Abstract
Few commentators (if any) would question Schrader's poignant observation that 'the doctrine of the thing in itself presents the single greatest stumbling block in the Kantian philosophy' [S5:49]. Understanding what Kant meant by the doctrine i.e., the role it plays both in his overall System and in his transcendental idealism can help prevent it from being discarded 'as a perversity' [49], inasmuch as it can be interpreted in such a way that it makes quite good sense [see VI.2]. Yet even the most coherent interpretation could not prevent the philosopher who demands knowledge from 'stumbling' over it; for, according to Kant, the thing in itself is by definition unknowable. In V.3 we saw, however, that there is one alternative to faith as the ultimate justification for its employment which, if successful, would satisfy even the most persistent skeptic: viz., to justify the thing in itself by constructing a valid transcendental argument for the necessity of its existence. Since any appeal to faith would thereby be rendered superfluous, we must now examine more carefully the possibility of realizing this goal. For, although Kant himself did not believe he required such a transcendental argument, it may be possible to reconstruct his System on the basis of a slightly different presupposition, such as that the thing in itself can, in fact, be proved to exist and to have certain knowable characteristics. Hence, in this Appendix I shall analyze the logical consistency of an affirmative answer to the metacritical question: Is the thing in itself knowable? Our answer to this question will inevitably determine to a large extent how we should approach the task of interpreting the elements of Kant's Critical philosophy (as in Part Three), so it is important to deal with it seriously