(a) The theory of “ideas” as entities “whose nature it is to be known” (or which are “essentially known”) is most explicitly formulated by Berkeley. To think of what is known as having a nature independent of its being known is, he says, to be guilty of “abstraction”. This error consists in thinking separately of things which cannot exist separately. Thus we cannot truly know any object without knowing “all about” it (its “whole nature”); for if we only knew something about it, we should be separating that something from other somethings which in fact are also about it. In terms of this theory, if a thing really is known, we cannot think of it otherwise than as known, or we should not be thinking of it. “Can there”, asks Berkeley, “be a nicer strain of abstraction than to distinguish the existence of sensible objects from their being perceived, so as to conceive them existing unperceived?”

It is, of course, impossible to maintain a view of this kind consistently, since strictly in accordance with it we could make no statements at all. That Berkeley does not do so is shown when he says, “It is not in my power to frame an idea of a body extended and moved, but I must withal give it some colour or other sensible quality.” He really ought to maintain, in the case of a coloured body which is extended and moved, that its being coloured and its being extended and its being moved and its being a body all mean precisely the same thing; in which case his argument is stultified. But otherwise he is admitting that we can conceive the

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thing as having any one of these characters, that we can truly assert something about it without saying “all about” it. He does in fact admit that, though it may be true of an object A that it is given to us by God as a sign of B, we can know A without knowing this fact. It may equally well be that we may know a thing which is known, without knowing that it is known. There is no reason for denying this, if its being known is only something about it. And the alternative, which Berkeley would have to follow, is that, since we can only conceive separately what may exist separately, the separate statement that a thing is known implies that nothing else can be said of it but that it is known. There could not then be a number of different known things; there would simply be the essence “known”. Indeed, since what I know must be “known by me” and there is nothing else that it must be, all that I can ever know is the single essence “known by me”.

The only sort of assertion that we could make in starting from such an essence as “known” would be the identity “The known is known”; and only by means of abstraction (passing from a whole nature to a supposed part of it) could any consequences appear to follow from such a statement. Now Berkeley does start from an identity, stated negatively, viz., “What is perceived cannot be unperceived”; which is merely an expression of the essence “perceived”. But he proceeds from this, as the first quotation shows, to draw the conclusion that what is perceived cannot be conceived to be unperceived. Now the only guarantee of this conclusion is the fact that the thing is perceived; and if this is a guarantee, it must be because the thing is perceived to be perceived. (Here the notion of “idea” emerges, in the form of the “percept”; the conceiving of “concepts” and the sensing of “sensa” are suppositions of the same type.) What is perceived to be perceived cannot be taken (there is no special force in “conceived” here) to be unperceived. The obtaining of the given conclusion from the identity thus depends on the substitution of “perceived to be perceived” for “perceived”. And the plausibility of the conclusion itself depends on ambiguity; it is plausible as meaning that we cannot conceive or suppose that “what is perceived is unperceived”, but not in the required sense that things which are perceived cannot be supposed not to be perceived and must be supposed to be perceived. This cannot be admitted, since the various things that are said to be perceived cannot have their whole nature constituted by being perceived.

The fact, then, that we can make such statements as that red, or something red, is perceived, is sufficient to dispose of Berkeley's theory that what is known must be known as known. It would, on the contrary, be true to say that we know things as independent of being known, since we can only know them as existing and having characters of their own. Berkeley's theory, it should be noted, is not dependent on the use of the term “perception”; it could be maintained in exactly the same way that “whatever is apprehended cannot be unapprehended”, without any reference to modes of apprehension. So that his criticism of Locke, who

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had first admitted the “essentially apprehended” and then presumed a further knowledge of independent things, is quite sound. The criticism applicable to both is that we never know “ideas”, but always independent things.

(b) Descartes's demonstration that there is something “whose nature it is to know”, or, as he puts it, “whose whole essence consists in thinking” (i.e., “consciousness”), proceeds in a similar fashion to Berkeley's substantiation of “ideas”; in fact, it may be said that Berkeley has simply applied to the known the principle of Descartes's argument about the knower. The latter is complicated by the fact that what guarantees the essential knowingness of a knower is the knower himself; but the same mechanism of essence, identity and ambiguity can be discerned. The assumption is that we cannot suppose ourselves, in knowing, not to know, i.e., we cannot suppose that when we know, we do not know; but it is employed as if it meant that we cannot, in knowing, suppose ourselves not to know. Or, putting the argument positively, we must suppose ourselves, in knowing, to know; hence we must, in knowing, suppose ourselves to know (or, in thinking, think that we think). By means of identity and ambiguity, therefore, Descartes arrives at the conclusion that we always know ourselves as knowing, and never know ourselves as anything else; because we can suppose ourselves, though knowing, not to have that other character. The method, once more, is that what can be conceived separately from a certain thing is not of its essence but is a different thing, while what cannot be conceived separately is of its essence. And the strict consequence would be that no positive (non-identical) assertion could be made, since we could only make it by specifying a distinct part of a “whole nature”.

The view that in knowing we know ourselves knowing, that we know as knowing or consciously know, is thus seen to be as ill-founded as the view that we know things as known. The identity “the known is known” does not imply that it is the same thing to know X and to know that X is known; nor does the identity “I know what I know” imply that I must know that I know it, or know anything about myself at all, in knowing it. Descartes, having taken his knowledge as a subject to be considered, cannot in the same argument doubt that he knows; but a man who knows need not have taken up this position, and might quite well doubt that he knew, or that he doubted, or that there was such a being as himself. The conclusion that a person could not know without knowing his knowing, as we have seen, depends on ambiguity, and the conclusion that he could not know himself without knowing his knowing depends on the assumption that he must know “all about” anything he knows. This theory being logically untenable, there is no ground whatever for supposing that we must know minds as “conscious” or for treating their knowing otherwise than as a relation to other things which is not part of their own “character”. We have no more right to talk of a “conscious state” than of an “on state” or an “above state”. And we may take it as possible that anything which knows may at another time not

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know, just as things which are known may at another time not be known.

It is not in the least implied that minds are not known, but only that they are to be known as having certain qualities. “The knower is not the known” has sometimes been taken to mean that the knower is not known; hence the doctrine of the transcendental ego. Alternatively, the distinction is taken to imply that the knower can only be known as knowing, i.e., known in a different way from things which are known as known. But all that is implied is that the relation has order; it is not asymmetrical, but at least it is “non-symmetrical”. When A knows B, B need not know A; and even if B does know A, this is a different state of affairs from A knowing B. Just as, in the relation of parenthood, “the parent is not the child” and yet is always the child of someone else, so, when I know a thing, someone else may know me and he may know my knowing the thing. Only if there are cases of this kind can it be possible for us to talk about “knowledge”. But the person's knowledge of my relation to the thing is distinct from his knowledge of my qualities.

As regards my knowledge of myself, this will have to be accounted for by saying that a certain process in my mind knows another, or knows myself, but without knowing itself. We can only know ourselves, in fact, as certain very familiar objects. And if it is urged that the process which knows does nevertheless belong to myself, the answer must be that what we know consists not of things simply but of states of affairs (or propositions). Suppose, then, that I know that I am angry, the “object” may be roughly expressed by saying that within a certain contour anger is occurring; and the fact that the process which knows it also occurs within the contour is not to the purpose, since we do not require to know “all” that occurs within the contour. That which knows a given occurrence is a different occurrence; it is not my anger which knows my anger. Detailed discussion of how we come to use the term “I” would be out of place here. It is enough to point out that on the realist theory the conception of a mind as a “unity” or indivisible whole cannot be sustained; according to that conception neither I nor anyone else could know anything about my mind.