualification;forwecannottellwhattheother“thing” is. In Wiggins’s terms, thing is not an adequate covering concept. This is to misunderstandWiggins’s view. We could put the question this way: Under what possible circumstances is the opensentence

xisapersonattand(∃y)yexistsatt*[≠t]andx=y

satisfied?NothingthatWigginssaysaboutcoveringconceptsimpliesthatthereisanythingillegitimateorincompleteorincomprehensibleaboutthisquestion.

2.Thisdefinitionisnotuniversallyaccepted.Chisholm,forexample,defines‘person’asanythingthatcan come to be rational and conscious (1977, 181). But this is no more than a verbal disagreement.Wiggins,however,forreasonsthatIfindobscure,arguesthattheLockeandefinitionof‘person’ismorallyandpoliticallypernicious(1976,164ff.).

3.ThusGert:

Though Ihold that somebodilycontinuity is anecessaryconditionofpersonal identity, and thatcompletebodilyidentityisasufficientcondition,thisdoesnotmeanthatIconsiderpsychologicalfeaturescompletelyirrelevant.Onthecontrary,ifabodydoesnothaveanypsychologicalfeatures,thenitisnotaperson,andhencethequestionofpersonalidentitydoesnotarise.(1971,475f.)

SeealsoJohnston1989b,449.4.Youmightthinkthatifpersonisasubstanceconcept,afurtherclaimmustfollow,namelythatonly

people have the persistence conditions for people. For if people shared their persistence conditionswithsomenon-people—gorillas,say—theywouldhavethosepersistenceconditionsbyvirtueoffallingundersomekindofthingthatincludedbothpeopleandgorillas(thinkingbeing,perhaps),ratherthanbyvirtueofbeing people.While itwould be true thatwewere people, and true that every personmust be a personthroughouther career, amore fundamental answer to thequestionWhat arewe?wouldbe thatweweresomekindofthingthatincludesbothourselvesandgorillas,sincethatwouldbethekindthatdeterminedourpersistenceconditions.Wigginsdefinessubstanceconceptsas“sortalconceptswhichpresent-tensedlyapplytoanindividualxateverymomentthroughoutx’sexistence”.These,hesays,“givetheprivilegedand(unless contextmakes it otherwise) themost fundamental kind of answer to the question ‘what is x?‘”(1967, 7). But perhaps something could be a substance concept in the first sense—an “abiding sort”(Snowdon1990,87)or“temporallyessentialattribute”(Lockwood1985,12)—withoutbeingasubstanceconceptinthesecondsense—withoutdeterminingthepersistenceconditionsforallandonlythingsofthatkind,and thuswithoutproviding themost fundamentalanswer to thequestionWhat is it?Wemightcallthosesubstanceconceptsthatdetermineacriterionofidentityforallandonlythingsofthatkind‘ultimatesorts’.ButIshallignorethiscomplication.

5.DerekParfithasrecommendedthisviewtome.6.Foradiscussionof this topic seevan Inwagen1985.Temporalparts arediscussed inChapter7,

SectionIIIbelow.7.VanInwagen(1985,106)showshowthetemporal-partstheoristcouldavoidthisconsequence.

NotestoChapter31. On Perry’s view, to be precise, there are three people there, one of whom becomes a spatially

scatteredobjectwhenyoudivide.2.E.J.Lowewrites,

Byaself,then,Imeanapossibleobjectoffirst-personreference...:abeingthatcanidentifyitselfasthenecessarilyuniquesubjectofcertainthoughtsandexperiencesandasthenecessarilyuniqueagentofcertainactions.(1991a,82)

Onthecurrentproposal,youandIshouldnotbeselvesinLowe’ssense.AsimilarproblemisdiscussedinChapter5,SectionV.

3.Arguments like thisare thecenterpieceofUnger1990.Although Icannothope to reproduce thebreadth or subtlety ofUnger’s arguments, I hope thatmy remarks in this section are general enough toapplytomostofthem.

4.Puccettiwrites,

Ifsomeonesuggestedtomethatmybodymightsurvivedeathoftheneocortex[e.g.,inapersistentvegetativestate]forseveralmonthsoryears,provideditwerefedandcleanedproperly,etc., thatwouldhavenogreaterappealtomethanpreservationofmyappendixinabottleofformaldehyde.For in the sense inwhich life has value for humanbeings, Iwouldhavebeendead all the time.(1976,252;myemphasis)

ThissentimentisperfectlycompatiblewiththeBiologicalApproach.5.EssayIl.xxvii,26.ElsewhereLockewrites,

InthispersonalIdentityisfoundedalltheRightandJusticeofRewardandPunishment;HappinessandMisery,beingthat,forwhicheveryoneisconcernedforhimself,notmatteringwhatbecomesofanySubstance,notjoinedto,oraffectedwiththatconsciousness.(18)

6.Hereisanothersuggestion:BrainyisaccountableforPrince’sactionsbecause,inadditiontobeingpsychologically continuous with Prince, Brainy has Prince’s brain. But unless we suspect that Prince’s“duplicate”isnotreallyexactlylikePrince,butsomehowlacksfreewillorthelike,itishardtoseehowthis couldmake any difference. In any case,we could defeat this suggestion by changing the example:supposethatPrinceundergoesfissioninsteadofbeingdestroyedandduplicated.

7.ThismaybethesortofargumentAnthonyQuintonhadinmindwhenhewrote,ofasimilarcase,

ItissurelyplainthatifthecharacterandmemoriesofBandCreallysurvivedintactintheirnewbodily surroundings those closely concerned with them would say that the two had exchangedbodies,thattheoriginalpersonswerewherethecharactersandmemorieswere.Forwhy,afterall,dowebother to identifypeoplesocarefully? ... Inourgeneral relationswithotherhumanbeingstheirbodiesareforthemostpartintrinsicallyunimportant.Weusethemasconvenientrecognitiondevicesenablingustolocatewithoutdifficultythepersistingcharacterandmemorycomplexesinwhichweareinterested,whichweloveorlike.(1962,402)

8.Again, onemight suggest thatBrainy is responsible forPrince’s actionsbecausehehasPrince’sbrain.Butthenwecouldreplacetheannihilation-and-replacementstorywithafissioncase.

NotestoChapter41.One interesting point of comparison is thatwhilemanyPVS patients have an intact swallowing

reflex,thefetusdoesnotacquirethatreflexuntilthefifthmonthofdevelopment(Matthews1979,156).2.Othersarelessspecific.Johnston,forexample,aftercriticizingaccountsofpersonalidentitybased

oncontinuityofmentalcontents,sayssimplythatonesurvivesaslongasone’smindcontinueson(1987,78).Althoughasix-month-oldfetusdoesnotseemtohaveamind,itisnotsoclearthataninfantlacksone.

3. Lockwood, for example, says that I persist just in casemy capacity for awareness is preserved(1985,212).

4.Butthereareexceptions.Warren(1981)defendsthemoralityofabortionbydenyingthatafetuscanbecomeaperson.Stone(1987)alsodiscussestheissue.SingerandKuhse,incomparingthemoralityofabortionandinfanticidewiththatofabstinence,write:

Wemust recall, however, thatwhenwe kill a newborn infant there is nopersonwhose life hasbegun.WhenIthinkofmyselfasthepersonInowam,IrealizethatIdidnotcomeintoexistenceuntilsometimeaftermybirth.AtbirthIhadnosenseofthefuture,andnoexperienceswhichIcannowrememberas“mine”.It is thebeginningof thelifeof theperson,rather thanof thephysicalorganism,thatiscrucialsofarastherighttolifeisconcerned.(1985,133)

ButitisnotclearthatSingerandKuhsemeantodenythatafetusorinfantmightlaterbeaperson,ortoclaimthatthepersonandthe“physicalorganism”aretwodifferentthings.(TheclaimthatatbirthIhadnosenseofthefutureseemstoimplythatIexistedthen.)TheymaymeanonlythatIwasn’tyetapersonatthetimeinquestion.

5.Forexample,Wiggins1967,48f.AnexceptionisD.Robinson1985.6.“[T]hebodyof thepatient inpersistentvegetativestateisstillalive,andcouldremainso,but the

patientisnot”(Wikler1988,45).7.TokeepthingssimpleIhaveomittedseveralqualificationsthatUngermakes(bothhereandlaterin

hisbook),includinga“non-branching”requirement.8.ForthesakeofsimplicityIhaveassumedherethatyouandImustbehumanbeingsthroughoutour

careers.However,manyfriendsofthePsychologicalApproach,includingUnger(1990,121f.),claimthatifone’sorganicpartsweregraduallyreplacedwithinorganiconesinsuchawaythatone’spsychologywaspreservedinaphysicallycontinuousway,onecouldbecomewhollyinorganic.Inthatcaseit isnotclearhowtheformulashouldbeworded.Itcouldnotbegin,“Ifxisapersonatt”,forifwewereoncefetuseswewerenotalwayspeopleeither.

9.IdonotunderstandwhySnowdon(1991,111)doubtsthatafetusisananimal.10. See also 139, 171 f., and the preface. Asked when she began to exist, the embryologist A.

McLarenreplied:

Ifwearetalkingnotabouttheoriginoflife...butabouttheoriginofanindividuallife,onecantrace back directly from the newborn baby to the foetus, and back further to the origin of theindividualembryoattheprimitivestreakstageintheembryonicplateatsixteenorseventeendays.If one tries to trace back further than that there is no longer a coherent entity. Instead there is alargercollectionofcells,someofwhicharegoingtotakepartinthesubsequentdevelopmentoftheembryoandsomeofwhicharen’t....TomethepointatwhichIbeganwasattheprimitivestreakstage.(1986,22;seealso14)

SeealsoDiamond1975;Grobstein1988,especially26–28;andvanInwagen1990b,152–157.11.Ontheotherhand,theembryologistC.R.Austinobserves,“Justwhichstage[inthedevelopment

oftheembryoorfetus]marksthestartofaperson’slifeisamatterofpersonalopinion”(1989,31).Butthe

phrase“thestartofaperson’slife”suggeststhatheisaskinganethicalquestionaboutwhenoneacquirescertainrights,ratherthanwhenonebegantoexist.Manywritersalsoregardthedefinitionofdeathasanethicalquestion,asweshallseeinthenextchapter.

12.DerekParfitsuggestedthistome.13.At least thisseems tomeavery reasonable thing tosay;Snowdon,however,hasdoubts (1991,

111).14.SomethinglikethisseemstobeAnscombe’sview:Icameintobeingatfertilization,butdidnot

becomeahumanorganismuntilsometwoweekslater,whentwinningwasnolongerpossible.But“Iwasalwayssomethinghuman”(1984,114).

NotestoChapter51.1984,113; seealso1970b,531.CompareWiggins:“Wehave two things,apersonandahuman

body, occupying (or being embodied or realized in) the same matter, and normally occupying itconcurrently for theperiodof the life of theperson.We thenhave twonon-identical things in the sameplaceatthesametime”(1967,48;seealso13;andLizza1993,361;Wikler1988,45).

2.ThefollowingisadevelopmentofanargumentsketchedbrieflybyHeller(1990,30f.)andmoreelaboratelybyBurke(1992);seealsoOlson1996.Nodoubtitsmainpointshaveoccurredtoothersaswell.

3.See,forexample,Brody1972;Doepke1982;Hirsch1982,59;Johnston1992;Kripke1971,note19;Lowe1991b,106;Pollock1989,32–37;Shoemaker1984,113;Thomson1983;Wiggins1968;thelistcouldbeextendedadnauseum.

4.AsHeller(1990,31)haspointedout.5.AsLizzasuggests:

To say that Paul Brophy was still alive in a persistent vegetative state is to equivocate on thereferenceof thepropername, “PaulBrophy”. In “theordinarywayof speaking”, “PaulBrophy”referstothepersonandthehumanbeing.However,afterBrophylosthigher-brainfunctions,“PaulBrophy” no longer refers to Paul Brophy, the person, since Paul Brophy, the person, no longerexists.Whatliesinthehospitalbedandwhatwerefertoby“PaulBrophy”isonlyPaulBrophy,thehumanbeing.(1993,361)

6. For that matter, there could not be objects just like living organisms but for their persistenceconditions. Imagine being told that there were apparently living things whose biochemical andphysiologicalproperties,eventheirevolutionaryhistory,wereprecisely thoseofawell-knownspeciesofprimate,butwhich, inspiteofappearances,werenotanimalsorevenlivingorganismsatall.I thinkyouwould assume that the bearer of this message was somehow confused about the meaning of the word‘organism’. At the very least it would be clear that she did not understand that term in the way thatbiologistsunderstandit(shemightbeavitalist,forexample).ButifyouandIarenotanimals,sheisright,and the biologists are wrong. For although you and I are paradigm cases of animals as far as ourphysiologicalpropertiesareconcerned—althoughwearealiveinthesamesenseasananimalisalive—ourpersistenceconditionswouldpreventusfrombeinglivingorganisms.

7.Forexample,T.Nagel1986,40–42;Wiggins1976,1980.Ungersaysthateachofuswasonceaweek-oldfetus,whichatleastsuggeststhatwearehumananimals(1990,6).

8.CompareSeifert:

Ifthefunctionofthebrainisdeemedtobesodecisiveforthelifeofthebodythatonitaloneshalldepend whether a person is dead or alive, it seems that a small and very partial sphere ofphenomenarelatedtohumanlifeistakenasidenticalwiththebiologicallifeofthewholeorganism.Thisseemsentirelyunjustifiedinviewofthenatureofbiologicallife.(1993,190)

9.Veatch,whoargues thatapersonshouldbeconsidereddeadwhenhishigher-brain functionsarelost,writesthat“thedefinitionofdeathdebateisactuallyadebateoverthemoralstatusofhumanbeings.Itisadebateoverwhenhumansshouldbetreatedasfullmembersofthehumancommunity.Sayingpeoplearealiveissimplyshorthandforsayingthattheyarebearersofsuchrights”(1993,21).Wikler,whourgesthesameview,understandsdeathas“anabsenceofeverythingforwhichpeoplevalueexistence”(1988,47).AccordingtoPeterSinger,deathis“theendofeverythingwevalue”.“Thereisno‘factofthematter’here,” hewrites. “Ifwe choose tomarkdeath at anymoment before thebodygoes stiff and cold (or toreallybeonthesafeside,beforeitbeginstorot)wearemakinganethicaljudgment”(1995,32;seealso104f.).Foranadmirablycleardiscussionoftheseissues,seeCulverandGert1982,chap.10.

10.HereIfollowvanInwagen(1990b,152f.).SeealsoWiggins1967,38,and1980,71.11. Perry, 1976a, 70; also Shoemaker 1984, 112 ff. Johnstonwrites, “[I]t is human beings thatwe

trace[viamemory],i.e.,beingsthatcouldoutlivethehumanorganismstheyareinvariablyconstitutedbyiftheirmindsweretocontinueon”(1987,78;seealso76).NotethatJohnstonuses‘humanbeing’tomeansomethinglikewhatImeanby‘humanperson’,whereasPerryapparentlyusesittomean‘humananimal’.

NotestoChapter61.NontechnicaldiscussionsofthistopicbyscientistscanbefoundinGrobstein1964,chaps.1and5;

Hoagland1977,chap.1;MaynardSmith1986,chap.1;Mayr1982,53f.;Miller1978,140f.;Monod1971,chaps.1and4;Sagan1990;Schrödinger1945,chap.6;andYoung1971,chaps.5–7.

2.Fortwoaccountsofteleology,seeBennett1990,chap.2,andE.Nagel1977.3.HereIdisagreewithAyers,whowrites,“Ingeneral,nodoubt,ananimalwouldnotsurvivebeing

rubbedawaytoaneighthofitssize,eveninthepurelylogicalsenseof‘survive’”(1990,237).4.AsGreenandWikler (1980,113) suggest.Singer (1995,30 f.) summarizes some recentmedical

developmentsinthisdirection.5.HereIagreewithGrisezandBoyle,

an organism is more than a collection of processes; it is a coordinated system. From athermodynamicpointofviewanorganismisanunstableopensystem,butitcontinuesbecauseitismaintained in dynamic equilibriumbyhomeostatic controls.These controls are of variouskinds,butinanorganismwhichiscomplexenoughtohaveanervoussystem,thissystemcoordinatesandintegrates the other control systems. This system is dispersed but centered in the brain; withoutsomebrainfunctioning,thewholesystemcannotbemaintained.Thuswhenthewholebrainceasestofunction,thedynamicequilibriumislost, thematerialswhichwereunifiedinthesystembeginbehaving without its control, and decomposition begins. . . . Death is the irreversible loss ofintegratedorganicfunctioning.(1979,76f.)

Singerapparentlydisagrees(1995,30).Butthenheunderstandsdeathas“theendofeverythingwevalue”,ratherthanasanessentiallybiologicalevent.

6.GrisezandBoylegiveasimilaranswertothe“artificial-brainstem”objection:

Ifthefunctioningofthebrain[asawhole]isthefactorwhichprincipallyintegratesanyorganismwhichhasabrain,thenifthatfunctionislost,whatisleftisnolongerasawholeanorganicunity.Ifthedynamicequilibriumoftheremainingpartsofthesystemismaintained,itneverthelessasawholeisamechanical,notanorganicsystem.(1979,77)

7.Essay,II.xxvii,4,5.Foranelaborateandfascinatingdiscussionofbiologicallives,seevanInwagen1990b, sections 9 and 14; also Young 1971, chap. 6. Ayers rejects Locke’s account of the identity oforganismsandarguesthatanorganismcancontinuetoexistafteritslifehasceased(1990,224).

8.vanInwagen1990b,91.Thexscomposesomethingyjustincaseeachofthexsisapartofyandeverypartofysharesapartwithoneormoreofthexs.

9. van Inwagen (1980) argues that the words ‘human body’ as they are used in philosophy aremeaningless,andthattheiroccurrenceinnonphilosophicallanguageislegitimatebuteliminable.

10.Swinburne1984,22.SeealsoShoemaker1976,andDescartes,SixthMeditation,ATVII76andPrinciples,part2,art.2,ATIXB41(Cottingham,Stoothoff,andMurdoch1985).

11.IowethissuggestiontoFrancesHoward-Snyder.12.Tye’sdefinition:

x’sbody=dfThematerialobjectthat(i)isthebearerofallthespatio-temporalpropertiesthatenterinto all the truths that are normally expressible, in ordinary language, in sentences with thegrammaticalform‘N is inpat t’,where‘N’refers toxand‘p’and‘t’ indicateaspatio-temporallocation, and (ii) is the bearer of all the physical properties that enter into all the truths that arenormallyexpressible,inordinarylanguage,insentenceswiththegrammaticalform‘NisØ’,where‘N’referstox,and‘Ø’isanon-relationalphysicalisticpredicate.(1980,181)

Tyedefines‘mybody’asifitwerethelatestneologismfromthefrontiersofscience.13.Strawson1959,104.Similarremarksonthemeaningof‘mybody’canbefoundinWilliams1970,

74,andRosenberg1983,48ff.

NotestoChapter71.Spinozathought that therewasonlyonesubstance, theworld,andthatallother thingswereonly

modificationsofit.Ithinkthisisbestunderstoodassayingthattalkaboutfamiliarthingslikepeopleandtables is just a loose and convenientwayof saying that theworld is “personalized”of “tabular”hereorthere (or more accurately, “thinking personally” and “extended tabularly”; see Bennett 1984, 92 ff.).Becausetheonlythingthatbearsthoseproperties—thoughtintheonecaseandextensionofacertainsortintheother—istheworld,whichisitselfneitherapersonnoratable,itfollowsthatthereareneitherpeoplenor tables, strictly speaking.Quite aside fromhisnotorious claim that there is no such thingas identity,Hume believed that a person was “nothing but a bundle or collection of different perceptions, whichsucceedoneanotherwithaninconceivablerapidity,andareinaperpetualfluxandmovement”(Treatise,I.iv.6:252).Therearethoughts,butnothinkingbeingswhohavethem.Russellonceheldasimilarview:“Allthatconstitutesapersonisaseriesofexperiencesconnectedbymemoryandbycertainsimilaritiesofthesortwecallhabit”(1967,73).RecentdefensesofcliminativismincludeStone1988andUnger1979a,1979b.Parfitsays that“inasense” therearenopeople; theexistenceofpeople is“onlyafactaboutourgrammar,orourlanguage”(1987,20;seealso1984,341).

2.Propernamesposetheirownproblemsfortheeliminativist.Forasuggestiononhowtodealwiththem,seevanInwagen1990b,136f.

3.Chisholm(1976,chap.3)offersanaccountofhowordinarytalkofpersistingtablescouldbetrueeventhoughnocomplexmaterialobjectstrictlypersiststhroughtime.

4. Of course it is not only four-dimensionalists who face this consequence. It is entailed by anycapaciousontologyofmaterialobjects—forexample,by theview thatanyparticleswhatevercomposeamaterialobject(seeUnger1980,andOlson1995).

5.IdiscussthismatteratgreaterlengthinOlson1997.

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Index

abortion76–77adverbs37–41amnesia14,41amoebas93,114amputees146–147Anscombe,G.E.M.174n.14Aristotle28,103Austin,C.R.174n.11Ayers,Michael19,169n.4,176n.177n.7

BiologicalApproachtopersonalidentityintroduced16–19

Blake,William128BodilyCriterionofpersonalidentity19–20,126,142–144,149–150body,human17,19,20,81,97,101,116,126,142–153,174n.6Boyle,Joseph176–177n.5,177n.6braindeath8braintransplant.Seecerebrumtransplantbrainstem7,10,45,133,140–142Brody,Baruch170n.12

capacities,psychological11–15,74–76,86–89,113cerebrumtransplant9–12,17–18,42–65,87,94,114–119,142,151,161,163Chisholm,Roderick95,170n.1171n.2,178n.3coma8complexity128–130composition138,156,158COMPROMISE(principle)86computers17,35,124–125constitution17,96,101continuity,psychological11,40,169n.5counterparttheory165–166counting166–167

Dawkins,Richard129death112–114,118–119,150–152Descartes,René155dualism,Cartesian96–97,125dualism,“property”126

embryos.Seefetusesevents138–140,162

fetuses4,73–93,111,160,163“fission”cases16,46–52,87Flanagan,Owen144Ford,Norman91Frankfurt,Harry103

Gert,Bernard171n.3gods17,35,70–71,124–126Grice,H.P.20Grisez,Germain176–177n.5,177n.6Grobstein,Clifford75

Heller,Mark175n.4hemispherectomy49–51Hospers,John20

Howard-Snyder,Frances177n.11Hume,David155

identitycriterionof22–27,33,36,84–85relative5–6,159–162

immortality71incarnation,divine72infants75–76

Johnston,Mark12,20,173n.2,176n.11

Kuhse,Helga173n.4

Leibniz,G.W.F.68Leibniz’sLaw160Lewis,David20lives11,114,136–140Lizza,John175n.5Locke,John20,57,103,125,136–138,172n.5Lockwood,Michael12,74,172n.4,173n.3Lowe,E.J.172n.2

Mackie,J.L.20Margolis,Joseph126McLaren,Anne174n.10memory13,66,170n.6mereologicalessentialism158metabolism127,130,135modality,dere161–162,165–166moralresponsibility57–62,65–66,107

Nagel,Thomas20,75nominalism154–155Noonan,Harold19,20Nozick,Robert20

organismsidentityof89–93,109–123,131–142natureof112,115–116,126–131,133–135

paraphrase156–159paraplegics147–148Parfit,Derek20,54–57,71,172n.5,174n.12,178n.1“Parfitiansuccessor”57,68Parfit-ShoemakerThesis54–57,59,71parts,temporal.Seetemporalpartspeoplevs.persons6Perry,John20,116,172n.1persistenceconditions.Seeidentity,criterionofpersistentvegetativestate7,17,74,87–88,94,111–114,119,159–160,165–166personhood24,102–108,167

LockeanAccount,introduced103phasesorts29–31physicalcriterionofpersonalidentity19,126Piaget,Jean75Pollock,John19,20,143Price,H.H.20pronouns89–90prudentialconcern53–57,59,65–66

PsychologicalApproachtopersonalidentityintroduced12

Puccetti,Roland169n.3,172n.4

Quinlan,Karen8Quinton,Anthony20,173n.7

reference160–161,163–167reincarnation72religiousconversion67resurrection71–72Rosenberg,Jay20,21,178n.13Russell,Bertrand20,155

Sacks,Oliver147Schechtman,Marya170n.6Seifert,Josef175–176n.8selves172n.2settheory162Shoemaker,Sydney20,55,71,96Singer,Peter173n.4,176n.9Snowdon,P.F.19,169n.3,172n.4,174n.9,n.13Spinoza,Baruch155spleen148Stone,Jim173n.4Strawson,P.F.20,152substanceconcepts27–31,36,84–85,110–111,122,144Swinburne,Richard103,126

teleology127–128,130temporalparts5–6,39,162–168Thomson,JudithJarvis19TransplantIntuition43–51,56,69TRICK(principle)84Tye,Michael148–149,177n.12

Unger,Peter15,20,37,75,82–84,172n.3,174n.8,175n.7UniquenessRequirement49

vanInwagen,Peter19,138,172n.6,177n.9Veatch,Robert176n.9

Warren,MaryAnne173n.4Wiggins,David20–21,27–29,84–85,122,151,170n.11,171n.1,n.2,172n.4,175n.1Wikler,Daniel176n.9Wilkes,Kathleen169n.3Williams,Bernard19,178n.13

zygote90–93