The Mind and the Brain/Book III/Chapter IV
CHAPTER IV
MODERN THEORIES
It may be thought that the objection taken above to parallelism and materialism is personal to myself, because I have put it forward as the consequence of my analysis of the respective shares of thought and matter in every act of cognition. This is not so. I am here in harmony with other philosophers who arrived at the same conclusions long before me, and it may be useful to quote them.
We will begin with the prince of idealists, Berkeley. “‘Everything you know or conceive other than spirits,’ says Philonous to Hylas, ‘is but your ideas; so then when you say that all ideas are occasioned by impressions made in the brain, either you conceive this brain or you do not. If you conceive it, you are in that case talking of ideas imprinted in an idea which is the cause of this very idea, which is absurd. If you do not conceive it, you are talking unintelligibly, you are not forming a reasonable hypothesis.’ ‘How can it be reasonable,’ he goes on to say, ‘to think that the brain, which is a sensible thing, i.e. which can be apprehended by the senses—an idea consequently which only exists in the mind—is the cause of our other ideas?’”[1]
Thus, in the reasoning of Berkeley, the function of the brain cannot explain the production of ideas, because the brain itself is an idea, and an idea cannot be the cause of all our other ideas.
M. Bergson’s argument is quite similar, although he takes a very different standpoint from that of idealism. He takes the word image in the vaguest conceivable sense. To explain the meaning of this word he simply says: “images which are perceived when I open my senses, and unperceived when I close them.” He also remarks that the external objects are images, and that the brain and its molecular disturbances are likewise images. And he adds, “For this image which I call cerebral disturbance to generate the external images, it would have to contain them in one way or another, and the representation of the whole material universe would have to be implicated in that of this molecular movement. Now, it is enough to enunciate such a proposition to reveal its absurdity.”[2] It will be seen that this reasoning is the same as Berkeley’s, though the two authors are reasoning on objects that are different; according to Berkeley, the brain and the states of conscience are psychical states; according to Bergson, the definition of the nature of these two objects designated by the term image is more comprehensive, but the essential of his argument is independent of this definition. It is enough that the two terms should be of similar nature for one to be unable to generate the other.
My own argument in its turn comes rather near the preceding ones. For the idea of Berkeley, and the image of Bergson, I substitute the term matter. I say that the brain is matter, and that the perception of any object is perception of matter, and I think it is not easy to explain how from this brain can issue this perception, since that would be to admit that from one matter may come forth another matter. There is certainly here a great difficulty. M. Bergson has thought to overcome it by attacking it in the following way. He has the very ingenious idea of changing the position of the representation in relation to the cerebral movement. The materialist places the representation after this movement and derives it from the movement; the parallelist places it by the side of the movement and in equivalence to it. M. Bergson places it before the movement, and supposes it to play with regard to it the part of exciting cause, or simply that of initiator. This cerebral movement becomes an effect of the representation and a motor effect. Consequently the nervous system passes into the state of motor organ; the sensory nerves are not, as supposed, true sensory nerves, but they are the commencements of motor nerves, the aim of which is to lead the motor excitements to the centres which play the part of commutators and direct the current, sometimes by one set of nerves, sometimes by others. The nervous system is like a tool held in the hand; it is a vehicle for action, we are told, and not a substratum for cognition. I cannot here say with what ingenuity, with what powerful logic, and with what close continuity of ideas M. Bergson develops his system, nor with what address he braves its difficulties.
His mind is remarkable alike for its power of systematisation and its suppleness of adaptation. Before commencing to criticise him, I am anxious to say how much I admire him, how much I agree with him throughout the critical part of his work, and how much I owe to the perusal of his book, Matière et Mémoire. Though I was led into metaphysics by private needs, though some of the ideas I have set forth above were conceptions of my own (for example, the criticism of the mechanical theory of matter, and the definition of sensation), before I had read M. Bergson’s book, it cannot be denied that its perusal has so strongly modified my ideas that a great part of these are due to him without my feeling capable of exactly discerning which; for ideas have a much more impersonal character than observations and experiments. It would therefore have been ungrateful to criticise him before having rendered him this tribute.
There are, in M. Bergson’s theory, a few assertions which surprise us a little, like everything which runs counter to old habits. It has always been supposed that our body is the receptacle of our psychological phenomena. We store our reminiscences in our nerve centres; we put the state of our emotions in the perturbations of certain apparatus; we find the physical basis of our efforts of will and of attention in the sensations of muscular tension born in our limbs or trunk. Directly we believe that the nervous system is no longer the depository of these states, we must change their domicile; and where are they to be placed? Here the theory becomes obscure and vague, and custom renders it difficult to understand the situation of the mind outside the body. M. Bergson places memory in planes of consciousness far removed from action, and perception he places in the very object we perceive.
If I look at my bookcase, my thought is in my books; if I look at the sky, my thought is in a star.[3] It is very difficult to criticise ideas such as these, because one is never certain that one understands them. I will therefore not linger over them, notwithstanding the mistrust which they inspire in me.
But what seems to me to require proof is the function M. Bergson is led to attribute to the sensory nerves. To his mind, it is not exact to say that the excitement of a sensory nerve excites sensation. This would be a wrong description, for, according to him, every nerve, even a sensory one, serves as a motor; it conducts the disturbance which, passing through the central commutator, flows finally into the muscles. But then, whence comes it that I think I feel a sensation when my sensory nerve is touched? Whence comes it that a pressure on the epitrochlear nerve gives me a tingling in the hand? Whence comes it that a blow on the eyeball gives me a fleeting impression of light? One must read the page where M. Bergson struggles against what seems to me the evidence of the facts. “If, for one reason or another,” he says, “the excitement no longer passes, it would be strange if the corresponding perception took place, since this perception would then put our body in relation with points of space which would no longer invite it to make a choice. Divide the optic nerve of any animal; the disturbance starting from the luminous point is no longer transmitted to the brain, and thence to the motor nerves. The thread which connected the external object to the motor mechanism of the animal by enveloping the optic nerve, is severed; the visual perception has therefore become powerless, and in this powerlessness consists unconsciousness.” This argument is more clever than convincing. It is not convincing, because it consists in exaggerating beyond all reason a very real fact, that of the relation which can be discovered between our sensations and our movements. We believe, with M. Bergson, that it is absolutely correct to see in action the end and the raison d’être of our intelligence and our sensibility. But does it follow that every degree, every shade, every detail of sensation, even the most insignificant, has any importance for the action? The variations of sensibility are much more numerous than those of movements and of adaptation; very probably, as is seen in an attentive study of infancy, sensibility precedes the power of motion in its differentiations. A child shows an extraordinary acuteness of perception at an age when its hand is still very clumsy. The correlation, then, is not absolute. And then even if it were so, it would not follow that the suppression of any movement would produce by rebound the suppression of the sensation to which this movement habitually corresponds. On this hypothesis, a sensation which loses its motor effect becomes useless. Be it so; but this does not prove that the uselessness of a sensation is synonymous with insensibility. I can very well imagine the movement being suppressed and the useless sensation continuing to evoke images and to be perceived. Does not this occur daily? There are patients who, after an attack of paralysis remain paralysed in one limb, which loses the voluntary movement, but does not necessarily lose its sensibility. Many clear cases are observed in which this dissociation takes place.
I therefore own that I cannot follow M. Bergson in his deduction. As a physiologist, I am obliged to believe firmly in the existence of the sensory nerves, and therefore I continue to suppose that our conscious sensations are consequent to the excitement of these nerves and subordinate to their integrity. Now, as therein lies, unless I mistake, the essential postulate, the heart of M. Bergson’s theory, by not admitting it I must regretfully reject the whole.
- ↑ I borrow this quotation from Renouvier, Le Personnellisme, p. 263.
- ↑ Matière et Mémoire, p. 3. The author has returned to this point more at length in a communication to the Congrès de Philosophie de Génève, in 1904. See Revue de Métaphysique et de Morale, Nov. 1904, communication from H. Bergson entitled “Le Paralogisme psycho-physiologique.” Here is a passage from this article which expresses the same idea: “To say that the image of the surrounding world issues from this image (from the cerebral movement), or that it expresses itself by this image, or that it arises as soon as this image is suggested, or that one gives it to one’s self by giving one’s self this image, would be to contradict one’s self; since these two images, the outer world and the intra-cerebral movement, have been supposed to be of the same nature, and the second image is, by the hypothesis, an infinitesimal part of the field of representation, while the first fills the whole of it.”
- ↑ Matière et Mémoire, p. 31