CONCEPTS and Ideas [On the use of the term “Idea” see Preface to the Revised Translation p. ix.] arise through thinking. What a concept is cannot be expressed in words. Words can do no more than draw our attention to the fact that we have concepts. When someone sees a tree, his thinking reacts to the stimulus of this observation. Thus an ideal element is added to the perceived object, and the perceiver regards the object and its ideal complement as belonging together. When the object disappears from the field of his observation, the ideal counterpart alone remains. This latter is the concept of the object. The wider the range of our experience, the larger becomes the sum of our concepts. Moreover, concepts are not by any means found in isolation one from the other. They combine to form a whole ruled by law. The concept “organism,” e.g., combines with those of “development according to law,” “growth,” and others. Other concepts based on particular objects fuse completely with one another. All concepts formed from particular lions fuse in the collective concept “lion.” In this way, all the separate concepts combine to form a closed, conceptual system within which each has its special place. “Ideas” do not differ qualitatively from concepts. They are but fuller, more saturated, more comprehensive concepts. I must attach special importance to the necessity of bearing in mind, here, that I make thinking my starting-point, and not concepts and Ideas which are first gained by means of thinking. These latter presuppose thinking. My remarks regarding the self-dependent, self-sufficient character of thinking cannot, therefore, be simply transferred to concepts. (I make special mention of this, because it is here that I differ from Hegel, who regards the concept as something primary and original.)
Concepts cannot be gained from observation. This is apparent from the fact that, as man grows up, he slowly and gradually forms the concepts corresponding to the objects which surround him. Concepts are added to observation.
A philosopher, widely read at the present day — Herbert Spencer — describes the mental process which we perform upon observation as follows: “If, when walking through the fields some day in September, you hear a rustle a few yards in advance, and on observing the ditch-side where it occurs, see the herbage agitated, you will probably turn towards the spot to learn by what this sound and motion are produced. As you approach there flutters into the ditch a partridge; on seeing this your curiosity is satisfied — you have what you call an explanation of the appearances. The explanation, mark, amounts to this — that whereas throughout life you have had countless experiences of disturbance among small stationary bodies, accompanying the movement of other bodies among them, and have generalized the relation between such disturbances and such movements, you consider this particular disturbance explained on finding it to present an instance of the like relation” (First Principles, Part I, par. 23). A closer analysis leads to a very different description from that here given. When I hear a noise, my first demand is for the concept which fits this observation. It is this concept only which points beyond the noise. Whoever does not reflect further, hears just the noise and is satisfied with that. But my reflecting makes it clear to me that the noise is to be regarded as an effect. Thus it is only when I combine the concept of effect with the percept of a noise that I am led to go beyond the particular observation and seek for its cause. The concept of “effect” calls up that of “cause,” and my next step is to look for the agent, which I find, say, in a partridge. But these concepts, cause and effect, can never be gained through mere observation, however many instances we bring under review. Observation evokes thinking, and it is this which shows me how to link separate experiences together.
If one demands of a “strictly objective science” that it should take its data from observation alone, one must demand also that it abandon all thinking. For thinking, by its very nature, transcends the objects of observation.
It is time now to pass from thought to the thinking being. For it is through the thinker that thinking is combined with observation. The human consciousness is the stage on which concept and observation meet and are linked to one another. In saying this, we already characterize this (human) consciousness. It mediates between thinking and observation. In so far as we observe an object, it seems to be given; in so far as we think, we appear to ourselves as being active. We regard the thing as object and ourselves as the thinking subject. When thinking is directed upon the observation we have consciousness of objects; when it is directed upon ourselves we have consciousness of ourselves or self-consciousness. Human consciousness must, of necessity, be at the same time self-consciousness, because it is a consciousness which thinks. For, when thinking contemplates its own activity it makes an object for study of its own essential nature, it makes an object of itself as subject.
It must not be overlooked that it is only by means of thinking that I am able to determine myself as subject and contrast myself with objects, Therefore, thinking must never be regarded as a merely subjective activity. Thinking transcends the distinction of subject and object. It produces these two concepts just as it produces all others. When, therefore, I, as thinking subject, refer a concept to an object, we must not regard this reference as something purely subjective. It is not the subject, but thinking which makes the reference. The subject does not think because it is a subject, rather it conceives itself to be a subject because it can think. The activity performed by man as a thinking being is thus not merely subjective. Rather it is neither subjective nor objective; it transcends both these concepts. I ought never to say that my individual subject thinks but rather that I myself, as “subject,” exist by the grace of thinking. Thinking is thus an element which leads me beyond myself and relates me to objects. At the same time it separates me from them, inasmuch as it sets me, as subject, over against them.
It is just this which constitutes the double nature of man. He thinks and thereby embraces himself and the rest of the world. But by this same act of thought he determines himself also as an individual, standing over against the things, as subject.
We must next ask ourselves how the other element, which we have so far simply called the object of observation and which comes, in consciousness, into contact with thinking, enters into consciousness at all?
In order to answer this question, we must eliminate from the field of observation everything which has been imported by thinking. For, at any moment, the content of our consciousness is always shot through with concepts in the most varied ways.
Let us imagine that a being with fully developed human intelligence originated out of nothing and confronted the world. All that it there perceived before its thinking began to act would be the pure content of observation. The world so far would appear to this being as a mere chaotic aggregate of objects of sensation — colours, sounds, sensations of pressure, of warmth, of taste, of smell, and, further, feelings of pleasure and pain. This aggregation constitutes the world of pure unthinking observation. Over it stands thinking, ready to begin its activity as soon as it can find a point of attack. Experience shows that the opportunity is not long in coming. Thinking is able to draw threads from one element of observation to another. It links definite concepts with these elements and thus establishes a relation between them. We have seen above how a noise which we hear is connected with another observation by our identifying the first as the effect of the second.
If now we recollect that the activity of thinking is on no account to be considered as merely subjective, then we shall not be tempted to believe that the relations thus established by thinking have merely subjective validity.
Our next task is to discover by means of thinking reflection what relation the above-mentioned immediately given content of observation has to the conscious subject.
The ambiguity of current speech makes it advisable for me to come to an agreement with my readers concerning the meaning of a word which I shall have to employ in what follows. I shall apply the word “percepts” to the immediate objects of sensation enumerated above, in so far as the conscious subject apprehends them through observation. It is, then, not the process of observation, but the object of observation which I call the “percept.”
I do not choose the term “sensation,” because this has a definite meaning in Physiology which is narrower than that of my concept of “percept.” I can speak of a feeling as a percept, but not as a sensation in the physiological sense of the term. I have knowledge of my feeling through its becoming a percept for me. The manner in which, through observation, we gain knowledge of our thinking is such that thinking, too, may be called a percept, when it first appears before our consciousness.
The unreflective man regards his percepts, such as they appear to his immediate apprehension, as things having an existence wholly independent of him. When he sees a tree he believes in the first instance that it stands in the form which he sees, with the colours of all its parts, etc., there on the spot towards which his gaze is directed. When the same man sees the sun in the morning appear as a disc on the horizon, and follows the course of this disc, he believes that the phenomenon exists and occurs (by itself) exactly as he observes it. To this belief he clings until he meets with further percepts which contradict his former ones. The child who has as yet had no experience of distance grasps at the moon, and does not correct its first impression as to the real distance until a second percept contradicts the first. Every extension of the circle of my percepts compels me to correct my picture of the world. We see this in everyday life, as well as in the spiritual development of mankind. The picture which the ancients made for themselves of the relation of the earth to the sun and other heavenly bodies had to be replaced by another when Copernicus found that it was not in accordance with some percepts which in those early days were unknown. A man who had been born blind said, when operated on by Dr. Franz, that the idea of the size of objects which he had formed before his operation by his sense of touch was a very different one. He had to correct his tactual percepts by his visual percepts.
How is it that we are compelled to make these continual corrections in our observations?
A simple reflection supplies the answer to this question. When I stand at one end of an avenue, the trees at the other end, away from me, seem smaller and nearer together than those where I stand. My percept-picture changes when I change the place from which I am looking. The form in which it presents itself to me is, therefore, dependent on a condition which inheres, not in the object, but in me, the percipient. It is all the same to the avenue where I stand. But the picture of it which I receive depends essentially on my standpoint. In the same way, it makes no difference to the sun and the planetary system that human beings happen to look at them from the earth; but the percept-picture of the heavens which human beings have is determined by the fact that they inhabit the earth. This dependence of our percept-picture on our places of observation is most easy to understand. The matter becomes more difficult when we realize further that our perceptual world is dependent on our bodily and spiritual organization. The physicist teaches us that within the space in which we hear a sound there are vibrations of the air, and that also there are vibrations in the particles of the body in which we seek the cause of the sound. These vibrations are perceived as sounds only if we have normally constructed ears. Without them the whole world would be for us for ever silent. Again, physiology teaches us that there are men who perceive nothing of the wonderful display of colours which surrounds us. In their percept-picture there are only degrees of light and dark. Others are blind only to one colour, e.g., red. Their world picture lacks this colour tone, and hence it is actually a different one from that of the average man. I should like to call the dependence of my percept-picture on my point of observation “mathematical,” and its dependence on my organization “qualitative.” The former determines the proportions of size and mutual distances of my percepts, the latter their quality. The fact that I see a red surface as red — this qualitative determination — depends on the organization of my eye.
My percept-pictures, then, are in the first instance subjective. The recognition of the subjective character of our percepts may easily lead us to doubt whether there is any objective basis for them at all. When we know that a percept, e.g., that of a red colour or of a certain tone, is not possible without a specific structure of our organism, we may easily be led to believe that it has no being at all apart from our subjective organization, that it has no kind of existence apart from the act of perceiving of which it is the object. The classical representative of this theory is George Berkeley, who held that from the moment we realize the importance of the subject for perception, we are no longer able to believe in the existence of a world apart from a conscious Spirit. “Some truths there are so near and obvious to the mind that man need only open his eyes to see them. Such I take this important one to be, viz., that all the choir of heaven and the furniture of the earth — in a word, all those bodies which compose the mighty frame of the world — have not any subsistence without a mind; that their being consists in their being perceived or known; that, consequently, so long as they are not actually perceived by me, or do not exist in my mind or that of any other created spirit, they must either have no existence at all or else subsist in the mind of some Eternal Spirit.” (Berkeley, Principles of Human Knowledge, Part I, Section 6.)
On this view, when we take away the fact of its being perceived, nothing remains of the percept. There is no colour when none is seen, no sound when none is heard. Extension, form, and motion exist as little as colour and sound apart from the act of perception. We never perceive bare extension or shape. These are always joined with colour or some other quality, which are undoubtedly dependent on our subjectivity. If these latter disappear when we cease to perceive, the former, being connected with them, must disappear likewise.
If it is urged that, even though figure, colour, sound, etc., have no existence except within the act of perception, yet there must be things which exist apart from consciousness and to which the conscious percept-pictures are similar, then the view we have mentioned would answer, that a colour can be similar only to a colour, a figure to a figure. Our percepts can be similar only to our percepts and to nothing else.. Even what we call a thing is nothing but a collection of percepts which are connected in a definite way. If I strip a table of its shape, extension colour, etc. — in short, of all that is merely my percepts — then nothing remains over. If we follow this view to its logical conclusion, we are led to the assertion that the objects of my perceptions exist only through me, and indeed only in as far as, and as long as, I perceive them. They disappear with my perceiving and have no meaning apart from it. Apart from my percepts, however, I know of no objects and cannot know of any.
No objection can be made to this assertion as long as we take into account merely the general fact that the percept depends partly on the organization of the subject. The matter would be far otherwise if we were in a position to say what part exactly is played by our perceiving in the bringing forth of a percept. We should know then what happens to a percept whilst it is being perceived, and we should also be able to determine what character it must already possess before it comes to be perceived.
This leads us to turn our attention from the object of a percept to the perceiving subject. I am aware not only of other things but also of myself. The content of my percept of myself consists, in the first instance, in being something stable in contrast with the ever coming and going flux of percept-pictures. The perception of the I can always come forth in my consciousness alongside of all other percepts. When I am absorbed in the perception of a given object I am, for the time being, aware only of this object. To this, then, the percept of my Self can come. I am then conscious, not only of the object, but also of my Self as opposed to and observing the object. I do not merely see a tree, I know also that it is I who see it. I know, moreover, that some process takes place in me when I observe the tree. When the tree disappears from my field of vision, an after-effect of this process remains in my consciousness, viz., an image of the tree. This image has become associated with my Self during my observation. My Self has become enriched; to its content a new element has been added. This element I call my representation [See Translator's Preface, p. ix.] of the tree. I should never have occasion to talk of representations did I not experience them in the percept of my own Self. Percepts would come and go; I should let them slip by. Only because I perceive my Self, and observe that with each percept the content of the Self, too, is changed, I am compelled to connect the observation of the object with the changes in my own condition, and to speak of my representation.
I perceive the representation in my Self in the same sense as I perceive colour, sound, etc., in other objects. I am now also able to distinguish these other objects, which stand over against me, by the name of the outer world, whereas the contents of my percept of my Self form my inner world. The failure to recognize the true relation between representation and object has led to the greatest misunderstandings in modern philosophy. The fact that I perceive a change in my Self, that my Self undergoes a modification, has been thrust into the foreground, whilst the object which causes these modifications is altogether lost sight of. It has been said that we perceive, not objects, but only our representations. I know, so it is said, nothing of the table in itself, which is the object of my observation, but only of the changes which occur within me when I perceive a table. This view should not be confused with the Berkeleyan theory mentioned above. Berkeley maintains the subjective nature of my perceptual contents, but he does not say that I can know only my own representations. He limits my knowledge to my representations because, in his opinion, there are no objects outside the act of representing. What I take as a table no longer exists, according to Berkeley, when I cease to look at it. This is why Berkeley holds that our percepts are created directly by the omnipotence of God. I see a table because God causes this percept in me. For Berkeley therefore, nothing is real except God and human spirits. What we call the “world” exists only in spirits. What the naive man calls the outer world, or corporeal nature, is for Berkeley non-existent. This theory is confronted by the now predominant Kantian view which limits our knowledge of the world to our representations, not because of any conviction that nothing beyond these representations exists, but because it holds that we are so organized that we can experience only the changes of our own selves, not the things which cause these changes. This view concludes from the fact that I know only my representations, not that there is no reality independent of them, but only that the subject cannot have direct knowledge of such reality. The subject can merely “through the medium of its subjective thoughts imagine it, invent it, think it, cognize it, or perhaps even fail to cognize it.” (O. Liebmann, Zur Analysis der Wirklichkeit, p. 28.) This (Kantian) conception believes it gives expression to something absolutely certain, indeed immediately evident, without any proof. “The most fundamental principle which the philosopher must bring to clear consciousness, consists in the recognition that our knowledge, in the first instance, is limited to our representations. Our representations are all that we immediately experience, and just because we have immediate experience of them the most radical doubt cannot rob us of our knowledge of them. On the other hand, the knowledge which transcends my representations — taking representations here in the widest possible sense, so as to include all psychical processes — is not proof against doubt. Hence, at the very beginning of all philosophizing we must explicitly set down all knowledge which transcends representations as open to doubt.” These are the opening sentences of Volkelt's book on Kant's Theory of Knowledge. What is here put forward as an immediate and self-evident truth is, in reality, the conclusion of a line of argument which runs as follows. Naive common sense believes that things, just as we perceive them, exist also outside our consciousness. Physics, Physiology, and Psychology, however, seem to teach us that for our percepts our organization is necessary, and that, therefore, we cannot know anything about external objects except what our organization transmits to us. Our percepts are thus modifications of our organization, not things-in-themselves. This train of thought has, in fact, been characterized by Ed. von Hartmann as the one which leads necessarily to the conviction that we can have direct knowledge only of our own representations (cf. his Das Grundproblem der Erkenntnistheorie, pp. 16 – 40). Because outside our organisms we find vibrations of physical bodies and of air, which are perceived by us as sounds, it is concluded that what we call sound is nothing more than a subjective reaction of our organisms to these motions in the external world. Similarly, colour and heat are inferred to be merely modifications of our organisms. And, further, these two. kinds of percepts are held to be produced in us through processes in the external world which are utterly different from what we experience as heat or as colour. When these processes stimulate the nerves in the skin of my body, I have the subjective percept of heat; when they stimulate the optical nerve I perceive light and colour. Light, colour, and heat, then, are the reactions of my sensory nerves to external stimuli. Similarly, the sense of touch reveals to me, not the objects of the outer world, but only states of my own body. In the sense of modern Physics one could somehow think that bodies are composed of infinitely small particles called molecules, and that these molecules are not in direct contact with one another, but have definite intervals between them. Between them, therefore, is empty space. Across this space they act on one another by attraction and repulsion. If I put my hand on a body, the molecules of my hand by no means touch those of the body directly, but there remains a certain distance between body and hand, and what I experience as the body's resistance is nothing but the effect of the force of repulsion which its molecules exert on my hand. I am absolutely external to the body and perceive only its effects on my organism.
The theory of the so-called Specific Nervous Energy, which has been advanced by J. Müller (1801 –1858), supplements these considerations. It asserts that each sense has the peculiarity that it reacts to all external stimuli in only one definite way. If the optic nerve is stimulated, light sensations result, irrespective of whether the stimulation is due to what we call light, or to mechanical pressure, or an electrical current. On the other hand, the same external stimulus applied to different senses gives rise to different percepts. The conclusion from these facts seems to be, that our sense-organs can only transmit what occurs in themselves, but nothing of the external world. They determine our percepts, each according to its own nature.
Physiology shows, further, that there can be no direct knowledge even of the effects which objects produce on our sense-organs. Through following up the processes which occur in our own bodies, the physiologist finds that, even in the sense-organs, the effects of the external vibrations are modified in the most diverse ways. We can see this most clearly in the case of eye and ear. Both are very complicated organs which modify the external stimulus considerably, before they conduct it to the corresponding nerve. From the peripheral end of the nerve the modified stimulus is then conducted to the brain. Here the central organs must in turn be stimulated. The conclusion is, therefore, drawn that the external process undergoes a series of transformations before it reaches consciousness. What goes on in the brain is connected by so many intermediate links with the external process, that any similarity to the latter is out of the question. What the brain ultimately transmits to the soul is neither external processes, nor processes in the sense-organs, but only such as occur in the brain. But even these are not perceived immediately by the soul. What we finally have in consciousness are not brain processes at all, but sensations. My sensation of red has absolutely no similarity to the process which occurs in the brain when I sense red. The sensation, again, occurs as an effect in the soul, and the brain process is only its cause. This is why Hartmann (Das Grundproblem der Erkenntnistheorie, p. 37) says, “What the subject perceives is therefore only modifications of his own physical states and nothing else.” However, when I have sensations, they are very far as yet from being grouped in what I perceive as “things.” Only single sensations can be transmitted to me by the brain. The sensations of hardness and softness are transmitted to me by the organ of touch, those of colour and light by the organ of sight. Yet all these are to be found united in one and the same object. The unification must, therefore, be brought about by the soul itself; that is, the soul combines the separate sensations, mediated through the brain, into bodies. My brain conveys to me singly, and by widely different paths, the visual, tactual, and auditory sensations which the soul then combines into the representation of a trumpet. Thus, this last link of a process (i.e., the representation of a trumpet), is for my consciousness the primary datum. In this result nothing can any longer be found of what exists outside me and originally impressed my sense-organs. The external object is lost entirely on the way to the brain and through the brain to the soul.
It would be hard to find in the history of human spiritual life another edifice of thought which has been built up with greater ingenuity, and which yet, on closer analysis, collapses into nothing. Let us look a little closer at the way it has been constructed. The theory starts with what is given in naive consciousness, i.e., with things as perceived. It proceeds to show that none of the qualities which we find in these things would exist for us, had we no sense-organs. No eye — no colour. Therefore, the colour is not, as yet, present in that which affects the eye. It arises first through the interaction of the eye and the object. The latter is, therefore, colourless. But neither is the colour in the eye, for in the eye there is only a chemical, or physical, process which is first conducted by the optic nerve to the brain, and there initiates another process. Even this is not yet the colour. That is only produced in the soul by means of the brain process. Even then it does not yet enter my consciousness, but is first referred by the soul to a body in the external world. There, upon this body, I finally believe myself to perceive it. We have traveled in a complete circle. We are conscious of a coloured object. That is the starting-point. Here the thought-operation begins. If I had no eye, the object would be, for me, colourless. I cannot, therefore, attribute the colour to the object. I start on the search for it. I look for it in the eye — in vain; in the nerve — in vain; in the brain — in vain once more; in the soul — here I find it indeed, but not attached to the object. I recover the coloured body only on returning to my starting-point. The circle is completed. I believe that I am cognizing as a product of my soul that which the naive man regards as existing outside him, in space.
As long as one stops here everything seems to fit beautifully. But we must go over the circle once more from the beginning. Hitherto I have used, as my starting-point, the object, i.e., the external percept of which up to now, from my naive standpoint, I had a totally wrong conception. I thought that the percept, just as I perceive it, had objective existence. But now I observe that it disappears with my act of representation, that it is only a modification of my soul condition. Have I, then, any right at all to start from it in my arguments? Can I say of it that it acts on my soul? I must henceforth treat the table of which formerly I believed that it acted on me and produced a representation of itself in me, as itself a representation. But from this it follows logically that my sense-organs, and the processes in them are also merely subjective. I have no right to talk of a real eye but only of my representation of the eye. Exactly the same is true of the nerve paths, and the brain process, and even of the process in the soul itself, through which things are supposed to be constructed out of the chaos of manifold sensations. If assuming the truth of the first circle of argumentation, I run through the steps of my act of cognition once more, the latter reveals itself as a tissue of representations which, as such, cannot act on one another. I cannot say that my representation of the object acts on my representation of the eye, and that from this interaction, results my representation of colour. Nor is it necessary that I should say this. For as soon as I see clearly that my sense-organs and their activity, my nerve- and soul-processes, can also be known to me only through perception, the train of thought which I have outlined reveals itself in its full absurdity. It is quite true that I can have no percept without the corresponding sense-organ. But just as little can I be aware of a sense-organ without perception. From the percept of a table I can pass to the eye which sees it, or the nerves in the skin which touch it, but what takes place in these I can, in turn, learn only from perception. And then I soon notice that there is no trace of similarity between the process which takes place in the eye and the colour which I perceive. I cannot get rid of my colour percept by pointing to the process which takes place in the eye during this perception. No more can I rediscover the colour in the nerve- or brain-processes. I only add new percepts, localized within the organism, to the first percept which the naive man localizes outside his organism. I only pass from one percept to another.
Moreover, there is a break in the whole argument. I can follow the processes in my organism up to those in my brain, even though my assumptions become more and more hypothetical as I approach the central processes of the brain. The method of external observation ceases with the process in my brain, more particularly with the process which I should observe, if I could treat the brain with the instruments and methods of Physics and Chemistry. The method of internal observation begins with the sensation, and continues up to the combination of things out of the material of sensation. At the point of transition from brain-process to sensation, there is a break in the sequence of observation.
The view which I have here described, and which calls itself Critical Idealism, in contrast to the standpoint of naive consciousness which it calls Naive Realism, makes the mistake of characterizing the one percept as representation, whilst taking the other in the very same sense as the Naive Realism which it apparently refutes. It establishes the representational (ideal) character of percepts by accepting naively, as objectively valid facts, the percepts connected with one's own organism; and, in addition, it fails to see that it confuses two spheres of observation, between which it can find no connecting link.
Critical Idealism can refute Naive Realism only by itself assuming, in naive-realistic fashion, that one's own organism has objective existence. As soon as the Idealist realizes that the percepts connected with his own organism are exactly of the same nature as those which Naive Realism assumes to have objective existence, he can no longer use the former as a safe foundation for his theory. He would, to be consistent, have to regard his own organism also as a mere complex of representations. But this removes the possibility of regarding the content of the perceptual world as a product of the spiritual organization. One would have to assume that the representation “colour” was only a modification of the representation “eye.” So-called Critical Idealism can be established only by borrowing the assumptions of Naive Realism. The apparent refutation of the latter is achieved only by uncritically accepting in another sphere its own assumptions as valid.
This much, then, is certain: Analysis within the world of percepts cannot establish Critical Idealism, and, consequently, cannot strip percepts of their objective character.
Still less is it legitimate to represent the principle that “the perceived world is my representation” as self-evident and needing no proof. Schopenhauer begins his chief work, The World as Will and Idea, with the words: “The world is my idea [Editor's footnote: The term “idea,” as used in the current translations of Schopenhauer, would be “representation” according to our translation.] — this is a truth which holds good for everything that lives and cognizes, though man alone can bring it into reflective and abstract consciousness. If he really does this, he has attained to philosophical self-consciousness. It then becomes clear and certain to him that what he knows is not a sun and an earth, but only an eye that sees a sun, a hand that feels an earth; that the world which surrounds him is there only as idea, i.e., only in relation to something else, the consciousness which is himself. If any truth can be asserted a priori, it is this; for it is the expression of the most general form of all possible and thinkable experience, a form which is more general than time, or space, or causality, for they all presuppose it ...” (The World as Will and Idea, Book I, par. I.) This whole theory is wrecked by the fact, already mentioned above, that the eye and the hand are just as much percepts as the sun and the earth. Using Schopenhauer's vocabulary in his own sense, I might maintain against him that my eye which sees the sun, and my hand which feels the earth, are my ideas (representations) just like the sun and the earth themselves. That, put in this way, the whole theory cancels itself, is clear without further argument. For only my real eye and my real hand could have the representations “sun” and “earth” as their own modifications; the representations “eye” and “hand” cannot have them. Yet it is only in terms of representations that Critical Idealism is allowed to speak.
Critical Idealism is totally unable to gain an Insight into the relation of percept to representation. It cannot make the distinction, mentioned on p. 45, between what happens to the percept in the process of perception and what must be inherent in it prior to perception. We must, therefore, attempt this problem in another way.