1. Introduction

Bertrand Russell opens his

Problems of Philosophy bydescribing his table in the idioms of the folk and thephysicist. The folk ascribe causal oomph to the table,or at least to states or events in which it figures: itsreflection of light causes us to see it; its solidity andsturdiness cause it to support the china; pushing on itcauses it to move. Science seems to brand the table anidler, telling us that the table’s microphysical con-stituents (and the fields and forces that guide them) actas the table’s stunt-doubles and bear full responsibilityfor all its apparent causal exploits. Russell uses theapparently conflicting pictures embraced by the vulgarand the learned to motivate the distinction betweenappearance and reality and thereby to raise two ques-tions: do we have reason to believe in the existence ofthe table, and if so, what is its nature?

If we take the physicist’s view, as articulated byRussell, at face value, we embrace a version of reduc-tionism according to which the causal potency of tables– and, by extension, of other ordinary macroscopicobjects – is illusory. The word ‘reductionism’ covers amultitude of Sinns. My usage, according to which itconnotes the eliminability of the table’s causal powers,is a central and familiar one.

Reductionism alone does not answer Russell’s twomain questions. Couple reductionism, however, with aplausible thesis about knowledge – that our knowledgeof tables depends on our causal interaction with them –and it answers the first: we can have no knowledge oftables.

What of the second question? Reductionism’s verdicton the nature of the table seems to be simply thattables, if they exist, are causally impotent. Couplingreductionism with Alexander’s dictum – “to be real isto have causal powers” – yields an even more strikingconclusion: tables (and other ordinary macroscopica)

do not exist. Even if Alexander’s dictum admits excep-tions, restricting it to ordinary (putative) macroscopicmaterial objects yields a thesis whose unquestionableobscurity does not detract from its overwhelming plau-sibility. For while “causal power” needs explication,it nonetheless seems obvious that no real table couldbe incapable both of being a cause or effect, and ofparticipating non-trivially in things that are causes oreffects. Hence it seems clear that reductionism entailseliminativism.

I will argue that the “causal argument for reduc-tionism” is epistemically self-defeating; hence the “epis-temic reductio” of my title, which sacrifices accuracyto brevity. Sacrificing brevity to accuracy would yield“An epistemic reductio ad absurdum of a causalargument for causal reductionism about ordinary com-posite physical objects.” The reductio I promise doesnot show that reductionism per se yields an absurd con-sequence, though denying the existence of macroscopicaseems absurd enough on its face. What I argue insteadis that anyone who accepts the conclusion of the causalargument for reductionism can have no epistemic justi-fication for accepting all of its premises. This is so, Iwill argue, even if Alexander’s dictum is false andreductionism does not entail eliminativism. So if thereis a compelling argument for reductionism, the causalargument is not it.

2. The causal argument for reductionism

We think naively that tables and books interact causally.Physicists say that tables (or putative tables) decomposeultimately into elementary particles. For now I maketwo simplifying assumptions: first, that all the elemen-tary particles are of the same “natural kind” – let us say,for simplicity’s sake, that they are all quarks; andsecond, that these elementary particles are physical

An Epistemic Reductioof Causal Reductionism1 Eugene Mills

Topoi 22: 151–161, 2003. 2003 Kluwer Academic Publishers. Printed in the Netherlands.

simples, not themselves composed of smaller particles.(I will loosen these restrictions later.)2 Beyond theserequirements – and as I will later argue, within themas well – nothing hinges on the exact nature of theparticles. The advance or decline of physics will notaffect my argument.

I believe the physicists. Now, suppose we couldexhaustively catalogue the causal relations that holdamong the quarks apparently composing the putativetable and the other putative macroscopic objects withwhich it interacts. Such a catalogue would presumablyinclude no mention of tables (or books or other macro-scopica). It seems, then, that no causal work wouldremain to the table: once we have casually explainedthe behavior of all the quarks composing the table, wehave causally explained the behavior of the (putative)table. So the table is either redundant or impotent. Eitherit causally overdetermines effects that already have suf-ficient quarky causes, or it causes nothing at all; if itsapparent effects are not overdetermined by indepen-dently sufficient quarky causes, then they are uncausedand hence no effects at all. Overdetermination seemspreposterous, so our verdict must be tabular causalimpotence – that is, reductionism. Given our assump-tion of a restricted version of Alexander’s dictum,tabular eliminativism follows. So, at any rate, theargument goes.3

The argument as I have just stated it jumps too hastilyfrom abstinence to impotence. Causal impotence is amodal notion, and it does not follow from the absenceof actual causal commerce. Even if causal abstinencedoesn’t rule out the table’s existence, however, it doesseem plausibly to rule out our knowledge of it, and thisruling is unnerving enough. Furthermore, while causalpotency seems essential to tables in a way that causalcommerce may not, it still seems overwhelmingly plau-sible that if there were tables, they would be causes oreffects (or components thereof).4 If we give reduction-ists this plausible thesis, together with their otherpremises, then we give them tabular eliminativism, andfrom this it follows trivially that tables have no causalpower. (On this way of arguing, eliminativism supportsreductionism rather than the reverse.) So I will not pressthe distinction between abstinence and impotence forpresent purposes.

The causal argument for reductionism just sketchedpresents two targets to opponents: the thesis that quarkycauses account for all the effects in view, and the rejec-tion of overdetermination as preposterous. Both have

rightly been questioned. I aim here not to show eitherof them mistaken but rather to show that we have goodreason for thinking that at least one of them must befalse if reductionism is true. My argument is not thequasi-Moorean one that the reductionist conclusion isless plausible than the denial of the conjunction ofreductionist premises, though I think this is true.5 It israther that if you accept reductionism, you cannot ratio-nally accept either premise without rejecting the other.Hence the causal argument for reductionism is epis-temically self-undermining.

3. The epistemic reductio

In this section I present my chief objection to the causalargument for reductionism. In the next section I willconsider some responses and refinements.

One premise of the causal argument as I have pre-sented it is that everything that we naively think of ascausing or being caused by tables is in fact caused byquarks acting in various ways. To justifiedly accept thispremise, we must justifiedly believe that quarks exist.What justifies us in believing this? For most of us non-physicists, it crucially involves the word of physicists.As with all such appeals to authority, though, ourassent rests on the assumption that the physicists havegood evidence and good arguments to back up theirclaims. The evidence and arguments may be beyond mymathematical or physical ken, but I know their broadshape. Quarks are “theoretical entities.” What makes anentity theoretical is its epistemic rather than its onto-logical status. (Deny this, and you deny reductionism.)Ultimately, perhaps via many layers of interveningtheory – and for us laypeople, layers of expert testimony– justified belief in entities like quarks must reston empirical observation and experimental evidencethat support a physical theory in which quarks areembedded.

I do not say that it must rest on this alone, but it mustappeal to it. The ‘must’ here concerns what is “humanlypossible.” Perhaps we could believe justifiedly in theexistence of quarks by having their existence directlyrevealed to us by God or by having sensory modalitiesradically different from our actual ones. Such possibil-ities exceed my concern here. I take it that causalreductionists would admit defeat if it turned out thatwe could not know the premises of their argument onordinary scientific grounds, given our actual faculties

152 EUGENE MILLS

and evidence, and it is such grounds that I will arguethe causal reductionist cannot have.

The standard picture of empirical confirmation,whose terminology we may as well adopt even if webalk at the theory of confirmation standardly associ-ated with it, puts it in terms of theoretical and obser-vational sentences. If Q is a sentence asserting theexistence of quarks, there will be observational sen-tences O1, O2, . . . , on whose truth our belief in quarkssinks or swims via conditionals like ‘if Q then O1’, ‘ifQ then O2’, ‘if not-Q then O3’, and so on. Among theseobservational sentences will be those that bear on com-peting theories, whose explanatory adequacy we judgeagainst that of the quark-theory. If suitable observationalsentences – involving both Q and its theoretical com-petitors – turn out to have the wrong truth-values, wegive up on Q. If they have the right ones, we warm toit.

Here arises the familiar flurry of worries that con-stitute the standard Introduction to the Philosophy ofScience. Q alone will not entail any observational sen-tences; it needs auxiliary hypotheses, rejection of whichcan be used ad nauseum in defense of Q if the obser-vational sentences prove false, without thereby violatinglogic. (Violating reason is another matter.) Affirmingthe consequent is a fallacy, a point that may seemrelevant where the observational sentences prove trueand there is no principled, informative characterizationof those general conditionals whose instances offer con-firmation. Observational sentences are hard to define,theory-laden, and context-relative. Rules for assessingthe relative explanatory adequacy of competing explana-tory theories are at best soft and slow rather than hardand fast. All true: science is more of an art than ascience.

Don’t let these worries distract you. They do nothingto challenge the claim that our belief in quarks mustrest on empirical observation – specifically, on obser-vations concerning implications of the existence ofquarks. Giving an adequate philosophical theory of goodscientific practice is a difficult and perhaps impossibleenterprise, but its difficulties should not interfere withthe simple recognition of such practice in particularcases.

Now, the observations (observational sentences, ifyou like) that undergird our belief in quarks involveordinary macroscopic objects – perhaps not the tablesin the physics lab, but the things that rest on them.“Pointers on dials, tracks in cloud chambers,” started

the old litany; digital instrument displays are less quaintbut no different in principle. Our belief in quarks restson inference to the best explanation (IBE), where theexplananda concern macroscopica. Once again, distin-guish hard philosophical problems about the properunderstanding and justification of IBE from the rela-tively uncontroversial assumption that IBE accounts forour understanding of quarks, if anything does.

Suppose that philosophical worries move you toreject IBE.6 Then you will go instrumentalist aboutquarks and other theoretical entities, interpreting talk ofthem as “as if ” talk about macroscopica, wherein realcausal potency lies. Hence you will reject the causalargument for reductionism. That argument appeals onlyto realists about quarks. If you are such a realist, I chal-lenge you to defend your belief in quarks withoutrecourse to IBE.

Now, since you haven’t met that challenge, considera claim to the effect that if quarks exist (here), thenpointer P will move to 0.01 on a certain scale.7 (Stifleyour amusement at my antique illustration.) Imaginethat in the particular context of scientific discovery, thisclaim concerns a “crucial experiment”: if the pointerreads what the quark-theory says it should, this willcount heavily for quarks, and a different reading willcount heavily against them. Imagine, then, that in the(under-described) case we are imagining, we will justi-fiably believe in quarks if and only if we justifiablybelieve that P moves to 0.01. Its showing this readingis ultimately explained by various facts about quarks,and this explanation cannot plausibly be understood asother than causal. Hence our belief in quarks dependson a belief that quarks interact causally with (macro-scopic) pointers. Thus our justification for it cannot besquared with the idea that macroscopic pointers arecausally inert.

Reductionists have it in for more than tables. Thepointers, dials, and LEDs in the physicist’s lab are justas causally impotent, if they are right. But this meansthat they cannot justifiably recognize that belief inquarks is supported by observation of the pointer’sreading so-and-so. For this support hinges on theassumption that quarks provide a causal explanationof the pointer’s behavior, while reductionists do notrecognize the pointer’s causal interaction with anything.

The point generalizes. Given the nature of nature, wecannot justifiedly believe in quarks except on the basisthat quark-theory meets some causal standard of fit(which may, again, involve a very attenuated connec-

AN EPISTEMIC REDUCTIO OF CAUSAL REDUCTIONISM 153

tion) with the behavior of macroscopic objects of thevery sort that reductionists would reduce. Lackingcausal potency for such objects, we lack any justifyingbasis for believing in quarks. Hence the reductionistcannot coherently counsel the acceptance of quarkswhile denying the causal potency of pointers, dials, andour beloved tables.

We arrived at quarks historically by way of atoms,and they provide a concrete, simple illustration of mypoint. Einstein’s famous (1905) paper on Brownianmotion clinched the case for atoms. Robert Brownnoticed pollen grains suspended in water caromingabout, apparently at random and without visible cause.Any fine particle may exhibit such “Brownian motion.”Einstein was the first to show that molecular collisionsoffer an elegant and accurate explanation.8 Einstein’spaper led physicists en masse to embrace the atomictheory, effectively settling what had been a matter ofcontroversy.

Brown’s grains are themselves microscopic, but fromthe point of view of reductionism they should fare nobetter than tables. For they are still unfathomably largein comparison with the atoms composing them, andreductionists would argue that all of their apparentcausality devolves onto that of their constituents. Unlessatoms figure causally in explaining the motion ofBrownian particles, however, Einstein’s explanation iswrong and the acceptance of atomic theory wrong-headed.

The causation is not all one-way. We look to theeffects of atomic events, but we also test the atomictheory by manipulating atoms. We do this indirectly,by manipulating macroscopic objects. Of course, as thereductionist will insist, our manipulation of allegedmacroscopica is the manipulation of atoms. Fair enough.Remember, though, that we focus here not on thetruth of atomic theory but on our epistemic basis foraccepting it. That basis requires that we see atomsexplaining macroscopic phenomena. One way suchexplanation works is by interposing atomic eventsbetween distinct macroscopic ones: macroscopic eventM1 causes various atomic events that in turn causemacroscopic event M2. With atomic theory, we have asatisfying explanation of the sequence from M1 to M2;without it, we don’t. I will focus for simplicity’s sakemainly on macroscopic effects of microscopic causes,which allow briefer description, but it is worth empha-sizing that my arguments would work just as well inthe reverse direction. It is not that macroscopica are

caused-but-uncausing epiphenomena. If my argumentsucceeds, it shows that justified belief in quarks requiresjustified belief in causal give and take between macro-and microscopica.

Once we accept atomic theory, we confront a genuinequestion about the causal role of macroscopica. For wemay well grant that for any macroscopic events therewill be corresponding microscopic – atomic or, ulti-mately, quarky – ones. Either the macroscopic eventshave causes and effects over and above purely quarkyones, or they overdetermine and are overdetermined bypurely quarky events; perhaps both. Which of theseoptions we should accept is a separate issue. We must,however, accept at least one of them, or – at the veryleast – accept that one of them is correct, even if wearen’t in a position to say which. We must, in otherwords, deny that both premises of the causal argumentfor reductionism are true. Accept causal reductionism,and you deny yourself the causal argument for it.

I revisit briefly the connection between causal reduc-tionism, eliminativism, and Alexander’s dictum. Acceptthe dictum, and causal reductionism entails elimina-tivism. Perhaps the causal reductionist could hang on totables by accepting their causal inertness and rejectingthe dictum. Leaving aside the intuitive implausibility ofthis move, it is not open to the causal reductionist. Forthe force of my argument is not merely that our knowl-edge of quarks depends on our knowledge of the exis-tence of tables, but rather that our knowledge of quarksdepends on our knowledge of the causal behavior oftables. So whether or not you accept Alexander’sdictum, you cannot coherently argue for the causal inert-ness of tables by appeal to the causal vitality of quarks.

4. Objections and refinements

A. Some might accuse me of ironically failing torecognize a reductio ad absurdum. We should under-stand the point about our knowledge of quarks, goes theobjection, as showing that the attribution of causalpotency to macroscopic objects leads to quarks andthrough them to the falsity of our initial attribution. Itis no objection to reducing the causal potency of tablesthat we start by supposing its existence, so long as weyield the supposition in the face of derived absurdity.

This objection misses the point. Causal reduction-ists deny the causal potency of tables because they thinkthat quarks exist and do all the work of tables. If we

154 EUGENE MILLS

take my argument as a reductio, we must take it asundermining our reasons for believing in quarks andhence for accepting reductionism. Reductionists of otherstripes – those who would reduce the external world orour knowledge of it to nothing or next to nothing, orthose who would try to preserve the table’s causalpowers while somehow “reducing” them to the causalpowers of quarks without thereby accepting overdeter-mination, or those who would reduce “quarks” to tablesand their ilk – could perhaps accept the causal argumentas a sound reductio. Causal reductionists, however,cannot accept the argument this way.

B. Our belief in quarks need not rest on the sort of beliefI have claimed – say, a belief to the effect that “thepointer moves to 0.01 on the scale.” Talk of pointers isfalse if construed literally (the objector claims), but itis useful because it allows another, figurative construal.Talk of pointers should be understood sympatheticallyas a kind of shorthand for describing quarks. My beliefneed only be to the effect that quarks “arranged pointer-wise” move to 0.01 on the scale – or, strictly speaking,that quarks arranged pointer-wise are arranged moving-to-0.01-on-the-scale-wise. (After all, scales and theirmarkings will have to go if reductionism is true.) Butthis could well be true.9

Perhaps it could, but its truth is not (yet) at issue.Belief in it, which is at issue, cannot form an epistemicbasis for believing in quarks, for such belief presup-poses belief in the existence of quarks. IBE justifiesbelief in explanatory entities by using those entities toexplain data that do not themselves presuppose the exis-tence of those entities. To build the allegedly explana-tory entities in question into the explananda destroyswhatever epistemic force IBE may have.

To revert to the atomic case, suppose Einstein hadargued merely for the conditional claim that if atomsexist, then atomic theory offers an elegant explanationfor why atoms in certain arrangements (“atoms arrangedgrain-wise”) move as they do. (Let’s suppose, as seemsreasonable, that reductionists of the time would haveplumped for atoms as fundamental, though contempo-rary quarkian reductionists would write off atoms asno better than tables.) Would this have been a goodreason for accepting atomic theory? Not unless we hadantecedent good reason to believe that there are atomsarranged grain-wise. If this how we are to interpretEinstein’s accomplishment, we cheapen it. On this ren-dering, Einstein’s explanation could not have clinched

the case for atoms, for if that case were not alreadyclinched, then Einstein’s explanation could not havegot off the ground. This is absurd. This objection, too,fails.

Let me forestall a possible misunderstanding. I amnot complaining here about any fallacy of affirming theconsequent. Don’t confuse the reductionist conditionalwith conditionals of the sort we actually invoke in con-firming atomic theory. We say, “If the atomic theory istrue, then Brownian particles will display such-and-suchbehavior.” Then we note that Brownian particles dodisplay this behavior. We take this affirmation of theconsequent as providing confirmation to the antecedent,without thereby committing the fallacy of affirming theconsequent.

If you think that the reductionist conditional shouldbe treated the same way, then you must think thatthings go as follows. We say, “If the atomic theory istrue, then atoms-arranged-Brownian-particle-wise willdisplay such-and-such behavior.” Then we note thatatoms-arranged-Brownian-particle-wise do display thisbehavior, and we can take this as confirmation of theatomic theory without thereby committing the fallacyof affirming the consequent.

The problem with this picture is not a fallacy ofaffirming the consequent but the practical impossibilityof justifiably believing the consequent in advance ofalready justifiably believing the antecedent. Given thisimpossibility, the reductionist picture of confirmationjust suggested cannot allow for our justified belief inatoms.

C. My focus on quarks and pointers may seem toconjure straws arranged man-wise, and in more than oneway. I will consider two such ways.

Reductionists are not wedded to quarks. If it turnsout that what we think of as a quark is really (as wewould non-reductively put it) a compound of smallerparticles – “quirks,” perhaps – arranged quarkwise, thenreductionists will be happy to dispense with quarks infavor of quirks. It is up to science to tell us what hasirreducible causal power. Reductionism does not sink orswim with current physical theory, so my claim thateliminativists are committed to quarks is mistaken. Sogoes the objection.

So far as it goes, the objection is correct. However,it doesn’t go far enough. Causal reductionism is notCartesian skepticism. The triviality that whatever hasfundamental causal power exists yields no knowledge

AN EPISTEMIC REDUCTIO OF CAUSAL REDUCTIONISM 155

of – or justified belief in – the external world, since itis compatible with the view that nothing has such power.To employ a causal argument for reductionism about thephysical world, we must allow that there are things ofsome physical type, F, such that we can justifiablybelieve that there are Fs, where the existence of Fs iscontingent. Of course, Fs need not be quarks: they couldbe Democritean atoms or quirks or who knows what.There is nothing special about quarks from the point ofview of reductionism, but by the same token nothing isgained by abandoning them. For they must be aban-doned in favor either of something in particular or ofnothing in particular. Neither way helps to salvagereductionism.

If we abandon quarks for something in particular(such as quirks), my argument for self-defeat runs: justmake the appropriate substitutions of ‘i’ for ‘a’. Evenif we characterize the “something in particular” with theapparently non-committal ‘microscopic entities’,10 myargument still works. For we have no justification forthinking that there are microscopica at all except insofaras we are justified in taking them to explain the behaviorof macroscopica.

If we abandon quarks for nothing in particular – forunspecified simples – we abandon causal reductionism.For then our conditional becomes ‘if unspecifiedsimples exist, then unspecified simples will be arrangedmoving-to-0.01-on-the-scale-wise’. But the truth of thisconditional and its consequent is entirely compatibleeven given reductionist scruples with the existence of amacroscopic, causally potent pointer. For such a pointermight itself be a simple. Absent some particular theo-retical account of its decomposition – into quarks orsomething like them – there is no basis in this condi-tional for reducing the causality of the pointer.

So far, then, there is no reason to think we will loseanything of importance by continuing to portray reduc-tionists as committed to quarks as the basic elementsof reality. So, for now, I shall do so. The complaint wehave been considering is unfounded.

D. I have stressed that reductionists want knowledgethat there are quarks (or whatever), not just knowledgethat there are otherwise unspecified objects arrangedtable-wise, pointer-wise, and otherwise. In consideringthe conditionals on which our belief in quarks rests,however, it may seem that we can avoid all my previousobjections at a stroke by invoking quarks in theantecedent and unspecified objects in the consequent.

That is, where ordinary idiom would say that our beliefrests on a claim to the effect that

O1 If quarks exist, then the pointer will move to 0.01on the scale,

reductionists would say that it rests on a claim to theeffect that

O2 If quarks exist, then simples arranged pointer-wisewill be arranged moving-to-0.01-on-the-scale-wise.

But the consequent of this conditional, unlike thatof our original, can be true compatibly with thereductionist’s claims and justifiably believed, it seems,without presupposing the existence of quarks.

The appearance misleads. I grant that one could inprinciple believe O2’s consequent without believing inquarks. I deny that a reductionist can consistently usebelief in O2’s consequent to justify belief in quarks viaO2, and for two independent reasons.

1. The first reason concerns the inevitable reductionistattitude towards the “simples” invoked in the conse-quent of O2. Begin by considering one way in whichthis consequent could be true. Although reductionistsinsist that macroscopica like pointers lack causalpotency, this is because the empirical facts support theview that such objects are not themselves simples andhave no causal powers independent of those of theirsimple constituents. If they were simples, then pointerscould well have causal potency. So to give full scopeto the reductionist view, we should understand ‘simplesarranged pointer-wise’ as applying, albeit degenerately,to simple pointers if such there be.

Suppose the pointer in our crucial experiment issimple. I take it for granted that there is no principledreason for thinking it unique in this respect. It wouldbe utterly ad hoc, not to mention utterly fantastic, tomaintain that the only macroscopica with causal potencyjust happen to be those mentioned in the consequentsof our theory-testing conditionals. So if our pointer issimple, so are other, relevantly similar, ordinary macro-scopica. But then what are quarks supposed ultimatelyto compose, if not those objects? Obviously, if ourpointer is simple, neither it, nor any of the array ofquotidian macroscopica, is composed of quarks. Butquarks are invoked precisely as the causally potent con-stituents of all such objects. We can know in advancethat if our pointer and its kin are simple, then there are

156 EUGENE MILLS

no quarks. Thus we can henceforth ignore our degen-erate allowance that ‘simples arranged pointer-wise’covers simple pointers, though I will briefly refer to thisallowance below.11

Now suppose we are causal reductionists in theposition of determining via crucial experiment whetherquarks exist. Our theory that gives us our grip on quark-hood tells us that quarks, if they exist, are the onlysimples, whose causality alone is real. But this meanswe must grant that O2 is equivalent to

O3 If quarks exist, then quarks arranged pointer-wisewill move to 0.01 on the dial.

This may not be obvious. I am not saying that “Quarksexist” is equivalent to or follows from “simples exist”from the point of view of the causal reductionist. Fromthat point of view we can allow that there could besimples that are not quarks. Hence I am not claimingthat causal reductionists are committed to the view thatthe consequent of O2 entails, much less is equivalentto, the consequent of O3.

However, the theory that gives sense to ‘quark’ tellsus not merely12 that quarks exist but also that the worldis so made that every material or physical thing eitheris a quark or is wholly composed of quarks.

Roughly, anyway. I digress briefly to smooth theroughness a bit. My claim that quark-theory tells us thatquarks constitute everything physical is not quite right,but nailing down the physics is both beyond my ken andbeside my point. Suppose the right theory tells us thatthere are simples besides quarks – strings, perhaps, orsomething else. Then we can substitute a disjunctiveterm – ‘quark or string’, or whatever – for ‘quark’, andmy argument will be unaffected. Thus I can relax myearlier assumption that quarks are the only elementaryparticles. Having relaxed it, I will continue to write asthough it holds, and you can make the necessarychanges if you see fit.

What of my other simplifying assumption – thatall the elementary particles are physical simples?Understanding ‘elementary’ in one way makes thisassumption tautologous: whatever has proper physicalparts is ipso facto not physically elementary. However,the sense of ‘elementary’ might seem at least partlycausal rather than merely mereological. Causal reduc-tionism focuses on the reducibility of an apparentcomposite’s causal powers to those of the things thatwould compose it, were it real. This reducibility is bestunderstood, to avoid rendering reductionism trivially

tautologous, in terms of supervenience. (Reductionismis not just the claim that only things with causal powerhave causal power.) It is no part of causal reductionismper se, however, that the causal powers of an apparentcomposite must supervene, as a matter of conceptualnecessity, on those of its constituents. Reductionists canconsistently countenance (say) atoms if, for example,they grant “downward causation” – the causal influenceof an atom on, say, one of its constituent protons, wherethis influence cannot be accounted for by the causalcontributions of the atom’s constituents. Reductioniststypically deny such an independent – non-supervenient– causal role for atoms or other composites, but theyneedn’t.13 They are committed only to denying a causalrole for things whose causal powers and relationswould, if those things existed, supervene on those oftheir constituents.

My argument will be unaffected if we take “ele-mentary particles” to be those that are causally ele-mentary – that is, those with causal powers and causalrelations that do not supervene on those of theirconstituents. On this understanding, a particle could beboth elementary and composite.14 Are there in fact anysuch composite elementary particles? I don’t know. Myignorance is, once again, blissfully irrelevant to myargument. Once again, I will talk of quarks alone,but you may read ‘quarks’ as shorthand for whateverdisjunction of actual causally elementary particlesphysics reveals.

With these caveats in hand, rejoin the argument fromwhich I have digressed. Given that our grasp of quarksseems to stem from the theory in which they areembedded,15 it seems arguable that necessarily,

QT if quarks exist, then quarks are the only simples.

The conjunction of QT and O2 is equivalent to O3. IfQT is indeed a necessary truth, then O2 is (broadly-)logically equivalent to O3. Even if QT is not necessary,it seems true, and so O2 is at least materially equiva-lent to O3, and knowably so.

Remember that our epistemic basis for believing inquarks is supposed to come from experimental evidence,and that this is partly a matter of being able to deter-mine the truth of our “crucial conditional” without pre-supposing the existence of quarks. Suppose we arereductionists with our wits about us, though. Then wecan see perfectly well that, if quarks exist, affirming thetruth of O2’s consequent is equivalent from our pointof view to affirming the truth of O3’s. And to do this

AN EPISTEMIC REDUCTIO OF CAUSAL REDUCTIONISM 157

is to presuppose the existence of quarks. We can alsosee perfectly that if quarks do not exist, then there isno such equivalence; but in that case, quarks do notexist. We know all this in advance. Hence we can seethat we cannot use O2 to justify belief in quarks.

This argument merits elaboration by illustration.Suppose I am a reductionist testing quark-theory. I seewhat we would describe in ordinary idiom as “thepointer moving to 0.01 on the scale.” As a reductionist,I give no pride of place to ordinary idiom. I acknowl-edge only three relevant possibilities concerning “thepointer.” First, as we have seen, it might be a causallypotent macroscopic simple. Second, it might be acausally impotent illusion that approximates the reduc-tionist truth of the matter, which is that there arecausally potent quarks arranged pointer-wise. Third, itmight be an illusion that approximates the truth of thematter, which is that there are causally potent micro-scopic simples that are not quarks arranged pointer-wise. In affirming the consequent of O2, I understandmyself to be affirming the disjunction of these threeclaims. But I can see in advance that, on any interpre-tation but the second, O2 comes out false if reduc-tionism is true. So if I embrace O2 and reductionism, Imust take myself to be witnessing quarks arrangedpointer-wise being arranged moving-to-0.01-on-the-scale-wise. This means I must antecedently take myselfto justifiedly believe in quarks in my effort to employO2 to arrive at justified belief in quarks. This circle isclearly a vicious one. We should not accept it.

You might complain that this argument must befallacious, because it proves too much. For non-reduc-tionists face the same three relevant possibilities, yet Iallow that they do somehow attain justified belief inquarks. My response is that non-reductionists can availthemselves of a fourth possibility not open to reduc-tionists: that the pointer is a causally potent compoundobject. In this case, of course, O2’s consequent wouldnot capture the movement of the pointer, though it couldconceivably be true. O1 would capture that movementand could underlie justified belief in quarks for non-reductionists.

2. I turn to the second reason why O2 offers no routeto justified belief in quarks. The previous argument wasaimed at showing that reductionists could not employO2 to arrive in the usual way at justified belief inquarks, because their justified belief in the consequentof O2 would presuppose justified belief in quarks and

so could not justify belief in them. I argue now thatwe cannot, as a practical matter, be justified in believingO2’s consequent, whether we are reductionists ornot.

The reason involves the meaning of the phrase‘simples arranged pointer-wise’. Where non-reduction-ists see a pointer, the reductionist sees “simples arrangedpointer-wise,” and this phrase is supposed to pick outsome simples and not others: it is supposed to pick outjust those simples that would constitute the pointer bythe non-reductionist’s lights.16 Now, the motion of thepointer takes time. Non-reductionists can allow that thepointer comprises microscopic simples, and they canalso allow that it comprises different simples at thebeginning of its motion than it does at the end. Now,which simples are picked out by ‘simples arrangedpointer-wise’? Any answer to this question yieldsunsatisfactory consequences.

Suppose that ‘simples arranged pointer-wise’ picksout those simples that would compose the pointer, bythe non-reductionist’s lights, at the beginning of thepointer’s motion. Do these simples – all of them – moveto 0.01 on the dial – that is, do they move so that at theend of the relevant temporal interval they are arrangedpointer-pointing-to-0.01-on-the-dial-wise? Conceivably,but not actually: most of them so move, but someescape, perhaps to be replaced by others. So althoughordinary idiom would say that the pointer moves to 0.01on the dial, the consequent of O2 would be false onthis interpretation of ‘simples arranged pointer-wise’.

Suppose ‘simples arranged pointer-wise’ picks outthose simples that would compose the pointer, by thenon-reductionist’s lights, at some other point in thetemporal interval over which “the pointer moves.” Thesame objection, or an obvious relative, will apply. (Forexample, if we pick the terminus of the interval –suppose the interval is closed – then the point is that notall of the simples arranged pointer-wise need havemoved into the terminal position.) Suppose instead that‘simples arranged pointer-wise’ picks out those simplesthat would compose the pointer, by the non-reduc-tionist’s lights, at any point in the interval. That is,suppose that if there is a simple that would compose thepointer at some point in the interval, by the non-reduc-tionist’s lights, then that simple is among those pickedout by ‘simples arranged pointer-wise’. Once again, itwill simply be false that these simples – all of them –are arranged pointer-pointing-to-0.01-on-the-dial-wiseat the end of the interval.

158 EUGENE MILLS

Causal reductionists typically do not claim to be ableto recast anything sanctioned by ordinary idiom intoliteral reductionist truth. They do, however, claim to beable to recast everything worth saving. The argument ofthis section is, in effect, that they cannot. They cannottell us what the conditional is whose consequent we canobserve to be true, thereby lending confirmation to theexistence of quarks. Given the facts about how we cometo accept scientific theories, causal reductionism rendersimpossible knowledge of the very entities whose exis-tence and causal role is supposed to undermine thecausal role – and hence the existence – of compositemacroscopica.

E. In Objects and Persons, Merricks considers in briefthe objection I raise here. His one-sentence response(p. 175) is that

just so long as our ‘laboratory equipment beliefs’ are nearly asgood as true, we can make use of those beliefs (or the true andwarranted tacit beliefs which are always linked to them) in comingto know about atoms or other microscopic entities.

A claim to the effect that “F exists” is nearly as goodas true, on Merricks’s stipulated usage, just in case ‘Fexists’ is false but there are things arranged F-wise. Thetrue and warranted tacit belief linked to the nearly-as-good-as-true belief that “F exists” is the belief that thereare things arranged F-wise.

Merricks’s response fails, for reasons implicit (andin some cases explicit) in what I have already said. Itwill be well, though, to address this response fully.

Merricks holds that typical “folk-ontological” beliefs(which would include the beliefs that tables exist andthat a certain pointer exists) are in some sense “com-mendable” even though they are both false and unwar-ranted. (Merricks holds that warrant entails truth. I donot hold this but will accept it for the sake of argument.)For one thing, typical such beliefs are initially justified(until we confront the reductionist arguments that defeatour justification). For another, they are nearly as goodas true. False commendable beliefs can serve not onlyto justify true beliefs but also, according to Merricks,to yield knowledge. False commendable beliefs to theeffect that a certain pointer exists could, on this view,yield knowledge that quarks exist.

Merricks argues only by example for his claim thatfalse commendable beliefs can yield knowledge. Twoof his examples simply assert what he needs to show.Here is one of them (Merricks, 2001, p. 174):

[S]uppose that, knowing my address, you locate my atomsarranged housewise. You then conclude that ‘Merricks lives here’on the basis of your nearly as good as true belief that my houseis in front of you. There are no houses. Your house belief is false.And so unwarranted. Nevertheless, assuming other conditions areright, that belief plays a key role in your knowing (and so in yourbeing warranted in believing) ‘Merricks lives here’.

Why should we think that you do know ‘Merricks liveshere’ in this case? Merricks does not say. Don’t be lulledinto acceptance by tacitly downplaying the elimina-tivism that Merricks asserts. If we take seriously theidea that your “knowledge” is based on a false beliefabout a house, it seems plain that we should not acceptthe knowledge-claim that Merricks asserts, at least inthe absence of some compelling argument or explana-tion for such knowledge. This example provides noargument whatsoever for Merricks’s crucial thesis.

Another example, however, seems more promisingbecause it does not beg the question in this way:

Imagine a society of Hellenic fundamentalists. Being Hellenic,they say things like ‘Apollo’s chariot moved behind the elms’;being fundamentalists, they thereby mean that Apollo’s chariotmoved behind the elms. [. . .] Now suppose a first member ofour imagined society says to a second ‘I shall be drinking teawhen Apollo’s chariot moves behind the elms’. I think that, ifother conditions are right, the second can – upon seeing the sunmove behind the elms – come to know (and so become warrantedin believing) that the first is drinking tea.

I agree with Merricks that “if other conditions are right”the second person can come to know that the first isdrinking tea. There is no reason, however, to think thatthis knowledge derives from the false belief that the firstwill be drinking tea when Apollo’s chariot movesbehind the elms. So I will argue.

Merricks says (174):

How exactly nearly as good as true beliefs are involved in thewarranting of other beliefs – the epistemological ‘diagnosis’ ofsuch cases – is not obvious. I’ll suggest two ways this could goin the ‘Merricks lives here’ case, just to illustrate that there ismore than one option. First, perhaps what warrants your beliefabout where I live is simply its being appropriately based on your(unwarranted but) nearly as good as true belief about a house. Or,second, perhaps your belief ‘Merricks lives here’ is warrantedby a true, warranted, and tacit belief that always accompanies yourhouse belief; perhaps your true belief about where I live is war-ranted because it is appropriately supported by your (tacit) trueand warranted belief about some things arranged housewise.

It does not matter which of these two diagnoses – or whethersome third diagnosis – is correct. What matters is that, as theexamples above show, nearly as good as true beliefs are intimatelylinked to the warranting of other beliefs.

AN EPISTEMIC REDUCTIO OF CAUSAL REDUCTIONISM 159

Since the ‘Merricks lives here’ case is utterly uncon-vincing, let’s focus instead on the case of Hellenic fun-damentalism. In this case, it seems plain that a diagnosisakin to Merricks’s second suggestion is available. Forit is plausible to suppose that when the second personbelieves falsely that Apollo’s chariot will move (or hasmoved) behind the elms, that person also has a true,warranted, and tacit belief to the effect that the sun will(or does) have a certain apparent position relative to theelms (or would have that apparent position if it were notobscured, for example, by clouds). And it is easy to seehow this true, warranted, and tacit belief, combined withother justified non-Hellenic beliefs, might yield knowl-edge that the first person is drinking tea. There is asense, then, in which the false belief about Apollo’schariot is “linked” to the warranting of other beliefs, butit does not do the warranting. It is the true, warranted,and tacit belief to which it is linked that does thewarranting.

Now remember Merricks’s response to my objection:

just so long as our ‘laboratory equipment beliefs’ are nearly asgood as true, we can make use of those beliefs (or the true andwarranted tacit beliefs which are always linked to them) in comingto know about atoms or other microscopic entities.

Consider first the parenthetical disjunct. As applied tothe case of quarks, this disjunct would have it that wecan use our tacit and warranted belief that there aresimples arranged pointer-wise to justify our belief inquarks. I have already argued at length that this is false;I will not repeat the arguments here. While the true andwarranted tacit belief held by the Hellenic fundamen-talist can warrant the belief about tea-drinking, the trueand warranted tacit belief that there are simples arrangedpointer-wise is utterly disanalogous in its epistemic roleand cannot possibly warrant belief in quarks or othermicrophysical simples.

Merricks’s other, non-parenthetical disjunct amountsto no more than the bald assertion that a nearly as goodas true belief can yield knowledge (and thus warrant).Merricks provides no non-question-begging examplethat shows this, nor does he say anything by way ofmaking it intelligibly plausible. The claim is utterly adhoc.

Merricks says that it does not matter which, if either,of his two suggested diagnoses is correct, because hisexamples force us to accept that nearly as good as truebeliefs can be “linked” to knowledge in some strong,relevant way. In fact, his examples do no such thing,

and without any diagnosis or any more compellingexample on offer, we ought not to accept either thatnearly as good as true beliefs in pointers, or true, war-ranted beliefs about simples arranged pointer-wise, canyield knowledge of quarks.

Finally, it is worth noting that, insofar as justifiedbelief in quarks is supposed to derive from justified,nearly as good as true beliefs in pointers, the reduc-tionist-cum-eliminativist shoots himself in the foot.Ordinary folk may be justified, given eliminativistscruples, in falsely believing in pointers and in infer-ring from their pointer-beliefs the existence of quarks.Reductionists are not. Merricks himself says that hisarguments undermine the justification of folk-ontolog-ical beliefs for those familiar with those arguments(172–173). As I have argued in section D, it follows thatreductionists cannot appeal to those nearly as good astrue beliefs as justification for their belief in quarks orother microphysical entities.

5. Conclusion

I have shown that the causal argument for reductionismis epistemically self-defeating. If I haven’t shown this,however, then I have at least shown that the argumentfaces a serious problem. At a bare minimum, reduc-tionists are not entitled to easy reliance on the quarks(or other microphysical simples) they would use tomalign the causal power of tables. I do not maintain thatknowledge claims in general must be explained to beacceptable. Where an alleged knowledge claim violatesour understanding of how the knowledge in questionmust be attained, however, then a demand for explana-tion is in order. Unless reductionists can give a plau-sible account of how we arrive at knowledge of quarks,an account consistent with their reductionism, they arenot entitled to the two main premises of the causalargument for reductionism.17 The prospects for such anaccount seem dim.

Notes

1 Thanks to Trenton Merricks and Peter Vallentyne for helpfulcomments on an earlier draft of this paper.2 We will need (among other things) to distinguish later betweencausal and mereological senses of ‘elementary’.3 The most explicit statements of arguments in this reductionist-cum-eliminativist mold are probably those of Trenton Merricks

160 EUGENE MILLS

(2001) and Cian Dorr (2002). Merricks exempts conscious organismsfrom elimination, but this is because he grants them irreducible causalpotency. His ontology is thus close, though not identical, to that ofPeter van Inwagen, 1990. Van Inwagen does not arrive at thisontology via the causal argument discussed here; see, however, note17. See also Sturgeon (1998).4 See Merricks (2001), pp. 80–81.5 Moore (1966) argues with respect to certain skeptical argumentsthat their conclusion is less plausible than each of their premises.Some arguments, however, have premises that are individually moreplausible than the conclusion but collectively less plausible. Thecausal argument for reductionism strikes some people as such anargument. In such a case you may be perfectly justified in believingthe conjunction of the premises false without being justified inbelieving any particular premise false. Perhaps you are no philoso-pher if you do not press on to find the false premise(s), but you maybe rational without being a philosopher.6 Perhaps following Bas van Fraassen (1980).7 Strictly, the pointer moves to ‘0.01’, not to 0.01, but I’ll omitquotes to save ink.8 Einstein was not the first to suggest that molecular collisionsexplain Brownian movement, but his account was the first rigorous,quantitative one.9 Van Inwagen is an eliminativist about most macroscopica whonevertheless maintains that ordinary existence-assertions, such as‘Pointers exist’, are true. He would say that what ordinary folk meanwhen they say ‘Pointers exist’ is just that there are simples arrangedpointer-wise (1990, pp. 98–114). Merricks (2001, pp. 162–170) givesgood reasons for thinking van Inwagen mistaken about this. In thispaper, I give another: If van Inwagen’s semantic thesis were correct,we could not (for reasons I will give) justifiably believe in the exis-tence of quarks or other microphysical entities; we can justifiablyso believe; so van Inwagen’s semantic thesis is false.10 As Merricks suggests in correspondence.11 Apparent macroscopica could conceivably be of two types:macroscopic simples, on the one hand, and (apparent) complexes ofmicroscopic simples on the other. Reductionists would grant causalpotency to the simples, large and small, but not to the apparent com-plexes of microscopica. If only the simple macroscopica figuredessentially in our epistemic basis for believing in the microscopicsimples, the obvious modification of my argument would not apply(but it’s hard to see how the simples could be quarks). Otherwise, itwould.12 And perhaps not even: physics arguably entails no existence-assertions concerning quarks.13 Merricks (2001) allows that certain composites – consciousbeings – escape reduction by exerting downward causation.14 If Merricks is right about conscious beings (see previous note),

they qualify on this score as “elementary particles”. An odd usage,I admit, but an unproblematic one. I might register here my own viewthat if the conjunction “causal powers and causal relations” werechanged to a disjunction, lots of composite objects would qualify ascausally elementary. I needn’t argue this here, though.15 This is false if living beings qualify as elementary particles andthus as “quarks”. I can live with the truth of this conditional, giventhe implausibility of its antecedent.16 See Merricks’s (2001) definition of ‘arranged statute-wise’ andhis subsequent discussion, pp. 4–6.17 There are non-causal arguments for eliminativism about macro-scopica that I have not addressed here. See, for example, van Inwagen(1990) and Unger (1979). It is worth mentioning that, insofar as thesearguments hinge on facts about quarks or other microphysicalsimples, my epistemic reductio threatens them no less than itthreatens the causal argument for reductionism.

References

Dorr, Cian: 2002, The Simplicity of Everything, Ph.D. dissertation,Princeton University.

Einstein, Albert: 1905, “Über die von der molekularkinetischenTheorie der Wärme geforderte Bewegung von in ruhendenFlüssigkeiten suspendierten Teilchen”, Ann. Phys. 17, 549–560.Translated (as “Movement of Small Particles Suspended in aStationary Liquid Demanded by the Molecular-Kinetic Theoryof Heat”) and reprinted in Investigations on the Theory ofBrownian Movement, Dover, New York (1956).

Merricks, Trenton: 2001, Objects and Persons, Clarendon Press,Oxford.

Moore, G. E.: 1966, “Four Forms of Scepticism”, in PhilosophicalPapers, Collier Books, New York.

Sturgeon, Scott: 1998, “Physicalism and Overdetermination”, Mind107, 411–432.

Unger, Peter: 1979, “There Are No Ordinary Things”, Synthese 41,117–154.

van Fraassen, Bas C.: 1980, The Scientific Image, Clarendon Press,Oxford.

van Inwagen, Peter: 1990, Material Beings, Cornell University Press,Ithaca.

Virginia Commonwealth UniversityRichmond, Virginia 23284-2025USAE-mail: emills@vcu.edu

AN EPISTEMIC REDUCTIO OF CAUSAL REDUCTIONISM 161