Alfred Binet (1905) The Mind and the Brain

Chapter II


p. 12:

Of the outer world we know nothing except our sensations.

p. 13

Sensation is the limit, and all objects are known to us by the sensations they produce in us, and are known to us solely in this manner.

p. 15

This limit set to our knowledge … much astonishes the uninstructed when first explained to them. And this astonishment, although it may seem so, is not a point that can be neglected, for it proves that, in the first and simple state of our knowledge, we believe we directly perceive objects as they are.

p. 17

the modifications produced within our nervous system are the only states of which we can have a direct consciousness;

p. 18

I see a dog pass in the street. I call this dog an external object; but, as this dog is formed, for me who am looking at it, of my sensations, and as these sensations are states of my nervous centres, it happens that the term external object has two meanings. Sometimes it designates our sensations; at another the exciting cause of our sensations.

p. 24

Therefore, when we attempt to understand the inmost nature of the outer world we stand before it as before absolute darkness. There probably exists in nature, outside of ourselves, neither colour, odour, force, resistance, space, nor anything that we know as sensation. Light is produced by the excitement of the optic nerve, and it shines only in our brain; as to the excitement itself, there is nothing to prove that it is luminous; outside of us is profound darkness … Not one of our senses, absolutely none, is the revealer of external reality. From this point of view there is no higher and no lower level sense. The sensation of sight, apparently so objective and so searching, no more takes us out of ourselves than do the sensations of taste which are localized on the tongue.

In short, our nervous system, which enables us to communicate with objects, prevents us, on the other hand, from knowing their nature. … We never go outside ourselves. We are walled in. And all we can say of matter and of the outer world is … that it is the unknown cause of our sensations, the inaccessible excitant of our organs of the senses


Up to the present there have been three principal ways of explaining the physical phenomena of the universe. The first, the most abstract, and the furthest from reality, is above all verbal, it consists in the use of formulas in which the quality of the phenomena is replaced by their magnitude, in which this magnitude, ascertained by the most precise processes of measurement, becomes the object of abstract reasoning which alows its modiificatios to be forseen under experimental conditions. This is pure mathematics, a formal science depending on logic.



P. 60

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.

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? …

the entire sensation, en bloc, is a psychological phenomenon, a modification of our consciousness and a peculiar state of our minds.



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 naive 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 naive opinion have, as they say in the law, the right of posession (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 favor. …

By its content sensation is confounded with matter.


sensation is so little distinct from [the objects they represent] that it is an error to consider it 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.

the entire sensation, taken en bloc and unanalysed, is to be termed a psychological phenomenon.

that this object or this impression was provoked in us by a physical reality which is kept in concealment, which we do not perceive, and which remains unknowable.


the distinction between physical and mental will have lost its raison d'ètre, since the existence of the physical is necessary to give meaning to the existence of the mental. We are brought, whether we like it or not, to an experimental monism, which is neither psychical nor physical; panpsychism and panmaterialism will have the same meaning.

P. 71

I have mentioned a third opinion, stating that it appeared to me to be radically false. … It supposes that sensation is an entirely psychological phenomenon. … [He later refers to this as the axiom of heterogeneity, or the principle of psychophysical dualism.]

P. 72 [the erroneous idea that...] "The cerebral motion is the physical phenomenon, the act of consciousness the psychical."

p. 73

[quoting Lotz] "However much we may follow the excitement through the whole length of the nerve, or cause it to change its form a thousand times … we shall never succeed in showing that a movement can … cease to exist as movement and be reborn in the shape of sensation."

[Quoting Fourier:] "But how is it that the molecular modifications in the cerebral cells coincide with the modifications of the consciousness …? These are problems we cannot solve."

[Quoting Du Bois Roymond 1880] "The astronomical knowledge of the encephalon, that is, the most intimate to which we can aspire, only reveals to us matter in motion. But no arrangement of motion of material particles can act as a bridge by which we can cross over into the domain of intelligence"

P. 74

These three quotations show very consclusvely that their authors thought they could establish the heterogeneity of the two phenomena by opposing matter to sensation. It must be recognized that they have fallen into a singular error; for matter, whatever it may be, is for us nothing but sensation; matter in motion, I have often repeated, is only a quite special kind of sensation.



p. 76

after sensations come images, ideas, and concepts; in fact, quite a collection of phenomena, which are generally considered as essentially psychological. So long as one does not carefully analyse the value of ideas, one remains under the impressions that ideas form a world apart, which is sharply distinguished from the physical world, and behaves towards it as an antithesis. For is not conception the contrary of perception? and is not the ideal in opposition to reality?

Thoughts have some characteristics of fancy, of freedom, even of unreality, which are wanting to the prosaicness of heavy material things. Thoughts sport with the relations of time and space; they fly in a moment across the gulf between the most distant objects; they travel back up the course of time; they bring near to us events centuries away; they conceive objects which are unreal; they imagine combinations which upset all physical laws, and, further, these conceptions remain invisible to others as well as to ourselves. They are outside the grip of reality, and constitute a world which becomes for any one with the smallest imagination, as great and as important as the world called real.

p. 79

Let us suppose that we are sitting down, dreaming and watching the passing by of our images. If, at this moment, a sudden noise calls us back to reality, the whole of our mental phantasmagoria disappears as if by the wave of a magic wand, and it is by thus vanishing that the image shows its falsity. It is false because it does not accord with the present reality.

But when we do not notice a disagreement between these two modes of cognition, both alike give us the impression of reality. … This continuity must even be considered as the normal condition. … The image seems to prepare the adaptation of the individual to his surroundings; it creates the foresight, the preparation of the means, and, in a word, everything which constitutes for us a final cause. Now, it is very necessary that the image appear real to be usefully the substitute of the sensation past or to come. …

the image not only appears as real as the sensation, it appears to be of the same nature; and the proof is that they are confounded one with the other, and that those who are not warned of the fact take one for the other. Every time a body is perceived … there are two images which affix themselves to the sensation unnoticed. We think we perceive when we are really remembering or imagining. This addition of the image to the sensation is not a petty and insignificant accessory; it forms the major part, perhaps nine-tenths, of perception.

That which we experience in the form of sensation, we can experience over again in the form of image, and the repetition, generally weaker in intensity and poorer in details, may, under certain favorable circumstances, acquire an exceptional intensity, and even equal reality; as is shown by hallucinations. Here, certainly, are very sound reasons for acknowledging that the images which are at the bottom of our thoughts, and form the object of them, are the repetition, the modification, the transposition, the analysis or synthesis of sensations experienced in the past. … I believe that there is neither more nor less spirituality in the idea than in the sensation.



p. 96

After having separated from the consciousness that which it is not, let us try to define what it is.

A theory has often been maintained with regard to the consciousness; namely, that it supposes a relation between two terms--a subject and an object, and that it consists exactly in the feeling of this relation.

p. 97

When we are engaged in a sensation, or when we perceive something, a phenomenon occurs which simply consists in having consciousness of a thing. If to this we add the idea of the subject which has consciousness, we distort the event. … we complicate it by adding to it the work of reflection. It is reflection which constructs the notion of the subject, and it is this which afterwards introduces this construction into the states of consciousness … the state of consciousness, by receiving this notion of subject, acquires a character of duality it did not previously possess. There are in short, two separate acts of consciousness, and one is made the subject of the other.

p. 107

Matter cannot exist without form, nor form without matter; it is the union of the two which produces cognition.

We have seen that the existence of the subject is hardly admissible, for it could only be an object in disguise.



p. 180

Many problems here present themselves. The first is that of the genesis or origin of the consciousness. It has to be explained how a psychical phenomenon can appear in the midst of material ones.

p. 182

It will force us to question a great metaphysical principle which, up till now, has been almost universally considered as governing the problem of the union of the mind with the body.

This principle bears the name of the axiom of heterogeneity, or the principle of psychophysical dualism.

[Quote Flournoy: Metaphysique et Psychologie] "body and mind, consciousness and the molecular cerebral movement of the brain, the psychical fact and the physical fact, although simultaneous, are heterogeneous, unconnected, irreducible, and obstinately two." … "This is evident of itself, and axiomatic. "

Let us not hesitate to denounce as false this proposition wihch is presented to us as an axiom.

The second proposition seems to us directly contrary to the facts, which show us that the phenomena of consciousness are incomplete phenomena. The consciousness is not sufficient for itself; … it cannot exist by itself.

p. 184

Mind and matter brought down to the essential, to the consciousness and its object, form a natural whole, and the difficulty does not consist in uniting but in separating them.

p. 186

If we had to seek paternity for ideas I would much rather turn to Aristotle. It was not without some surprise that I was able to convince myself that the above theory of relations between the soul and the body is to be found almost in its entirety in the great philosopher. … there can be no form without matter, and no matter without form. The two terms are correlative; each one implies the other, and neither can be realized or actualized without the other.

p. 188

[Quote Aristotle] "The soul is not a variety of body, but it could not exist without a body: the soul is not a body, but something which belongs or is relative to a body."

p. 190

Aristotle's theory recalls in a striking manner that of Kant on the a priori forms of thought.

"Thoughts without content given by sensation are empty; intuitions without concept furnished by the understanding are blind.'

p. 195

The ancient hylozoism, the monadism of Leibnitz, and the recent panpsychism of M. Strong are only different forms of the same doctrine.

p. 200

[Materialists v.s. idealists: matter produces mind v.s. mind produces matter] It may be sad that these two conceptions, opposed in sense, annul each other, and that each of these two philosophical systems has rendered us service by demonstrating the error of the opposing system.


P. 202

materialism is the metaphysics of those who refuse to be metaphysicians.

p. 204.

[Quote Karl Vogt] "The brain secretes thought as the kidney does urine"


physical phenomena are the only ones that are determined, measurable, explicable, and scientific.


p. 236

The manifestations of the consciousness are conditioned by the brain.

the consciousness remains in complete ignorance of these intra-cerebral phenomena. It does not perceive the neuro-wave which sets it in motion.

p. 240

The question of "How" consistes in explaining that the consciousness, directly aroused by a nerve-wave, does not perceive this undulation, but in its stead the external object.

Since it is only by the intermediary of our nervous system that we perceive the object, all the properties capable of being perceived are communicated to our nervous system and inscribed in the nerve wave.

all we perceive of the mechanical, physical, and chemical properties of a body is contained in the vibration this body succeeds in propagating through our cerebral atmosphere. There is in this a phenomenon of transmission analogous to that which is produced when an air of music is sent along a wire; the whole concert heard at the other extremity of the wire has travelled in the form of delicate vibrations.

There must therefore exist, though unperceived by our senses, a sort of kinship between the qualities of the external objects and the vibrations of our nerves. This is sometimes forgotten. The theory of the specific energy of the nerves causes it to be overlooked.

How is it that the nerve wave, if it be the depository of the whole of the physical properties perceived in the object, resembles it so little? It is because -- this is my hypothesis -- these properties, if they are in the undulation, are not there alone. The undulation is the work of two collaborators: it expresses both the nature of the object which provokes it and that of the nervous apparatus which is its vehicle. It is like the furrow traced in the wax of the phonograph which expresses the collaboration of an aerial vibration with a stylus, a cylinder, and a clock-work movement. This engraved line resembles, in short, neither the phonographic apparatus nor the aerial vibration, although it results from the combination of the two.

p. 251

My hypothesis much resembles the system of parallelism. It perfects it, as it seems to me, as much as the latter has perfected materialism. We indeed admit a kind of parallelism between the consciousness and the object of cognition; but these two series are not independent, not simply placed in juxtaposition as is possible in normal parallelism; they are united and fused together so as to complete each other.

I hold fast to this physical determinism, and accept a strictly mechanical conception of the functions of the nervous system. In my idea, the currents which pass through the cerebral mass follow each other without interruption, from the sensorial periphery to the motor periphery

p. 254

The idealist declares: "Thought creates the world." The materialist answers: "The matter of the brain creates thought." Between these two extreme opinions, the one as unjustifiable as the other in the excesses they commit, we take up an intermediate position.

p. 257


many observations and experiments show that, between the external object and ourselves, there is but one intermediary, the nervous system, and that we only perceive the modifications which the external object, acting as an excitant, provokes in this system. p. 259

no kind of our sensations--neither the visual, the tactile, nor the muscular--permits us to represent to ourselves the inmost structure of matter, because all sensations, without exception, are false, as copies of material objects.