Boyd MaterialismWoutReduction

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Materialism without Reductionism:What Physicalism Does Not EntailRichard Boyd

T N A RECENT WORK of substantialI importance, SauJ A. Kripke (1972\ of-fers an alternative to the received accountsof reference, necessity, and essential prop-erties. In a small section of the paper Krip-ke applies his account of necessity to cer-tain traditional "essentialist" obiections tomind-body identity-objections accord-ing to which mind and body cannot beidentical ecause they have different es-sential properties. According to Kripke,standard materialist iebuttals to these

Copyright @ 1980 by Richard Boyd. Anearly version of this paper was presented to thePhilosophy Discussion Club of the Sage Schoolof Philosophy at Cornell University. I am grate-ful for many helpful comments on that version,especially for the detailed comments of Carl Gi-net and Norman Malcolm. I am indebted to alarge number of other colleagues for helpful criti-cism and discussion of the positions defendedhere. I especially want to thank Rogers Albritton,Ned Block, Oswaldo Chateaubriand, Alex Gold-stein, Barbara Koslowski, Norman Kretzmann,Richard Miller, Hilary Putnam, Sydney Shoe-maker, Robet Stalnaker, Nicholas Sturgeon, andWilliam Wimsatt. lEditor's note: This paper wssolicited as a discussion of nonreductionist mate-rialism and its relation to "essentialist" critiquesof mind-body identity theses. The author kindlyagreed to expand the paper to include an intro-duction to the central linguistic issues raised bymaterialism.l

objections rest on a mistaken account ofessential properties. He suggests that, infact, no rebuttal is possible.In this paper I hope to accomplishtwo things. First, I intend to show thatKripke's discussion of reference and ne-cessity constitutes a significant contribu-tion to our understanding of the mind-body problem, not only because his ac-count explicates better certain obiectionsto materialism but also because somethinglike Kripke's account of reference is re-quired for a satisfactory defense of mate-rialism. Second, I intend to show that theparticular essentialist arguments Kripkedirects against materialist theories of mindare, though ingenious, entirely unsuccess-ful. l. "Essentialist" Obiectionsto Materialism

A striking thing about materialistsolutions to the mind-body problem is thestrong and conflicting philosophical intu-itions they seem to elicit. On the onehand. it has seemed to a great many phi-losophers and scientists that the doctrinethat mental phenomena are really a spe-cies of the physical is an almost unavoid-able conclusion in the light of the increas-ing success with which physical scientists


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68 Richard BoYdhave explained complex biological phe-nomena. It seems to them overwhelming-lv unlikely that physical explanations forfeatures of our mental life will not also beforthcoming.l On the other hand, manyof the same thinkers, some of the time,and a great many others, all of the time,,ha.e the contrary intuition that it is ab-surd and incoherent (or, perhaps, evenmad) to assert that mental phenomena arephysical. Mental phenomena are simplyih" *.ottg kind of thing to be physical;they are essentially nonphysical'At least since Descartes, such intui-tions have been understood in terms of aputative contrast between the essentialproperties of mental and physical phe-no-un". Mental phenomena are said tohave as essential properties certain prop-erties (like privacy or introspectability)that are not possessed or, at any rate, arenot possessed essentlly by physical phe-,,o-"nr; alternatively, physical phenom-ena are said to have certain essetx til prop-erties (like spatial location or publicity)that are not essential properties of mentalphenomena., It is sometimes maintainedthat mental and physical phenomena havecontradictory essential properties (thatphysical events are essentially spatial, forinstance, while mental events are essen-tially nonspatial). In all these cases, anti-matrialist intuitions are understood asintuitions that the properties that are logi-cally possible (logically necessary, logical-ly impossible) for mental phenomena areifferent from those properties that aelogically possible (logically necessary,lolically impossible) for phvsical phe-nomena, and therefore that mental phe-nomena must not be physical. It might bemaintained, for example, that Pain cannotbe a physical phenomenon, since it is logi-cally possible for there to be pain without,nuit", b.tt logically impossible fo thereto be any physical phenomenon withoutmatter.

2. The Standard Materialist RebuttalAgainst the obiction that mentaland physical phenomena have differentessential properties, modern materialistshave typically replied along roughly thefollowing lines.Materialism affirms that each mentalstate (event, process) is identical to somephysical state (event, process); it affirmsdentity statements like "Pain : C-fiber-firings." Such identities are supposed to becontngent rcther than necessary identities;they are supposed to be like "lNater :H,O," which is a contingent identity state-ment reflecting an empirical discovery'From such a contingent identity state-

ment it does not follow that the identifiedexpressions have the same meaning' Wateris ldentical to H,O even though the terms"water" and "HrO" have different mean-ings. From the identity "Water : H,O," itdo-es follow, of course, that water and H'Ohave the same ProPerties. However, aproperty that is an essential property ofiui", ,nd", the descriPtion ' H,O" flikecontaining hydrogen) need not be an essen-tial property of w ater under the descripton"u:iter." Provided that the identity "Water: HrO" is only contingently true (that is,that "water" and "H,O" haYe differentmeanings), it is quite unremarkable thatwater and H.O should have different essen-tial proPerties (under these two differentdescriptions). This state of affairs guaran-tees that the identity "Water = flrO" can-not be necessarily true, but it does not Pre-clude its contingent truth.Similarly, if "Pain : C-fiber-firings" isa contingent identity statement, then it iscertainlt unremarkable that pain shouldhave some property (such as, for example'introspectability) essentially under the de-scription "pain" but only contingentlyunJer the description "C-fiber-firings"' It ispart of the meaning of "pain" that pains areintrospectable, but not Part of the meaningof "C-fiber-firings" that C-fiber-firings areintrospectable. But this no more precludesthe possibility that pain is identical to C-


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Part Two Introduction 69fiber-firings, than the fact that "water" and"H,O" differ in meaning precludes the pos-sibility that water is identical to HzO. Con-tingent identity statements entail that theidentified entities have the same properties,but (since essential properties are descrip-tion-dependent) they do not entail that theidentified entities have the same essentialproperties.2

Against the claim that mental andphysical phenomena have contradictoryessential properties. the typical materialistrebuttal involves insisting that a seeming-ly necessary statement is refutable, and istherefoe actually contingent. Thus, forexample, against the claim that mentalphenomena are necessarily nonspatial,whereas spatial location is essential tophysical phenomena, it is typically repliedthat we do not know a priori that men-tal phenomena lack definite spatial loca-tion and, consequently, that suitable ex-perimental results could establish thatthoughts, for instance, do have locationin space. Lack of spatial location is thusshown (so the argument goes) to be at besta contingent property of thoughts, andthe claim that thoughts have essentialproperties inconsistent with those ofphysical phenomena is thus refuted.

3, The Lockean Account ofEssential PropertiesThe rebuttals iust described dependcrucially on an account of essential prop-erties and logical necessity according towhich logical necessity is always verbalnecessity-that is, an account accordingto which necessarily true statements arejust those whose truth follows from themeanings of their constituent terms. Suchaccounts have two important featues.First, they entail that the essential proper-ties of an entity are relatiae to a descrp-tion, so that something may have a prop-erty essentially with respect to one de-scription and contingently with respect to

another. Second, they entail that neces-sity and apriority coincide and thus that astatement may be shown to be contingentby showing that it is refutable. lt is iustthese two consequences that are essentialto the cogency of the standard materialistrebuttal to Cartesian criticisms of mate-rialism.Such accounts of necessity have beenthe received empiricist accounts ever sinceLocke, and such accounts rest upon an ac-count of the meaning of natural kindterms that-in various versions-has beenthe standard empiricist account since itsintroduction by Locke.t According tothese empiricist accounts, the meaning ofa natural kind term, or of general terms ofany sort, is given by conventionallyadopted criteria for telling which thingsfall under the term. According to such anaccount, for example, a term like "gold,""bachelor," "HzO," "water," or "pain"would have s fs meaning a set consistingof one or more properties by which gold,bachelors, HzO, water, and pain are rec-ognized. These properties are essentialproperties of gold, bachelor, HrO, water,and pain iust because they are part of themeanings of "gold," "bachelor," "H,O,""watet," "pain." Which properties should \be grouped together to form the meaning Iof a general term is not a question of fact; iit is entirely a matter of linguistic choice \or decision that we associate one set of Jproperties with each other as the meaning Iof a general term. ". . . our distinct spe-cies are nothing but complex ideas withdistinct names attached to them"; ". . .Each abstract idea with a name to it makesa distinct species" (Locke, 190, book III,chap. vi, secs. 8, 38).Following Locke and Hume, the mo-tivation for these accounts of necessityand of general terms has been antimeta-physical: the essence of a natural kind issaid to consist of its "nominal essence,"the conventional meaning of the term that

It ,^ ta


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70 Richard Boyddescribes it, precisely to rule out of courtmetaphysical questions about the real es-sence of natural kinds. Thus, for example,Locke holds that the question whetherbats are birds is a purely verbal question(190, book III, chap. xi, sec. 7). Bats arebirds if and only if the criteria convention-ally adopted for applying the. term 'tird"apply to bats. According to such a view,it would have been literally nonsense for aseventeenth-century biologist, living in alinguistic community that considered batsto be among the paradigm ca.ses of birds,to claim to have discovered that bats real-ly were not birds, that they lacked the es-sential features shared by other birds. Hecould propose to change the meaning of"bid" to make it true that bats did not fall,unde that tem, but there is no such thingas a fundamental principle governing theapplication of a general term's being mis-taken: such principles are true by defini-tion and ae the basis for all necessarytruths about natural kinds.Such empiricist positions regardinggeneral terms and necessity, particularlyin their modern (and most plausible)forms, derive their plausibility from veri-ficationist considerations. Questions re-garding the real essence of natural kindsare held to lie beyond the range of possi-ble empirical investigation and thus to in-volve unscientific and pointless specula-tion. It is impossible, according to such aview, for us to know the real essence ofanything.

4. The Importance of Non-LockeanAccounts of Language and NecessitySuch accounts of necessity de dicto-of necessity as resting on meaning and lin-guistic conventions-have been acceptedby the great maiority of recent authors onthe mind-body problem. In particular,antimaterialists who find essentialist ob-jections to materialist theories of mindconvincing typically accept the analysis ofnecessity upon which the rebuttals citedrest, and attack those rebuttals on other

grounds. In many respects, however, aLockean account of necessity and of es-sential properties seems inadequate for afull understanding both of the issuesraised by the essentialist obiections and ofthe position of materialists themselves.Whatever their merit may ultimatelybe, the essentialist intuitions in questiondo not seem to be fairly captured by aLockean account of essential properties.The views that physical events are essen-tially spatial, or that FtO contains hydro-gen essentially, or that consciousness is anessential feature of the experience of pain,do not-at first glance anyway-seem tobe judgments about meanings or linguisticusage. The philosopher to whom it seems

obvious that-whatever the atomic com-ponents of water may be-these compo-nents are essential to water-seems, atleast at first glance, to hold a positionabout the substance of water itself, notabout water under some particular de-scription ("HrO"). Water iust rs HrO, nomatter how it is described; being FtO isis essence-so the intuition Eoes-notmerely the essence of the linguistic expres-sion "HO".If, as Kripke maintains, an accountof necessity that justifies these iudgmentsis available, then it will not merely betterreflect the intuitions of antimaterialists. Itwill, as well, effectively disarm the stan-dad materialist rebuttals to their essen-tialist objections. For, if the intuitions in-dicated above can be made coherent, wewould have an account o necessity de re(not de dicto): an account according towhich the essential properties of a thing

do not depend on a particular descriptionof it. Such an account of necessity wouldalso preclude the strategy of showing thata statement is not necessary by showingthat it represents an empirical claim that isrefutable. The claim that water containshydrogen is certainly a refutable empiricalclaim, but-on a de re accounf of neces-sity-it might be a necessary truth as well.It is clear, therefore, that if (as, of


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course, many philosophers doubt) a co-herent account of necessity d.e re can besuccessfully defended, such an accountwould provide the basis for a more faith-ful formulation of essentialist obiectionsto materialism than does a Lockean ac-count. What is equally true-but less ob-vious-is that a Lockean account of ne-cessity and of general terms poses difficul-ties for materialists as well as for theiropponents. This claim may seem strange.Afte all, materialists typically insist thatthe entire body of mateialist doctrinesconcerning mental phenomena (and otherphenomena as well) are contingent empir-ical truths. The materialist, it seems, neednot affirm that any of his doctrines arenecessary truths; his interest in necessityis solely in rebutting essentialist objectionsto materialism and for that purpose theLockean account of necessity is ideal.The difficulty that the Lockean ac-count poses arises not because materialistsmust defend their doctrines as necessarytruths (although, as we shall see, Kripkebelieves that they must), but rather be-cause the ,antimetaphysical philosophy oflanguage-and, in particular, the accountof natural kind terms-upon which theLockean account rests, itself poses diffi-culties to the defender of materialism.It is a cucial feature of empiricist ac-counts of language that questions regard-ing the classification of entities undergeneral terms are always questions re-garding ezisting linguistic conztentions.The question whethe a particular entityfalls under a general term is nothing morethan the question whether its propertiessatisfy the criteia conventionally asso-ciated with the term. What is zot possible,according to this account, is that someentity should lack the criterial propertiesassociated with a term by current conven-tion. but be properly classified under thatterm nevertheless. It might seem that sucha state of affairs is possible: the entitymight possess qualities really essential tothe kind referred to by the general term,

Part Two Introduction 7'lbut might lack the properties by which thekind is generally identified. But this possi-bility is just what the Lockean account ofgeneral termsprecludes. Only the nominalessence of the term is at issue in classifi-cation. We do not-because we cannot-classify things according to their own realessences or according to the real essencesof the species into which they fall.aIn a similar way, relations of contain-ment and identity between natural kindsturn out to be matters of curent conven-tion. The question whether two generaltems name the same property, substance,or state, is merely the question whetherthese two terms are conventionally asso-ciated with the same criterial properties(or, perhaps with sets of criterial proper-ties between which there is a relation ofmutual meaning-entailment). It is not pos-sible, according to a Lockean account, fortwo general terms with different nominalessences to refer to what is really the sameproperty, substance, or state. If generalterms referred to real essences, of course,such a situation could obtain, but sinceonly nominal essences are involved, "eachabstract idea with a name to it makes adistinct species" (I-ocke, 1690, book III,chap. vi. sec. 38).The upshot of all this is that a Locke-an account of necessity-and the accountof general terms upon which it rests-hasthe effect of enshrining the status quo inmatters of classification: it portrays themost basic standards that we employ inapplying general terms as fixed by linguis-tic convention and immune from refuta-tion. There is simply no such thing as dis-covering that ou fundamental standardsof classifications are wrong. We canchange standards, of course (by changingthe meanings of our terms). It can, per-haps, even be rational to do so-but therationality cannot be the rationality ofcorrecting a mistaken belief in the face ofnew evidence.5It will now be evident why a Lockeanaccount of general terms poses such an


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7Z Richard Boydacute challenge to materialism. A Lockeanaccount of meaning enshrines our mostfundamental principles of classification asdefinitional truths not amenable to evi-sion. Dualism-and the principles of clas-sification that traditional dualism sup-ports-are among the most entrenchedof our classificatory principles. Thus aLockean materialist runs the risk of hav-ing to hold (because of his philosophy oflanguage) that, for instance, the statementthat pains are physical states of the centralnervous system is not merely false but self-contradictory. Afte all, pains are amongthe paradigm cases of states that we nowclassify as nonphysical; if there are classi-ficatory conventions at all (and the Lock-ean acconnt insists that there are), thensurely it must be a truth by conventionthat pains are nonphysical.What is ruled out, it must be remem-bered, by a Lockean account of generalterms-and by the associated empiricistepistemolbgical outlook-is the view that,although we do not now classify pains asphysical, nevertheless pain poses the sameessential features as do paradigmaticallyphysical states, and we could eventuallydiscover that they are really physical. Ac-cording to a Lockean analysis, all there is-o could be-to being physical is havingthe properties conventionally taken to bemarks of the physical.The view that a Lockean account ofgeneral terms, together with certain com-monplace facts about curent usage, islogically incompatible with materialism isnot, of course, held by materialists whoaccept a basically Lockean account ofgeneral terms. It does not even appear tobe defended-in exactly the terms present-ed above-by any critic of materialism.Nevertheless, closely related objections tomaterialism do occur in the literature, and-what is even more imPortant to thecurrent issue-many materialists modifythei accounts of materialism to accom-modate them to a Lockean account of

general terms and, in doing so, substan-tially weaken their own Position.Thus, for example, as we have seen,many materialists (and many of their criics) hold that materialism is committed tothe truth of identity statements of theform 'M : P" where "M" is a generalterm of classification for mental states('M" might be "pain") and "P" is somegeneral description of a physical state,couched in obviously physical (or physio-logical) terms ('?" might be. for example,"The firing of C-fibers," to use a nowstandard imaginary example). (lt will berecalled that it is iust statements of thissort that play so prominent a role in theessentialist obiections I am considering.)

It is conceded by materialists-n factthey typically insist on it-that 'M" and'?" hee have different meanings, and areassociated with different criteria. Theidentity is supposed to be contingent, nota priori. But, according to a Lockean ac-count of general terms, this is iust the sortof identity statement that cnnot be ttue.Each distinct set of criteria-each distinct"meaning"-gives rise to a distinct spe-cies. lf "M" and "P" are general terms,different in meaning, then, it would ap-pear, the statement "M : P"is necessarilyfalse! Now, this potential criticism of ma-terialism is-in vaious guises-seriouslytreated in the literature. Many materialistauthors ae at pains to insist that contin-gent, non-a priori identity statements aresometimes true and known to be true."Water : HrO" is, indeed, the standardexample.Of course, the fact that it is possibleto be a materialist, a Lockean about gen-eral terms, and a believer that water iscontingently identical to HzO does notshow that it is possible to hold all theseviews consistently. The tension betweenthem is revealed in the writings of recentmaterialists not by the admission that theyare inconsistent, but rather by a specialsort of exegesis offered for contingent


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Part Two Introductionidentity statements like "lNater : H,O,""Pain : C-fiber firings." Such identities,"theoretical identities" they are sometimescalled, ae not, strictly speaking, the ordi-nary garden-variety identities-so thissort of account goes.6 llhen, fo theoreti-cal reasons, we identifu two terms whoseordinary rules of usage are so different, itis not strict identity we are talking about.For example, it does not follow from thetheoretical identification of pain with C-fiber firings and from the fact that somepains feel vaguely cold, that some C-fiberfirings feel vaguely cold.Although proponents of this view arenot always clear about the matter, theirtreatment of the "identity theses" reallyamounts to this: we do not ask, for exam-ple, "Are pains identical to C-fiber fir-ings?"" The answer to that question is"No," and the negative answe is dictatedby linguistic convention. We ask instead,"Would it be reasonable, in the light ofcurrent scientific discoveries, to changeour conventions so that we can say, 'P ain: the firing of C-fibers' without fear ofself-contradiction?" This is the real issueof "theoetical identification." It is reveal-ing that the verb for "to identify with" isso often employed in discussions of thisview. We are really seen as facing thequestion whether or not ?re should iden-tify pain with C-fiber firings. that is,whether or not we should adoPt a newlinguistic conoention, to identify the ex-pressions "pain" and "C-fiber firing." Theissue is one of linguistic choce'q ln tteat-ing the issue this way, modern materialistscontinue the Lockean tradition of treatingdisputes over classification as "purelyverbal" rathe than as factual. In positivistterminology, they treat the issue whetherpains are C-fiber firings as the issuewhether or not to adoPt the "meaningconvention" expressed by the axiom "Pain: C-fiber firing."Although the practice of treating on-tological issues as though they were issues

of free linguistic choice, thus reformulat-ing fhem as issues expressible in the "for-mal mode of speech;" has an honorablehistory,' the fact emains that such a glosson materialism fundamentally distorts itsclaims. For better or worse, the materialistclaims that mental states, events, and pro-cesses are really physical. He does notclaim merely that we could adopt the con-oention of saying that they are. He claimsthey are already, anyway! If he says thatpain is identical to C-fiber firings, hemeans it. He does not mean that couldientify the one tem with the other term-he does not even mean that it would berational -to adopt such a conzsention. Hecertainly does not mean that, even thoughit is analytically false that pains are C-fiberfirings, it would be convenient to changethe meanings of our terms to make it ttue.What he means-for better or worse-isthat pains simply are C-fiber firings. In hisview it could, of course. be rational and(probably) convenient to say "Pain : C-fiber firings." but the rationality involvedwould be the rationality of accepting animportant discovery in the light of newevidence. not the Pragmatic rationality ofadopting a simpler language. A "Lockean"gloss makes materialism into a mere shad-ow of its former self.Worse things yet haPPen. As we haveseen, one of those problems that face ma-terialists is that there seem to be propertiesthat physical states possess and mentalstates essentilly lack, or vice versa. Thusphysical states possess special locations,whereas mental states may seem to beessentially nonspatial. Similarly' somethoughts are dim, fading, or nagging,lowhereas it would seem that physical statesessentially lack these propefties. How isthe materialist to deal with these difficul-ties? The "standard rebuttal" discussed insection 2 replies that, for example, it is nota necessary truth that brain states lack theproperty naggingness and that this can beseen by realizing that suitable experimen-


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74 Richard Boydtal esults (presumably those which con-firm a materialist theory of mind) couldshow that some brain states 4r nagging,however queer that may now sound. Sim-ilarly, this rebuttal requires a defense ofthe claim that we could discover that, forinstance, thoughts are located in the head,however queer that may sound.As we have seen, such rebuttals de-pend for their cogency on a Lockean ac-count of necessity. They proceed to estab-lish that a statement is not necessary bydemonstrating that it is not a prioi. Whatseveral defenders of materialism have rec-ognized is that this rebuttal seems to runafoul of the very Lockean account of gen-eral terms on which it rests. If there is aproblem about attributing naggingness tobrain states or location to thoughts, thenthe problem arises because such attribu-tions are linguistically deviant enough tobe counted as violating current rules oflinguistic usage. If-as the Lockean ac-count requires-there ae linguistic con-ventions governing general terms like "haslocation" or "is nagging," then linguisticnormalcy and linguistic deviance must bereflections of just those conoentions. So,there is a philosophical problem aboutpredicating location of thoughts or nag-gingness of brain states if and only if suchpredications iolate conaentions of lan-guage, that is. if and only if the denials ofsuch predications are, after all, really apriori, and the standard rebuttal, there-fore, unsuccessful. The ebuttal woksonly if it is not needed.11As a substitute, many defenders ofmaterialism have made proposals thatemphasize their (perhaps unintentional)commitment to the view that the issue ofmaterialism is (at least substantially) aquestion of nguistic decson. Thus, forexample, Shaffe (191) suggests that itwould be reasonable to change our con-ventions so as to alloto predicating loca-tion of thoughts, and Feyerabend (193)urges that mateialists recognize that theyare committed to proposing such meaning

changes in order to avoid a "dualism offeatures."Where materialists ought to say thatsince mental events are physical events,they certainly do have locations in space,these philosophers are led by their Lock-ean conception of general terms to assertmerely that we c ould decide to change thelanguage to make materialism true. Butthis retreat to conventionalism is not byany means the most heroic mesure takenby defenders of materialism who findthemselves in this Lockean bind. Rorty(1965) concerns himself with the problemof predicating mental properties like nag-gingness of brain processes, which seemsunavoidable if one acknowledges thatsome thoughts are nagging and also insiststhat each thought is identical to a brainprocess. His solution is to treat the rele-vant identity statements, those of theform 'M : P" where 'M" is a mentaltem and '?" a physical term, as express-ing a "disappearance" form of the identitythesis. In this view, such expressions donot express ordinary identity, but ratherexpress identity between "to put it crudely-existent entities and non-existent enti-ties." The statement "My thought at r -brain state B" really says that there is nosuch thing as my thought at f but thatbain state B is what we should talk aboutinstead. Since there are no thoughts-andhence no nagging thoughts-the problemof predicating naggingness of brain statedoes not arise. And, similarly, for otherdifficult cases of mental-physical identity.Although ingenious, this cure may beworse than the disease. It places our mate-rialist in the unenviable position of deny-ing that there are thoughts, pains, feelingsof joy or anguish, and so forth. It placeshim in an essentially untenable position. Itmust be pointed out that not all material-ists whose philosophy of language is em-piricist advocate these particular posi-tions. Indeed, some do not even recognizethe difficulties that their account of lan-guage poses to their materialism. What is


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Part Two Introduction 75important is that it does pose such prob-lems and that the available solutions(within a Lockean framework) all weakenthe claims of materialists to the point thattheir doctrine is either untenable or notvery interesting.

We have, therefore, a very interestingsituation. Both sides in the dispute be-tween materialists and "essentialist" dual-ists seem to be misrepresented if theirpositions are explicated in terms of aLockean account of general terms. Thematerialists' position is trivialized and theessentialists' intuitions regarding neces-sity seem altogether misunderstood. It isfor this reason that Kripke's efforts to findan alternative account of reference andnecessity-and to apply it to the mind-body problem-is of such great impor-tance for philosophy of mind.

5. "Rigid Designators" andKripke's Account of NecessityKripke's discussion of materialism,with which we are primarily concerned inthis essay, takes only eight of the ninetypages that constitute his development of a

theory of necessity. Although it will benecessary here to provide a broad outlineof the main features of Kripke's theory, Iam not going to attempt to summarize allof the important aspects of its develop-ment, nor am I going to adopt a positionregarding its soundness. What I do intendto show is that, assuming Kripke's accountof necessity to be sound, his criticisms ofmaterialism are not successful. I shall alsoindicate why the sort of account of refer-ence that forms the foundation for his ac-count of necessity is cucial to the defenseof materialism. Although Kripke's ac-count of necessity touches the issue ofmaterialism prirnarily with respect to theissue of essential properties of naturalkinds, and that of the way in which natu-ral kind terms function in language, hisexposition of necessity begins with a treat-ment of proper names. Since his doctrines

are clearest with respect to this issue, Ishall begin there, too.Consider the question how propernames (of people, countries, towns, andso on) refer. In certain situations, whensomeone uses the word 'Moses." by hisuse of the name "Moses" he efers to theleader of the Israelite exodus. Other usesof the name "Moses" refer to other men,as when someone now says, "My neigh-bor, Moses, is on vacation in Vienna."Many people are, or have been, named"Moses." What is it, about, for instance, ause of the term "Moses" that does refer tothe Isaelite leader that makes it refer tohim and not to someone else, or no one atall?

One influential answer (defended invarious forms by both Gottlob Frege andBertrand Russell) is closely analogous to aLockean account of general terms. In thisview, proper names like "Moses" (or anyother proper name) are "disguised definitedescriptions"; when someone uses a prop-er name, he means by the name some de-scription or other that (if the utteance inquestion refers at all) holds of one andonly one person. Thus, for example, if Iuse the name "Quine" in saying "Quine'sattack on analyticity was crucial to thedevelopment of early postpositivist phi-losophy of science," my use of the term"Quine" refers to the philosopher at Har-vard of that name because I use the name"Quine" as shorthand for some definitedescription of him, for example, "the phi-losopher who teaches at Harvard andwho is the author of 'Two Dogmas of Em-piricism.' " My use of the name "Quine"refers to the Quine at Harvard iust be-cause the definite description in questionis true only of him. My success in commu-nicating to a listener, in this case, depends,somehow, on a recognition of the fact thatit is this (or roughly this) definite descrip-tion that I have in mind (rather than, per-haps, "the man who owns the bakery onSeventh Street and Feigl Avenue"). Theman who says "Quine makes good cream


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76 Richard BoydT

I

puffs," and refers to Quine the baker,does so because he uses "Quine" as short-hand for iust such an altemative definitedescription.In the case of most proper names, it isnot entirely clear just how-on this the-ory's account-the listeners come to un-derstand a definite description relevantlylike that intended by the speaker. In thecase of historical figures like Moses, how-ever, the solution is easier. On most "dis-guised definite description" accounts ofsuch names there is a general linguis-tic convention that associates the term"Moses" (at least when it is used in dis-cussing biblical history) with a definiteset, or, perhaps, a "cluster" of the mostimportant properties by which hitoriansrecognize him: male, Israelite leader, livedfor a while in Egypt, led the exodus, diedin Canaan, and so on. It is, according tothese views, a matter of linguistic conen-tion thal the name "Moses" (used in theright sort of contexts) refers if and only ifthere is one person who has all (or, insome versions, most) of these properties.If there is such a person, "Moses" efers tohim. The sirhilarity between this sort ofaccount and Lockean accounts of generalterms is obvious. Like the Lockean ac-count of general terms, this Russellianaccount of proper names has the conse-quence that necessity and apriority coin-cide with respect to certain statements in-volving proper names. Thus, Moses has aproperty essentially if and only if thatproperty is entailed by the properties thatmake up the "definition" of the name"Moses." It is logically possible that Mo-ses had brown hair (o that he had redhair) because his hair color is not men-tioned in the definition of "Moses," where-as it is necessaily true (and a priori) thatif there was a Moses he performed all (or,by some accounts, most) of the historicalacts attributed to him in the definition.Likewise, it is logically impossible, and apriori rfutable, that Moses should have

been, for instance, an officer in the Egyp-tian army who opposed the exodus.Aside from any other difficulties thatit may face, such an account of propernames has some provocative consequencesregarding the essential properties of peo-ple. It is not surprising that Moses is notessentially brown-haired. What may seemcounterintuitive is that it is both true andknown a priori that there could be no pos-sible world in which Moses sought andreceived a commission in the Egyptianarmy, became an opponent of the exodus,and died in Thebes. We have strong intui-tions that such a state of affairs is logicallypossible, and that empiiical evidenceforms the only basis for our acceptance ofthe account that we actually believe.Against the Russellian account o{proper names-and in defense of thes,central intuitions-Kripke offers an alter-native "causal" theory of reference forproper names. On the Russellian view, aproper name is associated with exactly thesame "cluster" of defining properties inevery possible world (and refers to theiunique bearer, if there is one). On Kripke'sview, a proper name should be seen as re-ferring to exactly the same ndi,sidual inevery possible world in which it refers atall, whateve properties the individualmay have in that world. In his view, myemployment of the name "Moses" refersto Moses not because I am participating ina linguistic convention that associateswith the term "Moses" some definite de-scription, but ather because my employ-ment of that name bears the right sort ofcausal connection to the historical eventssurrounding the giving of the name "Mo-ses" (or whatever name it is from whichthe name "Moses" derives) to the manMoses. When I use the name "Moses" I, ineffect, "point" back in .time toward therelevant first employments of the name,and I refer to whatever was named "Mo-ses" in these initial "dubbing" uses of thename. In this respect-according to Krip-


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Part Two Introduction 77ke's account-my referring to Moses bythe term "Moses" is more like ostensivereference-reference by pointing, for ex-ample-than it is like referring via a defi-nite description. Similarly, when I use thename "Moses" to refer instead to Mosesthe literature teacher down the hall, I referto him rather than to the historical figurenot because I use his name as a disguiseddefinite description but because my use ofthe name "Moses" bears the appropriate,causal relation to, for example, the eventssurrounding his parents' naming him"Moses," and my use of the name does notbear the right causal relation to the "dub-bing" of the Israelite Moses. Certain socialand linguistic conventions are involved inour use of nmes, no doubt. But, Kripkemaintains, whateve conventionality isinvolved in naming, it does not result instatements about people that are true bydefinition.It might seem that, according to thisaccount, Moses, for instance, would haveno nontrivial essential properties (that is,no essential properties except those thatare dictated by principles of formal logiclike being eiiher living or nonliving). In-deed, such a view is compatible with theaccount of reference for roper names iustpresented. Kripke maintains, however,the plausible view that a person's parentsare essential to him: that a man who, insome possible world, had different par-ents from those Moses had in the actualworld, would not be Moses, whateveother properties he had. Although his ac-count of prope names does not entail it,it does make possible such an account ofdescription-independent (de re) essentialproperties of persons.Here we can also see how Kripke'saccount of reference and necessity makesnecessity and apriority distinct. Supposethat Moses' parents were Phiiip and Sa-mantha. Then it would be a necessarytruth (it would be true in all possibleworlds in which Moses exists) that Moses'

parents were Philip and Samantha; andthis sort of necessity obtains in the case ofevery person and his/her parents. But, ofcourse, we do not know a priori whosomeone's parents are; it is not part of themeaning of the name "Moses" that Moses'parents were Philip and Samantha. Thus,"Moses' parents were Philip and Saman-tha," if tue, is an a posteriori (indeed, arefutable) necessary truth.Thus Kripke's account of referenceand riecessity (which I have examined sofar only with respect to clear-cut cases ofproper names) provides for the existenceof a posteriori necessary truths. At least inthe case of proper names, it shows how anecessary truth might be unknown to us(as when we do not know who the parentsof a histoical figure were) and even con-trary to our most fundanental convic-tions (as when we arc uery sure we havecorrectly identified the parents of a histor-ical figure, but we are wrong). An illustra-tive example of the sort of a posteriorinecessary truth that plays a role in Krip-ke's evitalized essentialist obiections tophysicalism is provided by the identitystatement "Cicero : Tully." Suppose thatthere is a man who was called "Ciceo"and also called "Tully"-that each of theseproper names was "given" to him. SuP-pose I say "Cicero is identical to Tully,"and that the causal antecedents of myusages of the names "Cicero" and "Tully"are such that each of them refers to thisman. Then in any possible world the ref-erent of the terms "Cicero" and "Tully" isthat oery man, and the statement "Cicero: Tully" is, therefore, a necessary truth:it is tue in every possible world in whichits constituent terms refer.For our purposes, the interest of Krip-ke's work aises from the extension of hisaccount of poPer names to certain othereferring expressions. Kripke introducesthe expression "rigid designator" for thoseterms that, like proper names, refer to thesame thing in every possible world in


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78 Richard Boydwhich they refe at all. Kripke suggeststhat various natural kind terms and termsfor natural phenomena are also rigid des-ignators, for instance, "gold," "water,""heat," "hydrogen," "pain," and so forth.Kripke denies the standard Lockean ac-count according to which the reference ofthese terms is fixed by citerial attributesor defining characteristics that are "partof the meaning" of these terms. Thus, forexample, a Lockean might offer an analy-sis of the term "heat" according to whichthe property by which "heat" is defined isthe capacity to make us feel warm . "Heat"might be said to mean "that natural phe-nomenon that is present in all things thatmake us feel warm and that causes themto make us feel warm" or something ofthis sot. According to a view of this sort,the statement "Heat makes (most) peoplefeel warm" would be both a priori and(therefore) necessary.In Kripke's view, however, there isno difficulty in accepting the claim thatthere is a possible world in which, for in-stance, no animals ever developed a sensi-tivity to heat and in which heat producesno sensation at all in any person. Heatneed not possess the analytic definition"that which warms us," nor any other n-alytic definition at all. As is the case withprope names, there may well have beensome particular sensible characteristics bywhich people recognized heat when theyfirst started calling it "heat"-just as theremay have been some particular descrip-tion by which Moses' parents eferred tohim when they named him "Moses," butthese are not defining citeria for "heat"established by linguistic convention. Heatmight come to Iack these characteristics.or-in some possible world-might neverhave had them.Of equal importance (from our pointof view), the fact that "heat" possesses noanalytic definition makes certain funda-mental beliefs of ours about heat-whicha Lockean might believe to be true by con-vention-refutable in principle. Thus, for

example, there would be no logical impos-sibility to our discovering that there werekinds of heat that, although quite intense,produced no sensation in us at all. It willbe appreciated that this sort of treatmentof natural kind terms represents lust thesort of non-Lockean view of these termsrequired by the materialist who wishes tosay, without self-contradiction, that cer-tain of our most basic principles of classi-fication associated with the terms "men-tal" and "physical" are (and will be shownto be) fundamentally mistaken.l'zIf rigid designators are just thoseterms that have the very same referent inevery possible world in which they referat all, then, it must be noticed, some rigiddesignators may be definite descriptions.Suppose (as is plausible) that "hydrogen"and "oxygen" are igid designators. Con-sider the expression "HrO." It is reason-able to hold that "HrO" means "the com-pound whose molecules consist of twohydrogen atoms and one oxygen atom."Thus it is a definite description. But, sincethe terms "hydrogen" and "oxygen" areboth rigid designators, the description"the compound whose molecules consistof two hydrogen atoms and one oxygenatom" refers to exactly the same com-pound in every possible world in which itrefes at all. Thus. by this analysis of itsmening, "HzO" is a rigid designator.6. Rigid Designators and SurprisinglyNecessary Identities

"Cicero : Tully," it will be recalled,is necessary if true, and this is the case forall identities of the same form involvingproper names. Evidently the same is trueof all identities in which the identity signis flanked by rigid designators.This consequence of Kripke's theoryhas, itself, some surprising consequences.As we have seen, philosophers who de-fend materialist theories of mind, and arelooking for noncontroversial examples ofidentity statements between natual kinds,often cite the identity "Water : F{rO" as


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Part Two Introductionan especially clear example. Of course,"Water : FtO" is not an a priori truth,so, if apriority and necessity coincide (asempiricists claim), it is not necessary ei-ther. But according to Kripke's account,if, in the actual ztsorld, water really is iden-tical to HrO, then this identity is neces-sary: it holds in every possible world inwhich water (or F{zO) exists. Water, if it isHzO, is HO essentially. Similarly, everychemical compound, whatever atomicconstitution it has, has that constitutionessentially, even if its constitution is notmerely not known a priori, but not knownat all. Likewise. if heat is identical to mo-lecular vibrational kinetic energy (anotherstandard example of an a posteriori, "con-tingent" identity), then heat is essentiallymolecular vibrational kinetic energy. Allof these examples-if Kripke's account issound-are cases in which a substance ornatural phenomenon has an essentialproperty independently of any linguisticconvention or choice of description.Furthermore, all of these are cases ofa posteriori, refutble necessary truths;they provide concrete illustrations of thefact that Kiipke's account of necessity-because it does not rest on a Lockeanaccount of language-divorces apriorityfrom necessity. In particular, they showhow Kripke's account of necessity blocksany attempt to show that a statement isnot necessary that proceeds by showingthat it is refutable.These features of Kripke's account-it will be recognized-make it (at leastapparently) more suitable than the Locke-an account for the defense of the essential-ist arguments against materialism that Ihave been considering. Kripke's accounttreats essential properties of things as de-scription-independent (thereby blockingone feature of standard materialist rebut-tal) and allows for a posteriori but neces-sary truths (thus blocking the other). Itaccods with the intuition that a substanceitself may have its constituents as essentialfeatues-because without just those con-

stituents it would not exist-even thoughthe features are not specified in some ana-lytic definition of a term referring to thesubstance. Thus, just as Kripke's sketch ofa non-Lockean account of reference isparticularly well suited to a faithful exege-sis of materialist theories of mind, the cor-responding account of necessity seemsparticularly well suited to a faithful exege-sis of essentialist criticisms of those theo-ries.

7. Essentialist Criticisms RevisitedIt remains to be seen what the forceof essentialist criticisms of materialism is,if they are undestood according to Krip-ke's non-Lockean account of necessity andare, therefore, invulnerable to the stan-dard materialist ebuttals. In order to seewhat the force of such criticisms is, let usfirst consider the case of a less controver-sial "theoretical" identity: "Water is HzO."Imagine a defender of this water/hy-drogen oxide "identity thesis," who de-scribes his position according to the stan-dard analysis offered by materialists. Hemaintains that, although "water" and"H,O" differ in meaning, the identity"Water : HzO" is nevertheless an empiri-cal discovery and an example of a urelycontingent identity statement. On KriP-ke's account of necessity, our "identitytheorist" has already adopted an unten-able position. "Wate" and "HrO" arerigid designators. Therefore the identity"Water : HO," if it is tue at all, must bea necessary truth.lt cannot be contingent-ly true. Thus the "identity theorist" mustretract the claim that his identity thesis iscontingent. He must live with-and, moreimportant, he must defend-the claimthat water is essentially HrO, if he is toclaim that water ls HzO at all.This consequence of the identitY"Water : HrO" has, itself, additionalconsequences with which the "identitytheorist" must live. The expression "HrO"is not iust a rigid designator. It is alsowhat might be called a composition-speci-


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80 Richard Boydfying term (this terminology is not Krip-ke's). Whatever is HzO must-in any pos-.sible world-be made of hydrogen andoxygen. If "Water : HrO" is tue in theactual world-and hence in all possiblewolds-it then follows that having theparticula molecular composition speci-fied by "HrO" is an essentil feature ofwater. The identity theorist must. there-fore, defend this claim. He must, for ex-ample, be prepared to deny the seeminglyplausible claim that there is a possibleworld in which water does not have amolecular structure at all, because matterin that wold is continuous and does nothave a discrete microstructure. Similarly,the defender of the "theoretical" identity"Heat : molecular vibational kineticenergy" must hold that there is no possibleworld in which heat is not, for instance,dependent on molecular motions. A pos-sible world in which matter has no molec-ula microstructure is so facto a worldin which there is no heat!It should be emphasized that defend-ing these claims is by no means the hope-less task that it would be if one adopted aLockean account of necessity. Pai of thepoint of Kripke's account is that necessarytruths need not be a priori. Thus the de-fende of these "identity theses" does notface the hopeless task of trying, for exam-ple, to show that being made of moleculesis "part of the meaning" of the word "wa-ter." The identity theorist does, however,face an important essentialist challenge: intaking the identity statements "Water :FtO" and "Heat : molecular vibrationalkinetic energy" to be contingent, ratherthan necessary, our "identity theorist"was not merely following current fashion.We (or, at any rate, many of those whoconsider such issues) have strong intui-tions that, for example, water is only con-tingently identical to HrO or that therecould be heat in a possible world in whichheat lacks a molecular microstructure.The identity theorist must provide us with

sufficiently good reasons for rejectingthese strong philosophical intuitions.The same challenge, of course. facesthe materialist regarding his account ofmental phenomena. If, for example, heclaims that some identity statement like"Pain : C-fiber firings" is true, then hemust claim that it is necessarily true. Since"C-fiber firings" is a composition-specify-ing term that names a kind of physicalphenomenon, he must defend, for exam-ple, the claim that thee could be no painsin any possible wold in which thee is nomatter (indeed, thee could only be painin possible worlds in which matter is orga-nized into C-fibers that fire). Similarly, hemust defend the claim that it is impossiblefor there to be a world in which some C-fibers fire without a pain's being felt. Inthese cases, the identity theorist's claimsrun afoul of very strong philosophical in-tuitions indeed. As we shall see, Kripke'sview is that-while the defenders of "Wa-ter : FtO" and "Heat : molecular vi-brational kinetic energy'' can overcomethese difficulties-mind-brain identitytheorists cannot.

8. The Standard Materialist Rebuttal(New Version)Each of the "identity theses," "Wate: HrO," "Heat : molecula vibrationalkinetic energy," "Pain : C-fiber firings,"faces, at the outset, the same essentialistchallenges: each asserts the identity of en-tities that appear to have different essen-tial properties. The standard mateialistrebuttals, which we examined earlier, de-pend on a Lockean account of necessity:on the doctrine that the essential proper-ties of a thing are description-dependent,and on the doctine that refutable state-ments cannot be necessarily true.If Kripke's account of necessity andessential properties is correct, these rebut-tals are ruled out. The identity theoristmust hold that the identities in questionrepresent a posterioli necessary tuths and


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Part Two Introduction 81that the identified entities do have (de-scription-independently) the same essen-tial properties. It remains then for theidentity theorist to undermine philosophi-cal criticisms of these views-to explainaway the tendency to hold, for example,that water is only contingently HrO orthat heat might, in some possible world,be a nonmolecular fluid.In order to show how this may bedone, Kripke introduces what we maythink of as the standard strategy for ex-plaining away the apparent contingencyof necessary a posteriori statements. Thestrategy involves finding a genuinely con-tingent statement that corresponds in theright way to the apparently contingentnecessary statement, and attributing theapparent contingency of the second to therecognition of the actual contingency ofthe first. An example will make the strat-egy clear.In the case of the apparently contin-gent (but necessary) identity statement"Water : HrO," the corresponding con-tingent statement might be "The cooling,tasteless, odorless, wetting liquid thatquenches thirst : HrO." This statement lscontingent, since there could be a possibleworld in which some ther liquid thanwater satisfies the definite description onthe left of the identity sign. The contin-gency of this statement, furthermore, canbe adduced to explain the apparent con-tingency of "Water : HrO." The definitedescription "the cooling, tasteless . . ." istrue of water in the actual world, and ischosen so that it describes water in termsof the properties by which it is usuallyrecognized. If a Lockean account of termslike "water" were true, this definite de-scription would be a candidate for thedefinition of "water," and would refer towater in every possible world. The intui-tion that "Water : HrO" is contingent isexplained as resulting from th correctjudgment that the corresponding contin-gent sentence is contingent, together with

the mistaken belief that the definite de-scription in it is the definition of "water"and refers to water in every possibleworld.In general, in the case where the ap-parently contingent but necessary state-ment is an identity statement involvingrigid designators, "R1 : Rz," this strategyrequires that one find referring expres-sions 'D," and "Dr" such that, in the ac-tual world, "Dr" and "D2" aie coreferen-tial with 'Rr" and "R2," b where at leastone of "D1" and "Dr" is a nonrigid desig-nator that describes the properties that, inthe actual wold, are appopriate to thedetection of the refeent of the corre-sponding rigid designator. "D, : Di' willbe contingent and its contingency will (to-gether with a mistaken tockean accountof the rigid designators 'R"' and "Rr") ex-plain the apparent contingency of '?' :Rr." In the case of apparently contingentnecessary statements that are not identi-ties, the strategy is similar. The defenderof the identity statement "Heat : molecu-lar vibrational kinetic energy" must main-tain that it is a necessary truth that if thereis heat, there are molecules present. Theintuition that this is a merely contingentstatement can be explained by adducingthe corresponding genuinely contingentstatement "lf there is a natural phenom-enon whose presence makes us feel warm,then there are molecules present." Asbefore, the contingency of this statement,coupled with the mistaken belief that"the natural phenomenon whose presencemakes us feel warm" is the definition ofthe tem "heat" explain the apparent con-tingency of the necessary truth in ques-tion. In all of these cases, the apparentcontingency of an a posteriori necessarystatement is explained by finding a corre-sponding genuinely contingent statementin which one or more rigid designators arereplaced by qualitative descriptions of thesort a Lockean would offe as analyses of


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82 Richard Boydthe meaning of the rigid designators inquestion. What Kripke suggests is thatthis standard rebuttal does not work inthe case of the necessary-if-true state-ments to which a materialist theory ofmind is committed.

9. Kripke's Argument againstMaterialismAccording to the strategy of the stan-dard materialist rebuttal (new version),the apparent contingency of a necessarya posteriori statement "5" is explained byfinding a corresponding genuinely contin-gent statement "5*" in which (at least typ-ically) one or more rigid designators oc-curring in '5" are replaced by definite de-scriptions in terms of sensible properties.In every possible world these descriptionsrefer (if they refer at all) to some thing orproperty that has in that world the samesensible properties that the rigidly desig-nated thing or property has in the actualworld. In any possible world we would bein an "appropriate qualitatively identicalevidential situation" with respect to theeferents of these descriptions, as we arein the actual world with respect to the ref-eents of the rigid designators. Kripke'sclaim that the standard strategy fails forstatements that follow from a materialistaccount of mental phenomena rests on the(very plausible) claim that certain mentalstates have as essential properties the waythey feel. In any possible world, some-thing that feels like a pain is a pain, andno pain fails to feel painful. If. in someworld W, someone beas to an entity ea relation qualitatively identical to the e-lation we bear, in the actual world, to apain, then e is a pain in W.Consider, now, the mateialist whodefends a type-type version of the identitythesis. He holds, let us say. that each men-tal state is identical to a physical state offhe central nervous system. In particular,he holds that pain is identical to a physicalstate of the cental nevous system. Let usassume that the state of the cental ner-

vous system in question is the firing ofthe mythical "C-fibers." Our materialist,then, defends the identity "Pain : C-fiberfiring." If he is a typical materialist (andhas not read Kripke) he will explain thatthis is a contingent identity statement. Hewill agree with the Cartesian intuition thatit is logically possible that there might beC-fiber firings but no felt pain, and that itis logically possible that someone mightexperience a pain even though there areno C-fibers (and no other material objects,for that rnatter). These logical possibilitieswould be excluded-he will maintain-if"Pain : C-fiber firings" were a necessaryidentity; but it is a posteriori and hencecontingent.Of course, this position is one thatKripke's account of necessity (if it issound, as we assume here) rules out."Pain" and "C-fiber firings" are rigid des-ignators of natual kinds and, therefore,"Pain : C-fiber firings" is necessary iftrue. The "essentialist" challenge to thematerialist is to explain its aparent con-tingency. What he must explain, for ex-ample, are the intuitions that there is apossible world in which there are painsbut no C-fiber firings and that there is apossible world in which thee are C-fiberfirings but no one feels any painful sensa-tion.This is iust what Kripke says cannotbe done. In the case of the identity "Water: HrO," the corresponding problem is toexplain the intuitions (a) that there is apossible world in which there is water butno H'O, and (b) that there is a possibleworld in which there is HO but no water.The problem is soluble. To solve it, all weneed to establish is that there are possibleworlds & and W, such that (a) in Wr,thee is a liquid that is not FLO but thathas all the qualitative properties waterpossesses in the actual world and (b) inW, HO exists but fails to have the quali-tative properties by which we detect waterin the actual world. But, of course, it isquite reasonable to insist that such possi-


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Part Two Introduction 83ble worlds as Wt an,W, exist while main-taining that "Water : FlzO" is true inevery possible world.In the case of the identity "Pain : C-fiber firings," we might expect analogousmaneuvers to provide us with explana-tions for the intuitions (a) that there is apossible world in which there are painsbut no C-fiber firings and (b) that there isa possible world in which there are C-fiberfirings but no pains. By analogy to thecase of "Water : HrO," we might expectto explain these intuitions by finding pos-sible worlds WT and Wi such that (a) inW there are entities that have the sensibleproperties that pains have in the actualworld but they are not C-fiber firings. and(b) in Wi there are C-fiber firings but theydo not have the sensible properties thatpains have in the actual wold.This is the sort of explanation of theapparent contingency of "Pain : C-fiberfirings" that Kripke claims is impossible.If such possible worlds as Wi and Wi ex-ist, then the natural phenomena in Withat, in Wi, have the sensible propertiesthat pains have in the actual world, arenot C-fiber fiiings, and, therefore, are notpains. The C-fiber firings in Wi that, inWl. do not feel like pain, nevertheless arepains. But this is absurd. The sensiblequalities of pains are essential to painsand definitive of them. In any possibleworld, anything that feels like a pain is apain, and, thus, there is no such possibleworld as Wi. Similarly, in any possibleworld a natural phenomenon that is apain must feel the way pains feel in theactual world, and thus there is no suchpossible world as Wi.On the basis of these considerations,Kripke concludes that the standard mate-rialist rebuttal (new version), althoughadequate to the defense of identities like"lNater : FIu O," must fail for those iden-tities like "Pain : C-fiber firings" that areadvanced by philosophers who defend amaterialist theory of mental phenomena'Unless an entirely new sort of rebuttal can

be devised, which Kripke doubts, we mustreiect identities like "Pain : C-fiber fir-ings" and the mind-brain "identity thesis"in general.Some "identity theorists" deny that amaterialist account of mntal phenomenaentails "type" identities like "Pain : C-fiber firings." They hold that all an iden-tity theorist must maintain are "token"identities, which identify each particularoccurrence of a mental state, event, orprocess with some specific physical state,event, or process. In such a view, a mate-rialist account of mental phenomenawould entail the existence of true identitystatements of the form "Jones;s having apain at T where the righrhandexpression describes some quite specificphysiological or molecular configuration.The defender of such token identity state-ments, Kripke observes, faces exactly thesame sort of essentialist challenges as thedefender of "type" identities. In either ofthese cases, if Kripke is right, the material-ist cannot defend the required identitytheses against essentialist criticisms, andmaterialism seems to be unwokable as anaccount of the nature of those mental phe-nomena that, like pains, seem entirely de-fined by their sensible properties.

10. Reply to Kripke, I:The New Standard Rebuttal Does WorkAs we shall see, the greatest weaknessof Kripke's criticisms lies in the fact that-protests of its defenders notwithstanding-a materialist account of mental phe-nomena does not entail the sort of identitystatements to which Kripke's algumentapplies. I shall develop this theme in sec-tion 11.What is striking is that Kripke's argu-ments have an additional defect: he hasunderestimated the potential of the (new)standard materialist rebuttal to essential-ist criticisms. Recall that, given a neces-sary but apparently contingent identitystatement "Rr : Rz," where 'R"' and 'Rz"are rigid designators. the new standard re-


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84 Richard Boydbuttal requires forming a contingent iden-tity statement "D' : Dr," where at leastone of "Dr" and "D2" is a description ofthe referent of 'Rt" and 'Rz" in terms ofthe symptoms typically associated withthe replaced rigid designator.

The gist of Kripke's argument is thatthis strategy will fail if we attempt to ex-plain the contingency of a statement of theform "Pain : Rr" by finding a contingentstatement of the form 'D, : Rz," becauseif "D," is an expression that designatespain in terms of just the sensible qualitiesthat pains have in the actual world, then"Dr" designates pain in every possibleworld. '2" is itself a rigid designator. Ifwe agree with Kripke (as I have for thesake of this discussion) that the sensiblequalities that pains have in the actualwold are essential to pain and definitiveof it, then this must be right.What seems to have been overlookedis that the successful employment of thisstrategy does not require that it be the less"technical" or "scientific" term in the iden-tity that is replaced by a nonrigid desig-nator. As we have seen earlier, we can ex-plain the dpparent contingency of "Water: HrO" by insisting on the existence of apossible world in which the correspondingcontingent sentence "The cooling, taste-less. . . liquid. . . : HrO" is false. Thisemployment of the new standard strategyrelies on the fact that the sensible proper-ties by which we typically recognize waterare not essential properties of water. Butneither are the standard chemical testsappropriate to the term "FLO" logicallydefinitive of water. It is certainly logicallypossible that there should be a world inwhich a liquid that is not HzO satisfies allthe chemical tests that-in the actualwoId-are reliable indicators of HrO.Thus we could equally well have explainedthe apparent contingency of 'lVater :HrO" by appealing to the contingency ofthe corresponding qualitative statement"Water : the liquid that * * *," where'"***" describes the standard chemical

tests appropriate (in the actual world) tothe detection of HrO.Thus the employment of a corre-sponding contingent qualitative statementto explain away the apparent contingencyof "Pain : C-fiber firings" does not de-pend on the existence of a possible worldin which pain does not feel like (actualworld) pain or in which some nonpainfeels like an actual world pain: it does notdepend on a purely phenomenal descrip-tion of pain not being a rigid designator.All that is required is that eifftr the ex-pression'ain" or the description "C-fiberfirings" can be replaced by an appropriatepurely qualitative description that doesnot designate rigidly.

Of course, this can be done. For anyphysiological or anatomical descriptionlike the imaginary "C-fiber firings" thereis certainly a possible world in whichsomething has the qualitative propertiestypically associated with the tem in theactualwold, but really is not, in this case,an instance of "C-fiber firings." Someother sot of nerve cell might, in a differ-ent possible world, look iust the way C-fibers do in the actual wold, or theremight be specious indications that C-fibersare firing when they are really dormant.Thus we must conclude that, contrary toKripke's suggestions, the new standardmaterialist rebuttal does permit one to ex-plain the apparent contingency of mind-body identity statements like "Pain : C-fiber firings," and also to expiain the ap-parent contingenry of token-token iden-tity statements like "His pain at f : suchand such molecular event."It is evident that the same strategyallows the explanation of the apparentpossibility of worlds in which there arepains but no C-fibers, or in which C-fibersfire but no pain is felt. The apparent possi-bility of a world in which there are painsbut no matter at all can be explained bythe real possibility of a world in the fol-lowing sentence is true: "There are painsbut thee is nothing that ***," where


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Pat Two Introduction 85" + + +" describes all the ways in whichmatter makes itself evident to the senses.A possible world in which this sentence istue would not (if pain is identical to C-fiber firings) be a world without matter,but it would be a world in which the sensesfunctioned in such a way that nothingproduced the symptoms that we typicallytake to indicate the presence of matter.It would appear, then, that the (new)standard rebuttal to essentialism providesthe materialist with a more powerful de-fense than Kripke recognizes. The materi-alist who insists that he is committed tothe truth of identity statements like "Pain: C-fiber firings" or 'Jones's pain at f :such and such molecula configuration"can successfully employ the strategy ofthe (new) standard rebuttal against essen-tialist citicisms of his doctrine. What iseven more striking is that mateialists aremistaken in believing that they are com-mitted to the existence of true identitystatements of either of these forms.

11. Reply to Kripke, II:Materialism without ReductionismThe mterialist asserts that all natural

phenomena, all events, processes, objects,and so foth, are in fact physical: all ob-iects are composed solely of matte and allevents and processes consist solely in in-teractions between material things. Men-tal events, states, and pocesses, in partic-ular, differ from uncontroversially physi-cal events, states, and processes only inthe particular arrangements or configura-tions of matter and material forces thatrealize them. Pains are quite differentfrom, for instance, earthquakes; but thedifference is configurational, not constitu-tional. They are made of the same sorts ofstuff. The strategy of essentialist objec-tions to this claim is to insist that if true infact, materialism must be true necessarily,and then to attempt a refutation of thislatter claim.The position that mateialism must,if tue, be necessarily true, rests on the

conviction that materialists are committedto the identity thesis, that is, to the truthof mind-body identity statements like"Pain : C-fiber firings," which involverigid designators. As we have seen, the(new) standard materialist rebuttal is ef-fective in defending these "identity theses"against essentialist criticisms. It is not.however, necessary to invoke this rebut-tal. Materialism, properly understood,does not entail the sort of mind-bodyidentity statements against which the es-sentialist criticisms are diected. Indeed,as we shall see, materialism poses no difficulties for most of our intuitions regard-ing possible relations between mentalphenomena and physical phenomena. Inparticular, a materialist account of mentalphenomena is quite compatible with theview that there are possible worlds inwhich mental phenomena exist but arenonphysical.This conclusion, if sound, is signifi-cant for two reasons. First, the intuitionsabout necessity and possibility that under-lie the essentialist criticisms of materialismare very strong ones, and the new stan-dard materialist rebuttal does not estab-lish that these intuitions are unfounded. Itmerely offers a possible explanation forthem. The case for materialism is greatlystrengthened if it can be shown that mate-rialism does not even entail the sort ofmind-body identity statements againstwhich these criticisms are directed.Second, the claim that materialismdoes not entail the existence of true mind-body identity statements contradicts thestandard empiricist analyses of material-ism. According to such analyses, materi-alism asserts the syntactic reducibility ofthe vocabulary and laws of all the sciencesto.the vocabulary and laws of physics. Inparticular, a mateialist account of mentalphenomena, according to such analyses,entails the definability of all mental andpsychological states (or, on some ac-counts, all token mental and psychologi-cal states) in the vocabulary of physics.


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86 Richard BoydBut definitions of the sort required bysuch an analysis are iust the sorts of iden-tity statements linking mental and physi-cal states that I claim materialism does nofentail. Indeed, I shall show that the ver-sion of materialist psychology best sup-ported by available evidence entails thatmental and psychological states are t?otdefinable in physical terms.The eductionist analysis of material-ism shares with the empiricist account ofnatural kind terms discussed earlier thesame veificationist and antimetaphysicalmotivation: it epresents an attempt to"rationally econstruct" a metaphysicalquestion as a formal question about lan-guage. If, as I am arguing here, each ofthese empiricist interPretations results in amisleading account of the philosophicalconsequences and evidential status of ma-terialist psychology. then we have evengreater evidence for the claim made earlierthat the nonverificationist treatment ofnatural kind terms of the sort proposed byKripke is essential to a sound understand-ing of the issue of materialism, and. pre-sumably, of other scientific issues as well.A vaiiety of different considerationsdictate the conclusions outlined above. Ishall conside them in stages.Mind-Body ldentity, Mind-Body ldenttyStatements, and the Apparent Necessityof Materi alist D octrines

Part of the motivation for attemptsto formulate materialist psychology as an"identity thesis," aside from the empiricistreductionistic analyses, has been the de-sire to distinguish materialism from "epi-phenomenalism," the view that mentalstates ae not physical, but are universallycorrelated with distinct physical stateswhose causal powers explain the effectsnormally attributed to the correspondingmental states. Materialists, quite rightly,have been careful to insist that each men-tal state is identical to, not merely corre-lated with, some physical state.This "identity thesis" does not, how-

ever, entail the existence of true mind-body identity statements of the sort Krip-ke considers, nor does it entail that mate-rialism must be necessarily true if it is trueat all. To see the distinction between thesetwo sorts of "identity theses," conside thecase of water. "Water contains hydrogen"and "Water is rare in the Gobi Desert" areboth true statements, and they entail, re-spectively, the "identity theses" "Water isidentical to a substance that contains hy-drogen" and "Water is identical to a sub-stance rare in the Gobi Desert."Yet (assuming as I do here that Krip-ke's account of necessity is correct), watercontains hydrogen essentially, but wateris only contingently rare in the Gobi Des-ert. It is relatively easy to see why this isso. In the first place, neither of the "iden-tity theses" just discussed has the form ofidentity statements that link rigid desig-nators; neither is, as it stands, the sort ofidentity claim which must be necessary iftrue. Instead, each has the form "(Er) (wa-te : and P)" where "P" is ". ' . is asubstance containing hydrogen" or ". . . isa substance that is rare in the Gobi Des-e*." lEditor's tro; In this anthology, theordinary "E' is used instead of the back-ward "8" as the existential quantifier. ]In the first of these cases, we can con-clude that water contains hydrogen neces-sarily only because we can find a rigiddesignator 'R" such that (i) the identitystatement "lVater : R" is true in the ac-tual world, and hence in all possibleworlds, and (ii)'R" is such that anythingit designates must (in any possible world)contain hydrogen. The rigid designator"HrO" is such an 'R. " The corresPondingsituation does not obtain in the secondcase. Water is identical to a substance(water itself) that is, in the actual world,rare in the Gobi Desert, but (since beingrare in the Gobi Desert is not an essentialproperty of water), there is no rigid desig-nator "R" such that (i) the identity state-ment "Water : R" is true in the actualworld, and hence in all possible worlds,


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Pat Two Introduction 87and (ii) "R" is such that anything it desig-nates must (in any possible world) be rarein the Gobi Desert.We are able to show that water con-tains hydrogen essentially not iust becausewater is identical to a substance that con-tains hydrogen, but because we are ableto find another rigid designator for water(besides "water") that is formulated in aparticular vocabulary (in this case, thevocabulary of chemical formulae) andthat is such that whatever it names mustcontain hydrogen in every possible world.As we have seen, however, it is not al-ways the case that when a statement ofthe form " (Ex) (x is Rr and Px)" is true,where "R1" is a rigid designator, there is asecond rigid designator "&" such that (i)'R, : Rr" is true and (ii) 'Rz" is such thatwhatever it names must have fl in everypossible world.The point is that the essentialist argu-ment that purports to show that if mentalphenomena (such as pains) are physicalthen they must be necessarily physical de-pends for its cogency on a quite specifickind of analysis of materialism. It dependson an analysis of materialism according towhich, for example, the claim that pain isa physical process entails that there is arigid designator 'Rz" that is such that (i)"Pain : Rr" is true and (ii) 'Rr" is suchthat whatever it designates, in any possi-ble world, must be a physical process.As we have iust seen, in the case ofessential and contingent properties ofwater, the doctrine that pains are physicalprocesses trivially entails that pains areidentical to physical process, but this, byitself, provides no guarantee that (i) and(ii) are satisfied. It is thus perfectly consis-tent to affirm the "identity thesis" thatpain is identical to a physical process andto deny the existence of a rigid designator'1,," satisfying (i) and (ii). The philoso-pher who understands materialism to en-tail the stronger sort of "identity theses"represented by (i) and (ii) must maintainthat the required rigid designators satisfy-

ing (i) and (ii) always exist. It is this claimthat I deny.Plasticty : Co mp os itionaland Confgur ational

Let us turn now to the main issue:whether the doctrine that mental phenom-ena are physical phenomena entails theexistence of true mind-body identity state-ments linking rigd designators, that is.whether it entails the truth of statementslike "Pain : C-fiber firings." I shall con-centrate fist on the issue of whether amaterialist account of mental phenomenaentails the existence of true type-typeidentity statementi of this kind-that is,whether materialism entails that eachrnental type event, state, or process is de-finable (by a rigidly designating expres-sion) in a physical vocabulary. I shall turnto the issue of token-token identity state-ments after considering the type-typecase.My strategy is this: I shall introduce anotion of "plasticity" for type events,states, or processes, and I shall argue thatthe version of materialism best supportedby available evidence entails that mentalstates admit sufficient plasticity in theway in which they are realized that it islogically possible for mental states to benonphysically realized, even though inthe actual world all mental phenomenaare physically realized. By plasticity of atype of event, state, or process I under-stand its capacity to be realized in morethan one way; the plasticity of a type ofevent, state, or process is indicated by thedegree of variability in the particular(token) events,.states, or processes thatcould ealize it. Thus, for example, the(type) process of starting a car displaysmore plasticity than the (type) process ofstarting a !949 Ford, because the possibletoken processes that could realize the firsttype process display greater variation (inbrand of the constituent car, for example)than do the possible processes that couldrealize the latter.


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88 Richard BoydAt least roughly, we may distinguishtwo dimensions of plasticity (there maybe more, but these are particularly rele-vant to the issue at hand), compositionalplasticity and configurational plasticity.Compositional plasticity is displayed by a

type of state, event. or process to the ex-tent that there are possible realizationsof that state, event, or process that differin the sorts of substances or causal fac-tors that constitute them. Configurationalplasticity, in contrast, is displayed by atype of state, event, or process to the ex-tent that its possible token realizationsdiffer in the structural configuration oraffangement of their constituent parts,events, substances, or causal factors.Thus, for example, the smelting ofiron displays considerable configurationalplasticity, since there ae realizations ofiron smelting involving quite differentkinds and geometrical arrangements ofequipment and different temporal se-quences of constituent processes. Ironsmelting is importantly limited, however,in its compositional plasticity: all instancesof iron smelting must involve a quantityof iron. By contrast, the state of being an

inscription of the English sentence "Heri-tability is a populatin-relative statistic"displays very substantial compositionalplasticity: such an inscription can be writ-ten in ink on paper, carved on wood, castin bronze, chiseled into marble, pressedinto plastic, and so on. Yet the state ofbeing an inscripiion of this important En-glish sentence displays quite limited con-figurational plasticity: any two inscrip-tions of this sentence will have fundamen-tally similar structures; indeed, except formisspelled inscriptions, they will be iso-morphic at the level of constituent letters.An important class of states seems topossess unlimited compositional plastic-ity, but relatively limited configurationalplasticity. "Computational states," suchas being a realization of a computation ofex for input r : 9, or (what is a differentcomputational state) being a realization of

a computation of ex for inPut r : 9 ac-cording to machine-language program P(for some definite P), or (still different)being a realization of a computation of erfor input : 9 according to a machine-language program that is a member ofsome definite set 5 of machine-languageprograms, all seem to possess maximalcompositional plasticity: in any particularpossible world, only the causal laws gov-erning that world limit the possible com'position of realizations of such computa-tional states; such states have no essentialproperties that constain the sorts of sub-stances or causal factors that can be con-stituents of their realizations.What I shall argue here-followingthose philosophers and psychologists whohave defended the view that mental andpsychological states are "functional" statesof organisms-is that mental events,states, and processes are like computa-tional states in being entirely configura-tional, that is, in possessing maximalcompositional plasticity. It will followthat-even though mental states may al-ways be physically ealized in the actualworld-there is no logical impossibility oftheir being nonphysically realized in someother possible world. Befoe turning to adefense of this claim, I must clarify somedetails of the notion of. plasticity that arecucial to a correct assessment of the plas-ticity of mental states.What is cucial to this discussion isthe way in which plasticity is assessed inthe case of events, states, or processes thatare essentially relational. The problemcan be illustrated by reconsidering theissue of the plasticity of computationalstates, like the state of being a calculationof I according to machine-language pro-gram P, for the input x : 9. I have saidthat this is a purely configurational state,and that the only properties essential to its(token) realizations are those configura-tional properties that are dictated by theprogram P. In a perfectly clea sense thisis true: in any possible world W, a com-


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Part Two Introduction 89puter capable of embodying program P,and acting on input 9 can be made ofwhatever arrangement of causal factorsare capable-given the causal laws gov-erning W-of realizing the required con-figuration of machine states and the re-quired transitions between them.At the same time, more is required inorder for a computational state of the sortin question to be actually realized than theexistence of a machine of the right sort,operating on the right sort of input. andfunctioning normally. It is perfectly pos-sible for there to be one computer C1,which is in the state of computing er ac-cording to machine language program P,for input : 9, and for there to be an-other computer G, which goes throughexctly the s4rne succession of physicalstates (and, therefore, exactly the samesequence of configurational internal states)such that Cz is not in the state of comput-ing er according to machine language Pfor input : 9. This state of affairs ispossible because the same computer pro-gram can be used to compute quite differ-ent mathematial functions depending onthe interpretation given to the language inwhich its inputs and outputs are repre-sented.The state of being a computation ofet according to machine-language pro-gram P for input r : t has essentially arelational component. It is realized in apossible world W if and only if there is inW some arrangement of causal factorsthat realizes the program P and the input9 and that ls suitably related to users of itsprogramming language whose conven-tions for its use are such that, with respectto them, the program P should be inter-preted as computing er. This sort of rela-tion to user(s) is an essential property ofthe computational state in question.The existence of states, events, andprocesses that are essentially relational inthis way forces one to refine the notion ofplasticity. When one assesses the plastic-ity of a type of state, event, or process,

one assesses the variability in the sorts ofparticular (token) states, events, or pro-cesses that can realize it. The outcome ofthis assessment will, in the case of essen-tially relational states, depend on whetherone adopts a narrow or boad construalof what might be termed the "scope" ofthe particular states, events, or processeswhose variability is to be assessed."By a narrow-scope construal I under-stand one according to which a particularrealization of a type of state, event, orprocess is understood to consist of thosenatural phenomena that actually go to-gether to constitute the occurrence of thestate, event, or process, at the time, andin the place, whee it occurs, even if thereare other phenomena such that if they hadnot occurred the particular state, event,or process would not have had whateverrelational properties are essentia to thetype of state, event, or process in question.By a broad-scope construal, I understandone according to which a realization of atype of state, event, or process consists ofthe occurrence of those phenomena thatconstitute it according to the narrow-scope construal, together with all thoseoccurrences by virtue of which the partic-ular state, event, or process has the rela-tional properties essential to the type ofstate, event, o process in question.What is important to my purposeshere is that plasticity can be assessed withespect to either construal, and that theresults may differ according to the con-stual chosen. Thus, for example, thecomputational state I have been discuss-ing might seem to have more configura-tional plasticity on the broad-scope con-strual than on the narrow. On the narrow-scope construal all realizations are iso-morphic (actually, since a computation ofa real-valued function may be nontermi-nating, what is really true is that any twoequally long computations are isomorphicon the narow-scope construal), whereason the broad-scope construal there maybe significant structural variety among


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90 Richard Boydrealizations, since there may be structur-ally quite different social processes thatesult in the adoption of the same inter-pretation for a programming language.More important for mY PurPoses, thechoice of broad- or narrow-scope con-strual will often affect assessments ofcompositional plasticity.It is uncontroversial in that there aresome mental states that are essentially re-lational in a way that precludes their beingpurely configurational when their scope isconstr

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