The Mind and the Brain
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But let us bring our dream to an end. The interest of our discussion does not lie in the hypothetical substitution of hearing or any other sense for sight. It lies in the complete suppression of all explanation of the noumenal object in terms borrowed from the language of sensation. And that is our last word. We must, by setting aside the mechanical theory, free ourselves from a too narrow conception of the constitution of matter. And this liberation will be to us a great advantage which we shall soon reap. We shall avoid the error of believing that mechanics is the only real thing and that all that cannot be explained by mechanics must be incomprehensible. We shall then gain more liberty of mind for understanding what the union of the soul with the body9 may be.
CHAPTER IV
ANSWERS TO SOME OBJECTIONS, AND SUMMARY
I have set forth the foregoing ideas by taking the road which to me seemed the best. On reflection it has occurred to me that my manner of exposition and demonstration may be criticised much more than my conclusion. Now, as it is the conclusion alone which here is of importance, it is expedient not to make it responsible for the arguments by which I have supported it.
These arguments resolve themselves into the attestation that between objects and our consciousness there exists an intermediary, our nervous system. We have even established that the existence of this intermediary is directly proved by observation, and from this I have concluded that we do not directly perceive the object itself but a tertium quid, which is our sensations.
Several objections to this might be made. Let us enumerate them.
1. It is not inconceivable that objects may act directly on our consciousness without taking the intermediary of our nervous system. Some authors, the spiritualists notably, believe in the possibility of disembodied souls, and they admit by implication that these souls remain in communication with the terrestrial world, witness our actions, and hear our speech. Since they no longer have organs of sense, we must suppose that these wandering souls, if they exist, can directly perceive material objects. It is evident that such hypotheses have, up till now, nothing scientific in them, and that the demonstrations of them which are given raise a feeling of scepticism more than anything else. Nevertheless, we have not the right to exclude, by a priori argument, the possibility of this category of phenomena.
2. Several German authors have maintained in recent years, that if the nervous system intervenes in the perception of external objects, it is a faithful intermediary which should not work any change on those physical actions which it gathers from outside to transmit to our consciousness. From this, point of view colour would exist as colour, outside our eyes, sound would exist as sound, and in a general way there would not be, in matter, any mysterious property left, since we should perceive matter as it is. This is a very unexpected interpretation, by which men of science have come to acknowledge the correctness of the common belief: they rehabilitate an opinion which philosophers have till now turned to ridicule, under the name of naïve realism. All which proves that the naïveté of some may be the excessive refinement of others.
To establish scientifically this opinion they batter down the theory of the specific energy of the nerves. I have recalled in a previous page10 of what this theory consists. I have shown that if, by mechanical or electrical means, our different sensory nerves are excited, notwithstanding the identity of the excitant, a different sensation is provoked in each case—light when the optic nerve is stimulated, sound when the acoustic, and so on. It is now answered to this argument based on fact that the nature of these excitants must be complex. It is not impossible, it is thought, that the electric force contains within itself both luminous and sonorous actions; it is not impossible that a mechanical excitement should change the electric state of the nerve affected, and that, consequently, these subsidiary effects explain how one and the same agent may, according to the nerves employed, produce different effects.
3. After the spiritualists and the experimentalists, let us take the metaphysicians. Among them one has always met with the most varying specimens of opinions and with arguments for and against all possible theories.
Thus it is, for example, with the external perception. Some have supposed it indirect, others, on the contrary, that it acts directly on the object. Those who uphold the direct theory are inspired by Berkeley, who asserts that the sensitive qualities of the body have no existence but in our own minds, and consist really in representative ideas. This doctrine is expressly based on this argument—that thought differs too much in nature from matter for one to be able to suppose any link between these two substances. In this particular, some authors often make an assertion without endeavouring to prove it. They are satisfied with attesting, or even with supposing, that mind can have no consciousness of anything but its own states. Other philosophers, as I have said, maintain that "things which have a real existence are the very things we perceive." It is Thomas Reid who has upheld, in some passages of his writings at all events, the theory of instantaneous perception, or intuition. It has also been defended by Hamilton in a more explicit manner.11 It has been taken up again in recent years, by a profound and subtle philosopher, M. Bergson, who, unable to admit that the nervous system is a substratum of knowledge and serves us as a percipient, takes it to be solely a motor organ, and urges that the sensory parts of the system—that is to say, the centripetal, optic, acoustic, &c., nerves—do not call forth, when excited, any kind of sensation, their sole purpose being to convey disturbances from periphery to periphery, or, say, from external objects to the muscles of the body. This hypothesis, surely a little difficult to comprehend, places, if I mistake not, the mind, as a power of perception and representation, within the interval comprised between the external object and the body, so that the mind is in direct contact with external objects and knows them as they are.
It will be noticed that these three interpretations, the spiritualistic, the experimental, and the metaphysical, are in formal opposition with that which I have set forth earlier in these pages. They deny the supposition that the nervous system serves us as an intermediary with nature, and that it transforms nature before bringing it to our consciousness. And it might seem that by contradicting my fundamental proposition, those three new hypotheses must lead to a totally different conclusion.
Now, this is not so at all. The conclusion I have enunciated remains entirely sound, notwithstanding this change in the starting point, and for the following reason. It is easy to see that we cannot represent to ourselves the inner structure of matter by using all our sensations without distinction, because it is impossible to bring all these sensations within one single and identical synthetic construction: for this they are too dissimilar. Thus, we should try in vain to unite in any kind of scheme a movement of molecules and an odour; these elements are so heterogeneous that there is no way of joining them together and combining them.
The physicists have more or less consciously perceived this, and, not being able to overcome by a frontal attack the difficulty created by the heterogeneity of our sensations, they have turned its flank. The ingenious artifice they have devised consists in retaining only some of these sensations, and in rejecting the remainder; the first being considered as really representing the essence of matter, and the latter as the effects of the former on our organs of sense; the first being reputed to be true, we may say, and the second being reputed false—that is subjective, that is not representing the X of matter.12 I have refuted this argument by showing that all our sensations without exception are subjective and equally false in regard to the X of matter, and that no one of them, consequently, has any claim to explain the others.
Now, by a new interpretation; we are taught that all sensations are equally true, and that all faithfully represent the great X. If they be all equally true, it is absolutely the same as if they were all false; no one sensation can have any privilege over the others, none can be truer than the others, none can be capable of explaining the others, none can usurp to itself the sole right of representing the essence of matter; and we thus find ourselves, in this case, as in the preceding, in presence of the insurmountable difficulty of creating a synthesis with heterogeneous elements.
All that has been said above is summed up in the following points:—
1. Of the external world, we only know our sensations. All the physical properties of matter resolve themselves for us into sensations, present, past, or possible. We may not say that it is by the intermediary, by the means of sensation, that we know these properties, for that would mean that the properties are distinct from the sensations. Objects are to us in reality only aggregates of sensations.
2. The sensations belong to the different organs of the senses—sight, hearing, touch, the muscular sense, &c. Whatever be the sense affected, one sensation has the same rights as the others, from the point of view of the cognition of external objects. It is impossible to distinguish them into subjective and objective, by giving to this distinction the meaning that certain sensations represent objects as they are, while certain others simply represent our manner of feeling. This is an illegitimate distinction, since all sensations have the same physiological condition, the excitement of a sensory nerve, and result from the properties of this nerve when stimulated.
3. Consequently, it is impossible for us to form a conception of matter in terms of movement, and to explain by the modalities of movement the properties of bodies; for this theory amounts to giving to certain sensations, especially those of the muscular sense, the hegemony over the others. We cannot explain, we have not the right to explain, one sensation by another, and the mechanical theory of matter has simply the value of a symbol.
BOOK II
CHAPTER I
THE DISTINCTION BETWEEN COGNITION 13 AND ITS OBJECT
After having thus studied matter and reduced it to sensations, we shall apply the same method of analysis to mind, and inquire whether mind possesses any characteristic which allows it to be distinguished from matter.
Before going any further, let me clear up an ambiguity. All the first part of this work has been devoted to the study of what is known to us in and by sensation; and I have taken upon myself, without advancing any kind of justifying reason, to call that which is known to us, by this method, by the name of matter, thus losing sight of the fact that matter only exists by contra-distinction and opposition to mind, and that if mind did not exist, neither would matter. I have thus appeared to prejudge the question to be resolved.
The whole of this terminology must now be considered as having simply a conventional value, and must be set aside for the present. These are the precise terms in which this question presents itself to my mind. A part of the knowable consists in sensations. We must, therefore, without troubling to style this aggregate of sensations matter rather than mind, make an analysis of the phenomena known by the name of mind, and see whether they differ from the preceding ones. Let us, therefore, make an inventory of mind. By the process of enumeration, we find quoted as psychological phenomena, the sensations, the perceptions, the ideas, the recollections, the reasonings, the emotions, the desires, the imaginations, and the acts of attention and of will. These appear to be, at the first glance, the elements of mind; but, on reflection, one perceives that these elements belong to two distinct categories, of which it is easy to recognise the duality, although, in fact and in reality, these two elements are constantly combined. The first of these elements may receive the generic name of objects of cognition, or objects known, and the second that of acts of cognition.
Here are a few examples of concrete facts, which only require a rapid analysis to make their double nature plain. In a sensation which we feel are two things: a particular state, or an object which one knows, and the act of knowing it, of feeling it, of taking cognisance of it; in other words, every sensation comprises an impression and a cognition. In a recollection there is, in like manner, a certain image of the past and the fact consisting in the taking cognisance of this image. It is, in other terms, the distinction between the intelligence and the object. Similarly, all reasoning has an object; there must be matter on which to reason, whether this matter be supplied by the facts or the ideas. Again, a desire, a volition, an act of reflection, has need of a point of application. One does not will in the air, one wills something; one does not reflect in the void, one reflects over a fact or over some difficulty.
We may then provisionally distinguish in an inventory of the mind a something which is perceived, understood, desired, or willed, and, beyond that, the fact of perceiving, of understanding, or desiring, or of willing.
To illustrate this distinction by an example, I shall say that an analogous separation can be effected in an act of vision, by showing that the act of vision, which is a concrete operation, comprises two distinct elements: the object seen and the eye which sees. But this is, of course, only a rough comparison, of which we shall soon see the imperfections when we are further advanced in the study of the question.
To this activity which exists and manifests itself in the facts of feeling, perceiving, &c., we can give a name in order to identify and recognise it: we will call it the consciousness14 (la conscience), and we will call object everything which is not the act of consciousness.
After this preliminary distinction, to which we shall often refer, we will go over the principal manifestations of the mind, and we will first study the objects of cognition, reserving for another chapter the study of the acts of cognition—that is to say, of consciousness. We will thus examine successively sensation, idea, emotion, and will.
It has been often maintained that the peculiar property of mind is to perceive sensations. It has also been said that thought—that is, the property of representing to one's self that which does not exist—distinguishes mind from matter. Lastly, it has not failed to be affirmed that one thing which the mind brings into the material world is its power of emotion; and moralists, choosing somewhat arbitrarily among certain emotions, have said that the mind is the creator of goodness. We will endeavour to analyse these different affirmations.
CHAPTER II
DEFINITION OF SENSATION
When making the analysis of matter we impliedly admitted two propositions: first, that sensation is the tertium quid which is interposed between the excitant of our sensory nerves and ourselves; secondly, that the aggregate of our sensations is all we can know of the outer world, so that it is correct to define this last as the collection of our present, past, and possible sensations. It is not claimed that the outer world is nothing else than this, but it is claimed with good reason that the outer world is nothing else to us.
It would be possible to draw from the above considerations a clear definition of sensation, and especially it would be possible to decide henceforth from the foregoing whether sensation is a physical or a mental phenomenon, and whether it belongs to matter or to mind. This is the important point, the one which we now state, and which we will endeavour to resolve. To make the question clearer, we will begin it afresh, as if it were new, and as if the facts hitherto analysed did not already prejudge the solution. Let us begin by giving a definition of sensation from the point of view of experimental psychology.
Sensation, then, is the phenomenon which is produced and which one experiences when an excitant has just acted on one of our organs of sense. This phenomenon is therefore composed of two parts: an action exercised from outside by some body or other on our nervous substance; and, then, the fact of feeling this action.
This fact of feeling, this state of consciousness, is necessary to constitute sensation; when it does not exist, it is preferable to give the phenomenon another name, otherwise the fault is committed of mixing up separate facts. Physiologists have, on this point, some faults of terminology with which to reproach themselves: for they have employed the word sensibility with too little of the critical spirit. Sensibility, being capacity for sensation, presupposes, like sensation itself, consciousness. It has, therefore, been wrong, in physiology, to speak of the sensibility of the tissues and organs, which, like the vegetable tissues or the animal organs of vegetative life, properly speaking, feel nothing, but react by rapid or slow movements to the excitements they are made to receive. Reaction, by a movement or any kind of modification, to an excitement, does not constitute a sensation unless consciousness is joined with it, and, consequently, it would be wiser to give unfelt excitements and reactions the name of excitability.
The clearest examples of sensation are furnished by the study of man, and are taken from cases where we perceive an external object. The object produces upon us an action, and this action is felt; only, in such cases, the fact of sensation comprises but a very small part of the event. It only corresponds, by definition, to the actual action of the object. Analysis after analysis has shown that we constantly perceive far beyond this actual action of objects. Our mind, as we say, outruns our senses. To our sensations, images come to attach themselves which result from sensations anteriorly felt in analogous circumstances. These images produce in us an illusion, and we take them for sensations, so that we think we perceive something which is but a remembrance or an idea; the reason being that our mind cannot remain in action in the presence of a sensation, but unceasingly labours to throw light upon it, to sound it, and to arrive at its meaning, and consequently alters it by adding to it. This addition is so constant, so unavoidable, that the existence of an isolated sensation which should be perceived without the attachment of images, without modification or interpretation, is well-nigh unrealisable in the consciousness of an adult. It is a myth.
Let us, however, imagine this isolation to be possible, and that we have before us a sensation free from any other element. What is this sensation? Does it belong to the domain of physical or of moral things? Is it a state of matter or of mind?
I can neither doubt nor dispute that sensation is, in part, a psychological phenomenon, since I have admitted, by the very definition I have given of it, that sensation implies consciousness. We must, therefore, acknowledge those who define it as a state of consciousness to be right, but it would be more correct to call it the consciousness of a state, and it is with regard to the nature of this state that the question presents itself. It is only this state which we will now take into consideration. It is understood that sensation contains both an impression and a cognition. Let us leave till later the study of the act of cognition, and deal with the impression. Is this impression now of a physical or a mental nature? Both the two opposing opinions have been upheld. In this there is nothing astonishing, for in metaphysics one finds the expression of every possible opinion. But a large, an immense majority of philosophers has declared in favour of the psychological nature of the impression. Without even making the above distinction between the impression and the act of cognition, it has been admitted that the entire sensation, taken en bloc, is a psychological phenomenon, a modification of our consciousness and a peculiar state of our minds. Descartes has even employed this very explicit formula: "The objects we perceive are within our understanding." It is curious to see how little trouble authors take to demonstrate this opinion; they declare it to be self-evident, which is a convenient way of avoiding all proof. John Stuart Mill has no hesitation in affirming that: "The mind, in perceiving external objects, can only take notice of its own conditions." And Renouvier expresses the same arbitrary assertion with greater obscurity when he writes: "The monad is constituted by this relation: the connection of the subject with the object within the subject."15 In other words, it is laid down as an uncontrovertible principle that "the mental can only enter into direct relations with the mental." That is what may be called "the principle of Idealism."
This principle seems to me very disputable, and it is to me an astonishing thing that the most resolute of sceptics—Hume, for example—should have accepted it without hesitation. I shall first enunciate my personal opinion, then make known another which only differs from mine by a difference of words, and finally I will discuss a third opinion, which seems to me radically wrong.
My personal opinion is that sensation is of a mixed nature. It is psychical in so far as it implies an act of consciousness, and physical otherwise. The impression on which the act of cognition operates, that impression which is directly produced by the excitant of the nervous system, seems to me, without any doubt, to be of an entirely physical nature. This opinion, which I make mine own, has only been upheld by very few philosophers—Thomas Reid perhaps, and William Hamilton for certain; but neither has perceived its deep-lying consequences.
What are the arguments on which I rely? They are of different orders, and are arguments of fact and arguments of logic. I shall first appeal to the natural conviction of those who have never ventured into metaphysics. So long as no endeavour has been made to demonstrate the contrary to them, they believe, with a natural and naïve belief, that matter is that which is seen, touched and felt, and that, consequently, matter and our senses are confounded. They would be greatly astonished to be informed that when we appear to perceive the outer world, we simply perceive our ideas; that when we take the train for Lyons we enter into one state of consciousness in order to attain another state of consciousness.
Now, the adherents of this natural and naïve opinion have, as they say in the law, the right of possession (possession d'état); they are not plaintiffs but defendants; it is not for them to prove they are in the right, it has to be proved against them that they are in the wrong. Until this proof is forthcoming they have a presumption in their favour.
Are we here making use of the argument of common opinion of mankind, of which ancient philosophy made so evident an abuse? Yes, and no. Yes, for we here adopt the general opinion. No, for we only adopt it till the contrary be proved. But who can exhibit this proof to the contrary? On a close examination of the question, it will be perceived that sensation, taken as an object of cognition, becomes confused with the properties of physical nature, and is identified with them, both by its mode of apparition and by its content. By its mode of apparition, sensation holds itself out as independent of us, for it is at every instant an unexpected revelation, a source of fresh cognitions, and it offers a development which takes place without and in spite of our will; while its laws of co-existence and of succession declare to us the order and march of the material universe. Besides, by its content, sensation is confounded with matter. When a philosopher seeks to represent to himself the properties of a material object,—of a brain, for example—in order to contrast them with the properties of a psychical activity, it is the properties of sensation that he describes as material; and, in fact, it is by sensation, and sensation alone, that we know these properties. Sensation is so little distinct from them that it is an error to consider it as a means, a process, an instrument for the knowledge of matter. All that we know of matter is not known in or by sensation, but constitutes sensation itself; it is not by the aid of sensation that we know colour; colour is a sensation, and the same may be said of form, resistance, and the whole series of the properties of matter. They are only our sensations clothed with external bodies. It is therefore absolutely legitimate to consider a part of our sensations, the object part, as being of physical nature. This is the opinion to which I adhere.