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brain and that of the monkey, the more it is demonstrated that difference in intelligence depends upon some condition which the senses do not show us.
I add that if these proportions were demonstrated, materialism would gain nothing, for it is enough to admit that the brain is the condition of thought without being its cause, to explain the facts named, by one hypothesis as by the other. Indeed suppose, for an instant, that human thought is of such a nature that it cannot exist without sensations, without images, without signs, (it is not proved that there can be no thought save this;) suppose, I say, that such is the condition of human thought; do we not understand that then a nervous system would be needed to render sensation possible, and a nervous center to render possible the concentration of sensations, the formation of images and signs? The brain would be, in this theory, the organ of imagination and language, without which there would be no thought for the human soul. It would result that, as a blind man wants one source of impressions, and consequently one source of ideas, so the mind that should want a certain part of the brain, or that should be attainted in the cerebral conditions necessary to the formation of images and signs, would become incapable of thinking, since pure thought without connection with what comes through sensation seems impossible in the actual conditions of our finite being. We perceive that the relations of the brain to thought are quite as conceivable under the spiritualistic theory as under the materialistic, and even that difficulties which the latter presents would vanish before the former. For instance, what would become of the difference between man and brutes? It would have its cause no longer in the difference of brains, but in the difference of the internal force, the thinking force, which in the animal can combine only a small number of images, and which cannot transform natural into artificial signs. The physical conditions of thought would be identical in both cases; the entirely non-material conditions of the thinking power alone would be modified. It would be the same in cases of lunacy which might have as causes, now organic changes which would affect the organ of imagination and of signs, now changes wholly moral which would unfit the soul to govern its sensations, to combine images and signs,
which would make it pass from the active to the passive condition. If we admit with certain physiologists a cerebral dynamics, and if we explain insanity or imbecility by the varitions of intensity in the cerebral forces, why may I not admit an intellectual and moral dynamics resident in an elementary and indivisible substance, which is equally susceptible of certain variations of intensity, of which the cause is now within now without itself? It was then only by taking a wholly superficial point of view, and by not sufficiently examining all the aspects of the question, that materialism believed itself authorized, from the fact that the brain is indispensable to the production of thought, to conclude that the brain is itself the thinking subject.
But it is not enough to show that the facts cited by materialists are explained also, and perhaps better, by the contrary hypothesis, for it would only result that the mind ought to remain indifferent and in suspense between the two theories. There is something further: there are certain decisive facts, we think, certain eminent characteristics of thought, which seem absolutely irreconcilable with materialism. These facts are well known. Whoever has studied this subject a little, divines that we are thinking of personal identity and the unity of thought. I shall insist principally upon personal identity, striving to push its consequences somewhat further than is usually done.
We do not define personal identity, but we feel it. Each one of us knows that he continues to be himself at every moment of the duration which composes his being, and this is what we call identity. It manifests itself very clearly in three principal facts, thought, memory, and responsibility. The simplest fact of thought supposes that he who thinks abides the same at two different moments. All thought is successive; if this is questioned in judgment it will not be questioned in reasoning; if it is questioned in the simplest form of reasoning it will not be questioned in demonstration, which consists of a series of reasonings. We must admit that it is the same mind which continues through all the moments of a demonstration. Conceive three persons of whom one thinks a major, another a minor, the third a conclusion; will you have a common thought, a common demonstration? No, the three elements must unite
in one and the same mind. Memory brings us to the same conclusion. I remember only of myself, M. Royer Collard very justly said: exterior things and other persons enter into my memory only through having passed into my cognitive powers, and it is this cognition that I remember, not the thing itself. I could not, then, remember what another than I did, said, or thought. Memory supposes a continued bond between the I of the past and the I of the present. Finally no one is responsible save for himself; if one is so for others it is only as he can act upon or by them. How could I answer for what another did before I was born? Thus thought, memory, responsibility are startling witnesses to our identity. That is one of the capital facts which characterize our mind. There is likewise in the human body a capital and characteristic fact, but it is the opposite of the preceding; this is what has been called the vital vortex, or the perpetual exchange of matter which goes on between living animals and the exterior world. We know that organized bodies have need of nutrition, that is, of borrowing from foreign bodies a certain quantity of matter to repair the losses that they continually suffer. If, indeed, living bodies preserved all acquired matter and incessantly introduced new, we ought to see their size constantly growing. This is what we do see up to a certain age; but this increase of size stops, and the body remains stationary in its dimensions. It is thereby evident that the body loses as much as it gains, and that life is a circulation. Further, the greatest naturalists have acknowledged the fact. I will above all cite the fine words of Cuvier. "In living bodies," says he, "no particle keeps its place; all enter and depart in succession; life is a continual whirlpool, whose direction, all complicated as it is, remains constant, as well as the kind of particles which are drawn into it, but not the individual particles themselves. The present matter of the living body, on the contrary, will soon be no longer in it, and yet it is the depository of a force which will constrain the future matter to move in the same path as itself. So the form of these bodies is more essential to them than their matter, since this constantly changes while that is preserved."
Without insisting upon a fact whose confirmation will be found in all physiologists, let us say that the problem for
materialists is to conciliate the personal identity of the mind with the perpetual mutability of the organized body. Now we must admit that materialists have not taken much pains to solve this problem, and Dr. Büchner does not even mention it. It does not depend upon him, however, that the identic should result from change, or unity from composition. If that is so, it must still be explained how it can be. The first explanation which might be given, is that indicated in the passage from Cuvier cited above. The vital whirlpool, it is said, has a constant direction; in the change of matter, there is always something left, form. The materials are displaced and replaced, but always in the same order and in the same relations. Thus the features of the face remain ever nearly the same, despite the change of the parts; the scar always remains, though the wounded particles have long ago disappeared. The living body has a historic oneness, which results from the persistence of relations, and which is the foundation of the identity of the I.
Such an explanation, however, can only satisfy those who do not take good account of the conditions of the problem, for in supposing that we may explain this fixity of the type, whether individual or generic, by a simple play of matter, by chemical or mechanical action, it must not be forgotten that an identity so produced will ever be only an apparent and wholly external identity, like that of those petrifactions in which vegetable molecules have been gradually replaced by mineral molecules, without the form of the object's experiencing any change. I say that such an object is not really identical, and especially that it is not so to itself, and that in such a theory you will find no foundation for the consciousness and the memory of identity, for I demand, where will you place memory in this ever-moving object? Shall it be in the elements, in the molecules themselves? But as they disappear, those which enter cannot remember those that depart. Shall it be in the relation of the particles? It must be, for that is the only thing that truly continues; but what is a relation which itself thinks, remembers, and is responsible? These are so many unintelligible abstractions to which our readers are welcome.
One might turn to the following hypothesis. It might be said: In proportion as the molecules enter into the body, for
instance into the, brain, they place themselves where the preceding ones were; there they are found in the same relation with the neighboring particles, they are drawn into the same vortex as those they replace. Ah well? so, by hypothesis, thought is a vibration of the cerebral fibers; since to-day everything is explained by vibrations, each new molecule will come in its turn to vibrate exactly as the preceding; it will give the same note, and you will believe you hear the same sound; this then will be the same thought, though the molecule has changed. Having the same thought, the man I will be the same individual. Such an explanation, however, is nowise satisfactory, for identity of persons is not attached to identity of thoughts. I may vacillate between the most opposite ideas and feelings without ceasing to be myself; two men thinking of the same thing at once, the series of numbers for example, will not therefore become one and the same man; several cords emitting the same sound are not one cord. Thus identity of vibrations, no more than persistence in form, explains the consciousness of personal identity.
It may be rejoined: You reason upon a false theory. You seem to believe that the human brain totally changes from moment to moment, from second to second. This is not so; the brain only changes in succession. On the other hand is the I then immobile? Does it not change also from moment to moment? Is the youth the same as the mature man, the mature as the aged man? So neither is change absolute in the body, nor immobility in the soul. Could we not come into harmony? The consciousness of identity in us would correspond to the durable part of the brain, the consciousness of change to the changing part. So that, in man, would be united, according to the expression of Plato, the one and the many, the same and another. That is, I think, the profoundest thing that can be said in favor of materialism; but I do not believe it has ever taken the trouble to go so far in its defense: we take pains to furnish it with arms. However that may be, this last turn no more satisfies me than the preceding. At the outset it is something strange that man should every moment lose a part of himself, and that he should recomplete himself every moment. At the end of a certain time I should have but three fourths of myself, then a half, then a fourth,