I just finished reading Kant’s Critique of Practical Reason. Having thus reached another benchmark on my journey through the major works and essays of Immanuel Kant, I feel this is a good space to pause and reflect on the substance of Kant’s thought.

Apart from the obvious rigor and judiciousness with which Kant undertook his first two Critiques, the nobility of the man’s thought cannot be too highly esteemed. The distinctions he draws, however tedious, are central to the feasibility of his system. It works as a functioning whole, despite its unfortunate dualisms and the murky connection which ostensibly unites them (“freedom,” according to the second Critique).

So, without going too much into the specifics of Kant’s argumentation (an exhaustive discussion would prove far too long for popular presentation), a few words might be said about the general “direction of fit” in his first two major works.

The Critique of Pure Reason deals with theoretical cognition. It moves from objects given to us by sensory intuition and proceeds to the categories of our understanding and their derived principles by which we make such objects intelligible. The second Critique, by contrast, deals with practical volition. It proceeds from the moral law prescribed by our will to a formal principle (the famed Categorical Imperative) to fundamental concepts of good and evil and then finally to the world of sensibility, which we hope to effect by our rational action upon it. This can be (analytically) organized as follows:

First Critique: Noumenal source of intuition → Sensibility (Aesthetic) → Pure concepts or categories of the understanding (Logic) → Natural principles

Second Critique: Noumenal source of volition → Moral principles → Pure concepts of the understanding (good and evil) → the Sensible world

An interesting incongruity lies between the implied noumenal sources in each case. (The difficulty in any positive description of these sources is obviously compounded by the fact that Kant claims that we cannot say anything about their constitution). In the first case, it would appear that the objects in-themselves (apart from our cognition of them) are the causa noumena of objective appearances. In the second case, it would appear that the transcendental freedom of the will is the causa noumenon of the moral law. Might this be a contradiction? It is difficult to say, because Kant only allows for noumena to occupy a purely negative place in his exposition.