Immanuel Kant's Critique of Pure Reason — trans. F. Max Müller

If reason is the faculty of deducing the particular from the general, the general is either certain in itself and given, or not. In the former case nothing is required but judgment in subsuming, the particular being thus necessarily determined by the general. This I shall call the apodictic use of reason. In the latter case, when the general is admitted as problematical only, and as a mere idea, while the particular is certain, but the universality of the rule applying to it is still a problem, several particular cases, which are all certain, are tested by the rule, whether they submit to it ; and in this case, when it appears that all particular cases which can be produced are subjected to it, the rule is concluded to be [p. 647] universal, and from that universality of the rule conclusions are drawn afterwards with regard to all cases, even those that are not given by themselves. This I shall call the hypothetical use of reason.

The hypothetical use of reason, resting on ideas as problematical concepts, ought not to be used constitutively^ as if we could prove by it, judging strictly, the truth of the universal rule, which has been admitted as an hypothesis. For how are we to know all possible cases, which, as subject to the same principle, should prove its universality } The proper hypothetical use of reason is regulative only, and intended to introduce, as much as possible, unity into the particulars of knowledge, and thus to approximate the rule to universality.

The hypothetical use of reason aims therefore at the systematical unity of the knowledge of the understanding, and that unity is the toiLchsto7te of the truth of the rules. On the other hand, that systematical unity (as a mere idea) is only 2. projected unity, to be considered, not as given in

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itself, but as a problem only, though helping us to discover a principle for the manifold and particular exercise of the understanding, and thus to lead the understanding to cases also which are not given, and to render it more systematical.

We have learnt, therefore, that the systematical unity, introduced by reason into the manifold know- [p. 648] ledge of the understanding, is a logical principle, intended to help the understanding by means of ideas, where by itself it is insufficient to establish rules, and at the same time to impart to the variety of its rules a certain harmony (or system according to principles), and by it a certain coherence, so far as that is possible. To say, however, whether the nature of the objects or the nature of the understanding which recognises them as objects, were in themselves intended for systematical unity, and whether to a certain extent we may postulate real unity a priori y without any reference to the peculiar interest of reason, maintaining that all possible kinds of knowledge of the understanding (therefore the empirical also) possess such unity and are subject to such general principles from which, in spite of their differences, they can all be derived, would be to apply a transcendental principle of reason, and to render systematical unity necessary, not only subjectively and logically as a method, but objectively also.

We shall try to illustrate this use of reason by an example. One of the different kinds of unity, according to the concepts of the understanding, is that of the causality of a substance, which we call power. The different manifestations of one and the same substance display at first so much diversity that one feels constrained to admit at first almost as many powers as there are effects. Thus

522 Transcendental Dialectic we see, for instance, in the human mind sensa- [p. 649] tion, consciousness, imagination, memory, wit, discrimination, pleasure, desire, etc. At first a simple logical maxim tells us to reduce this apparent diversity as much as possible by discovering, through comparison, hidden identity, and finding out, for instance, whether imagination connected with consciousness, be not memory, wit, discrimination, or, it may be, understanding- and reason. The idea of a fundamental power^ of which logic knows nothing as to its existence, is thus at least the problem of a systematical representation of the existing diversity of powers. The logical principle of reason requires us to produce this unity as far as possible, and the more we find that manifestations of one or the other power are identical, the more probable does it become that they are only different expressions of one and the same power which, relatively speaking, may be called their fitndamental power. The same is done with the others.