mind brain unified science of the neurophilosophy: toward a...~~~~ 0-262-53085-6mit presschurchland,...

Neurophilosophy: Toward aUnified Science of theMind‑BrainPatricia Smith Churchland

�MIT Press~~~~ 0-262-53085-6Churchland, Patricia S.Neu roph i losophy�

ISBN 0-262-03116-7 (hardcover)0-262-53085-6 (paperback)

Eleventh printing, 2000First MIT Press paperback edition, 1989

@ 1986 by The Massachusetts Institute of Technology

All rights reserved . No part of this book may be reproduced in any form by any

electronic or mechanical means ( including photocopying , recording , or information

storage and retrieval ) without permission in writing from the publisher .

Printed and bound in the United States of America

Library of Congress Cataloging - in - Publication Data

Churchland , Patricia Smith .

Neurophilosophy : toward a unified science of the mind - brain .

( Computational models of cognition and perception )

" A Bradford book . "

Bibliography : p .

Includes index .

1 . Neuropsychology - Philosophy . 2 . Mind - brain

identity theory . 3 . Neurology - Philosophy . I . Title . II . Series .

[ DNLM : 1 . Neurology . 2 . Neuropsychology .

WL 100 C562n ]

QP360 . C49 1986 152 85 - 23706

Chapter 7

Reduction and the Mind -Body Problem

�

. . . [metaphysical systems] are the only means at our disposal forexamining those parts of our knou1ledge which have already becomeobservational and are therefore inaccessible to a criticism lion the basis ofobservation. II

Paul K. Feyerabend, 1963

7.1 Introduction

In concluding the last chapter, I foreshadowed the implications forphilosophy of mind of the major revisions in the platform features oflogical empiricism . These changes permitted the development of anaturalistic conception that envisioned research on the mind -brain asan empirical investigation of the nature of mental states and processes,their causes, and their effects. Naturalism follows hard upon theheels of the understanding that there is no first philosophy . Inevit -ably the naturalistic approach leads us to inquire into the possibilityof a unified theory of the mind -brain , wherein psychological statesand processes are explained in terms of neuronal states and pro-cesses. A fundamental question concerning this possibility can be putas follows : Can mental states and processes be reduced to brain statesand processes? Can one be a reductionist ?

Not everyone expects mental states to reduce to brain states. Onthe contrary , it has been my' observation that many philosophers andcognitive scientists, most of the artificial intelligentsia , not a fewneuroscientists and biologists , and theologians generally, reject thepossibility as unlikely - and not merely as unlikely , but as flatly pre-posterous. But what , precisely, are they denying , and what is reduc-tion ? The aim of this and the subsequent two chapters will be tounderstand and evaluate the objections to reductionist strategies.This is central to my program , for obviously , if reductionism is ahopeless cause, then it would be foolish to search for an explanationof mental states and processes in terms of brain states and processes.

278 The Philosophy of Science

Indeed , if reductionist strategies really are absurd , then it may well be

wondered how neuroscience can be relevant to research in psychol -

ogy , let alone to philosophical questions .

In chapter 8 I consider objections posed by dualists and by tho :se

who consider there to be an irreducible set of properties distin -

guishing mental states from any sort of physical state . In chapter 9 I

consider antireductionist arguments formulated by contemporary

philosophers who are part of the functionalist movement . Here I lay

the groundwork for those chapters by offering an account of what

reduction is , and what it is not .

7 . 2 Intertheoretic Reduction

The word " reduction " has a bewildering range of applications in the

literature . " Reductionism " has come in some quarters to be used as a

general term of insult and abuse . Sometimes it is used as a synonym

for " behaviorism " ( which is a case of the vague hounding the vague ) ,

or as a synonym for such diverse sins as " materialism , " " bourgeois

capitalism , " " experimentalism , " " vivisectionism , " " communism , "

" militarism , " " sociobiology , " and " atheism . " With such diversity ,

equivocation is inevitable , and often as not opposing sides in a debate

on reductionism go right by each other because they have not agreed

upon what they disagree about . How " reductionism " came to acquire

such indiscriminate uses is beyond my ken , and perhaps it would be

best to drop the word altogether and so avoid the inappropriate con -

notations . The dilemma is , however , that for the subject matter under

consideration , " reduction , " in the sense to be specified , is the right

word . It is the word traditionally used in the relevant literature in

science and in the philosophy of science , and there is no other word

that begins to be appropriate . Therefore , I have decided to take my

chances with " reduction " and to guard against misunderstanding by

specifying the meaning I intend .

In the sense of " reduction " that is relevant here , reduction is first

and foremost a relation between theories . Most simply , one theory ,

the reduced theory T R , stands in a certain relation ( specified below ) to

another more basic theory T B . Statements that a phenomenon PR

reduces to another phenomenon PB are derivative upon the more

basic claim that the theory that characterizes the first reduces to the

theory that characterizes the second .

Before I amplify and illustrate these points , a word about tactics . In

order to clarify the nature of intertheoretic reduction and to begin to

assess the prospects for reduction of psychological theories to neuro -

science , it will be wisest not to focus on the very case at issue , namely

Reduction and the Mind -Body Problem 279

neurobiological theories and psychological theories, but on cases atsome remove from what is contentious . Otherwise , we not only loseclarity but also run the risk of begging all the important questions.The account of intertheoretic reduction should not be tailored to suit

the specific case at issue but should be adequate to reduction in thesciences generally . Moreover , there do not yet exist fleshed-outneurobiological theories with reductive pretensions, let alone reduc-tive success, and to introduce neuroscientific fiction in the analysisstage would only be confusing . By contrast, physics, chemistry , andgenetics provide well -studied examples of theories that have reducedto other theories . Therefore, it will be most efficient to draw uponthose examples in the history of science where two theories haveeventually enjoyed an intertheoretic reduction and where the exam-ples have been analyzed by historians and philosophers of science.Hence, examples from physics, chemistry , and biochemistry willfigure prominently in illustrating the analysis of reduction . With anaccount of the intertheoretic relations and dynamics of reduction inhand, we can reopen the question of the ultimate reducibility of psy-chological theories to neurobiological theories.

To return to the issue, reduction is a relation between theories, andone phenomenon is said to reduce to another in virtue of the reduc-tion of the relevant theories . For example, the claim that light hasbeen reduced to electromagnetic radiation means (a) that the theoryof optics has been reduced to the theory of electromagnetic radiationand (b) that the theory of optics is reduced in such a way that it isappropriate to identify light with electromagnetic radiation . Similarly ,when we entertain the question of whether light is reducible to elec-tromagnetic radiation , the fundamental question really is whether thetheory of optics is reducible to the theory of electromagnetic radia-tion . Hence, when we raise the question of whether mental states arereducible to brain states, this question must be posed first in terms ofwhether some theory concerning the nature of mental states is reduc-ible to a theory describing how neuronal ensembles work , and secondin terms of whether it reduces in such a way that the mental states ofT R can be identified with the neuronal states of T B. A good deal ofmuddle concerning reduction can be avoided with this initialclarification regarding reductive relations .

A consequence of intertheoretic reduction is explanatory uni -fication , and in the sciences such unification is considered a goodthing . If one theory can be explained by another and thus reduced toit , then our understanding of the phenomena described by the theoryis greatly enhanced. For example, as a result of the reduction of thetheory of optics to the theory of electromagnetism we came to under -


stand why the laws of optics are as they are, and to this extent ourunderstanding of how light behaves and what it is was enhanced.

Another important consequence of intertheoretic reduction is on-tological simplification . Ontology pertains to what entities and prop -erties exist, and in the event of intertheoretic reduction it may turnout that where we had thought there existed two different kinds ofphenomena characterized by the laws of two different theories, thereis in fact but one kind of phenomenon that is described by boththeories.

For example, in the mid -nineteenth century it was widely sup-posed that light was one sort of phenomenon , and electromagneticeffects quite another . By the turn of the century the laws of optics hadbeen reduced to the laws of electromagnetic theory , and we under -stood that light is electromagnetic radiation . We understood whatlight is for the very first time , in the sense that we understood whythe laws of optics are as they are.

Ontological simplification may also be achieved, not by the reduc-tion of one theory to another , but by the elimination of one theory byanother . For example, the elimination of the caloric theory of heat bythe kinetic theory of heat achieved ontological simplification , notby the identification of caloric with molecular kinetic energy, but bythe claim that there is no such thing as caloric. Ontologicalsimplification - simplification concerning what kinds of things wethink exist- is thus a typical feature of reductions , and as these con-trasting examples illustrate , the simplification may be achieved eitherthrough reduction and identification or through elimination . Thegeneral conditions under which the simplification takes one formrather than another will be discussed shortly .

Having said that reduction is a relation between theories, we mustnow characterize that relation . Under what conditions is one theorysaid to reduce to another? Recall that the crux of the answer providedby the logical empiricists was that for T R to reduce to T B it must belogically derived from T B plus some extra stuff . This extra stuff includeddomain -specific boundary conditions , limiting assumptions, approxi -mations, and so forth , but also crucial were the bridge principles . Asprescribed by logical empiricism , it was the function of bridge princi -ples to connect properties comprehended by the laws of TR to proper -ties comprehended by the laws of T B. In the most straightforwardcase the bridge principles would identify the properties in the reducedtheory with properties in the more basic theory .

The logical empiricist account is a huge improvement on the woollyintuitions that abound concerning reduction . By making theories thefundamental relata, much of the metaphysical bewilderment and dot-


tiness concerning how entities or properties could be reduced simplyvanished . Nevertheless , just as the logical empiricist accounts of em -pirical foundations and of meaning were revolutionized , so was theaccount of intertheoretic reduction . As historians and philosophers ofscience examined the dynamics of science, they found it necessary todisensnare themselves from a background myth abetting logical em-piricism - namely , the myth that science is mainly a smoothly cumu-lative , orderly accretion of knowledge . Historians and philosophersof science began to see that science is a rather more turbulent affairand that sometimes one theory is completely displaced by another .Evidently , sometimes there are scientific revolutions in which theformer assumptions about what is the correct theory , about what arethe facts against which to test theories , and about what needs to beexplained , are junked holus bolus . (See especially Kuhn 1962 andFeyerabend 1962.) Even the favored instances of apparently orderlyaccretions have turned out to be surprisingly disorderly on close in-spection . Indeed , there is not one example from the history of sciencethat exactly fits the logical empiricist pattern of reduction , and someoutstanding cases do not fit at all , force and bowdlerize how you will(Hooker 1981 ) .

The problem was that theories invariably had to be corrected andmodified to get something suitable that could be deduced from thebasic: theory . With the modifications accomplished, it was not ofcourse the ola theory itself that was deduced, but at best a correctedversion of the old theory . Theories range themselves on a spectrum ofhow much correction and revamping they require to get into deduc -ible form . Some require relatively little correction in order to be re-duced (as for example in the case of reducing the theory of optics toelectromagnetic theory ), but in other cases so much correction isneeded that almost nothing save a few low -level , homey " generaliza -tions can be retained . Phlogiston theory of combustion and the de-monic possession theory of nervous disorders are two such examples.In these cases the correction required was so thorough that it seemedmore appropriate to think of the old theoretical ontology as displacedentirely by the new theoretical ontology . The spectrum accordinglyhas at one end reduced theories that have been largely retained afterthe reduction and at the other end theories that have been largelydisplaced, with sundry cases falling in between.

If the old theory has to be corrected before it can be logically de-rived from the new theory , then the logical empiricist conception ofreduction needs modification . In particular , the expectation that thebridge principles are always necessary , and that their function is tocorrelate phenomena in the old theory with phenomena in the new ,

must be reconfigured . And this is a reconfiguring of enormous im-portance in thinking about reduction vis-a-vis psychology andneuroscience. Should the old theory be largely displaced, then bridgelaws are typically dispensed with . We do not identify phlogiston withoxygen, nor do we identify the demons that were said to possessshaking palsy patients with dopamine deficiency . Presumably wecould do so, inasmuch as there is no strictly formal (logical) reasonnot to, but there is no theoretical utility in these identifications . Onthe contrary , such identifications might perpetuate misunderstand -ing of what the new theories do. Instead, we say there is no suchthing as phlogiston , and there are no such things as demons. In thesecases, therefore , bridge principles play no role whatever .

In other cases where correlations are usefully forged, properties inthe new theory are matched up with properties in the corrected versionof the old theory . However , the reconfigured properties of the cor-rected version of the old theory are never more than approximationsto the properties in the original theory . The rub is, therefore, thatwhenever the corrections to the old theory are anything more thanrelatively minor , it is always tendentious to claim that phenomena inthe old theory are to be identified with phenomena in the reducingtheory .

This dimension of scientific dynamics is important for our consider-ations because many standard objections to the possibility of a unifiedtheory of the mind -brain depend on the assumption that the com-monsense understanding of mental states- of consciousness, beliefs,desires, and so forth - is correct. Using this assumption , it is oftenargued that no identification between neuronal states and mentalstates is forthcoming . In a sense, this conviction too can be seen as alegacy of logical empiricism , which cited immediate experience asGiven and hence as the certain foundation supporting the edifice ofknowledge . In seeing that reductions typically involve revision andmodification of the reduced theory , and that even outright elimina -tion as well as reduction is a possibility , we should acknowledge thenecessity of relaxing our conviction concerning the basic correctnessof our understanding of the mental . To appreciate the kinds of pos-sibilities inherent in the future evolution in neurobiological theory ,we should consider how philosophers of science have improvedupon the logical empiricist story .

If the logical empiricist account of reduction is procrustean andwrong , how then should the conditions for intertheoretic reductionbe specified? Roughly , as follo ,"Is : Within the new, reducing theoryT 8, construct an analogue T~ of the laws, etc., of the theory that is to bereduced, T R' The analogue T~ can then be logically deduced from the



reducing theory T B plus sentences specifying special conditions (e.g.,frictionless surfaces, perfect elasticity). Generally, the analogue willbe constructed with a view to mapping expressions of the old theoryonto expressions of the new theory , laws of the old theory ontosentences (but not necessarily laws) of the new . Under these condi-tions the old theory reduces to the new . When reduction is success-fully achieved, the new theory will explain the old theory , it willexplain why the old theory worked as well as it did , and it will explainmuch where the old theory was buffaloed . (To see this account'\J\Torked out in detail , see Paul M . Churchland 1979 and Hooker 1981.See also Patricia S. Churchland 1982.)

To digress briefly , I should mention that there are of course nonfor -mal conditions on reduction as well . For example, it must be rea-sonable to believe that T B is true- implying as well that T B must havethe right sort of fit with the rest of established science. Furthermore ,T B should apply to the same domain of phenomena as T R' I hasten topoint out , however , that the conditions for rationally preferring onetheory to another have not, notoriously , been worked out (Kuhn1962). Moreover , it is my view that they will not be well understooduntil we have a much more complete account of what the mind -brainis doing in virtue of which it constructs theories, and of what rational -ity of mind -brain processing really consists in . Clearly , therefore,although my account of intertheoretic reduction ideally should besupplemented by a theory of rationality , we shall nonetheless have tomake do with an inchoate understanding of rationality , which is allwe have, until neuroscience and psychology yield a more completetheory of mind -brain function .

How much of, or how closely, the old theory is mirrored in theanalogue varies from case to case and is a function of how muchcorrection the old theory requires. Most of the theory of optics couldbe preserved, only some of classical thermodynamics , and almo?tnothing of the caloric theory of heat and temperature . If a reduction issmooth, in the sense that most principles of T R have close analoguesin T B, then the matching of cohort terms denoting properties canproceed and identities can be claimed. Informally , a similarity -fitmeans that property PR of the reduced theory has much the samecausal powers as the cohort property PB of the basic theory .

Determining when the fit is close enough to claim identities be-tween properties and entities of the old and those of the new is not amatter for formal criteria , and the decision is influenced by a varietyof pragmatic and social considerations . The whim of the central inves-tigators, the degree to which confusion will result from retention ofthe old terms, the desire to preserve or to break with past habits of

thought , the related opportunities for publicizing the theory , cadginggrants, and attracting disciples all enter into decisions concerningwhether to claim identities and therewith retention or whether tomake the more radical claim of displacement . 1 In fact, I do not think itmatters very much that we establish criteria for determining when thereduced and the reducing theory resemble each other sufficiently toherald identities of properties (Patricia 5. Churchland 1982).

The evolving unifications seen in science therefore encompass notonly smootn reductions with cross-theoretic identifications but alsorather " bumpy " reductions where cross-theoretic identifications areproblematic and involve revision of the old theory 's concepts, andoutright elimination with no cross-theoretic identifications at all .Phlogiston , caloric fluid , the spirit of sal ammoniac, and demons areall examples in which the embedding theory was eliminated aRd nocross-theoretic identifications were made.

It \s singularly important for the discussion of the reduction ofmental states to brain states that intertheoretic unification does not

require cross-theoretical identification of states and things , and thatreduction may involve substantial correction of the reduced theory .For it is often assumed that a unified theory of the mind -brain re-quires a smooth reduction , such that types of mental states (as nowconceived) are identified with types of brain states (as now con-ceived). However , to make such identifications a requirement is tohobble severely the theoretical development of neuroscience, for itimplies that only a reduction on the retentive end of the spectrum willdo, and that neither will any of the variously revisionary styles ofreductive relations be acceptable nor will displacement be consideredeven possible.

50 far as we can tell now , that may be analogous to the requirementthat only a retentive reduction of alchemy will do, or only a retentivereduction of caloric theory . The requirement is excessively conserva-tive insofar as it insists on the preservation of the reduced theory . Atthe same time, it is excessively bold , since it in effect predicts that ofall the possible places on the reductive spectrum where it might fall ,this reduction will in fact be at the retentive end.

Moreover , theories at distinct levels often co-evolve (Wimsatt1976a), as each informs and corrects the other , and if a theory at onestage of its history cannot reduce a likely candidate at a higher level, itmay grow and mature so that eventually it does succeed in the reduc-tive goal. In the meantime the discoveries and problems of eachtheory may suggest modifications , developments , and experimentsfor the other , and thus the two evolve toward a reductive consumma-tion . Transmission genetics and molecular genetics exemplify this



sort of co-evolution . As things stand, molecular genetics has not com-pletely reduced transmission genetics, but its development toward aricher theory that can effect the reduction is guided in part by resultsand hypotheses in transmission genetics, whose research is in ' turninspired in part by questions arising from molecular genetics. In thecourse of their co-evolution it has become evident that the " genes" ascharacterized in early transmission genetics, likened unto beads on astring , do not exist, and consequently the generalizations of transmis-sion genetics have had to accommodate the molecular discoveries.(See especially Philip Kitcher 1982; see also chapter 9.)

In chapter 9, where the co-evolution of theories will be discussed inmore detail , we will see that early signs of such mutual influencingare now to be found in research on memory as neurobiologists , psy-chologists, and neurologists inform and correct one another . And inchapter 10 I shall present an example of the co-evolution , albeit in theearly stages, of neurobiological and psychological hypotheses con-cerning the nature of attention . ~oth the reductive hypotheses fromneurobiology and the behavioral observations from psychology areessential to the wider program of figuring out how the informationstorage and retrieval system(s) works and how each corrects andinforms the other . It is of course conceivable that a richly developedpsychology of memory will never be reduced by a richly developedneurobiology of memory , nor transmission genetics by molecular ge-netics, however the pairs co-evolve. On the other hand, it would befallacious to argue and reckless to predict that since the reduction isnot now available, it never will be.2 (The genetics example is furtherdiscussed in chapter 9.)

It is often in this gradual co-evolutionary development of theoriesthat the corrections and extensions to both theories are made, andfrom such theoretical interanimation may ultimately emerge a unifiedtheoretical framework . At this final stage the reduced theory will havean explanation - of its properties , laws, entities, and so forth - interms of the reducing theory . However , as Francis Crick has re-marked (in conversation), by the time we get to the point of beingable to sit down and crank out the derivation of one theory! fromanother, most of the really exciting science is over- the inspiredmodeling , the wild and woolly imaginative flights , the wall -tumblingexperiments, the fitting and revising and revolutionizing are prettymuch behind us.

Admittedly , this is something of an exaggeration, inasmuch asscientific theories are ever incomplete , and there is always fun to behad. Nonetheless, this view is correct in emphasizing the importanceof the co-evolutionary process in achieving a reductively integrated

theory . The logical empiricists , in focusing exclusively on the finalproducts of a long history of theoretical evolution , overlooked thedynamics of theoretical evolution . This is a serious oversight , since itis typically in a theory 's evolution that the major reductive links areforged and the major revisions- categorial and ontological - arewrought .

Reductive achievements sometimes fall short of the complete re-duction of one theory to another because the available mathematics isinsufficient to the task . Thus , quantum mechanics has succeeded in

explaining the macro properties of only the simplest of atoms, andwhether more will be forthcoming depends on developments inmathematics. Some people tend to want to make a lot of this (forexample, Popper (1977)), but it has seemed to me not to be a lesson ofany great significance in contemplating a reductive strategy for psy -chology and neuroscience. In the case of quantum mechanics themathematical limitations do not entail that the macro properties of themore complex atoms are emergent in some spooky sense, but onlythat for want of mathematical solutions , an approximation will haveto suffice . In any case, whether the appropriate mathematics will bedeveloped is very much an open question, and since the date ofPopper's original remarks, more reductions have been accomplishedby quantum mechanics. The important point is that the general out -lines of the reductive story are in place. Finally , we have no reason atthis stage for assuming that a reductive program in neuroscience willbe stopped dead in its tracks because the enabling mathematics isunavailable .

Because I think it most unlikely that a theoretical unification ofneuroscience and psychology will involve a retentive reduction ofmental states as currently understood with neuronal states as currentlyunderstood, it may be useful to dwell briefly on several examples inwhich one theory largely displaces another . Classical mechanics(Newtonian mechanics) was succeeded by Einstein's special theory ofrelativity (STR). This theoretical development is generally recognizedas an instance of reduction , and initially it may seem to be a case thatfalls at the retention end of the spectrum . After all, it might bepointed out , the two theories have a common subject matter : mass ,motion , acceleration , and so on .

The appearance of retention , and thus the appearance of identify -ing phenomena in one theory with phenomena in the other , is decep-tive , however , and the differences between the two theories are

sufficiently radical to call STR a displacement rather than a retentivereduction of classical mechanics (CM ). To illustrate , consider mass .As conceived within CM , massCM is a property I intrinsic to an entity ;


it does not vary from observer to observer as a function of his velocityrelative to the object whose massCM is at issue. MassSTR is entirelydifferent . It is a relation between an entity and countless referenceframes; and it will have a different value for each observer with adifferent velocity relative to the object whose massSTR is at issue.

If STR is correct, there is no such thing as massCM; conversely, ifCM is correct, there is no such thing as massSTR. Properties intrinsic toobjects are not relations between objects; more different they cannotbe. Which means therefore, that massCM is not identifiable withmassSTR. Similar points can be made about momentum , energy, andso on (Feyerabend 1962).

Here, then, is an instance where an entire theoretical network of

laws and concepts is reconfigured at the hands of the reducingtheory . The laws of CM are not deducible from the laws of STR, andthis for two reasons: (1) the laws of CM " hold " only under certainlimiting conditions , and if we are to deduce anything resembling CMfrom STR we must add in the (false) assumption that these limitingconditions obtain, and (2) where the terms of CM express intrinsicproperties , the corresponding terms of STR all express relations.Given this latter fact, CM is not deducible from STR at all . What canbe logically deduced from STR (plus the false assumptions) is a setCM* of analogues of the laws of CM, analogues still expressed in therelativized vocabulary of SIR . Insofar as this deduction explains theset of analogue laws CM* in terms of STR, it thereby explains classicalmechanics.

Speaking more strictly , the deduction explains why CM was as suc-cessful as it was, within the classical limits . And the deduction doesshow that SIR has the resources to " take over" the explanatory andpredictive jobs performed in the past by the original CM . That is whythis case still counts as a successful intertheoretic reduction , despitethe lack of a systematic set of intertheoretic identity statements.

A concern may yet linger : " What about mass itself - what about thephenomenon that exists in nature? Perhaps massCM is not identical tomassSTR, but does mass itself reduce to massSTR or not?" In order tounderstand the question , we must know what the speaker means by" mass." Suppose he says, " Well , it is that property which thingsdifferentially have such that one thing is harder to push than another ,


CM

STR, plus Limiting Assumptions~ logically entails

CM *

which is isomorphic with

The Philosophy of Science288

such that some things weigh more than others, etc." Notice that ingiving the answer, in effect he gives a theory of sorts- a dinky littletheory perhaps, but his beliefs about what mass is are inevitably tiedto generalizations of some sort . Because if he is to use the word , hemust have classificatory schemata and some rule of application , bethey homespun or not .

At this stage the earlier discussion of epistemological matters - ofempirical foundations , theories , and observations - is particularlyhelpful . To suppose that there is a phenomenon , namely mass , thatcan be apprehended and understood independently of any theory isan illusion . Bare facts, neutral observation, theory -independent ac-cess to the world , and absolute foundations have gone to the wall with

logical empiricism . (See chapter 6.) In the case under considerationthe speaker ' s " mass " is characterized by the theory he provides , andhence his question boils down to this : does his dinky -theory (DT ) thatspecifies massOT reduce to STR in such a way that massOT can beidentified as the same thing as massSTR? Now the question is an-swerable , and the answer is an unambiguous " no ," since in hisdinky -theory mass is a property , not a relation . Assuming that STR iscorrect; there is nothing in nature that corresponds to the speaker'sconception of mass - nor , for that matter , to mass as conceived byCM . What is in nature , says SIR , is relativistic mass - mass as de -scribed in STR .

What gets reduced are theories, and the stuff in the universe keepsdoing whatever it is doing while we theorize and theories come andgo . So the question " Does mass itself get reduced ?" does not makeany sense .

The second example also illustrates displacement, but this time it isa folk theory that is displaced by another . Such an example is especiallypertinent to the mind -brain issue for the following reason: it is com-mon for objections to the possibility of a theoretical unification ofneuroscience and psychology to lean heavily on our current intuitionsabout our mental lives . The framework of concepts for such intuitions

is frequently credited with being observationally true or self-evidentlytrue . And this framework is often alleged to be irreducible to anytheory in neuroscience . My strategy is to draw attention to the rangeof fates that can befall a conceptual framework , no matter that it is anintuitive , " observational " framework . If it is irreducible , that may be

owed to its being so inadequate that it deserves displacement, or itmay be that it will not be smoothly reduced, but instead revised,either in large or in small measure . As this example will show , even" observable" concepts may be reconfigured or eliminated , and oc-cupying the station of " intuitive framework " or " folk theory " pro-


tects that framework neither from reduction of the revisionary typenor from outright elimination . (That our intuitive understanding ofmental states and processes can be understood as a folk theory will bediscussed in detail in section 7.3.)

Newtonian classical mechanics was itself the innovTative challengerto a more primitive theory of motion derived from Aristotle . Thecentral wisdom of Aristotle 's theory of mechanics was this law : Anobject will continue in motion if and only if a force is continuouslyapplied to keep it in motion . As Aristotle reasoned, if one stops push-ing a boulder , it will stop moving ; ~Then sufficient force is applied ,the boulder begins to move again, and it will continue to move solong as the force is applied . The motion of projectiles appeared to be aproblem for the theory , since a rock hurled from a catapult , for ex-ample, continues in motion after release from the catapult and henceafter release from the force applied by the catapult .

According to the theory , once the external force of the catapult is no~longer applied , the object should drop straight down . Medieval phys-icists tried to solve the problem of projectile motion by postulating aninternal force imparted to the object by the catapult . The rock con-tinues to move after release from the catapult because it has beengiven an impetus that keeps it in motion . Why then does the objecteventually fall? Because, the theory said, the internal force slowly"dissipates, whereupon the object's weight causes it to fall . The theoryrecognized nothing fundamentally different between rectilinear mo-tion and curvilinear motion - it was all just motion . Thus, a corollaryto the theory was that objects could be given curved impetus , so thatan object twirled around the end of a string allegedly continued in acircular path when released from the string .

This was the impetus theory of projectile motion , and it was todominate physics until Galileo set the subject on the path that finallywound to Newton . The example is important for a number of rea-sons. First, it is crucial to understand that impetus theory was notsmoothly reduced and largely retained by Newton 's theory but wasfalsified and displaced by it . As a theory of mechanics, the impetustheory is misconceived and muddled from top to bottom . In contrastto the central wisdom of Aristotle , Newton 's first law states that abody in uniform rectilinear motion will continue in uniform rectilin -ear motion unless acted on by a force; a force is required to accelerate abody but not to keep it in uniform motion . On Newton 's theory thereis no such thing as impetus at all; there is simply nothing in classicalmechanics \l\rith which to identify impetus . " Momentum " may sug-gest itself , but momentum is not a force, whereas being a force was thewhole point of impetus .

Additionally , the distinction fundamental to impetus theory -between being in motion and being at rest- is irrelevant to Newto -nian dynamics , which instead draws a fundamental distinctionbetween moving at constant velocity (either at rest or at unchangingspeed) and moving at changing velocity (acclerating and decelerat-ing). In addition , the failure to see the differences between motion instraight lines and motion deviating from straight lines was disastrous.The corollary concerning curved impetus was a muck-up and caneasily be observed to be false- so easily, in fact, that the untroubledclaims to have observed verifying instances look like first -rate cases ofseeing what we believe.

The example is interesting for a second reason- namely, thatsomething rather like impetus theory seems to be what many humansuninformed of classical mechanics tend to believe and act upon , evenin the twentieth century . In a series of studies performed by McClos-key (1983), it was found that both in their behavior with regard tomoving objects and in their verbal predictions and explanations, stu-dents were far more Aristotelian than Newtonian . In one test collegesubjects were asked to jog along and try to "bomb" a stationary targetby dropping a golf ball on it . Typically , they thought the ball wouldfall straight down when released, and some even thought it wouldmove backward . Therefore, they did not drop the ball until the handholding it was directly over the target or even past it . In other experi-ments subjects tried to make a puck slide in a curved path by movingtheir arm in a curved path before releasing the puck . Additionally ,they explained projectile motion in terms of a force imparted to ob-jects that keeps them in motion but slowly dissipates, after whichgravity takes over- an explanation reminiscent not of Newton but ofthe medieval physicists . Among students acquainted with classicalmechanics there was a tendency to try to assimilate that theory to theimpetus theory , for example by construing momentum as a cause ofmotion and in effect using " momentum " in much the same role inwhich the old theory used " impetus ."

These experiments indicate that apart from the scientific commu-nity , most humans seem to employ a sort of folk physics or, as McClos-key calls it , intuitive physics. Although a person might not describe hisset of beliefs concerning motion as a theory , given the role of suchbeliefs in explaining and predicting motion , it is nonetheless appro-priate to credit the person with a folk theory . The set of beliefs is notlikely the product of self-conscious theorizing , but insofar as they areused to explain and predict motion of objects, they function for the person thelvaya consciously constructed theory functions. Perhaps the folk theory iscasually acquired as one learns one's native language, or perhaps

The Philosophy of Science290

there is some innate structure in the brain that fastens on this theoryfirst . Whatever its origins , folk theory there does seem to be, and tosomeone uninformed of Newton 's laws the folk theory seems to beself-evident and observably true- a bit of rock-solid commonsense.Moreover , like earlier impetus theorists, ordinary folk think theyhave observed what we know to be impossible trajectories for projec-tiles. (See McCloskey , Caramazza, and Green 1980, Clement 1982.)

To someone unacquainted with Newtonian theory the central wis-dom of Aristotle 's physics does seem intuitively dead obvious , andNewton 's first law may well seem counterintuitive and outlandish .Only when it is experimentally shown how impetus theory and New -ton's laws predict different effects- only when it is demonstratedhow Newton 's laws can explain why impetus theory worked as wellas it did and how much more Newton 's laws could explain- does thesuperiority of Newton 's laws begin to dislodge the old dogma rootand branch . Once the new theory becomes second nature, observa-tions are made within its framework , not within the framework of theabandoned theory . Unless the old theory is deliberately dislodgedand its falsity explicitly recognized, the inclination seems to be toforce the new theory to knit itself , somehow or other , in to the oldtheory .

This example illustrates several points that will be useful in thediscussion of reducing mental states to brain states: first , that in re-ductive developments one theory can displace and falsify another;second, that sometimes what is displaced and falsified is a folk theorywithin which those who hold it make their observations; third , thatdespite the self-evidence of the folk theory , it can be demonstrated tobe misconceived; and fourth , that as a newly acquired theory be-comes familiar , it can be as routinely and casually used as the old folktheory . For example, a seasoned engineer uses Newtonian mechanicsas effortlessly and " intuitively " as McCloskey's subjects use impetustheory . With routine use of a theory , one naturally makes economiesin the sequence of inferential steps and comes to be able to predict thetrajectory of a projectile without laborious deductions . One justknows , and knows without conscious effort at Newtonian reasoning,that a puck will not move in a curved path after release from a handswung in a circle, and it will seem faintly bizarre that anyone shouldhave thought otherwise .

A further pertinent observation is that even after a theory has beendisplaced by a competing theory , some people may continue tounderstand phenomena in terms of the displaced theory , quite asthough it were not false. Unless explicitly taught to think of motion ina Newtonian framework , people seem disposed to employ the im-



petus theory . That they do so does not imply that the old theory hasnot really been falsified by the new theory ; it merely means that somepeople do not know or care that it has been falsified . To construct anew theory and reduce the old is one thing ; for the reducing theory tofind its way into our hearts and minds is another .

A similar account can be given of folk thermodynamics , ahodgepodge theory of heat and temperature that was displaced byclassical thermodynamics , which in turn was reduced, not verysmoothly , by statistical mechanics. (See Paul M . Churchland 1979.) Isuspect somewhat the same story can be told for folk theory of designin nature , which explained the organizatidn exhibited in the workingof the eye or the nature of reproduction , for example, in terms of anintelligent designer . That theory has been displaced by biology andthe theory of evolution .

I do not suppose there is a neat sorting out of what is folk theoryand what is a subsequent development that eventually found wide -spread acceptance in a particular culture . Alchemy might not be con-sidered a folk chemistry , though many of its concepts and ideasbecame common coin, whereas animistic theories of weather andseasons, say, might be considered folk meteorology . I set no greatstore by getting a rigorous criterion to demarcate the folk theory fromthe folk -plus-one theory from protoscientific theory from genuinelyscientific theory . Theories are, after all, natural phenomena; theyevolve, and they cause changes in what people mean by certain ex-pressions, in how they think , and in how they see the world . Someslip easily into the vernacular , others are isolated to small com-munities of the cognoscenti. Some are readily adopted by childrenbut always seem foreign to their parents. Some, like heliocentrismand the theory of evolution , are disruptive of the wider metaphysics;others, like the germ theory of disease, are relatively inoffensive tothe wider metaphysics; some are stopped in their tracks by war ,barbarians, plagues, famine , or other acts of God.

To the extent that the new theory substantially displaces the old ,there is a reconfiguring of what needs to be explained. Previous consen-sus on the explananda dissolves, and new explananda, conceivedwithin the framework of the new theory , come to dominate research.For example, in Ptolemaic theory the Earth was the center of theuniverse around which revolved the celestial sphere, roughly asthough the Earth were a small pea inside a gigantic revolving basket-ball . Indeed, it was thought that the sphere could be observed to turndaily around the inert Earth, an observation that seemed unprob -lematic and straightforward . Ptolemaic theorists therefore had to an-swer the question " What makes the celestial sphere turn ?" and

Reduction and the Mind -Bod)1 Problem 293

assorted hypotheses were advanced and discussed concerning themechanism . However , since Newtonian theory dispensed altogetherwith the celestial sphere, the mechanism of its movement is no longersomething that needs to be explained, and claims to have observedthe sphere and its movement are misconceived and false.

Hence, Newtonian theory did not solve the problem of what makesthe celestial sphere move by postulating an intricate set of gears,pulleys , and what have you . It rejected the explanandum as miscon-ceived . There is no celestial sphere , so there is no problem about whatmakes it move . Moreover , one cannot observe it or its movements ,

though the apparent movement of the stars can be explained in New -tonian theory by reference to the Earth's motion . In addition , ofcourse , the seemingly self -evident datum that the Earth is stationaryis falsified by Newtonian theory . Thus can the observational data ofone theory be revised by the victorious new theory .

Explananda of many earlier theories have suffered a kindred fate :Harvey did not try to explain how animal spirits are concocted in theheart ; instead , he said that the heart is a pump for blood and tried to

explain how it pumped . Modern biologists do not try to explain howvital spirit makes things alive ; instead , they try to explain otherthings , such as how information is coded in DNA . (See Feyerabend1963a. )

It is the contrast between competing theories that highlights flaws ,foibles , and misconceptions in theories , and without that contrast it isoften hard to avoid simply taking for granted the explananda ,methods , and " self -evident data " of the prevailing paradigm . For thisreason , Feyerabend exhorts us to encourage as many competing theo -ries to bloom as possible, and to keep aflame the humbling thoughtthat new theories may revise our old conceptions entirely , includingour conceptions of what is obvious and what are the " facts " that needto be explained .

The relevance of this to the issue of an eventual unified theory ofthe mind -brain is this : what we take to be obvious or observational

within the framework of intuitive psychology is not guaranteed cor -rectness or survivability simply on the strength of that obviousnessand observationality . As we have seen, even intuitive frameworks ,and even observational concepts , can be reconfigured as science pro -ceeds . Perhaps only by looking first at examples where the emotionalstakes are lower can we begin to get enough distance to see that our" intuitive " conceptual framework for understanding ourselves, forintrospecting , for observing , for explaining and predicting behaviormay require revision or even elimination .

For the sake of completeness I should add that the theory of


scientific explanation I adopt here is a modified form of the deductive -nomological (ON ) model worked out by the logical empiricists (chap -ter 6; see also E. Nagel 1961). The important modifications aretwofold . (1) Intertheoretic reduction is an instance of ON explanation ,where what is explained is not a single event but a law or set of laws .Insofar as the account of intertheoretic reduction deviates from the

logical empiricist conception , there are corresponding modificationsin the theory of explanation . In particular , the theory must bemodified to allow for explananda to be reconfigured rather than de-duced as they stand . The model accommodates this change withoutstrain . As noted earlier in the discussion of intertheoretic reduction ,

sometimes what is deduced is not the old law itself but a reconfiguredversion or analogue of the old law . Accordingly , it is not the old lawthat is explained , but its analogue . (2) Not all laws are universalgeneralizations ; some are statistical generalizations . Thus , the basicmodel must be broadened to encompass explanations where the cov -ering laws are probabilistic . This modification will not in fact playasignificant role in the issues raised in this book , but to see how itworks , interested readers should consult Salmon 1971. (A great manydetails concerning the deductive -nomological model of explanationthat I must ignore here are cogently discussed in E. Nagel 1961 andRescher 1970. For a more recent paper that answers many of theobjections to this model , see Cupples 1977.)

Having declared my preference for the deductive -nomologicaltheory of explanation , I emphatically add that I neither wish nor needto be doctrinaire about this . On the contrary , I adopt this theor )' onlyas a first approximation that enables us to discuss without folderolthe important aspects of intertheoretic reduction . Accordingly , theframework for reduction and explanation is intended to accommo -date explanations of the form described by Cummins (1983), in whicha capacity at one level of organization is explained in terms of thecoordinated functioning of capacities at a lower level of organization .The points that I find central are that reduction involves explanationand that typically reductions involve corrections of those levels of de-scription that supply the explananda .

In any case I think the theory of explanation is bound to be provi -sional , since I expect that as theories of brain function mature , we willacquire a far deeper sense of what the brain is doing when it seeksexplanations , what it counts as explanatory fit , what understandingcomes to , and so on . And my conviction is that this deeper sense willtake us beyond the paradigm in which explanations in general arecharacterized on the model of logical relation between sentences. (Seechapters 9 and 10.) Rather , it may hypothesize very different sorts of


relations between cognitive structures very different from sentences .Indeed, some of the shortcomings visible in the ON model cut sodeep as to suggest the need for a very different paradigm (Van Fraas-sen 1980, Cummins 1983) . In short , it may well be that as neurosci -ence matures, it will change profoundly our conception of cognitiveactivity and therewith our epistemology .

7.3 Mental States and Folk Psychology

What Theory Will Reduce to Neurobiological Theory?The fundamental point of the foregoing section was that questionsconcerning the reduction of mental states to brain states front for thereal question , which is whether one theory is reducible to anothertheory. The first piece of business , therefore , is to determine whichtheories are candidates for the relevant intertheoretic reduction . This

crucial first step is often missed in discussion of reduction (see forexample Sperry 1980, MacKay 1978, Eccles 1977), with the conse-quence that it is often hard to see what the issues are and what mightcount as evidence one way '" or another . In these circumstances the

debates about reduction threaten to become an unavailing clash be-tween precarious metaphors and amorphous intuitions .

What theory , then, is the candidate for reduction to neurobiologicaltheory ? It is the integrated body of generalizations describing thehigh -level states and processes and their causal interconnections thatunderlie behavior . Broadly speaking, this is the domain of scientificpsychology , and especially in the last hundred years an enormousresearch effort has gone into discovering important generalizationsabou t such functions as memory , learning , perception , development ,language use, and so forth . Nevertheless, it is acknowledged on allsides that although some generalizations have been discovered, theredoes not yet exist an integrated body of generalizations - a com -prehensive Theory - that delineates the psychological states and pro-cesses mediating perception , learning and memory , problem solving ,cognitive mapping of an environment , and so forth . There is still anenormous amount we simply do not understand at the -psychologicallevel about the cognitive and sensorimotor capacities of organisms .There is therefore a great deal of research yet to be done , and it is

evident that the candidate for reduction to neurobiological theory issome future theory . It is a yet-to-be-devised integrated account of thecausal connections between psychological states and behavior .

Granting the unfinished status of scientific psychology , it is never-theless clear that for many of the generalizations and discoveries that


have been made by psychologists, the question of a future reductionto neurobiological generalizations is not tendentious . Consider, forexample, the following generalizations :

1. Extinction of a learned response R is slower if on the learningtrials the conditioned stimulus was correlated with the uncon -

ditioned stimulus with a probability less than 1.2. An organism will not learn a response R to a conditionedstimulus K if K is presented simultaneously with or after theunconditioned stimulus L .

3. If two stimuli , such as two bars of light or two circles of light ,are presented in a properly timed succession, the scene is .per-ceived as one object moving in space.4. Prelinguistic infants are able to give discriminative responsesto every phoneme from every natural human language, but chil -dren who have learned a language are able to discriminate onlythose phonemes found in the language they have learned.5. If a light -colored rectangle is placed flush against a dark-colored rectangle, one will see at the border a darkening of thelighter color (the Mach bands discussed in chapter 2).

The list could easily grow to encyclopedic length , but the point isthat the possibility of a neurobiological reduction of these generaliza-tions tends not to offend anyone . For the most part it is expected thatbrain-based explanations of why these generalizations and similargeneralizations hold true will eventually be forthcoming . It is ex-pected, for example, that learning curves of rats in T -mazes will havea neurobiological explanation , and research on the hippocampus andthe cerebellum (interpositus nuclei) already lends support to this ex-pectation (alton , Becker , and Handelmann 1979, McCormick 1984).

Even so, some misgivings may linger about the possibility of reduc-tion should it be assumed that a reductive strategy means an exclu -sively bottom -up strategy or that in the aftermath of the intertheoreticreduction the high -level theory will somehow wither away or beuseless or in disgrace. These misgivings are really just bugbears, andthey have no place in my framework for reduction .

Recall that on my account of intertheoretic reduction , one theory isreduced to another if it (or a corrected analogue of it ) is explained byanother . This does not entail that the reduced theory will somehowcease to be, or that the phenomena it describes cease to be . On thecontrary , if the reduction is smooth , its reduction gives it - and itsphenomena- a firmer place in the larger scheme of biological theory .If the reduction involves major correction , the corrected , reducedtheory continues to playa role in prediction and explanation , and it


too has a place in the larger scheme of things . Only if one theory iseliminated by another does it fall by the wayside .

Nor , it must be emphasized, does intertheoretic reduction imply anessentially " compositional " research strategy. By a " compositionalstrategy" is usually meant that one must first know all about themicro properties (the parts ) before addressing the macro properties(the whole ). True enough , higher -level capacities will be explained interms of lower -level capacities or structures , but the order of discoveryis not the same as the order of explanation. As a matter of discovery,coevolution of higher -level and lower -level theories is certain to bemore productive than an isolated bottom -up strategy.

But if a reductive future for generalizations such as (1) through (5)of scientific psychology is not considered to be impossible or evencontentious , then what is the issue ? Is there a residual source of

objections to intertheoretic reduction even after the story of the na-ture of intertheoretic reduction dispels some of the antireductionistbugbears ? The answer is clearly yes . The residual problems are quitecomplex, and they condense around two substantial points . Sim-plified , the first can be stated thus : " Our ordinary understanding ofour mental states provides the observational base against which theadequacy of any psychological theory must be tested, and this , it isargued on various grounds , is not reducible to neurobiology . Theframework features of our commonsense understanding are unrevis -able and inalienable ." The reasons for this conclusion are very di -

verse , and the arguments supporting this general sense of thecorrectness of the commonsense framework will be the focus of

chapter 8.The second condensation point concerns representations and the

nature of the computations over representations . Simplified , it runsas follows : " Theories of human cognition wilJ be radically incompleteunless they can provide some characterization of representations andthe transitions between representations. If cognition involves computa -tion , then it involves operations on representations . So far the onlyline on such a characterization of representations depends on a con -ception of representation embodied in our ordinary understanding ofmental states . But this is a conceptiolL that resists reduction , andgeneralizations concerning representations will not be reducible toneurobiological generalizations . " Examples of generalizations that re-fer to representations can be found in social psychology , linguistics Iperceptual psychology , and cognitive psychology . Consider as exam-ples the following generalizations, drawn from Nisbett and Ross1980 :


6. People ' s inferences about what caused an event or an action

are strongly influenced by the concreteness or the imaginabilityof available information .

7. When someone has an opinion on a emotionally significantmatter , conflicting evidence is treated as if it were supporting ,impressions formed on the basis of early evidence survive expo-sure to inconsistent evidence presented later, and beliefs survivethe total discrediting of their evidence base.

Or consider a different sort of generalization from developmentallinguistics :

8. There is a stage in language learning during which children" regularize" common irregular verbs, even though they havenever heard instances of such regularizations . For example , theymay say " camed " instead of " came ," " gived " instead of " gave ,"" supposen' t" instead of " isn"t supposed to," and so forth .

The resistance to the goal of a unified theory , therefore, devolvesnot upon generalizations of such mien as (1) through (5) but upongeneralizations that pertain to representations . If a significant part ofhuman information processing involves operations on representa -tions, and I agree that it must , then the quarrel is a singularly impor -tant one, for it concerns the future development of that domain ofscientific psychology which addresses the cognitive capacities ofhumans and other organisms . Moreover , this antireductionist argu -ment is relevant not only to the wider question of neuroscience -psychology unity of theory but also to the question of a unified theoryat the psychological level . The reason is this : if generalizations (1)through (5) and their kind are reducible to neurobiological theory , but(6) through (8) and their kind are not , this forecasts a fragmentation oftheory at the level of psychological states and processes.

It is important to try to find out whether or not the argumentsagainst the unified conception are right , for the issue bears upon howwe decide to do research. If we are persuaded that a unified theory isimpossible and that some explanations of cognition , perception , andso forth , cannot ever be explained in terms of neurobiological theory ,then this profoundly affects how we conceive of our long-term re-search goals, and that affects our more immediate research strategies.Which research intuitions to weed out and which to culture , which

research visions to abandon and which to nurture , are affected in

subtle and in substantial ways by how we come down on the questionof intertheoretic reduction . If the antireductionist arguments are cor -rect, then perhaps neurobiological research is largely irrelevant to


research on cognition , perception , learning , and so forth . Becausethese two lines of resistance to intertheoretic reduction of psychologyto neurobiology have methodological consequences, they deserve tobe examined carefully . I am persuaded by neither line of resistance tothe reductionist strategy, and in chapters 8 and 9 I shall try to explainwhy .

Virtually all arguments against reductionism , if they are not justconfusions about what intertheoretic reduction is, depend on thedesignation of some aspect of our commonsense framework as cor-rect and irreducible . Accordingly , the discussion of the soundness ofthese arguments must focus on that commonsense framework , itsrelation to scientific psychology , and its epistemological status. In thissection I want to establish something that is of pivotal significance tolater arguments - namely , the correctability of commonsense under -standing of mental states and processes. In chapters 8 and 9 I shallextend that claim further by arguing that both the defining categoriesand the fundamental generalizations of our commonsense frameworkshould be improved upon ; that is, in all likelihood they ought to berevised . The theme of the co - evolution of scientific theories will be the

background unification of all my arguments .

What Is Folk Psychology?So far I have referred to our " commonsense framework for under -

standing mental states and processes " without being very preciseabout what is meant . For brevity 's sake, I shall begin by replacing thatlong-winded description with a shorter label, namely " folk psy-chology ~" Now by folk psychology I mean that rough -hewn set ofconcepts , generalizations , and rules of thumb we all standardly use inexplaining and predicting human behavior . Folk psychology is com-monsense psychology - the psychological lore in virtue of which weexplain behavior as the outcome of beliefs, desires, perceptions, ex-pectations, goals, sensations, and so forth . It is a theory whosegeneralizations connect mental states to other mental states , to per -ceptions, and to actions. These homey generalizations are what pro-vide the characterization of the mental states and processes referred

to ; they are what delimit the " facts " of mental life and define theexplananda. Folk psychology is " intuitive psychology ," and it shapesour conceptions of ourselves. As philosophers have analyzed it , thepreeminent elements in folk psychological explanations of behaviorinclude the concepts of belief and desire. Other elements will of coursefigure in , but these two are crucial and indispensable .

As an example of how the theory is put to work , we may start with


a very simple case in which we need to explain why John flipped onthe light switch :

(1) " He wanted to see if his copy of Middlemarch was on his desk ,he believed that the best way to find out was to turn on the lightand look , he believed that in order to turn on the light he had toflip on the light switch , so he flipped on the light switch ."

Ordinarily , it is not necessary to make so much explicit - indeed , itwould be ludicrously pedantic to do so- and successful explanationcan be highly elliptical . Depending on the situation , " He wanted tosee if his copy of Middlemarch was on his desk " will frequently do ,because all the rest can be left understood . The " fill " is not unneces -

sary ; it is just so obvious that we can take it for granted . Two peoplewho know each other very well may leave so much unspoken that itis hard for another to follow (see for example the dialogue in JohnFowles ' s Daniel Martin ) . Sometimes , though , with small children orwith someone unfamiliar with the culture , a greater degree of explic -itness is required . Not even the explanation (1) is maximally explicit ,however , for explanations require generalizations , and its general -izations are in the wings . Unspoken (" understood " ) generalizationsdo indeed serve in the background here , though they are sufficientlyfamiliar and obvious that they are made explicit only on special occa-sions . One such generalization , albeit a low -level specimen , is this :

(2) " Whenever a person wants to bring about a state 5, and hebelieves that his doing p is a way to bring about 5, and he believestha t he can do p, and he can do p, then , barring conflicting desiresor preferred strategies , he will do p,"

Like the generalizations asserting a regularity between copper ' sbeing heated and its expanding , or between spinal injury and hyper -reflexivity , this generalization purports to describe a regularity innature . Something rather like it seems to function in the routine rea-soning about why persons behave as they do . Whether the general -ization is accurate and whether it should be improved upon are not atissue here . The central point is that background generalizations ,sometimes with a home -brewy lack of subtlety , figure in our day -to -day explanations of human behavior . Insofar as it enables us to makesense of and explain a certain range of phenomena , folk psychologyresembles the folk physics discussed in section 7.2.

The network of generalizations of folk psychology appears to beextremely rich and complicated , and undoubtedly there are variationsbetween the theoretical networks of diverse individuals . Henry Jamessurely employed a more sophisticated psychological theory than Er-


nest Hemingway , though presumably they shared many general be-liefs about why humans behave as they do. One way to begin to limnthe generalizations that figure in t,he commonsense theory of humanbehavior is to press for expansions of action explanations in order toforce the implicit and " understood " background assumptions intothe open. This is similar to the method used to limn folk physics. Forexample, many people thought that Richard Nixon knew about thecover-up of the Watergate break-in . Why ? Because, it will be said, hewas in the room when it was discussed. Why is that relevant?Crudely , because if someone x has normal hearing, and someone elsey says " p" in a normal speaking voice in x's vicinity , and x knows thelanguage, then x hears that p. Similarly , we may conclude that aperson was lying because he must have seen the body (anyone withnormal vision , in broad daylight , standing two feet away wouldhave), that someone did believe that there was money in the safe(why else did he break in and jimmy the lock), and so forth . Fodor(1981) suggests other instances: " seeing that a is F is a normal cause ofbelieving that a is F; statements that p are normally caused by beliefsthat p; the belief that a thing is red is a normal cause of the inferencethat the thing is colored .. ." (p. 25) (For more discussion on the back-ground generalizations, see Paul M . Churchland 1970, 1979.)

Those who find these generalizations to have an excessively crac-ker-barrel flavor should recall that they are up for discussion preciselyso that antireductionist arguments citing the essential correctness offolk psychology can be addressed. Admittedly , the generalizations dohave a cracker-barrel quality , but this is characteristic of folk theorygenerally, and it does not in the least imply that they are simple-minded . On the contrary , however folkish it is, folk psychology as aframework of understanding is very complex. Moreover , folk psy-chology is where scientific psychology began, and if scientific psy-chology is to revise and improve upon folk psychology , it must knowwhat that framework consists of and whether and to what extent itcan be revised .

The insight that our psychological concepts are nodes in a back-ground theory and that our explanations of human action proceedwithin the framework of that theory is owed mainly to Sellars (1963)and Feyerabend (1963b,c). It is an insight that has profoundly in-fluenced research in the philosophy of mind . Together with the re-lated work in epistemology and philosophy of science, the " theor)T"theory of our commonsense beliefs about the mind has engenderednew understanding of the nature of mental concepts and renderedtractable some baffling traditional questions, some of which pertain toreduction .3 Before discussing how these insights can help in confront -


ing the question of reduction and the mind -body problem , certainpreliminary issues should be addressed.

The Origins of Folk TheoryOne query to be raised about the Sellars-Feyerabend thesis is this :How do persons come by the folk theory ? And where did it comefrom in the first place? Apparently , we do not learn folk psychologyin the way we learn Newtonian theory or molecular genetics, nor dowe typically make conscious or labored use of folk psychologygeneralizations .

Some of the theory may be acquired as we learn the language, andsome of it may be acquired in a nonchalant and unreflective way aspart of growing up among conspecifics . Some of it may indeed in -volve explicit instruction of old saws (" The bearer of bad news may behimself the object of dislike ," " People don ' t like show -offs " ), andsome of it may involve imparting rather more recent information(" Pupil size of the person one is looking at affects beliefs about howfriendly the person is" ). The etiology of an individual 's possession ofa folk psychology is probably much like the etiology of his possessionof a folk physics, and folk thermodynamics , and so forth . For all wecan tell now , the mind -brain may have an innate disposition to favorand " grow " the rudiments of certain folk theories, including folkpsychology and folk physics.. As to where the theory came from , certainly the image of a homohabilis Newton squatting at the cave mouth , pondering how to ex-plain human behavior and finally sketching out the basics of folkpsychology with jawbone and berry juice, is not very plausible . Theancestry of folk physics, folk thermodynamics , and folk theory ofmatter is similarly clouded in the mists of the far distant past, and ajawbone and berry juice theory is not plausible for any of them .

Sellars tells a kind of " just -so" story in which a primitive peoplebegin to fashion a folk psychology by postulating inner states charac-terized on the model of overt speech . The folk discover it useful incertain conditions to say that someone is in a state analogous to thestate he is in when he says out loud , " There is a rabbit ." Thus , theycome to attribute covert or inner speech states to each other , andthereby they come to attribute thoughts to each other . But this storywas designed not so much to be anthropologically reasonable as toemphasize a logical point . Sellars ' s thesis was that beliefs and desiresare beliefs that p and desires that p, and hence that the logic of suchexpressions is importantly related to the logic of overt utterancesof " p . , ,4

In order to characterize folk psychology , folk physics, and all the


rest as theories, what is important is not that they originated in self-conscious construction , but that in their explanatory and predictiverole they function as theories. In this respect, folk psychology and folkphysics deserve to be called theories . Although it would be satisfyingto know the origins of commonsense lore and to know how anyindividual comes to have the lore he has , our ignorance on thesematters in no way impugns the claim that the lore should be consid -ered a theory in the defined sense. For that claim concerns the epis-temological status and function of the lore, not its origins .

Folk Theory and RationalityPropositional attitudes are those mental states whose identity de-pends on a proposition specifying the content . If Jones has the beliefthat hawks eat mice , then the proposition " Hawks eat mice " specifiesthe content or " object" of his belief- in other words , it specifies whathis belief is. Additionally , Jones might be afraid that hawks eat mice orhope that hawks eat mice , or expect or wish or wonder whether hawks eatmice , and in each case it is the proposition " Hawks eat mice " thatdefines the content of the propositional attitude . (Pains , tickles , anditches, by contrast, are not propositional attitudes .) We can chart thelogical relations between propositional attitudes in virtue of the logi-cal relations that obtain between the content sentences . Jones ' s beliefthat hawks eat mice and his belief that Leonard is a hawk entail his

belief that Leonard eats mice . And so on .

Much dwelt upon is the observation that explanations of humanbehavior proceed by showing how the behavior was rational in thelight of the subject's beliefs and desires, where it is the content of thebeliefs and desires that make rational sense of the behavior . For ex -

ample, Smith might say his reason for butchering the calves was thatthe cost of feed was increasing and that the price of beef cattle wasdeclining . Smith ' s private deliberations must have gone somethinglike this : " The cost of feed is increasing , the beef cattle market isdeclining , if I want to make a profit - and I do- my outlay must notexceed my income , therefore I should butcher the calves no \,\T. " Re -

place " The cost of feed is increasing " with " I could never proveFermat ' s last theorem , " and the decision to butcher the calves is no

longer reasonable in light of the contents of the mental states.The point is, there is a " rational -in-the-light -of" relation between

the contents of the mental states and the content of the decision , and

some philosophers have wished to argue that this distinguishes abso-lutely explanations of intentional action from explanations in physics,biology , and other branches of science. According to this view , even ifpsychological explanations conform to the deductive -nomological


pattern , it is not the deductive relation obtaining between the cover-ing laws, initial conditions , and the explanandum that is important ;rather, it is the internal , rational -in -the-light -of relations between thecontents of mental states that do the explanatory work .

In particular , this special relation has been cited as grounds forrejecting the claim that explanations within folk psychology arecausal explanations and that the generalizations of folk psychologyare causal-explanatory . On the contrary , it has been argued, thegeneralizations are not causal, and the style of explanation in whichthey have a role is uniquely rational as opposed to causal. (See forexample Dray 1963.) What produces human behavior , it is said,are reasons , not causes , and we understand behavior in virtue of

finding a suitable rationale, not in virtue of finding causal conditions.And this has sometimes functioned as the basis for antireductionist

arguments .

The observation that in explanations of human behavior a rational -ity relation connects statements about beliefs and desires with state -ments about behavior is entirely correct. What is mistaken is theinference that beliefs and desires therefore do not cause behavior .

More generally , it is false that the existence of a rational relationbetween statements characterizing events precludes, or is somehowat loggerheads with , a causal connection between the events. Thiscan be straightforwardly seen in a computer executing a deductivelogic program , where the states the computer runs through are re-lated by logic and by cause. Indeed, the program is precisely designedso that when certain causal relations obtain between machine states ,

then the appropriate logical relations also obtain between statementsdescribing those states.

This existence of abstract or formal relations defined over contents

or objects of " attitudes " is not , moreover , a feature unique to psy -chology . Ironically , it is in fact a point of deep similarity betweenpsychological laws and laws elsewhere in science. There are lawscontaining numerical attitudes , between which arithmetical relationshold ; laws containing vectorial attitudes , between which algebraicrelations hold ; and so forth . Once noticed, this parallel is striking ,and it speaks for , rather than against, the similarity between folkpsychology and other theories in the sciences . (See Paul M . Church -land 1970, 1979, 1981.) Consider the following :

Numerical Attitudes Propositional Attitudesx . . . has a maSSkg of n . . . believes . that p

. . . has a chargecoul of n . . . desires that p

. . . has a temperatureK of n . . . perceives that p


Folk Theory and Self-KnowledgeThe hypothesis that we operate with a folk psychology in virtue ofwhich we attribute psychological states to others and to ourselvesmay be resisted because the attribution to ourselves seems directlyobservational, without any mediating framework of categories andconcepts. The attribution of beliefs and perceptions to others may bemediated by theory and inference, it may be argued, but surely onehas direct and unmediated awareness of one's own mental states. No

. . . has energYj of n . . . hopes that petc. etc.

Not only is there a parallel ""Tith respect to attitudes identified viaabstract objects (propositions and numbers); there is also a parallel inthe laws that specify the abstract relations (logical and numerical ) thatobtain between distinct states. Recall the generalizations with whichthis section began and compare, for example, the following :

9. If a body x has a mass m, and if x suffers a net force off , then xaccelerates at flm .10. If a gas has a pressure P, and a volume V, and a quantity m,then barring very high pressure or density , it has a temperatureof PVlmR, where R is the gas constant.

What I have wished to emphasize here is that there is nothingespecially mentalistic , mystical , or noncausal about generalizationsthat exploit abstract relations between abstract objects. Generaliza-tions in folk psychology do it , but so do generalizations in physicsand chemistry . The existence of " rational -in-the-light -of" relationsbetween objects of propositional attitudes fails to imply that psycho-logical explanations are noncausal explanations . (See also chapter 9.)

Finally , it should be observed that propositions and the logicalrelations defined over them constitute an impressively powerfulstructure , and insofar as folk psychology exploits propositions as itsdomain of abstract objects, it inherits the power of that structure .That is, it inherits as part of psychology that systematicity which isinherent in the logical system of propositions . (See Fodor 1975.) It isthis insight , made the more appealing by the discoveries of modernlogic and by the construction of electronic devices conforming tologic, that has engendered a certain " logicist" conception of themind . On this conception , the mind is fundamentally a sententialcomputing device, taking sentences as input from sensory transduc-ers, performing logical operations on them, and issuing other sen-tences as output .

theory is invoked , and none needed , to recognize what mental statesone has . Or so it seems .

The impression of immediacy cannot , however , be taken at facevalue . To begin with , knowledge of the external world can seem quiteas direct and immediate as knowledge of one ' s inner states . When Ilook out my window , it seems I immediately see a tree , and im -mediately see that it is larger than my computer , though I am un -aware of deliberate classification or ponderous inferring - or even oflightning -fast inferring , for that matter . So far as data from introspec -tion are concerned , I simply see a tree . Sometimes , to be sure , I haveto undertake a bit of reasoning if I am puzzled about what I see, butcorrelatively , sometimes I undertake a bit of reasoning to determinewhat I really want or whether my current feeling of unease is embar -rassment , anger , or frustration .

As far as the sheer impression of immediacy is concerned , outerperceptions seem as immediate as inner perceptions . But failure tointrospect evidence of cognitive engagement of a conceptualframework does not imply that no conceptual framework is engaged .In the case of perception of the external world we certainly do nottake introspection ' s impression of immediacy to be correct . Complexinformation processing , pattern recognition , and conceptualizing cer-tainly underlie ostensibly simple and " direct " perceptual judgments .Consider for example a perceptual effect such as size constancy , inwhich the visual impression of a tree will be seen as larger than thevisual impression of one ' s thumb , even though the latter occupiesa larger area of the visual field . The perceptual judgment is asimmediate as anything can be, inasmuch as there is no awarenessof a period of calculation and reasoning . Nevertheless , the infor -mation processing enabling the judgment is likely to be subtle andcomplex .

Part of the trouble in addressing the " immediacy " objection is sim -ply that it is hard to know what " immediate " is supposed to meanhere . If it means " not mediated by subcognitive processes ," the thesisis obviously mistaken . If it means " not mediated by cognitive pro -cesses," it is just as surely mistaken . If someone asks " Would you liketo fly a hang -glider ?" , and Jones ponders a bit and says " Yes," thenfrom what we already know in neurobiology and psychology , we cantake it as read that a highly orchestrated sequence of complex mind -brain processes made it possible for Jones to tell us what he desires .

The intuition that recognition of mental states is somehow sheerlyobservational and free of cognitive interpretation must eventuallyconfront the arguments considered earlier that undermined the logi -cal empiricist conception of observation . The upshot of those argu -



ments (see section 6.4) was that there is no independent observationlanguage ; that all observation terms are nodes in a conceptualframework and thus are interlaced with other observation terms andwith theoretical terms ; that all observation terms derive at least some

of their meaning from the generalizations that embed them (Hesse1970, Paul M . Churchland 1979) . The observation predicates used inthe recognition of inner states are no less interconnected with theorythan the observation predicates used to describe the external world .Learning to apply mental predicates crucially involves learning ap -propriate generalizations that specify the conditions of correctapplication .

Just as learning the word " dog " involves learning generalizationsabout dogs , so learning words such as " is in pain " involves learningsuch things as that hunger , a bang on the thumb with a hammer ,holding a snowball in bare hands for a long time , having one 's hairpulled , eating too much candy , and sustaining a cut all cause pains ;similarly for such expressions as " is anxious ," " wants that p," " isfrustrated ," " likes a," and " believes that p." These generalizationsare cut from fustian stuff , but the claim is not that they are truegeneralizations of folk psychology , but just that they are generaliza -tions of folk psychology , and it is in virtue of such generalizationsthat the embedded categories are implicitly defined . Whether thesegeneralizations are true , or grossly misconceived , or in need of majormodification or minor fine tuning , are distinct questions .

Notice too that the conditions of application are really very diverseand that the felt sensations can be very different and yet still be calledpain (Churchland and Churchland 1981) . Certainly there is a learnedcomponent in the recognition of mental states , though presumablythere is an innate mechanism for such learning . Awareness of innerstates is a species of perception that is directed internally rather thanexternally , and the observational predicates employed in recognitionof mental states enjoy no special status . Moreover , what may be apredicate applied by ponderous inference at one stage of life (e.g " thepredicate " feeling intellectual satisfaction " ) may subsequently cometo be routinely used and thus without studied application of therules .

A traditional reason for supposing that introspective apprehensionis unique derived from the epistemological enthusiasm for bedrockfoundations to support the structure of knowledge , and it dependedon the assumption that one could not err in recognition of one ' s O\l\7nmental states . By contrast , error in perceiving the external world or inattributing mental states to others was considered commonplace .Now even supposing it were true that " inner sense" does not in fact


err, notice that it does not follow that no theory (no categorialframework ) is employed . The remarkable accuracy could be owed to aremarkably accurate application of a true theory in inner perception .But the traditional view wanted more , and hence it was argued thatone could not be wrong - not merely that one mercifully , but contin -gently , escaped error . If we could not be wrong , that allegedly wouldbe evidence for immediacy and directness.

The trouble is that we can be wrong and often are . Sometimes

behavior is the outcome of desires we explicitly disavow or beliefs weexplicitly deny . Even when the conditions are in no way pathological ,we sometimes mistake the causes of our choices and judgments andmisidentify the assorted influences on our behavior (Nisbett and Ross1980, Gazzaniga and LeDoux 1978). A sensation of extreme cold canbe mistaken for a sensation of heat , a dreamed pain can be seen to beunreal upon awakening , and in general expectation effects can induceerrors in the perception of our mental states (Paul M . Churchland1985) .

Even though we may be understood to apprehend inner statessuch as beliefs and desires within the confines of a categorialframework , and even though it is agreed that we can err in the appli -cation of the categories of that framework , nevertheless it may besupposed that awareness itself is what is immediately apprehended ,and hence apprehended without benefit of a categorial framework .Moreover , it may seem that in the phenomenon of awareness, thosewith enthusiasm for absolute foundations will have found what theyseek . For it may seem that we cannot be mistaken that we are aware .

This may be supposed to be the Cartesian corker that shows that

some domain of our mental life is immediately and incorrigiblyapprehended .

There has long been much ado about Descartes's argument andwhat it implies with regard to the self and self-knowledge . Afterseeing the possibility of doubting the truth of most of his beliefs aboutthe world , Descartes found a case that he took to be immune to

reasonable doubt . Paraphrasing, he said, " I cannot reasonably doubtthat I think - that I am aware ." Thus Descartes ' s memorable conclu -

sion : " I think , therefore I am " (Cogito ergo sum ). Now the issue inthis section concerns whether one understands the mental states of

oneself and others within a theoretical framework . For this issue ,

what is important is that the Cartesian argument fails to show thatour inner goings-on are directly and immediately presented to us. Itfails to show that no categorial framework or theory is employed inthe application of predicates to one's own mental states.

Here's why . The first point is a reiteration of the earlier' observa-

tion : awareness, whatever its neurobiological identity , is bound to bethe outcome of much processing and brain activity . This is unconten -tioUS.5 Second, if cognitive categories figure in that processing, that issufficient for my purposes . Given a suitably liberal reading of ' /cogni-tive," knowing that one is aware involves cognitive use of the conceptof awareness. This is surely quite as uncontentious .6 Third , it is com-patible with the Cartesian argument that the relevant theoreticalframework and the mechanisms for its application are such thatwhenever the brain goes into a state with the content 1'1 am aware," itis always true that one is aware. But this will only be a matter ofcontingent fact about the way the brain works , not a necessary factdrawn from a priori philosophy .

Alternatively , for all we know no~Y, it may happen that one's braindoes sometimes go into a state with the content 'II am aware" when itis false that one is aware, perhaps, for example, when the brain is incertain kinds of coma. Such might even be the stock response of thebrain to sudden severe trauma . I certainly do not know that this neverhappens or never could happen . Intuitions consulted from the com-fort of the armchair may be quite misleading concerning the nature ofthe empirical facts, here as elsewhere. From the armchair , it mighthave seemed to be safe to assume that if one is blind one cannot fail to

be aware that one is blind or that if one makes accurate perceptualjudgments about the world one must be perceptually a",,-'are. Y et, aswe have seen (section 5.6) the assumptions seem to be false given theneurological data. The armchair hypotheses should present them-selves as hypotheses open to evidence from the world , not ashidebound and unassailable truths of reason.

Here is a deeper reason for pausing : it is possible that the folktheory that gives " awareness" its meaning might turn out to be dis-placed by a superior theory . Accordingly , just as it turned out thatthere was no such thing as impetus , there may be no such thing asawareness. This is not as bizarre as it first sounds. Presumably there issome monitoring mechanism or other chugging away in the mind -brain in virtue of which our current employment of the concept' I awareness" can get a foothold - just as there is something or othergoing on in the world in virtue of which the employment of theconcept " impetus " got a foothold . But we may misapprehend it , folkpsychology may be a thoroughly muddled theory of mental business,and a newer and better theory may yield a theoretically more satisfac-tory characterization of it . What is it? Well , whatever it is that \t\renow , perhaps mistakenly , characterize as awareness, which somefuture theory may characterize in a quite different way .

In summary , introspective capacities do not appear to be incompat -



ible with the " theory " theory of our commonsense understanding ofmental life . On the contrary , one's apprehension of one's own mentalstates is a cognitive process that at some level exploits a conceptualframework . The nature of that process, the degrees of plasticity itmay have, and the nature of the representations and their role in thatprocess remain to be empirically discovered by cognitive neurobiol -ogy. Moreover , the notion of a conceptual or theoretical framework isstill only roughly delimited and will itself need to be revised, ex-tended, or perhaps eventually displaced, by cognitive neurobiology . Iview the " theory " theory as a provisional conception that enables usto disentangle ourse.lves from a confining epistemology and aconfining philosophy of mind . As neuroscience and scientific psy-chology collectively come to understand more about the nature ofinformation processing, so we shall come to understand whattheorizing is, and our inchoate conceptions will mature . Ultimately ,to invoke again Neurath 's metaphor , this plank in our boat will itselfbe changed. This is not a philosophical flaw in the " theory" theory ; itis just a frank acknowledgment that we do not understand much at allabout what it is for a brain to theorize .

Folk Psychology and a Nonphysical MindFinally , it may be argued against the " theory " theory of mental predi -cates that if mental states are states of a nonphysical mind , then ouraccess to them must be direct rather than theory -mediated . The argu-ment is simply a non sequitur . Even if the mind should be nonphys -ical, its access to its states and processes may be via a theory , and itmay have lots of nonconscious mental reasoning and processing andlots of nonconscious beliefs and desires. Moreover , even the nonphy -sical mind may make mistakes and have false theories, one of whichmay be about its own states and how they interact . Nonphys -icalness in and of itself implies nothing about immediacy, directness,and privileged access. The ontological question about what sort ofsubstance the mind is must be distinguished from the epistemologicalquestion concerning how the mind knows itself .

7.4 Conclusions

lntertheoretic reduction is fundamentally a relation between theories,such that one theory T 1 is said to reduce to another theory T 2 if T 1 (oran analogue of it ) is deducible from T2. One phenomenon PI is said toreduce to another P2 if the theory that characterizes PI reduces to atheory that characterizes P2. Reductions in science are only rarelysmooth reductions with uncomplicated cross-theoretical identifica -


tions . More typically , they are bumpy and thus involve varyingdegrees of revision to the reduced science. Sometimes the correctionrequired is so massive that the candidate theory is better describedas having been displaced outright .

Accordingly , neuroscientists should not at this stage of their in -quiries feel compelled to envision the details of a future reduction offolk psychological generalizations , nor should they suppose them-selves obliged to seek identifications between neurobiological statesand psychological states as characterized uJithin folk psychology.Identifications may be forthcoming , but then again they may not .Whether they are is an empirical matter, not an a priori matter . Thecrucial point is that identities are not required for reductions at aremove from the retentive end of the spectrum . So unless neuroscien-tists can tell in advance that they will not find any reason either torevise or to displace folk psychology , they are not honor bound todesign their research to turn up such identities .

The objections to the reductionist program that envisions a unifiedtheory of the mind -brain , in which psychological theory is ultimatelyexplained by neurobiological theory , derive from two sources: (1)from a conviction that a subset of generalizations in scientific psychol-ogy are of such a nature as to resist reduction , and (2) from a convic-tion that folk psychology is both substantially correct and essentiallyirreducible to neurobiology . The generalizations in scientific psychol-ogy that are thought to be problematic are typically in the domains ofcognitive psychology and social psychology and make reference tobeliefs, inferences, or, in general, propositional representations . In-sofar as these problematic generalizations rely on a theory of repre-sentations drawn from folk psychology , these two patterns ofobjection have a common element .

Although folk psychology has a profound familiarity and ob-viousness, and although the categories of folk psychology are obser-vationally applied , it nevertheless remains true that folk psychologyis a theoretical framework and hence a framework whose adequacycan be questioned and assessed. The adequacy of folk psychology isin no way secured by its seeming to be overwhelmingly obvious., byits being observationally applied , by its being applied introspectively ,or even by its being innate, if such be the case. If we see that folkpsychology has no right to epistemological privilege , and no immu -nity to revision and correction , then we can begin to see that itsgeneralizations and categories can be corrected and improved upon .Indeed, an underlying theme in scientific psychology is that they canand are being modified and even superseded.


Once it is recognized that folk psychology is not immune toscientific improvement , this reveals the possibility that what willeventually reduce to neuroscience are generalizations of scientificpsychology that have evolved a long way from the home " truths " ofextant folk psychology . Moreover , as I shall argue in chapters 8 and 9,these generalizations will likely to be the product of a long co-evolution with neurobiology . What may eventually transpire , there-fore, is a reduction of the evolved psychological theory I and thisevolved theory may end up looking radically different from folk psy-chology- different even in its categorial profile . In other words , thepsychological generalizations that are eventually considered ripe fo~reduction may be both richer and substantially revised relative tocurrent generalizations in folk psychology . If that is the directiontaken by the co-evolution of psychology and neuroscience , futurehistorians of science will see folk psychology as having been largelydisplaced rather than smoothly reduced to neurobiology .

I have not argued that this will be the fate of folk psychology I butonly that once we have seen that folk psychology has no more epis-temological privilege than folk physics, that the categorial structure offolk psychology has no more sanctity and a priori consecration thanthat of folk physics, we can rid ourselves of a huge weight of argu-ment that tempts us by appeal to the obviousness and the certaininviolability of folk psychology .

It must now be determined whether the two lines of argumentagainst the reductionist program can show what is both irreducibleand correct about folk psychology . It will not be sufficient for thesearguments to defend just irreducibility , since irreducibility in a theorycan be owed to its being so radically amiss that wholesale displace-ment is exactly what it deserves. Assuming that this chapter hasestablished that folk psychology is assessable for its empirical ade-quacy and improvable by empirical research if found wanting , it willalso not be enough for these arguments simply to point to a catego-ry 's being observationally applied or seeming to be obvious . So muchis entirely compatible with the inadequacy and falsity of a theory .Nor , of course, can the arguments quietly help themselves to as-'sum ptions about the correctness of the generalizations and ca tego-ries. The focus of chapter 8 will be a set of arguments pertaining to thenature of our subjective experiences, and chapter 9 will examine andevaluate the arguments based on the theory of the nature ofrepresen ta tions .

Reduction and the Mind-Body Problem 313

Selected Readings

Churchland, Paul M. (1979). Scientific realism and the plasticity of mind. Cambridge:Cambridge University Press.

Feyerabend, Paul K. (1981). Philosophical papers. Vols. 1 and 2. Cambridge: CambridgeUniversity Press.

Hooker, C. A. (1981). Towards a general theory of reduction. Part I: Historical andscientific setting. Part II: Identity in reduction. Part III : Cross-categorial reduction.Dialogue 20:38- 59, 201- 236, 496- 529.

Kuhn, Thomas S. (1962). The structure of scientific revolutions. 2nd ed. (1970). Chicago:University of Chicago Press.

Wimsatt, William (1976). Reductive explanation: a functional account. In PSA 1974(Proceedings of the Philosophy of Science Association), ed. R. S. Cohen, C. A.Hooker, A. C. Michalos, and J. W. van Evra, 671- 710. Dordrecht, Holland: D.Reidel.

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