A theoretical knowledge.[292]—i.e. Kant explicitly leaves aside the further problem, whether such judgments may not also be possible in the practical (moral) and other spheres.
How is pure natural science possible?[293]—The note which Kant appends shows that he is here taking natural science in the relative sense.[294] The same irrelevant instances are again cited.
As these sciences really exist.[295]—Cf. below, p. 44 ff.
The poor progress which metaphysics has hitherto made.[296]—Cf. Preface to the second edition; Prolegomena, § 4, and A 175 ff.
How is metaphysics as a science possible?[297]—We may now consider how this and the three preceding questions are related to one another and to the various divisions of the Critique.[298] The four subordinate questions within the main problem—How are synthetic a priori judgments possible?—are here stated by Kant as:
1. How is pure mathematics possible?
2. How is pure natural science possible?
3. How is metaphysics as natural disposition possible?
4. How is metaphysics as science possible?
There is little difficulty as regards 1 and 2. The first is dealt with in the Aesthetic, and the second[299] in the Analytic, though, owing to the complexity of the problems, the Aesthetic and Analytic are wider than either query, and cannot be completely separated. Applied mathematics is dealt with in the Analytic as well as in the Aesthetic, and in both the determination of the limits of scientific knowledge is equally important with that of accounting for its positive acquisitions. The third and fourth questions raise all manner of difficulties. Notwithstanding the identical mode of formulation, they do not run on all fours with the two preceding. The first two are taken as referring to actually existing and valid sciences. It is the ground of their objective validity that is sought. But what is investigated in the third question falsely lays claim to the title of science; we can enquire only as to the ground of its subjective possibility. In the fourth question, the problem takes still another form. Kant now seeks to determine whether a new, not yet existing, science of metaphysics is possible, and in what manner it can be validly constructed. The manifoldness of the problems is thus concealed by the fixity of the common formula.[300] Now with what divisions of the Critique are the two last questions connected? It has been suggested[301] that the third question is dealt with in the Dialectic and the fourth in the Methodology, the four questions thus corresponding to the four main divisions of the Critique. But this view is untenable, especially in its view of the fourth question. The division of the Critique is by dichotomy into doctrine of elements and doctrine of methods, the former including the Aesthetic and Logic, and the Logic being again divided into Analytic and Dialectic. Its problems stand in an equally complex subordination; they cannot be isolated from one another, and set merely side by side. Secondly, it has been maintained[302] that the third question is dealt with in the introduction to the Dialectic (in its doctrine of Ideas), and the fourth in the Dialectic proper. This view is fairly satisfactory as regards the third question, but would involve the conclusion that the fourth question refers only to transcendent metaphysics, and that it therefore receives a negative answer. But that is not Kant’s view of metaphysics as a science. The Critique is intended to issue in a new and genuine body of metaphysical teaching.