In the sphere of metaphysics we vacillate between dogmatism, skepticism and indifference, metaphysics “has hitherto been a merely random groping”. Against this background, Kant makes his famous announcement of a Copernican revolution in philosophy: “Hitherto it has been assumed that all our knowledge must conform to objects”, but since this assumption has conspicuously failed to yield any metaphysical knowledge, we “must therefore make trial whether we may not have more success in the tasks of metaphysics, if we suppose that objects must conform to our knowledge.”

Metaphysics, as a natural predisposition of reason, is actual, but it is also of itself dialectical and deceitful. In order that metaphysics might, as science, be able to lay claim, not merely to deceitful persuasion, but to insight and conviction, a critique of reason itself must set forth the entire stock of a priori concepts, their division according to the different sources.

Section 40 - 45

Kant distinguishes concepts of reason and concepts of understanding. Concepts of understanding are immanent, which means they refer to experience, whereas concepts of reason extend to the completeness, i.e., the collective unity of the whole of possible experience, are transcendent. Hence only concepts of understanding needs categories, reason contains in itself the basis for ideas.

Section 14-35

Nature is the existence of things, insofar as that existence is determined according to universal laws. The cognition is not in themselves, since I can not know things apart from my concept. We can not know things in themselves either a priori or a posteriori.

Section 7-13

All mathematical cognition has this distinguishing feature, that it must present its concept beforehand in intuition and indeed a priori, consequently in an intuition that is not empirical but pure, and can exemplify its apodictic teachings through intuition but can never derive them from it. Pure mathematics must be grounded in some pure intuition or other, in which it can present, or, as one calls it, construct all of its concepts in concreto yet a priori. Pure intuition is like empirical intuition since we can form concepts out of them, but with the difference that it is a priori, and is bound with the concept before all experience or individual perception.