Brain–mind identities in dualism and materialism: a historical perspective

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Abstract

So-called identity theories that postulate the identity of mental phenomena with brain states are usually associated with materialistic ontology. However, the historical picture of the actual attempts at spelling out the mind–brain identities is more complex. In the eighteenth century such identities were most enthusiastically proposed by dualists (for example by Charles Bonnet), whereas non-reductionistic materialists such as Diderot tried to get along without them. In the nineteenth century physiologists such as Broca, Charcot and Wernicke, who postulated discrete and localizable neural correlates for ideas and mental images, ended up, despite their professed materialism, defending theories that resembled Cartesian schemes and the theories of their eighteenth-century dualistic predecessors. Some problems resulting from the use of these theoretical models postulating local and discrete traces, images or representations in the brain in the context of materialist ontology are obviously related to their dualistic origins and to the fact that they are necessarily bound up with dualistic presuppositions. In the context of the criticism of the nineteenth-century memory trace paradigm it is, however, important to bear in mind that functional localization as such is not dependent on the notion of localizable representations. Nor are materialist theories of the mind necessarily dependent on postulating specific type–type identities between the mental and the physiological.

Introduction

Riese & Hoff (1950, n. 11) have claimed that the decomposition of the ‘soul’ into its elements was a result or a by-product of the doctrine of cerebral localization. But, in fact, as I hope to show in this paper the relationship between the analysis of the soul and cerebral localization is more complex. Often it has been the decomposition of the soul into its elements that has determined what one has attempted to localize. And historically there have been at least two different ways of analysing the soul. The first is functional. The soul is analysed as a whole consisting of more or less separate functions: for example, of sensation, memory and reason. This kind of analysis was already prevalent in the medieval faculty psychology. In contemporary psychology, different and more fine-grained distinctions are made, for example, between short and long-term memories or semantic or episodic memories. Another way of analysing the soul into elements consists of the attempt to analyse the contents of mental phenomena in order to arrive finally at its non-analysable atomistic elements, those of which all complex mental representations are presumably composed, such as Lockean simple ideas or Humean impressions.

As far as cerebral localization is concerned, one could respectively try to localize functions or representations in the brain. In the first case one would claim that diverse parts of the brain carry out different mental functions. In the latter case one would claim, for example, that for each simple idea or representation there exist corresponding specific anatomical structures or memory traces in the brain. One could expect that these models of localization correspond to the previously mentioned ways of decomposing the soul, based respectively on functional analysis and the analysis of representations. And this often seems to be the case. For example, in the medieval faculty psychology the three faculties—imagination, reason and memory—were each localized in different cerebral ventricles (see, for example, Clarke & Dewhurst, 1984). And although the analysis of the soul or mind into its simple elements carried out by Locke, Hume or Condillac originally developed relatively independently of any attempts at identifying ideas with localizable anatomical correlates in the brain, later, when mechanistic physiological explanations of mental phenomena gained popularity, physicians and philosophers interested in finding the anatomical correlates. Thus eighteenth-century authors such as Jean Astruc, François-Joseph Collet and Charles Bonnet were interested in finding the anatomical correlates of ideas (Kaitaro, 1999a). It was, in fact, a logical step to correlate the results of the ‘anatomy of the soul’ with those of the anatomy of the body, once both these sciences were believed to have reached the ultimate elements of the soul and of the brain respectively.

So the decomposition of the soul into its elements was eventually paired with attempts at localizing these elements. It is, however, important to notice that the analysis of representations did not result directly in functional localization. In the development of the latter the role of Franz Joseph Gall (1758–1828) seems to be central. Without Gall one might have continued to look for correlations between ideas and fibres along the lines of Astruc, Collet and Bonnet. Gall’s model was based on the biological notion of the correspondence between an organ and a function. In the latter half of the nineteenth century this functional localization was, however, combined with the paradigm of localizable memory traces, which, like the theories of the eighteenth-century localizationists, was based on postulating representational and localizable entities in the brain (Kaitaro, 2001a). Robert Young (1990, p. 15) has contrasted the biological psychology of Franz Joseph Gall with the epistemological psychology of Locke and Condillac. Analogously, the doctrine that localizes representational elements inherited from the empiricist and sensualistic tradition could be called epistemological localization in order to distinguish it from functional localization proper. These two models of localization are based on somewhat different presuppositions about the nature of mind and of representation, and the reinterpretation in the latter half of the nineteenth century of Gall’s functional localization in terms of the localization of representations seems to be quite accidental in the sense that the organ-function model does not as such require that it be interpreted as a special case of the localization of memory traces.

Although the decomposition of the soul into its elements was not a by-product of cerebral localization but rather the other way round, Riese and Hoff are correct in pointing out that the two are related: what are generally localized are the results of the analysis of the soul into its elements, faculties or functions. And, of course, in a more general way anatomy has had an influence on the decomposition of the soul: the fact that one attempted to ‘anatomize’—as Charles Bonnet (1760, p. iv) describes his analytical method—the soul into its simple elements was obviously related to the development and progress of anatomy and its becoming a theoretical model for psychology.

So, one could say that when one has looked for the neural or anatomical correlates of mental functions or mental items, such as ideas, memories, thoughts and so on, one has usually performed two separate analyses and then tried to correlate the results of these analyses. On the one hand, one has analysed the mind into separate faculties or into a collection of separate items, for example ideas or impressions. On the other hand, one has by dissection discovered and distinguished the parts of which the brain consists. Then one has made the (often groundless) supposition that these analyses must meet each other: that the mental elements correspond to the anatomical or physiological elements. A series of identities is thus formed between the mental and the physiological. Of course the metaphysical interpretation of these identities depends on whether one is a materialist or a dualist, but on the basis of the historical analysis of localizationist doctrines it seems that the postulation of such identities in itself is not committed to dualism or materialism. However, one could make a good case—as I attempt to do in this paper—for the claim that in so far as the identification of representations with anatomical entities in the brain is concerned, such identifications are more compatible with dualism than materialism. In order to do this I will first examine eighteenth-century theories, mainly that of Charles Bonnet, which hoped to find the anatomical correlates of ideas in the brain by identifying simple ideas with the action of specific fibres in the brain. As we shall see, such theories were presented by dualists, and the materialist contemporaries of these dualist tended rather to eschew the identification of mental phenomena with specific brain structures. In the next section I will examine how the idea of localizable representations was used in buttressing the localization of functions in the nineteenth century and how this idea, which was originally developed by the dualists, was given a materialist interpretation in the context of medical materialism. As a typical, and perhaps the most consistent of the theories reducing functional localization to the localization of representations, I shall examine the theory of Charcot, which explained practically all neurological dysfunctions, paralysis included, in terms of the destruction of representations in the brain. At the end I try to speculate on the possible reasons for the fact that an originally dualistic theory ended up being taken up by materialist authors, and to examine some problems that result from the postulation of brain–mind identities, inherited from dualistic models, in the context of materialistic theories.

Section snippets

Mind–brain identities and dualism in the eighteenth century

In fact, the historical development of the doctrines of cerebral localizations during the eighteenth and nineteenth centuries provides evidence for the claim that ‘materialism in itself has no organic relation to the doctrine of cerebral localization’ (Riese & Hoff, 1950). The relationship between materialism and cerebral localization seems to vary according to the strategic needs of materialists, depending on different intellectual and rhetorical situations.

In Descartes’s view localization

Changing strategies

When we arrive at the nineteenth century a curious inversion seems to take place. The image of the soul as a collection of separate ideas or sensations and the corresponding idea of the brain as a receptacle of corresponding traces end up being at the service of a materialistic view of the mind. The doctrines of localization which the materialists more often than not had avoided and which the dualists often had adopted now changed hands. During the nineteenth century there seems to have been a

The intellectual background of the nineteenth-century doctrines of localization

If there is no natural connection between materialism and the doctrines of physiological correlates for ideas in the form of localizable memory traces, one should pose the question why such a connection was forged in the nineteenth century? In so far as the reasons for this predilection to use memory as a general paradigm for mental functions in the latter half of the nineteenth century are concerned, obviously no simple explanations should be looked for. But some features in the intellectual

Traces of Descartes

Interestingly, the medical materialists who inherited the ‘ideas-in-the-brain’ model based on the existence of specific mnestic traces from the dualists inherited some of its problems. This resulted in attempts at postulating a counterpart for Descartes’s seat of the soul in the form of an ‘ideational centre’ or the ‘centre of ideas’. The function of these pseudocentres would be to explain the unity of mental representations in the absence of a soul and to provide the required semantic mental

Conclusions

There seems to be no necessary or logical connection between functional localization and the idea of specific memory traces, only contingent historical motives. That the connection between the postulation of specific memory traces and functional localization was not necessary but forged during the nineteenth century should also be kept in mind when reading the critics of the eighteenth-century localizationist doctrines. Discarding the notion of local memory traces does not necessarily entail

Uncited References

Anon, 1969, Diderot and d’Alembert, 1751-1772.

Acknowledgments

The author wishes to thank all those who have contributed to this paper by making critical comments on different versions during its preparation. First of all, I would like to express my gratitude to the participants of the Boston University Colloquium on Philosophy and Neuroscience on 9 May 2001, where I had the opportunity to submit the first version of the paper to discussion. I am indebted to Tuula Tanska and Charles T. Wolfe for their comments on the manuscript. Finally, I would like to

References (53)

  • T. Kaitaro

    La Peyronie and the experimental search for the seat of the soul: Neuropsychological methodology in the eighteenth century

    Cortex

    (1996)
  • Anon
  • O. Bloch

    Sur l'image du matérialisme français du XVIIIe siècle dans l'historiographie philosophique de la première moitié du XIXe siècle: Autour de Victor Cousin

  • C. Bonnet

    Essai analytique sur les facultés de l'âme

    (1760)
  • J.-B. Bouillaud

    Recherches cliniques propres à démontrer que la perte de la parole correspond à la lesion des lobules antérieurs du cerveau, et à confirmer l'opinion de M. Gall, sur le siège de l'organe du langage articulé

    Archives Générales de Médicine

    (1825)
  • J.-B. Bouillaud

    Recherches cliniques propres à démontrer que le sens du langage articulé et le principe coordinateur des mouvements de la parole résident dans les lobules antérieurs du cerveau

    Bulletin de l'Académie royale de Médecine

    (1848)
  • P. Broca

    Remarques sur le siège de la faculté du langage articulé, suivies d'une observation d'aphémie (perte de la parole)

    Bulletin de la Société Anatomique de Paris

    (1861)
  • P.J.G. Cabanis
  • J.-M. Charcot

    Oeuvres complètes, Vol. III. Leçons sur les maladies du système nerveux

    (1890)
  • P.M. Churchland

    Matter and consciousness

    (1984)
  • E. Clarke et al.

    Histoire illustrée de la fonction cérébrale

    (1984)
  • E. Clarke et al.

    Nineteenth-century origins of neuroscientific concepts

    (1987)
  • P. Damiron
    (1834)
  • M. Dax et al.

    Lésions de la moitié gauche de l'encéphale coincidait avec l'oubli des signes de la pensée

    Gazette Hebdomadaire de Médecine et de Chirurgie

    (1865)
  • R. Descartes
  • J. Gasser

    Aux origines du cerveau moderne: Localisations, langage et mémoire dans l'oeuvre de Charcot

    (1995)
  • M. Gauchet et al.

    Le vrai Charcot. Les chemins imprévus de l'inconscient

    (1997)
  • D. Gil

    Is consciousness a brain process

    Graduate Faculty Philosophy Journal

    (2000)
  • I. Hacking

    Rewriting the soul: Multiple personality and the sciences of memory

    (1995)
  • M. Hammond

    Anthropology as a weapon of social combat in late nineteenth-century France

    Journal of the History of the Behavioral Sciences

    (1980)
  • A. Harrington

    Medicine, mind, and the double brain. A study in nineteenth-century thought

    (1987)
  • H. Hécaen et al.

    La naissance de la neuropsychologie du langage 1825-1865

    (1969)
  • T. Kaitaro

    Diderot's holism: Philosophical anti-reductionism and its medical background

    (1997)
  • T. Kaitaro

    Ideas in the brain: The localization of memory traces in the eighteenth century

    Journal of the History of Philosophy

    (1999)
  • T. Kaitaro

    Descartes’ dualism and the localization of mental functions

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