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Table of Contents

Chapter 1

Chapter 2

Chapter 3

Chapter 4

Chapter 5

Chapter 6



Further Reading

The Mysterious Matter of Mind

Chapter Two

Cartesian Dualism: Mind and Brain Interaction

      Dualism is an ancient concept and deeply rooted in Greek thought. The Greeks held that a man's soul was of an entirely different essence than his body. Furthermore, they held that these dual entities had no interaction with one another. Indeed, the Greeks saw them as alien to one another, the body being the prison house of the soul. Thus dualism means much more than a mere numerical designation. It implies the dichotomy of soul and body, an absolute split.
     Rene Descartes (1596—1650) marks the beginning of modern psychology. He was a remarkable individual: primarily a philosopher, he was also a scientist, physiologist, and a mathematician.
     He believed in an independent non-material soul inhabiting and finding expression in a mechanically operated body. The reality of the body needed no proof, the reality of the soul did. Descartes used his famous aphorism as proof: cogito ergo sum, "I reflect, therefore I am." It is a neat form of proof and seems unanswerable. We cannot doubt the existence of our

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own self, because we cannot doubt it unless there is a self to do the doubting.
     It is interesting that the idea did not originate with Descartes, though it is usually credited to him. Some twelve hundred years before Descartes, Augustine in his City of God (11.26) wrote:

     Without any delusive representation of images and phantasms, I am most certain that I am, and that I know and delight in this. In respect of these truths, I am not afraid of the arguments of the Academicians, who say, "What if you are deceived?" For if I am deceived, I am. For he who is not, cannot be deceived; and if I am deceived, by this same token I am.

     Descartes was concerned about how the non-material could interact with the material and how the "extended" substance of body could house the "unextended" spirit called soul. He resolved the problem of the incompatibility of the two entities by his dualism; that is to say, by giving the problem a name.
     He held that the two components which constitute man had an independent origin and are of a fundamentally different nature. The body could be divided up by the removal of a leg or an arm, but the soul was indivisible. The soul occupied the whole body in all its parts, but the reduction of the body in any way did not reduce the soul. The body was procreated, the soul was created. Though the two realities were of an entirely different nature, they could react upon each other, the soul on the body and the body on the soul. How this reaction takes place is a mystery nevertheless; only Descartes spelled it differently — dualism.
     But he became the father of the mind/body theory of interactionism.

Descartes' Interactionism

     Descartes held that the brain (along with the rest of the body) was purely mechanistic in its principle of operation. This is true when body is considered without soul — as he proposed was always the case in the animal world where soul is lacking. Thus animals are pure automatons. This mechanistic view of the body, including the brain, was not questionable if soul is not

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made any essential part of its operation. So Descartes was free to proceed with his physics of physiology.
     But what then is the nature of the soul? His answer is simple: the sense perceptions and physical passions of men are dependent upon the body, but awareness of them lies in the soul. The important thing then is to inquire how the soul becomes aware (i.e., conscious and self-conscious) and how it succeeds in acting upon the body. Its awareness is due to the action of the body upon it, but how does it in turn act upon the body when it exercises will?
     The point of interaction, according to Descartes, was at the site of the pineal gland, the only place he thought that is not duplicate as all other brain structures were thought to be. The soul was not, however, to be viewed as somehow shut up in the pineal gland. The gland is merely the point of interaction, not the seat of the soul in any fuller sense.
     The body is extended matter: the soul is unextended spirit. When, however, the extended is acted upon by the unextended, some definite point of interaction is required and it is to be found in the pineal gland. Yet the "soul is united to all parts of the body conjointly." The whole body is the soul's proper housing so long as the body remains intact. When a member of the body — an arm or a leg, for example — is cut off, there is no loss of part of the soul as a consequence because the soul is unitary and indivisible. It then occupies what is left of the body.
     So without attempting to resolve all the problems, he simply stated that there is a dualism of mind and body, and their interaction is clearly real. The brain is the major locus for the mind or consciousness of the soul, yet mind or consciousness is distributed throughout the whole body. The point of interaction between the two is the pineal gland.
     Descartes lent his authority to the long-held view that the mind is associated in a particular way with the brain, but he made mind and brain separate entities, dependent upon each other only as a fountain pen and ink are interdependent. The pen will not write without the ink and the ink carries no message without the pen.
     Descartes "substantialized" consciousness as

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unextended reality, something that can exist in the body but does not occupy space. Mind was real, yet entirely separate from matter and therefore from brain. Interactionism is his form of dualism. One extended and the other unextended, they nevertheless interact, and this interaction occurs at a specific site, the pineal gland. The theory cannot be disproved so long as there are mental phenomena whose neural correlates remain unknown. That there are mental phenomena cannot be doubted for reasons which are logically compulsive and were adopted (though not invented) by Descartes; they cannot be doubted because the very act of doubting them establishes their reality. The reality of conscious existence is confirmed each time it is denied.
     Matter and mind he construed as created substance, each constituting a radically different and independent form of reality. Their interaction does not stem, he held, from a common origin. His inability to satisfy even his most ardent admirers on the nature of their interaction resulted in some of them adopting a view which came to be known as occasionalism, according to which each apparent interaction of mind and body was the result of direct divine intervention.

     In the end, the Cartesian mechanistic view exempted only two phenomena from its all-embracing sweep, God and the soul of man. All else, all animal life below man and man himself save only for his soul, was encompassed in the universal chain of mechanistic causality. The concept was a grand one and ultimately proved too appealing to permit the one exception to be any hindrance to its application everywhere else. The soul was first ignored, then virtually denied, or made a mere outgrowth of the machine that was the body and the brain. In a lecture on Thomistic psychology given at the University of Ottawa in 1957, Professor R. H. Shevenell summed up Descartes' influence by saying:

     With Descartes, psychology lost its soul and found its mind:
with British Empiricists, soul lost its mind and found its consciousness:
with Watson and the Behaviorists, soul lost its consciousness and found its reflexes.

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     Descartes marked a turning point for the study of man, especially for the study of the mind/body relationship.

     Most of the important thinkers who followed Descartes rejected interactionism. It was not a testable hypothesis. Above all, it introduced the supernatural into the picture and thus removed the concept from the scientific laboratory into the theological seminary.
     Critics of his ideas objected that if soul and body were substances of entirely different natures, interaction between them was in fact impossible. This Descartes protested against, but he never satisfied his critics. Nor did occasionalism fare any better because interaction between mind and brain was now simply reduced to miracle, and miracles are not the domain of experimental science with its prime emphasis upon repeatability and quantification. It seemed the problem was insoluble and needed a new approach.
     What emerged was a determination to reduce everything to physics and chemistry, or perhaps more precisely to physics and mathematics (though there are chemists who do not look kindly upon viewing their science as a branch of physics). But it must have encouraged Claude Bernard's approach to the body as a machine, and the success which attended this approach advanced our understanding of the body so remarkably that it became heresy to speak of dualism in the Cartesian sense.
     But slowly, as the evidence has accumulated, it appears that the monistic* view is showing signs of insufficiency and a new dualism is in the making.

* Monistic: the opposite of dualistic, dichotomous, hyphenate.

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Copyright © 1988 Evelyn White. All rights reserved

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