II. CRITICK OF THE PRACTICAL REASON.—With the Critick of the Practical Reason, we enter a wholly different world, where the reason richly recovers that of which it was deprived in the theoretical province. The essential problem of the Critick of the Practical Reason is almost diametrically different from that of the critick of the theoretical reason. The object of investigation in the critick of the speculative reason, was,—how can the pure reason know objects apriori; in the practical reason it is,—how can the pure reason determine apriori the will in respect of objects. The critick of the speculative reason inquired after the cognizableness of objects apriori: the practical reason has nothing to do with the cognizableness of objects, but only with the determination of the will. Hence, in the latter critick, we have an order directly the reverse of that which we find in the former. As the original determinations of our theoretical knowledge are intuitions, so the original determinations of our will are principles and conceptions. The critick of the practical reason must, therefore, start from moral principles, and only after these are firmly fixed, may we inquire concerning the relation in which the practical reason stands to the sensory.
Freedom, says Kant, is given to us apriori as an inner fact, it is a fact of the inner experience. While, therefore, the reason in the theoretical field had only a negative result, because, when it would attain to a true thing in itself it became transcendent, yet now in the practical province it becomes positive through the idea of freedom, because with the fact of freedom we have no need to go out beyond ourselves, but possess a principle immanent to the reason. But why then give a critick of practical reason? In order to determine the relation of freedom to the sensory. Since the free will works through its acts upon the sensory, there must be a point of contact between the two. This is found in the sensuous motives of the will, which exist implanted in it by nature, in the impulses and inclinations which, as the principle of the empiric in opposition to the free or pure will, bear in themselves the character of a want of freedom. Since, then, freedom cannot be touched, a critick of the practical reason can only relate to these empirical motives, in the sense of divesting these from the claim of being exclusively the motives by which the will is determined. While, therefore, in the theoretical reason the empirical element was immanent, and the intelligible transcendent, the reverse is the case in the practical reason, since here the empirical is transcendent, and the intelligible immanent. It is the object of the Analytic to show the relation of these two momenta of the will, and the highest moral principle which springs therefrom, while it belongs to the Dialectic to solve the antinomies which result from the contradiction of the pure and empiric will.