THE IDEAS OF REASON, THE CATEGORIES OF UNDERSTANDING AND THE FORMS OF INTUITION IN THE CRITIQUE OF PURE REASON

If we ask what use Kant had for the Idea in the first Critique then we can provide at least two answers. One of these would assert that in fact the Idea plays a very restricted role. It arises primarily in the Transcendental Dialectic, which itself appears to be a text aimed at demarcating clearly where the limits of reason lie, criticizing those who have stepped beyond these limits, and pointing out why they are wrong to do so (CPR A293–704/B349–732).

In this context, Kant states that there are, in fact, only three true Ideas of reason. These are the Soul, the World and God. Kant says that they are regulatory principles. They help to focus and organize the thought and activity of finite rational beings. They are not, however, possible objects of experience in themselves. We cannot have “knowledge” of these principles in the same way that we can have empirical knowledge of parts of our “internal” and “external” experience. Indeed, we must not think of them as normal empirical objects at all. To the extent that they are objects in any sense, they are, for the purposes of the reasoning subject, what he calls “unconditioned” objects. That is, they do not depend on anything other than themselves for their existence; they are self-subsistent totalities. Theoretical reason, however, always involves making sense of things by developing an understanding of their conditions. Consequently these Ideas of reason cannot, by definition, be “understood” in any normal sense. As objects of knowledge they always remain transcendental aspirations, forever unreachable.