MIND AND BODY

35. IS THE MIND IN THE BODY?—There was a time, as we have seen in the last chapter (section 30), when it did not seem at all out of the way to think of the mind as in the body, and very literally in the body. He who believes the mind to be a breath, or a something composed of material atoms, can conceive it as being in the body as unequivocally as chairs can be in a room. Breath can be inhaled and exhaled; atoms can be in the head, or in the chest, or the heart, or anywhere else in the animal economy. There is nothing dubious about this sense of the preposition "in."

But we have also seen (section 31) that, as soon as men began to realize that the mind is not material, the question of its presence in the body became a serious problem. If I say that a chair is in a room, I say what is comprehensible to every one. It is assumed that it is in a particular place in the room and is not in some other place. If, however, I say that the chair is, as a whole, in every part of the room at once, I seem to talk nonsense. This is what Plotinus and those who came after him said about the mind. Are their statements any the less nonsensical because they are talking about minds? When one speaks about things mental, one must not take leave of good sense and utter unmeaning phrases.

If minds are enough like material things to be in anything, they must be in things in some intelligible sense of the word. It will not do to say: I use the word "in," but I do not really mean in. If the meaning has disappeared, why continue to use the word? It can only lead to mystification.

Descartes seemed to come back to something like an intelligible meaning when he put the mind in the pineal gland in the brain. Yet, as we have seen, he clung to the old conception. He could not go back to the frank materialization of mind.

And the plain man to-day labors under the same difficulty. He puts the mind in the body, in the brain, but he does not put it there frankly and unequivocally. It is in the brain and yet not exactly in the brain. Let us see if this is not the case.

If we ask him: Does the man who wags his head move his mind about? does he who mounts a step raise his mind some inches? does he who sits down on a chair lower his mind? I think we shall find that he hesitates in his answers. And if we go on to say: Could a line be so drawn as to pass through your image of me and my image of you, and to measure their distance from one another? I think he will say, No. He does not regard minds and their ideas as existing in space in this fashion.

Furthermore, it would not strike the plain man as absurd if we said to him: Were our senses far more acute than they are, it is conceivable that we should be able to perceive every atom in a given human body, and all its motions. But would he be willing to admit that an increase in the sharpness of sense would reveal to us directly the mind connected with such a body? It is not, then, in the body as the atoms are. It cannot be seen or touched under any conceivable circumstances. What can it mean, hence, to say that it is there? Evidently, the word is used in a peculiar sense, and the plain man cannot help us to a clear understanding of it.

His position becomes intelligible to us when we realize that he has inherited the doctrine that the mind is immaterial, and that he struggles, at the same time, with the tendency so natural to man to conceive it after the analogy of things material. He thinks of it as in the body, and, nevertheless, tries to dematerialize this "in." His thought is sufficiently vague, and is inconsistent, as might be expected.

If we will bear in mind what was said in the closing section of the last chapter, we can help him over his difficulty. That mind and body are related there can be no doubt. But should we use the word "in" to express this relation?

The body is a certain group of phenomena in the objective order; that is, it is a part of the external world. The mind consists of experiences in the subjective order. We have seen that no mental phenomenon can occupy space—real space, the space of the external world—and that it cannot even have a position in space (section 34). As mental, it is excluded from the objective order altogether. The mind is not, then, strictly speaking, in the body, although it is related to it. It remains, of course, to ask ourselves how we ought to conceive the relation. This we shall do later in the present chapter.

But, it may be said, it would sound odd to deny that the mind is in the body. Does not every one use the expression? What can we substitute for it? I answer: If it is convenient to use the expression let us continue to do so. Men must talk so as to be understood. But let us not perpetuate error, and, as occasion demands it, let us make clear to ourselves and to others what we have a right to understand by this in when we use it.

36. THE DOCTRINE OF THE INTERACTIONIST.—There is no man who does not know that his mind is related to his body as it is not to other material things. We open our eyes, and we see things; we stretch out our hand, and we feel them; our body receives a blow, and we feel pain; we wish to move, and the muscles are set in motion.

These things are matters of common experience. We all perceive, in other words, that there is an interaction, in some sense of the term, between mind and body.

But it is important to realize that one may be quite well aware of all such facts, and yet may have very vague notions of what one means by body and by mind, and may have no definite theory at all of the sort of relation that obtains between them. The philosopher tries to attain to a clearer conception of these things. His task, be it remembered, is to analyze and explain, not to deny, the experiences which are the common property of mankind.

In the present day the two theories of the relation of mind and body that divide the field between them and stand opposed to each other are interactionism and parallelism. I have used the word "interaction" a little above in a loose sense to indicate our common experience of the fact that we become conscious of certain changes brought about in our body, and that our purposes realize themselves in action. But every one who accepts this fact is not necessarily an interactionist. The latter is a man who holds a certain more or less definite theory as to what is implied by the fact. Let us take a look at his doctrine.

Physical things interact. A billiard ball in motion strikes one which has been at rest; the former loses its motion, the latter begins to roll away. We explain the occurrence by a reference to the laws of mechanics; that is to say, we point out that it is merely an instance of the uniform behavior of matter in motion under such and such circumstances. We distinguish between the state of things at one instant and the state of things at the next, and we call the former cause and the latter effect.

It should be observed that both cause and effect here belong to the one order, the objective order. They have their place in the external world. Both the balls are material things; their motion, and the space in which they move, are aspects of the external world.

If the balls did not exist in the same space, if the motion of the one could not be towards or away from the other, if contact were impossible, we would manifestly have no interaction in the sense of the word employed above. As it is, the interaction of physical things is something that we can describe with a good deal of definiteness. Things interact in that they stand in certain physical relations, and undergo changes of relations according to certain laws.

Now, to one who conceives the mind in a grossly material way, the relation of mind and body can scarcely seem to be a peculiar problem, different from the problem of the relation of one physical thing to another. If my mind consists of atoms disseminated through my body, its presence in the body appears as unequivocal as the presence of a dinner in a man who has just risen from the table. Nor can the interaction of mind and matter present any unusual difficulties, for mind is matter. Atoms may be conceived to approach each other, to clash, to rearrange themselves. Interaction of mind and body is nothing else than an interaction of bodies. One is not forced to give a new meaning to the word.

When, however, one begins to think of the mind as immaterial, the case is very different. How shall we conceive an immaterial thing to be related to a material one?

Descartes placed the mind in the pineal gland, and in so far he seemed to make its relation to the gland similar to that between two material things. When he tells us that the soul brings it about that the gland bends in different directions, we incline to view the occurrence as very natural—is not the soul in the gland?

But, on the other hand, Descartes also taught that the essence of mind is thought and the essence of body is extension. He made the two natures so different from each other that men began to ask themselves how the two things could interact at all. The mind wills, said one philosopher, but that volition does not set matter in motion; when the mind wills, God brings about the appropriate change in material things. The mind perceives things, said another, but that is not because they affect it directly; it sees things in God. Ideas and things, said a third, constitute two independent series; no idea can cause a change in things, and no thing can cause a change in ideas.

The interactionist is a man who refuses to take any such turn as these philosophers. His doctrine is much nearer to that of Descartes than it is to any of theirs. He uses the one word "interaction" to describe the relation between material things and also the relation between mind and body, nor does he dwell upon the difference between the two. He insists that mind and matter stand in the one causal nexus; that a change in the outside world may be the cause of a perception coming into being in a mind, and that a volition may be the cause of changes in matter.

What shall we call the plain man? I think we may call him an interactionist in embryo. The stick in his hand knocks an apple off of the tree; his hand seems to him to be set in motion because he wills it. The relation between his volition and the motion of his hand appears to him to be of much the same sort as that between the motion of the stick and the fall of the apple. In each case he thinks he has to do with the relation of cause and effect.

The opponent of the interactionist insists, however, that the plain man is satisfied with this view of the matter only because he has not completely stripped off the tendency to conceive the mind as a material thing. And he accuses the interactionist of having fallen a prey to the same weakness.

Certainly, it is not difficult to show that the interactionists write as though the mind were material, and could be somewhere in space. The late Dr. McCosh fairly represents the thought of many, and he was capable of expressing himself as follows;[1] "It may be difficult to ascertain the exact point or surface at which the mind and body come together and influence each other, in particular, how far into the body (Descartes without proof thought it to be in the pineal gland), but it is certain, that when they do meet mind knows body as having its essential properties of extension and resisting energy."

How can an immaterial thing be located at some point or surface within the body? How can a material thing and an immaterial thing "come together" at a point or surface? And if they cannot come together, what have we in mind when we say they interact?

The parallelist, for it is he who opposes interactionism, insists that we must not forget that mental phenomena do not belong to the same order as physical phenomena. He points out that, when we make the word "interaction" cover the relations of mental phenomena to physical phenomena as well as the relations of the latter to each other, we are assimilating heedlessly facts of two different kinds and are obliterating an important distinction. He makes the same objection to calling the relations between mental phenomena and physical phenomena causal. If the relation of a volition to the movement of the arm is not the same as that of a physical cause to its physical effect, why, he argues, do you disguise the difference by calling them by the same name?

37. THE DOCTRINE OF THE PARALLELIST.—Thus, the parallelist is a man who is so impressed by the gulf between physical facts and mental facts that he refuses to regard them as parts of the one order of causes and effects. You cannot, he claims, make a single chain out of links so diverse.

Some part of a human body receives a blow; a message is carried along a sensory nerve and reaches the brain; from the brain a message is sent out along a motor nerve to a group of muscles; the muscles contract, and a limb is set in motion. The immediate effects of the blow, the ingoing message, the changes in the brain, the outgoing message, the contraction of the muscles—all these are physical facts. One and all may be described as motions in matter.

But the man who received the blow becomes conscious that he was struck, and both interactionist and parallelist regard him as becoming conscious of it when the incoming message reaches some part of the brain. What shall be done with this consciousness? The interactionist insists that it must be regarded as a link in the physical chain of causes and effects—he breaks the chain to insert it. The parallelist maintains that it is inconceivable that such an insertion should be made. He regards the physical series as complete in itself, and he places the consciousness, as it were, on a parallel line.

It must not be supposed that he takes this figure literally. It is his effort to avoid materializing the mind that forces him to hold the position which he does. To put the mind in the brain is to make of it a material thing; to make it parallel to the brain, in the literal sense of the word, would be just as bad. All that we may understand him to mean is that mental phenomena and physical, although they are related, cannot be built into the one series of causes and effects. He is apt to speak of them as concomitant.

We must not forget that neither parallelist nor interactionist ever dreams of repudiating our common experiences of the relations of mental phenomena and physical. Neither one will, if he is a man of sense, abandon the usual ways of describing such experiences. Whatever his theory, he will still say: I am suffering because I struck my hand against that table; I sat down because I chose to do so. His doctrine is not supposed to deny the truth contained in such statements; it is supposed only to give a fuller understanding of it. Hence, we cannot condemn either doctrine simply by an uncritical appeal to such statements and to the experiences they represent. We must look much deeper.

Now, what can the parallelist mean by referring sensations and ideas to the brain and yet denying that they are in the brain? What is this reference?

Let us come back to the experiences of the physical and the mental as they present themselves to the plain man. They have been discussed at length in Chapter IV. It was there pointed out that every one distinguishes without difficulty between sensations and things, and that every one recognizes explicitly or implicitly that a sensation is an experience referred in a certain way to the body.

When the eyes are open, we see; when the ears are open, we hear; when the hand is laid on things, we feel. How do we know that we are experiencing sensations? The setting tells us that. The experience in question is given together with an experience of the body. This is concomitance of the mental and the physical as it appears in the experience of us all; and from such experiences as these the philosopher who speaks of the concomitance of physical and mental phenomena must draw the whole meaning of the word.

Let us here sharpen a little the distinction between sensations and things. Standing at some distance from the tree, I see an apple fall to the ground. Were I only half as far away, my experience would not be exactly the same—I should have somewhat different sensations. As we have seen (section 17), the apparent sizes of things vary as we move, and this means that the quantity of sensation, when I observe the apple from a nearer point, is greater. The man of science tells me that the image which the object looked at projects upon the retina of the eye grows larger as we approach objects. The thing, then, may remain unchanged; our sensations will vary according to the impression which is made upon our body.

Again. When I have learned something of physics, I am ready to admit that, although light travels with almost inconceivable rapidity, still, its journey through space does take time. Hence the impression made upon my eye by the falling apple is not simultaneous with the fall itself; and if I stand far away it is made a little lat............