this criterion is, we learn from the chapter on "The Discipline of Pure Reason." "Our reason," it is there stated, "ought to be compared to a sphere the radius of which may be determined from the curvature of the arc of its surface (corresponding to the nature of synthetical propositions a priori), which enables us likewise to fix the extent and periphery of it with perfect certainty."[1] To determine the sphere of reason, which is the object of the Critique, what is given is the curvature of its arc, namely, a priori synthetic judgments. And the method of solving this problem is itself a priori, so that the results are absolutely indisputable. The subject of investigation for the Critique is a priori knowledge and the investigation itself (i.e. the Critique) is a priori knowledge.
It is a flattering view of one's own work that makes it as definitive and as absolute as a proposition in mathematics. But in Kant's case it was not the result of vanity. He believed in a mythological entity called reason, a self-poised organic unity, which was the source of a priori knowledge, and ought therefore, he supposed, to determine a priori what a priori knowledge it possessed and the conditions of it. Kant's absolutist pretensions are the natural counterpart of a heaven-scaling rationalism which will have "all or nothing." But since the outcome of the Critique is that we can have a priori knowledge only of objects of a possible sense-experience, it is not easy to see how the Critique itself can claim to be such a priori knowledge. If a priori knowledge is explained and justified as a condition of the possibility of experience, is it pretended that the Critique is also necessary to experience? If not, it is not a priori knowledge, has no claim to absoluteness or necessity, and remains merely an hypothesis to account for a (assumed) fact. Does not the Critique open with the declaration that all our knowledge begins with impressions of sense? Whence then your knowledge of the a priori forms?
I have called reason, in Kant's sense, a mythical faculty. Consider only what functions he attributes to it. It knows a priori; it criticises a priori what it knows a priori, and it
- ↑ III, 506 (652-3).
