Abstract

IN HIS CRITICAL METAPHYSICS OF MORALS, Kant insists on keeping the purely rational concepts, laws, and principles of moral philosophy strictly separate from the empirical elements of practical anthropology. This is not to say that he treats the a priori part of the doctrine of morals in isolation from empirical psychological concepts and observations about the special nature of human beings. He allows that such elements are necessarily brought into the formulation of the system of pure morality. Still, he maintains that their integration with this system cannot detract from the purity of the highest principles and fundamental a priori concepts of morality themselves, or cast any doubt on the a priori origin of all practical laws in pure reason alone. Within the system of the metaphysics of morals, the pure part of moral philosophy must therefore be logically dissociated from any particular theory of human nature that includes the principles of a specifically human moral psychology. This measure is mandatory if moral philosophy is not to rely on species-dependent presuppositions when, on the basis of its pure part, it plays its distinctive legislative role for humans as rational beings. As Kant states in the Grundlegung zur Metaphysik der Sitten of 1785, “all moral philosophy rests wholly upon its pure part, and, when applied to the human being, it borrows not the least thing from the knowledge of that being, but rather gives to the human being, as a rational being, laws a priori.” Accordingly, the foundational task of the metaphysical theory of morals must be to investigate the “ideas and the principles of a possible pure will, and not the actions and conditions of human willing [Wollen] as such, which for the most part are drawn from psychology.”