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Limits to the Scientific Understanding of ManAuthor(s): Gunther S. StentSource: Science, New Series, Vol. 187, No. 4181 (Mar. 21, 1975), pp. 1052-1057Published by: American Association for the Advancement of ScienceStable URL: http://www.jstor.org/stable/1739279 .

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least cost ration problems. Information aboutkinds of programs available and their use isdetailed in B. F. Lanpher, Ed., Inventoryof EDP programs used in Agricultural Ex-tension (Extension Service, Department ofAgriculture, Washington, D.C., 1973). Initialefforts in use of computers for real-time fore-casting are described in R. T. Huber andR. L. Giese, Proc. North Cent. BranchEntomol. Soc. Am. 28, 139 (1973).12. We presented these concepts in verbal andwritten form as a part of a cropping systemproposal to officials of the USDA in Sep-tember 1971. Represented were the ExtensionService, Cooperative States Research Service,Animal and Plant Health Inspection Service,and Agricultural Research Service.13. A. B. Clymer, Simulation 15, 50 (1970).14. G. E. Miles, Purdue Univ. Agric. Exp. Sta.Bull. No. 50 (1974).15. J. A. Witz, Agric. Sci. Rev. Coop. StateRes. Serv. U.S. Dep. Agric. 11, 37 (1973).

least cost ration problems. Information aboutkinds of programs available and their use isdetailed in B. F. Lanpher, Ed., Inventoryof EDP programs used in Agricultural Ex-tension (Extension Service, Department ofAgriculture, Washington, D.C., 1973). Initialefforts in use of computers for real-time fore-casting are described in R. T. Huber andR. L. Giese, Proc. North Cent. BranchEntomol. Soc. Am. 28, 139 (1973).12. We presented these concepts in verbal andwritten form as a part of a cropping systemproposal to officials of the USDA in Sep-tember 1971. Represented were the ExtensionService, Cooperative States Research Service,Animal and Plant Health Inspection Service,and Agricultural Research Service.13. A. B. Clymer, Simulation 15, 50 (1970).14. G. E. Miles, Purdue Univ. Agric. Exp. Sta.Bull. No. 50 (1974).15. J. A. Witz, Agric. Sci. Rev. Coop. StateRes. Serv. U.S. Dep. Agric. 11, 37 (1973).

For the past two centuriesscientists,particularlyin English-speakingcoun-tries, have generally viewed their at-tempt to understand the world fromthe epistemologicalviewpoint of posi-tivism. All the while, positivism hadbeen under attack from philosophers,but it is only since the 1950's that i.tspowerful hold on the students of na-ture finally seems to be on the wane.There is as yet no generally accepteddesignationfor the philosophicalalter-natives that are replacing positivism,but the view of man known as "struc-turalism,"which has informed certainschools in the human sciences, appearsto be centralto the latter-dayepistemo-logical scene (1). As I shall try to showin this article, in addition to the philo-sophical and psychological argumentsthat have been advanced in its behalf,

For the past two centuriesscientists,particularlyin English-speakingcoun-tries, have generally viewed their at-tempt to understand the world fromthe epistemologicalviewpoint of posi-tivism. All the while, positivism hadbeen under attack from philosophers,but it is only since the 1950's that i.tspowerful hold on the students of na-ture finally seems to be on the wane.There is as yet no generally accepteddesignationfor the philosophicalalter-natives that are replacing positivism,but the view of man known as "struc-turalism,"which has informed certainschools in the human sciences, appearsto be centralto the latter-dayepistemo-logical scene (1). As I shall try to showin this article, in addition to the philo-sophical and psychological argumentsthat have been advanced in its behalf,

The author is Professor of Molecular Biologyat the University of California, Berkeley 94720.This article is adapted from a lecture given ata seminar on Mobility under the joint auspicesof the American Foundation for the Blind andSt. Dunstan's Society, held at Trinity College,Cambridge in September 1973.1052

The author is Professor of Molecular Biologyat the University of California, Berkeley 94720.This article is adapted from a lecture given ata seminar on Mobility under the joint auspicesof the American Foundation for the Blind andSt. Dunstan's Society, held at Trinity College,Cambridge in September 1973.1052

16. For a more complete description of the plantsimulation, see G. E. Miles, R. J. Bula, D. A.Holt, M. M. Schreiber, R. M. Peart, ASAE(Am. Soc. Agric. Eng.) Pap. No. 73-4547(1973).17. G. E. Miles, T. R. Hintz, A. B. Pritsker,M. C. Wilson, R. M. Peart, in Proceedingsof the 5th Annual Pittsburgh Conference onModeling and Simulation (University of Pitts-burgh, Pittsburgh, Pa., 1974), pp. 1157-1161;G. E. Miles, R. M. Peart, R. J. Bula, M. C.Wilson, T. R. Hintz, ASAE (Am. Soc. Agric.Eng.) Pap. No. 74-4022 (1974).18. D. L. Haynes, R. K. Brandenburg, P. D.Fisher, Environ. Entomol. 2, 889 (1973).19. The acronym MIRACLE stands for multi-disciplinary integrated research activities incomplex laboratory environments. This isdiscussed in greater detail in R. B. Harringtonand R. L. Giese, Proc. Fed. Exp. Biol. 33(No. 12), 2393 (1975); D. C. Beckwith, Am.Lab. (Greens Farms, Conn.) 5, 77 (1973).

16. For a more complete description of the plantsimulation, see G. E. Miles, R. J. Bula, D. A.Holt, M. M. Schreiber, R. M. Peart, ASAE(Am. Soc. Agric. Eng.) Pap. No. 73-4547(1973).17. G. E. Miles, T. R. Hintz, A. B. Pritsker,M. C. Wilson, R. M. Peart, in Proceedingsof the 5th Annual Pittsburgh Conference onModeling and Simulation (University of Pitts-burgh, Pittsburgh, Pa., 1974), pp. 1157-1161;G. E. Miles, R. M. Peart, R. J. Bula, M. C.Wilson, T. R. Hintz, ASAE (Am. Soc. Agric.Eng.) Pap. No. 74-4022 (1974).18. D. L. Haynes, R. K. Brandenburg, P. D.Fisher, Environ. Entomol. 2, 889 (1973).19. The acronym MIRACLE stands for multi-disciplinary integrated research activities incomplex laboratory environments. This isdiscussed in greater detail in R. B. Harringtonand R. L. Giese, Proc. Fed. Exp. Biol. 33(No. 12), 2393 (1975); D. C. Beckwith, Am.Lab. (Greens Farms, Conn.) 5, 77 (1973).

structuralism can draw support alsofrom biological insights into the evolu-tionaryoriginsand mannerof functionof the brain. But whereas the work ofstructuralistscientistshas shownup theessentialbarrennessof the positivist ap-proach to human behavior, even thestructuralistprogram,however merito-rious, is unlikely to lead to a scientifi-cally validated understandingof man.

PositivismThe principaltenet of positivism,asformulated in the 18th century mainlyby David Hume and the French En-cyclopaedists,is that, since experienceis the sole source of knowledge, themethods of empirical science are theonly means by which the world can beunderstood(2). Accordingto this view;the mind at birth is a clean slate onwhich there is gradually sketched arepresentationof realitybuilt on cumu-lative experience.This representationisorderly, or structured,because, thanks

structuralism can draw support alsofrom biological insights into the evolu-tionaryoriginsand mannerof functionof the brain. But whereas the work ofstructuralistscientistshas shownup theessentialbarrennessof the positivist ap-proach to human behavior, even thestructuralistprogram,however merito-rious, is unlikely to lead to a scientifi-cally validated understandingof man.

PositivismThe principaltenet of positivism,asformulated in the 18th century mainlyby David Hume and the French En-cyclopaedists,is that, since experienceis the sole source of knowledge, themethods of empirical science are theonly means by which the world can beunderstood(2). Accordingto this view;the mind at birth is a clean slate onwhich there is gradually sketched arepresentationof realitybuilt on cumu-lative experience.This representationisorderly, or structured,because, thanks

20. R. M. Peart, R. T. Huber, W. H. Blake,D. R. Wolf, G. E. Miles, ASAE (Am.Soc. Agric. Eng.) Pap. No. 74-5043 (1974).21. We express appreciation for principal con-tributions in this integrated team effort toR. J. Bula (plant physiology), C. R. Edwards(Entomology Extension), R. B. Harrington(MIRACLE Computing Center), T. R. Hintz(insect impact), D. A. Holt (plant physiology),G. E. Miles (systems analysis), and M. C.Wilson (insect population dynamics). ThePurdue Alfalfa Pest Management project issponsored by the Purdue Agricultural Experi-ment Station, the USDA Agricultural Re-search Service (Agreement No. 12-14-3001-218), and the USDA Animal and PlantHealth Inspection Service and ExtensionService (Agreement No. 12-16-100-150). Thisarticle is approved for publication by thedirector of the Purdue Agricultural Experi-ment Station as Journal Paper No. 5627.

to the principleof inductivereasoning,we can recognize regular features ofour experience and infer causal con-nections betweenevents that habituallyoccur together.The possibilityof innateor a priori knowledgeof the world, acentral feature of the 17th-centuryrationalismof Rene Descartes, is re-jectedas a logical absurdity.It is unlikely that the widespreadacceptanceof positivismhad a signifi-cant effect on the developmentof thephysical sciences, since physicistshavelittle need to look to philosophersforjustificationof their researchobjectivesor workingmethods.Moreover,once aphysicist has managed to find an ex-planation for some phenomenon, hecan be reasonably confident of theempirical test of its validity. For in-stance, the positivist rejection of theatomic theory in the late 19th century,on the grounds that no one had ever"seen" an atom, did not stop chemistsand physicists from then laying thegroundworkfor ourpresentunderstand-ing of microscopicmatter.However, inthe humansciences,particularlyin psy-chology and sociology, the situationwas quite different. Here positivismwas to have a most profound effect.One reason for this is that practitionersof the human sciences are much moredependenton philosophical support oftheir work than are physical scientists.In contrast to the clearly definablere-search aims of physical science, it isoften impossibleto state explicitly justwhat it really is about human behaviorthat one wants to explain.This in turnmakes it quite difficult to set forthclearly the conditionsunder which any

20. R. M. Peart, R. T. Huber, W. H. Blake,D. R. Wolf, G. E. Miles, ASAE (Am.Soc. Agric. Eng.) Pap. No. 74-5043 (1974).21. We express appreciation for principal con-tributions in this integrated team effort toR. J. Bula (plant physiology), C. R. Edwards(Entomology Extension), R. B. Harrington(MIRACLE Computing Center), T. R. Hintz(insect impact), D. A. Holt (plant physiology),G. E. Miles (systems analysis), and M. C.Wilson (insect population dynamics). ThePurdue Alfalfa Pest Management project issponsored by the Purdue Agricultural Experi-ment Station, the USDA Agricultural Re-search Service (Agreement No. 12-14-3001-218), and the USDA Animal and PlantHealth Inspection Service and ExtensionService (Agreement No. 12-16-100-150). Thisarticle is approved for publication by thedirector of the Purdue Agricultural Experi-ment Station as Journal Paper No. 5627.

to the principleof inductivereasoning,we can recognize regular features ofour experience and infer causal con-nections betweenevents that habituallyoccur together.The possibilityof innateor a priori knowledgeof the world, acentral feature of the 17th-centuryrationalismof Rene Descartes, is re-jectedas a logical absurdity.It is unlikely that the widespreadacceptanceof positivismhad a signifi-cant effect on the developmentof thephysical sciences, since physicistshavelittle need to look to philosophersforjustificationof their researchobjectivesor workingmethods.Moreover,once aphysicist has managed to find an ex-planation for some phenomenon, hecan be reasonably confident of theempirical test of its validity. For in-stance, the positivist rejection of theatomic theory in the late 19th century,on the grounds that no one had ever"seen" an atom, did not stop chemistsand physicists from then laying thegroundworkfor ourpresentunderstand-ing of microscopicmatter.However, inthe humansciences,particularlyin psy-chology and sociology, the situationwas quite different. Here positivismwas to have a most profound effect.One reason for this is that practitionersof the human sciences are much moredependenton philosophical support oftheir work than are physical scientists.In contrast to the clearly definablere-search aims of physical science, it isoften impossibleto state explicitly justwhat it really is about human behaviorthat one wants to explain.This in turnmakes it quite difficult to set forthclearly the conditionsunder which anypostulatedcausal nexus linking the ob-served facts could be verified. Never-theless, positivism helped to bring thehuman sciences into being in the firstplace, by insisting that any eventual

SCIENCE, VOL. 187

postulatedcausal nexus linking the ob-served facts could be verified. Never-theless, positivism helped to bring thehuman sciences into being in the firstplace, by insisting that any eventualSCIENCE, VOL. 187

Limits to the ScientificUnderstandingof Man

Human sciences face an impasse since their centralconcept of the self is transcendental.

Gunther S. Stent

Limits to the ScientificUnderstandingof Man

Human sciences face an impasse since their centralconcept of the self is transcendental.

Gunther S. Stent


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understanding of man must be basedon the observation of facts, rather thanon armchair speculations. But, by limit-ing inquiry to such factual observationsand allowing only propositions that arebased on direct inductive inferencesfrom the raw sensory data, positivismconstrained the human sciences to re-main taxonomic disciplines whose con-tents are largely descriptive with littlegenuine explanatory power. Positivismclearly informed the 19th-centuryfounders of psychology, ethnology, andlinguistics. Though we are indebted tothese founders for the first corpus ofreliable data concerning human behav-ior, their refusal to consider these datain terms of any propositions not de-rived inductively from direct observa-tion prevented them from erecting atheoretical framework for understand-ing man.

StructuralismStructuralism transcends the limita-

tion on the methodology, indeed on theagenda of permissible inquiry, of thehuman sciences imposed by positivism.Structuralism admits, as positivism doesnot, the possibility of innate knowledgenot derived from direct experience. Itrepresents, therefore, a return to Carte-sian rationalist philosophy. Or, moreexactly, structuralism embraces this fea-ture of rationalism as it was later re-worked by Immanuel Kant for hisphilosophy of critical idealism. Kantheld that the mind constructs realityfrom experience by use of innate con-cepts, and thus to understand man itis indispensable to try to fathom thenature of his deep and universal cogni-tive endowment. Accordingly, struc-turalism not only permits propositionsabout behavior that are not directlyinducible from observed behavioraldata, but it even maintains that therelations between such data, or surfacestructures, are not by themselves ex-plainable. According to this view thecausal connections that determine be-havior do not relate to surface struc-tures at all. Instead, the overt behav-ioral phenomena are generated bycovert deep structures, inaccessible todirect observation. Hence any theoret-ical framework for understanding manmust be based on the deep structures,whose discovery ought to be the realgoal of the human sciences.

Probably the best known pioneer ofstructuralism is Sigmund Freud, towhom we owe the fundamental insight21 MARCH 1975

that human behavior is governed notso much by the events of which we areconsciously aware in our own minds orwhich we can observe in the behaviorof others, but rather by the deep struc-tures of the subconscious which aregenerally hidden from both subjectiveand objective view. The nature of thesecovert deep structures can only be in-ferred indirectly by analysis of the overtsurface structures. This analysis has toproceed according to an elaboratescheme of psychodynamic concepts thatpurports to have fathomed the ruleswhich govern the reciprocal transfor-mations of surface into deep and ofdeep into surface structures. The greatstrength of Freudian analytical psychol-ogy is that it does offer a theoreticalapproach to understanding human be-havior. Its great weakness, however, isthat it is not possible to verify its prop-ositions. And this can be said also ofmost other structuralist schools activein the human sciences. They do try toexplain human behavior within a gen-eral theoretical framework, in contrastto their positivist counterparts whocannot, or rather refuse to try to do so.But there is no way of verifying thestructuralist theories in the manner inwhich the theories of physics can beverified through critical experiments orobservations. The structuralist theoriesare, and may forever remain, merelyplausible, being, maybe, the best wecan do to account for the complex phe-nomenon of man.

Ethnology and LinguisticsFor instance, positivist ethnology, asconceived by one of its founders, FranzBoas, sought to establish as objectivelyand as free from cultural bias as possi-ble the facts of personal behavior andsocial relations to be found in diverse

ethnic groups. Insofar as any explana-tions are advanced at all to account forthese observations, they are formulatedin functionalist terms. That is to say,every overt feature of behavior or so-cial relation is thought to serve someuseful function in the society in whichit is found. The explanatory work ofthe ethnologist would be done once hehas identified that function and verifiedits involvement by means of additionalobservations. Accordingly, the generalaim of this approach to ethnology isto show how manifold and diverse theways are in which man has adapted hisbehavior and social existence to therange of conditions that he encountered

in settling the earth. By contrast, struc-turalist ethnology, according to one ofits main exponents, Claude Levi-Strauss,views the concept of functionality asa tautology, devoid of any real explana-tory power for human behavior. Allextant behavior is obviously "function-al" since all "disfunctional" behaviorwould lead to the extinction of the eth-nic group that exhibits it. Instead offunctionality, so Levi-Strauss holds,only universal and permanent, deepstructural aspects of the mind can pro-vide any genuine understanding of so-cial relations. The actual circumstancesin which different peoples find them-selves no more than modulate the overtbehavior to which the covert deep struc-tures give rise. In other words, thepoint of departure of structuralist eth-nology is the view that the apparent;diversity of ethnic groups pertains onlyto the surface structures and that attheir deep structural level all societiesare very much alike. Hence, the generalaim of structuralist ethnology is to dis-cover those universal, deep mentalstructures which underlie all humancustoms and institutions.

Positivist linguistics, as conceived byits founders, such as Ferdinand de Saus-sure and Leonard Bloomfield, addressesitself to the discovery of structural re-lations among the elements of spokenlanguage. That is to say, the work ofthat school is concerned with the sur-face structures of linguistic perform-ance, the patterns which can be ob-served as being in use by speakers ofvarious languages. Since the patternswhich such classificatory analysis re-veals differ widely, it seemed reason-able to conclude that these patterns arearbitrary, or purely conventional, onelinguistic group having chosen to adoptone, and another group having chosento adopt another convention. Therewould be nothing that linguistics couldbe called on to explain, except for thetaxonomic principles that account forthe degree of historical relatedness ofdifferent peoples. And if the variety ofbasic patterns of various human lan-guages is indeed the result of arbitraryconventions, study of extant linguisticpatterns is not likely to provide anydeep insights into any universal prop-erties of the mind. By contrast, thestructuralist approach to linguistics, ac-cording to its main modern proponent,Noam Chomsky, starts from the prem-ise that linguistic patterns are not ar-bitrary. Instead, all men are believed topossess an innate, a priori knowledgeof a universal grammar, and that de-

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spite their superficial differences, allnatural languages are based on thatsame grammar (3). According to thatview, the overt surface structure ofspeech, or the organization of sentences,is generated by the speaker from a cov-ert deep structure. In his speech act,the speaker is thought to generate firsthis proposition as an abstract deepstructure that he transforms only sec-ondarily according to a set of rules intothe concrete, surface structure of hisutterance. The listener in turn fathomsthe meaning of the speech act by justthe inverse transformation of surfaceto deep structure. Chomsky holds thatthe grammar of a language is a systemof transformational rules that deter-mines a certain pairing of sound andmeaning. It consists of a syntactic com-ponent, a semantic component, and aphonological component. The surfacestructure contains the information rele-vant to the phonological component,whereas the deep structure contains theinformation relevant to the semanticcomponent, and the syntactic com-ponent pairs surface and deep struc-tures. Hence, it is merely the phono-logical component of grammar that hasbecome greatly differentiated during thecourse of human history, or at leastsince the construction of the Tower ofBabel. The semantic component hasremained invariant and is, therefore,the "universal" aspect of the universalgrammar, which all natural languagesembody. And this presumed constancythrough time of the universal grammarcannot be attributable to any causeother than an innate, hereditary aspectof the mind. Hence, the general aim ofstructuralist linguistics is to discoverthat universal grammar.

Transcendental ConceptsNow, in retrospect, at a time when

positivism and its philosophic and sci-entific ramifications appear to be mori-bund, it seems surprising that theseviews ever did manage to gain such ahold over the human sciences. Hume,though one of its founders, already sawthat the positivist theory of knowledgehas a near-fatal logical flaw. As henoted, the validity of inductive reason-ing-which, according to positivismforms the basis of our knowledge ofthe regularity of the world, and hencefor our inference of causal connec-tions between events-can neither bedemonstrated logically nor can it be

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based on experience. Instead, inductivereasoning is evidently something thatman brings to rather than derives fromexperience. Not long after Hume, Kantshowed that the positivist doctrine thatexperience is -the sole source of knowl-edge derives from an inadequate under-standing of the mind. Kant pointed outthat sensory impressions become ex-perience, that is, gain meaning, onlyafter they are interpreted in terms ofa priori concepts, such as time andspace. Other a priori concepts, such asinduction (or causality) allow the mindto construct reality from that experi-ence. Kant referred to these conceptsas "transcendental," because they tran-scend experience and are thus beyondthe scope of scientific inquiry. Butwhy was it that, although Kant wieldedan enormous influence among philoso-phers, his views had little currencyamong scientists? Why did positivismrather than Kant's "critical idealism"come to inform the explicit or implicitepistemological outlook of much of19th- and 20th-century science? At leasttwo reasons can be advanced for thishistorical fact. The first reason is sim-ply that many positivist philosophers,especially Hume, were lucid and effec-tive writers whose message could bereadily grasped after a single readingof their works. The texts of Kant, andof his mainly Continental followers,are, by contrast, obscure and hard tounderstand.

The second reason for the long sci-entific neglect of Kant is more pro-found. After all, it does seem verystrange that if, as Kant alleges, webring such concepts as time, space, andcausality to sensation a priori, thesetranscendental concepts happen to fitour world so well. Considering all theill-conceived notions we might havehad about the world prior to experi-ence, it seems nothing short of miracu-lous that our innate concepts just hap-pen to be those that fill the bill (4).Here the positivist view that all knowl-edge is derived from experience a pos-teriori seems much more reasonable.It turns out, however, that the way toresolve the dilemma posed by the Kant-ian a priori has been open since CharlesDarwin put forward the theory ofnatural selection in the mid-19th cen-tury. Nevertheless, few scientists seemto have noticed this until Konrad Lo-renz drew attention to it 30 years ago(5). Lorenz pointed out that the posi-tivist argument !that knowledge aboutthe world can enter our mind only

through experience is valid if we con-sider only the ontogenetic developmentof man, from fertilized egg to adult.But once we take into account also thephylogenetic development of the hu-man brain through evolutionary his-tory, it becomes clear that individualscan also know something of the worldinnately, prior to and independent oftheir own experience. After all, thereis no biological reason why such knowl-edge cannot be passed on from genera-tion to generation via the ensemble ofgenes that determines the structure andfunction of our nervous system. Forthat genetic ensemble came into beingthrough the process of natural selectionoperating on our remote ancestors. Ac-cording to Lorenz, "experience has aslittle to do with the matching of apriori ideas with reality as does thematching of the fin structure of a fishwith the properties of water" (5). Inother words, the Kantian notion of apriori knowledge is not implausible atall, but fully consonant with presentmainstream evolutionary thought. Thea priori concepts of time, space, andcausality happen to suit the world be-cause the hereditary determinants ofour highest mental functions were se-lected for their evolutionary fitness,just as were the genes that give rise toinnate behavioral acts, such as suckingthe nipple of mother's breast, whichrequire no learning by experience.The importance of these Darwinianconsiderations transcends a mere bio-logical underpinning of the Kantianepistemology. For the evolutionary ori-gin of 'the brain explains not only whyour innate concepts match the worldbut also why these concepts no longerwork so well when we attempt to fath-om the world in its deepest scientificaspects. This barrier to unlimited sci-entific progress posed by the a prioriconcepts which we necessarily bringto experience was a major philosophicalconcern of Niels Bohr (6). Bohr recog-nized the essentially semantic natureof science, pointing out... as the goal of science is to augmentand order our experience, every analysisof the conditions of human knowledgemust rest on considerations of the char-acter and scope of our means of com-munication. Our basis [of communica-tion] is, of course, the language developedfor orientation in our surroundings andfor the organization of human communi-ties. However, the increase of experiencehas repeatedly raised questions as to thesufficiency of concepts and ideas incor-porated in daily language.

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The most basic of these concepts andideas are preciselythe Kantian a priorinotions of time, space, and causality.The meaning of these terms is intui-tively obvious and graspedautomatical-ly by every child in the course of itsnormal intellectual development,with-out the need to attend physics classes.Accordingly, the models that modernscience offers as explanationsof realityare pictorial representations built ofthese intuitiveconcepts.This procedurewas eminently satisfactory as long asexplanationswere sought for phenom-ena that are commensurate with theevents that are the subjectof our every-day experience (give or take a feworders of magnitude). For it was pre-cisely for its fitness to deal with every-day experience that our brain was se-lected in the evolutionarysequencethatculminated in the appearanceof Homosapiens. But the situation began tochange when, at the turn of this cen-tury, physics had progressedto a stageat which problems could be studiedwhich involve either tiny subatomic orimmense cosmic events on scales oftime, space, and mass billions of timessmaller or larger than our direct ex-perience. Now, according to Bohr,"therearosedifficultiesof orientingour-selves in a domain of experience farfrom that to the descriptionof whichour means of expressionare adapted."For it turned out that the descriptionof phenomena in this domain in or-dinary, everydaylanguageleads to con-tradictions or mutually incompatiblepictures of reality. In order to resolvethese contradictions,time andspacehadto be denatured into generalized con-ceptswhosemeaningno longermatchedthat provided by intuition. Eventuallyit appearedalso that the intuitive no-tion of causalityis not a useful one forgiving account of events at the atomicand subatomic level. All of these devel-opments were the consequence of thediscoverythat the rational use of intui-tive linguisticconceptsto communicateexperience actually embodies hithertounnoticed presuppositions.And it isthesepresuppositionswhich lead to con-tradictionswhen the attemptis made tocommunicate events outside the experi-mentaldomain.Now, whereasthe scopeof science was enormously enlargedbyrecognizingthe pitfalls of everydaylan-guage, this was achieved only at theprice of denaturingthe intuitivemean-ing of some of its basic concepts withwhich man starts out in his quest forunderstandingnature.21 MARCH 1975

The BrainIn addition to explaining in evolu-tionary terms how the human brainand its epiphenomenon,the mind, cangain possessionof a prioriconceptsthatmatch the world, modern biology hasalso shown that the brain does appearto operate accordingto principlesthatcorrespondto the tenets of structural-ism. By this statement I do not meanthat the neurologicalcorrelates of anyof the structuralistnotions, particularlynot of Freud'ssubconscious,or of Levi-

Strauss' ethnological universals, or ofChomsky'suniversalgrammar,have ac-tually been found. Such a claim wouldbe nonsensical,inasmuchas it is noitevenknown in which parts of the brain thecorrespondingprocesses occur. What Ido mean, however, is that neurologicalstudies have indicated that, in accordwith the structuralisttenets, informa-tion about the worldreaches the depthsof the mind, not as raw data but ashighly processed structures that aregeneratedby a set of stepwise, precon-scious informationaltransformationsof

L'H M M E

xCommxv Et deplus, pourentendreicy paroccafion, comment,vie iJec lors que les deux yeux de cetre machine, & les organes depctit eftre , , r rc5pofcadcplufieurs autresde fesfens font tournez vers vn mefmephlfi,ritsobje, il nesen forme paspour cela plufieursideesdansql porift fon cctveau, mais vne feule, il faut penfer que c'eft tou-(]l'I f'ul jours des mcfines points de cette fuperficie de la glande

H que tortent les Efprits, qui tendant vers divcrs tuyauxpeuvent tourner divers membres vers les mefines objers:Conme icy que c'eft du feul point b que fortent IcsEf-prits, qui tendant vers les tuyaux 4, 4, & 8, tournenr enmefinc temps les deux yeux &le bras droit vers l'objet B.Fig. 1. Descartes' theory of visual perception, as published posthumously in his Traitede l'Homme(1667). The pear-shapedcerebralstructurelabeled "H" is the pinealgland, thoughtby Descartes to be the gateway to the soul, where the percept is formed.Thus, according to this view, it is to the pineal)gland that information from the inputpart projects and it is from the pineal gland that the commands to the effector partissue. [From the Kofoid collection of the Biology Library of the University of Cali-fornia, Berkeley. Courtesy of the University of California]

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the sensory input. These neurologicaltransformationsproceed accordingto aprogramthatpreexistsin the brain.Theneurologicalfindingsthus lend biologi-cal support to the structuralistdogmathat explanationsof behavior must beformulated in terms of such deep pro-gramsand reveal the wrong-headednessof the positivist approachwhich rejectsthe postulation of covert internal pro-grams as "mentalism."One set of such neurologicalfindingsconcerns the manner in which the nerv-ous system of higher vertebrates, in-cludingman, converts the light rays en-tering the eyes into a visual percept.For the purposeof this discussionit isuseful to recall that the nervoussystemis divisibleinto threeparts: (i) an inputor sensorypart that informsthe animalabout its external and internal environ-ment; (ii) an output, or effector, partthat produces motion by commandingmuscle contraction;and (iii) an inter-nuncial part that connects the sensoryand effector parts. The most elaborateportion of the internuncialpart is thebrain. The brain does much more thanmerely connect sensory and effectorparts,however:It processesinformation.This processing consists in the! mainin making an abstraction of the vastamount of data continuously gatheredby the sensory part. In order to ab-stract, the brain destroys selectivelyportions of the input data and thustransformsthese data into manageablecategories,or structuresthat are mean-ingful to the animal. It is on the basisof the perceivedmeaningthat the inter-nuncial part issues the relevant com-mands to the effector part which thenresults in an appropriate behavioralresponse.

The Visual PathwayFor vision, the input partof the nerv-ous system is located in the retina atthe back of the eye (Fig. 1). There atwo-dimensional array of about a hun-

dred million primary light receptorcells-the rods and the cones-convertsthe radiant energy of the image pro-jected via the lens on the retina into apattern of electrical signals, as does atelevision camera. Since the electricalresponse of each light receptor cell de-pends on the intensity of light that hap-pens to fall on it, the overall activitypattern of the light receptor cell arrayrepresents the light intensity existing ata hundred million different points in thevisual space. The retina contains notonly the input part of the visual system,

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however,but also the firststages of theinternuncialpart. These first internun-cial stages include another two-dimen-sional arrayof nerve cells, namely, themillion or so ganglion cells. The gan-glion cells receive the electrical signalsgenerated by the hundred million lightreceptor cells and subject them to in-formationprocessing.The resultof thisprocessing is that the activity pattern ofthe ganglioncells constitutesa more ab-stractrepresentationof the visual spacethan the activitypatternof the light re-ceptor cells. For instead of reportingthe light intensity existing at a singlepoint in the visual space, each ganglioncell signals the light-dark contrast whichexists between the center and the edgeof a circular receptive field in the visualspace (7). Each receptive field consistsof about a hundred contiguous pointsmonitored by individual light receptorcells. The physiologicalmechanismsbymeans of which the input point-by-point light intensity information is ab-stracted to yield light contrast informa-tion are more or less understood. Theycan be epitomized simply by statingthat the light receptor cells reportingfrom points at the center or the edgeof the receptive field make respectivelyexcitatory or inhibitory connectionswith their correspondent ganglion cell.Thus the ganglioncell is maximallyex-cited if the field center receptors arestruck by bright light while the fieldedge receptors are in the dark. In thisway, the point-by-point fine-grainedlight intensity information is boiled downto a somewhat coarser field-by-fieldlight contrast representation, thanks toan algebraic summation of the outputsof an interconnected ensemble of ahundred contiguous light receptor cells.As can be readily appreciated, suchlight contrast information is essentialfor the recognition of shapes and formsin space, which is what visual percep-tion mainly amounts to.For the next stage of processing thevisual information leaves the retina viathe nerve fibers of the ganglion cells.These fibers connect the eye with thebrain, and after passing a way stationin the midbrain the output signals ofthe ganglion cells reach the cerebralcortex at the lower back of the head.Here the signals converge on a set ofcortical nerve cells. Study of the corti-cal nerve cells receiving the partiallyabstracted visual input has shown thateach of them responds only to lightrays reaching the eye from a limited setof contiguous points in the visual space.But the structure of the receptive fieldsof these cortical nerve cells is more

complicatedand theirsize is largerthanthat of the receptivefieldsof the retinalganglion cells. Instead of representingthe light-darkcontrastexistingbetweenthe center and the edge of circularre-ceptive fields, the cortical nerve cellssignal the contrast which exists alongstraight line edges whose lengthamounts to many diametersof the cir-cular, ganglion cell receptive fields. Agiven cortical cell becomes active if astraightline edge of a particularorien-tation-horizontal, vertical, or oblique-formed by the border of contiguousareas of high and low light intensity ispresent in its receptive field (8). Forinstance, a vertical bar of light on adark backgroundin some part of thevisual field may produce a vigorousre-sponse in a particular cortical nervecell, and that responsewill cease if thebar is tilted away from the vertical ormoved outside the receptive field. Ac-tually, there exist two different kindsof such nerve cells in the cerebralcor-tex: simplecells and complexcells. Theresponse of simple cells demands thatthe straight edge stimulus must notonly have a given orientationbut alsoa preciseposition in the receptivefield.The stimulus requirementsof complexcells are less demanding,however, inthat their response is sustained uponparallel displacements (but not upontilts) of the straightedge stimuli withinthe receptivefield. Thus the process ofabstraction of the visual input begunin the retina is carried to higherlevelsin the cerebralcortex. The simple cells,which evidently correspondto the firstcorticalabstractionstage, transformthedata supplied by the retinal ganglioncells concerningthe light-darkcontrastwithin small circular receptive fieldsinto information concerning the con-trastpresent alongsets of circularfieldsarrangedin straightlines. And the com-plex cells carry out the next corticalabstractionstage. They transform thecontrast data concerning particularstraight line sets of circular receptivefields into information concerning thecontrast present at parallel sets ofstraightlines.

The GrandmotherCellIt is not clear at present how farthis process of cerebral abstractionby

convergence of visual channels can beimagined to go. Nerve cells have al-ready been found in the cerebral cortexwhich respond optimally to straight-line ends or corners in their receptivefields (9). Evidently, the output of

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these cells represents an even higherlevel of abstraction than the parallelstraight lines of a given orientation towhich the complex cells respond. Butshould one suppose that the cellularabstraction process goes so far thatthere exists for every meaningful struc-ture of whose specific recognition aperson is capable (for example, "mygrandmother") at least one particularnerve cell in the brain that responds ifand only if the light and dark patternfrom which that structure is abstractedappears in its visual space (10)?This could very well be the case forlower animals, with their limited be-havioral repertoire. For instance, thereis neurologicalevidence that the visualsystem of the frog abstracts its inputdata in such a way as to produce onlytwo meaningful structures, "my prey"and "my predator," which, in turn,evoke either of two alternative motoroutputs, attack or flight (11). But inthe case of man, with his vast semanticcapacities, this picture does not appearvery plausible, despite the fact that thehuman brain has many more nervecells than the frog's brain. Somehow,for man the notion of the single cere-bral nerve cell as the ultimate elementof meaning seems worse than a grossoversimplification; it seems qualitativelywrong. Yet, so far at least, it is theonly neurologically coherent schemethat can be put forward. Admittedly,ever since the discipline of neurophysi-ology came into being more than a cen-tury ago, there have been adherents ofa "holistic" theory of the brain. Thistheory envisions that specific functionsof the brain, including perception, de-pend not on the activity of particularlocalized cells or centers but on generaland widely distributed activity patterns.Such holistic theories, however, amountto little more than phenomenologicalrecapitulations of neurological corre-lates of behavior or mental activity.They are not, therefore, explanatory ina scientific sense. This does not meanthat the holistic approach to the brainis necessarily wrong; it merely meansthat it concedes at the outset that thebrain cannot be explained.

The SelfWe thus encounterthe barrierto an

ultimate scientific understanding of manwhich Descartes had recognized morethan three centuries ago. Descartes hadclearly outlined the nature of the prob-lem posed by vision (Fig. 1), and themodernneurologicalfindingsmentioned21 MARCH 1975

in the preceding paragraphsrepresentlatter-day triumphs of the Cartesianapproach.At the same time, Descarteshad realized that physiological studiesreally leave the central problemof vis-ual perception untouched. For the per-cept is obviously a function of the soul,or in modern psychological parlance, ofthe self, whose nature Descartes thoughtto be inaccessible to scientific analysis.No matter how deeply we probe intothe visual pathway, in the end we needto posit an "inner man" who trans-forms the visual image into a percept.And, as far as linguistics is concerned,the analysis of language appears to beheading for the same conceptual im-passe as does the analysis of vision. Ithink it is significant that Chomsky,who views himself as carrying on theline of linguistic analysis begun byDescartes and his disciples (12), hasencountered difficulty with the postu-lated semantic component. Thus far,it has not been possible to spell outhow the semantic component managesto extract meaning from the informa-tional content of the deep structure.It is over just the problem of mean-ing that disputes have arisen betweenChomsky and some of his students, andit does not seem that any solution is atpresent in sight (13). The obstacle inthe way of giving a satisfactory accountof the semantic component appears toreside in defining explicitly the problemthat is to be solved. That is to say, forman the concept of "meaning" can befathomed only in relation to the self,which is both ultimate source and ulti-mate destination of semantic signals.But the concept of the self, the corner-stone of Freud's analytical psychology,cannot be given an explicit definition.Instead, the meaning of "self" is intui-tively obvious. It is another Kantiantranscendental concept, one which webring a priori to man, just as we bringthe concepts of space, time, and cau-sality to nature. The concept of selfcan serve the student of man as longas he does not probe too deeply. How-ever, when it comes to explaining theinnermost workings of the mind-thedeep structure of structuralism-thenthis attempt to increase the range ofunderstanding raises, in Bohr's terms,"questions as to the sufficiency of con-cepts and ideas incorporated in dailylanguage." Thus, the image of man asa Russian doll, with the outer bodyencasing an incorporeal inner man, isevidently a presupposition hidden inthe rational linguistic use of the term"self," and the attempt to eliminate theinner man from the picture only de-

natures that intuitive concept beyondthe point of psychological utility (14).From this ultimate insufficiency of theeveryday concepts which our brainobliges us to use for science it doesnot, of course, follow that further studyof the mind should cease, no more thanit follows from it that one should stopfurther study of physics. But I thinkthat it is important to give due recog-nition to this fundamental epistemo-logical limitation to the human sciences,if only as a safeguard against the psy-chological or sociological prescriptionsput forward by those who allege thatthey have already managed to gain ascientifically validated understanding ofman (15).

References and Notes1. An excellent overview of the structuralistmovement can be obtained from H. Gardner,The Quest for Mind (Knopf, New York, 1973).2. 1 am referring to Hume as a founder ofpositivism, even though the name of that

philosophical view was invented much laterby Auguste Comte, because he shaped 17th-century empiricism into the anti-metaphysicaloutlook that informed much of 19th- and20-century science.3. Unfortunately, calling Chomsky a "struc-turalist" is bound to raise confusion. Amongstudents of linguistics, Chomsky is called a"generative grammarian," whereas not hebut his positivistic predecessors, whose lim-ited goals Chomsky has sought to transcend,are known as "structuralists." But in view ofChomsky's evident philosophical affinity toFreud, Levi-Strauss, and other "structuralist"contributors to the human sciences, thereseems to be no way to avoid this termino-logical confusion in a general discussion ofhis position.4. Kant himself rejected the only resolution ofthis dilemma available at his time, namely,that it was God who put these concepts intoman's mind.5. K. Lorenz, Bl. Dtsch. Philos. 15, 94 (1941).6. N. Bohr, Atomic Physics and Human Knowl-edge (Science Editions, New York, 1961).7. S. W. Kuffler, J. Neurophysiol. 16, 37 (1953).8. D. H. Hubel and T. N. Wiesel, J. Physiol.(Lond.) 160, 106 (1962).9. -- , J. Neurophysiol. 28, 229 (1965).10. A fuller discussion of the crucial importanceof this question for an eventual neurologicalaccount of perception is given by H. B.Barlow, Perception 1, 371 (1972).11. J. Y. Lettvin, H. R. Maturana, W. S.McCulloch, W. H. Pitts, Proc. Inst. RadioEng. 47, 1940 (1959).12. N. Chomsky, Language and Mind (Harcourt,Brace & World, New York, 1968).13. J. Searle, New York Rev. 29 June (1972), p.16.14. Thus I reject S. Toulmin's claim [in TheNeurosciences, G. C. Quarton, T. Melnechuck,F. O. Schmidt, Eds. (Rockefeller Univ.Press, New York, 1967), p. 822] that thepicture of the inner man is merely a legacy

of the applications of 17th-century physicsto the study of man and that the need forthe concept vanishes within the frame ofreference of 20th-century physics. Referringto an entirely different nonscientific tradition,we may note that the satori of Zen Buddhismdemands purging the mind of its innate selfconcept and that the deep insights into mangained thereby cannot consequently be com-municated by explicit verbal discourse.15. After this article had gone to press I cameupon Seelenglaube und Psychologie (Deuticke,Leipzig, 1930) by Freud's disciple and criticOtto Rank. Using many of the same argu-ments that I put forward here, including theepistemological parallels between 20th-centuryphysics and psychology, Rank concluded thatthe unavoidable concept of the soul limits theeventual scientific understanding of man. Iam indebted to A. Wheelis for calling myattention to Rank's book.1057

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