In the Preface to the Fundamental Principles of the Metaphysics of Morals Kant sketches out the proper divisions of philosophy according to their proper subject matter. Before I go on to discuss what I find so interesting about Kant’s appropriation of the various divisions of the discipline of philosophy, I think it’s important to step back and consider what philosophy might or might not hope to accomplish. Without delving too far into details, beginning with Thales, we find that, very generally speaking, the philosopher was concerned with making sense of the world and the human being’s place within it. Cliche as it may sound, one might ask, to what extent is Kant attempting accomplish this vague idea of what philosophy should hope to do? Granted, unlike Thales, Kant was ‘doing’ philosophy within the context of a historical narrative which set forth the central problems of philosophy in a relatively clear formulation. But still, it seems fair to pose the above question, was Kant trying to make sense of the world and the human being’s place within it? In a very specific sense, yes. His division of philosophy adds to the original three divisions of philosophy provided by the Greeks, viz., “Physics, Ethics, and Logic”, by adding “rational knowledge” as “either material or formal” (4:387). The former Kant says, “considers some object, and the latter is concerned only with the form of the understanding and of the reason itself, and with the universal laws of thought in general without distinction of its objects” (4:387). Within Formal philosophy then, there is Logic, within Material philosophy however, there is both “natural philosophy and moral philosophy” (4:387). What’s interesting is that Kant places moral philosophy under the category of material philosophy because material philosophy “has to do with determinate objects and the laws to which they are subject … for these laws there are either laws of nature or of freedom” (4:387). If Kant were genuinely concerned with understanding the world and the human being’s place, or in Kant’s language, “man’s” place in it, then it would seem that Kant should justify his assumption that “man’s freedom” is a “determinate object” that is equally subject to the assumption that it may be approached as if it admits of laws governing it in the same way that the objects of the laws of nature do. That is to say, Kant owes his readers a justification for both of the assumptions he makes and the methodology he employs in virtue of those assumptions. After all, why should we assume, from the outset, that moral philosophy should adopt the, or at least aspire to adopt some reflection of the, methodological principles adopted to do natural philosophy? What guiding reason motivates Kant to assume that moral philosophy should be a kind of material philosophy?
Granted, Kant might reply that he isn’t treating “the Science of Ethics” as a purely empirical matter, and so he isn’t treating man’s freedom as an object in exactly the same way he’s treating the objects of natural philosophy: moral philosophy has to do with “the laws of the human will, so far as it is affected by nature … according to which everything ought to happen”. Morality proper then, for Kant, is primarily concerned with the human will and so requires a “metaphysic of morals” whereby “its doctrines [are delivered] from a priori principles” as “restricted to definite objects of the understanding” (4:388). In this sense, Kant might argue that although the human will is treated as a determinate object, this shouldn’t stop Kant from doing real philosophy, from actually making sense of the world and the human being’s place in it.
Yet still, I take issue with Kant’s assumption-saddled approach to the human will. At the outset, there’s no reason to assume that the human will is a determinate object, or that it admits of laws. Furthermore, why assume there’s a human will in the first place? Is Kant not simply stipulating the human will? I’m reminded of a passage from Merleau-Ponty’s Phenomenology of Perception:
“phenomenology is also a philosophy which puts essences back into existence, and does not expect to arrive at an understanding of man and the world from any starting point other than that of their ‘facticity’. It is a transcendental philosophy which places in abeyance the assertions arising out of the natural attitude, the better to understand them; but it is also a philosophy for which the world is always ‘already there’ before reflection begins—as an inalienable presence; and all its efforts are concentrated upon re-achieving a direct and primitive contact with the world, and endowing that contact with a philosophical status” (Preface, vii).
This passage captures the intuition that my argument operates on. Philosophy, it seems, especially moral philosophy, to put it crudely, should primarily go about its business realistically, and subordinate to that, idealistically. Why say that this applies especially to moral philosophy? Moral philosophy takes for its considerations what does happen in order to judge what ought to have happened. Which is to say, Kant’s moral philosophy makes the mistake of assuming what is (as evidenced by his treatment of the human will) instead of inquiring into what is.