Besides the categories or conceptions of the understanding, which have been considered, and which are especially important for experience, though often applied erroneously beyond the province of experience, there are other conceptions whose peculiar province is only to deceive; conceptions whose express determination is to pass beyond the province of experience, and which may consequently be called transcendent. These are the fundamental conceptions and principles of the previous metaphysics. To examine these conceptions, and destroy the appearance of objective science and knowledge, which they falsely exhibit, is the problem of the _Transcendental Dialectics_ (the second part of the transcendental logic).
3. THE TRANSCENDENTAL DIALECTICS.—In a strict sense, the reason is distinguished from the understanding. As the understanding has its categories, the reason has its ideas; as the understanding forms fundamental maxims from conceptions, the reason forms principles from ideas, in which the maxims of the understanding have their highest confirmation. The peculiar work of the reason is, in general, to find the unconditioned for the conditioned knowledge of the understanding, and to unify it. Hence the reason is the faculty of the unconditioned, or of principles; but since it has no immediate reference to objects, but only to the understanding and its judgments, its activity must remain an immanent one. If it would take the highest unity of the reason not simply in a transcendental sense, but exalt it to an actual object of knowledge, then it would become transcendent in that it applied the conceptions of the understanding to the knowledge of the unconditioned. From this transcending and false use of the categories, arises the transcendental appearance which decoys us beyond experience, by the delusive pretext of widening the domain of the pure understanding. It is the problem of the transcendental logic to discover this transcendental appearance.
The speculative ideas of the reason, derived from the three kinds of logical conclusion, the categorical, the hypothetical, and the disjunctive, are threefold.
(1.) The psychological idea, the idea of the soul, as a thinking substance (the object hitherto of rational psychology).