Groundwork of The Metaphysic of Morals

Ancient Greek philosophy was divided into three sciences: physics, ethics, and logic. Pure philosophy must come first, and without it there can be no moral philosophy at all. Nevertheless a completely isolated metaphysic of morals, mixed with no anthropology, no theology, no physics or hyperphysics, less with occult qualities, is not only an indispensable substratum of all theoretical and precisely defined knowledge of duties, but is at the same time a desideratum of the utmost importance for the actual execution of moral precepts. Thus physics will have its empirical part, but it will also have a rational one; and likewise ethics – although the empirical part might be called specifically practical anthropology, while the rational part might properly be called morals. The moral law in its purity and genuineness is to be looked for nowhere else than in a pure philosophy.