Kant's Theory of Knowledge

by H. A. Prichard

This presupposition that what is known exists independently of being known is quite general, and applies to feeling and sensation just as much as to parts of the physical world. It must in the end be conceded of a toothache as much as of a stone that it exists independently of the knowledge of it. There must be a pain to be attended to or noticed, which exists independently of our attention or notice. The true reason for asserting feeling and sensation to be dependent on the mind is that they presuppose not a knowing, but a feeling and a sentient subject respectively. Again, it is equally presupposed that knowing in no way alters or modifies the thing known. We can no more think that in apprehending a reality we do not apprehend it as it is apart from our knowledge of it, than we can think that its existence depends upon our knowledge of it. Hence, if 'things in themselves' means 'things existing independently of the knowledge of them', knowledge is essentially of 'things in themselves'. It is, therefore, unnecessary to consider whether idealism is assisted by the supposition of a non-finite knowing mind, correlated with reality as a whole. For reality must equally be independent of it. Consequently, if the issue between idealism and realism is whether the physical world is or is not dependent on the mind, it cannot turn upon a dependence in respect of knowledge.

That the issue does not turn upon knowledge is confirmed by our instinctive procedure when we are asked whether the various realities which we suppose ourselves to know depend upon the mind. Our natural procedure is not to treat them simply as realities and to ask whether, as realities, they involve a mind to know them, but to treat them as realities of the particular kind to which they belong, and to consider relation to the mind of some kind other than that of knowledge. We should say, for instance, that a toothache or an emotion, as being a feeling, presupposes a mind capable of feeling, whose feeling it is; for if the mind be thought of as withdrawn, the pain or the feeling must also be thought of as withdrawn. We should say that an act of thinking presupposes a mind which thinks. We should, however, naturally deny that an act of thinking or knowing, in order to be, presupposes that it is known either by the thinker whose act it is, or by any other mind. In other words, we should say that knowing presupposes a mind, not as something which knows the knowing, but as something which does the knowing. Again, we should naturally say that the shape or the weight of a stone is not dependent on the mind which perceives the stone. The shape, we should say, would disappear with the disappearance of the stone, but would not disappear with the disappearance of the mind which perceives the stone. Again, we should assert that the stone itself, so far from depending on the mind which perceives it, has an independent being of its own. We might, of course, find difficulty in deciding whether a reality of some particular kind, e. g. a colour, is dependent on a mind. But, in any case, we should think that the ground for decision lay in the special character of the reality in question, and should not treat it merely as a reality related to the mind as something known. We should ask, for instance, whether a colour, as a colour, involves a mind which sees, and not whether a colour, as a reality, involves its being known. Our natural procedure, then, is to divide realities into two classes, those which depend on a mind, and may therefore be called mental, and those which do not, and to conclude that some realities depend upon the mind, while others do not. We thereby ignore a possible dependence of realities on their being known; for not only is the dependence which we recognize of some other kind, e. g. in respect of feeling or sentience, but if the dependence were in respect of knowledge, we could not distinguish in respect of dependence between one reality and another.

Further, if reality be allowed to exist independently of knowledge, it is easy to see that, from the idealist's point of view, Kant's procedure was essentially right, and that all idealism, when pressed, must prove subjective; in other words, that the idealist must hold that the mind can only know what is mental and belongs to its own being, and that the so-called physical world is merely a succession of appearances. Moreover, our instinctive procedure[2] is justified. For, in the first place, since it is impossible to think that a reality depends for its existence upon being known, it is impossible to reach an idealistic conclusion by taking into account relation by way of knowledge; and if this be the relation considered, the only conclusion can be that all reality is independent of the mind. Again, since knowledge is essentially of reality as it is apart from its being known, the assertion that a reality is dependent upon the mind is an assertion of the kind of thing which it is in itself, apart from its being known.[3] And when we come to consider what we mean by saying of a reality that it depends upon the mind, we find we mean that it is in its own nature of such a kind as to disappear with the disappearance of the mind, or, more simply, that it is of the kind called mental. Hence, we can only decide that a particular reality depends upon the mind by appeal to its special character. We cannot treat it simply as a reality the relation of which to the mind is solely that of knowledge. And we can only decide that all reality is dependent upon the mind by appeal to the special character of all the kinds of reality of which we are aware. Hence, Kant in the Aesthetic, and Berkeley before him, were essentially right in their procedure. They both ignored consideration of the world simply as a reality, and appealed exclusively to its special character, the one arguing that in its special character as spatial and temporal it presupposed a percipient, and the other endeavouring to show that the primary qualities are as relative to perception as the secondary. Unfortunately for their view, in order to think of bodies in space as dependent on the mind, it is necessary to think of them as being in the end only certain sensations or certain combinations of sensations which may be called appearances. For only sensations or combinations of them can be thought of as at once dependent on the mind, and capable with any plausibility of being identified with bodies in space. In other words, in order to think of the world as dependent on the mind, we have to think of it as consisting only of a succession of appearances, and in fact Berkeley, and, at certain times, Kant, did think of it in this way.

That this is the inevitable result of idealism is not noticed, so long as it is supposed that the essential relation of realities to the mind consists in their being known; for, as we have seen, nothing is thereby implied as to their special nature. To say of a reality that it is essentially an object of knowledge is merely to add to the particular nature ordinarily attributed to the existent in question the further characteristic that it must be known.[4] Moreover, since in fact, though contrary to the theory, any reality exists independently of the knowledge of it, when the relation thought of between a reality and the mind is solely that of knowledge, the realities can be thought of as independent of the mind. Consequently, the physical world can be thought to have that independence of the mind which the ordinary man attributes to it, and, therefore, need not be conceived as only a succession of appearances. But the advantage of this form of idealism is really derived from the very fact which it is the aim of idealism in general to deny. For the conclusion that the physical world consists of a succession of appearances is only avoided by taking into account the relation of realities to the mind by way of knowledge, and, then, without being aware of the inconsistency, making use of the independent existence of the reality known.

Again, that the real contrary to realism is subjective idealism is confirmed by the history of the theory of knowledge from Descartes onwards. For the initial supposition which has originated and sustained the problem is that in knowledge the mind is, at any rate in the first instance, confined within itself. This supposition granted, it has always seemed that, while there is no difficulty in understanding the mind's acquisition of knowledge of what belongs to its own being, it is difficult, if not impossible, to understand how it can acquire knowledge of what does not belong to its own being. Further, since the physical world is ordinarily thought of as something which does not belong to the mind's own being, the problem has always been not 'How is it possible to know anything?' but 'How is it possible to know a particular kind of reality, viz. the physical world?' Moreover, in consequence of the initial supposition, any answer to this question has always presupposed that our apprehension of the physical world is indirect. Since ex hypothesi the mind is confined within itself, it can only apprehend a reality independent of it through something within the mind which 'represents' or 'copies' the reality; and it is perhaps Hume's chief merit that he showed that no such solution is possible, or, in other words, that, on the given supposition, knowledge of the physical world is impossible.

Now the essential weakness of this line of thought lies in the initial supposition that the mind can only apprehend what belongs to its own being. It is as much a fact of our experience that we directly apprehend bodies in space, as that we directly apprehend our feelings and sensations. And, as has already been shown,[5] what is spatial cannot be thought to belong to the mind's own being on the ground that it is relative to perception. Further, if it is legitimate to ask, 'How can we apprehend what does not belong to our being?' it is equally legitimate to ask, 'How can we apprehend what does belong to our own being?' It is wholly arbitrary to limit the question to the one kind of reality. If a question is to be put at all, it should take the form, 'How is it possible to apprehend anything?' But this question has only to be put to be discarded. For it amounts to a demand to explain knowledge; and any answer to it would involve the derivation of knowledge from what was not knowledge, a task which must be as impossible as the derivation of space from time or of colour from sound. Knowledge is sui generis, and, as such, cannot be explained.[6]

Moreover, it may be noted that the support which this form of idealism sometimes receives from an argument which uses the terms 'inside' and 'outside' the mind is unmerited. At first sight it seems a refutation of the plain man's view to argue thus: 'The plain man believes the spatial world to exist whether any one knows it or not. Consequently, he allows that the world is outside the mind. But, to be known, a reality must be inside the mind. Therefore, the plain man's view renders knowledge impossible.' But, as soon as it is realized that 'inside the mind' and 'outside the mind' are metaphors, and, therefore, must take their meaning from their context, it is easy to see that the argument either rests on an equivocation or assumes the point at issue. The assertion that the world is outside the mind, being only a metaphorical expression of the plain man's view, should only mean that the world is something independent of the mind, as opposed to something inside the mind, in the sense of dependent upon it, or mental. But the assertion that, to be known, a reality must be inside the mind, if it is to be incontestably true, should only mean that a reality, to be apprehended, must really be object of apprehension. And in this case 'being inside the mind', since it only means 'being object of apprehension', is not the opposite of 'being outside the mind' in the previous assertion. Hence, on this interpretation, the second assertion is connected with the first only apparently and by an equivocation; there is really no argument at all. If, however, the equivocation is to be avoided, 'inside the mind' in the second assertion must be the opposite of 'outside the mind' in the first, and consequently the second must mean that a reality, to be known, must be dependent on the mind, or mental. But in that case the objection to the plain man's view is a petitio principii, and not an argument.

Nevertheless, the tendency to think that the only object or, at least, the only direct object of the mind is something mental still requires explanation. It seems due to a tendency to treat self-consciousness as similar to consciousness of the world. When in reflection we turn our attention away from the world to the activity by which we come to know it, we tend to think of our knowledge of the world as a reality to be apprehended similar to the world which we apprehended prior to reflection. We thereby implicitly treat this knowledge as something which, like the world, merely is and is not the knowledge of anything; in other words, we imply that, so far from being knowledge, i. e. the knowing of a reality, it is precisely that which we distinguish from knowledge, viz. a reality to be known, although—since knowledge must be mental—we imply that it is a reality of the special kind called mental. But if the knowledge upon which we reflect is thus treated as consisting in a mental reality which merely is, it is implied that in this knowledge the world is not, at any rate directly, object of the mind, for ex hypothesi a reality which merely is and is not the knowledge of anything has no object. Hence it comes to be thought that the only object or, at least, the only direct object of the mind is this mental reality itself, which is the object of reflection; in other words, that the only immediate object of the mind comes to be thought of as its own idea. The root of the mistake lies in the initial supposition—which, it may be noted, seems to underlie the whole treatment of knowledge by empirical psychology—that knowledge can be treated as a reality to be apprehended, in the way in which any reality which is not knowledge is a reality to be apprehended.

We may now revert to that form of idealism which maintains that the essential relation of reality to the mind is that of being known, in order to consider two lines of argument by which it may be defended.

According to the first of these, the view of the plain man either is, or at least involves, materialism; and materialism is demonstrably absurd. The plain man's view involves the existence of the physical world prior to the existence of the knowledge of it, and therefore also prior to the existence of minds which know it, since it is impossible to separate the existence of a knowing mind from its actual knowledge. From this it follows that mere matter, having only the qualities considered by the physicist, must somehow have originated or produced knowing and knowing minds. But this production is plainly impossible. For matter, possessing solely, as it does, characteristics bound up with extension and motion, cannot possibly have originated activities of a wholly different kind, or beings capable of exercising them.