A Commentary to Kant's 'Critique of Pure Reason'

by Norman Kemp Smith

“That something actual without us not only corresponds but must correspond to our external perceptions can likewise be proved....”[1025]

IV. “Prolegomena,” Second Part of the Appendix.—Kant here returns to the distinction, drawn in Section 13, Note iii., between what he now calls “idealism proper (eigentlicher),”[1026] i.e. visionary or mystical idealism, and his own.

“The position of all genuine idealists from the Eleatics to Bishop Berkeley is contained in this formula: ‘All cognition through the senses and experience is nothing but mere illusion, and only in the ideas of pure understanding and Reason is there truth.’ The fundamental principle ruling all my idealism, on the contrary, is this: ‘All cognition of things solely from pure understanding or pure Reason is nothing but mere illusion and only in experience is there truth.’”[1027]

This mode of defining idealism can, in this connection, cause nothing but confusion. Its inapplicability to Berkeley would seem to prove that Kant had no first-hand knowledge of Berkeley’s writings.[1028] As Kant’s Note to the Appendix to the Prolegomena[1029] shows, he also had Plato in mind. But the definition given of “the fundamental principle” of his own idealism is almost equally misleading. It omits the all-essential point, that for Kant experience itself yields truth only by conforming to a priori concepts. As it is, he proceeds to criticise Berkeley for failure to supply a sufficient criterion of distinction between truth and illusion. Such criterion, he insists, is necessarily a priori. The Critical idealism differs from that of Berkeley in maintaining that space and time, though sensuous, are a priori, and that in combination with the pure concepts of understanding they

“...prescribe a priori its law to all possible experience: the law which at the same time yields the sure criterion for distinguishing within experience truth from illusion. My so-called idealism—which properly speaking is Critical idealism—is thus quite peculiar in that it overthrows ordinary idealism, and that through it all a priori cognition, even that of geometry, now attains objective reality, a thing which even the keenest realist could not assert till I had proved the ideality of space and time.”[1030]

V. Sections added in Second Edition at the Conclusion of the Aesthetic. (B 69 ff.)—Kant here again replies to the criticism of Pistorius that all existence has been reduced to the level of illusion (Schein). His defence is twofold: first, that in naming objects appearances he means to indicate that they are independently grounded, or, as he states it, are “something actually given.” If we misinterpret them, the result is indeed illusion, but the fault then lies with ourselves and not with the appearances as presented. Secondly, he argues that the doctrine of the ideality of space and time is the only secure safeguard against scepticism. For otherwise the contradictions which result from regarding space and time as independently real will likewise hold of their contents, and everything, including even our own existence, will be rendered illusory. “The good Berkeley [observing these contradictions] cannot, indeed, be blamed for reducing bodies to mere illusion.” This last sentence may perhaps be taken as supporting the view that notwithstanding the increased popularity of Berkeley in Germany and the appearance of new translations in these very years, Kant has not been sufficiently interested to acquire first-hand knowledge of Berkeley’s writings.[1031] The epithet employed is characteristic of the rather depreciatory attitude which Kant invariably adopts in speaking of Berkeley.

VI. “Refutation of Idealism” in Second Edition of the “Critique.” (B 274-9, supplemented by note to B xxxix.).—The refutation opens by equating idealism with material idealism (so named in contradistinction to his own “formal or rather Critical” teaching). Within material idealism Kant distinguishes between the problematic idealism of Descartes, and the dogmatic idealism of Berkeley. The latter has, he says, been overthrown in the Aesthetic. The former alone is dealt with in this refutation. This is the first occurrence in the Critique of the expression “problematic idealism”: it is nowhere employed in the first edition.[1032] Problematic idealism consists in the assertion that we are incapable of having experience of any existence save our own; only our inner states are immediately apprehended; all other existences are determined by inference from them. The refutation consists in the proof that we have experience, and not mere imagination of outer objects. This is proved by showing that inner experience, unquestioned by Descartes, is possible only on the assumption of outer experience, and that this latter is as immediate and direct as is the former.

Thesis.—The empirically determined consciousness of my own existence proves the existence of objects in space outside me.[1033]

Proof.—I am conscious of my own existence as determined in time. Time determination presupposes the perception of something permanent. But nothing permanent is intuitable in the empirical self. On the cognitive side (i.e. omitting feelings, etc., which in this connection are irrelevant), it consists solely of representations; and these demand a permanent, distinct from ourselves, in relation to which their changes, and so my own existence in the time wherein they change, may be determined.[1034] Thus perception of this permanent is only possible through a thing outside, and not through the mere representation of a thing outside. And the same must hold true of the determination of my existence in time, since this also depends upon the apprehension of the permanent. That is to say, the consciousness of my existence is at the same time an immediate awareness of the existence of other things outside me.

In the note to the Preface to the second edition[1035] occurs the following emphatic statement.