 In the first Critique there are only hints as to the form Kant’s moral theory would  take.[16]  The account of practical reason in the Groundwork of the Metaphysics of Morals (1785) and Critique of Practical Reason (1788) is radically new. Kant now claims to have discovered the supreme principle of practical reason, which he calls the Categorical Imperative. (More precisely, this principle is an imperative for finite beings like us, who have needs and inclinations and are not perfectly rational.) Notoriously, Kant offers several different formulations of this principle, the first of which runs as follows: “act only in accordance with that maxim through which you can at the same time will that it become a universal law” (4:421). (On the different versions of the Imperative, which Kant claims are equivalent, see  Kant’s moral philosophy, §§5-9.)  Kant holds this principle to be implicit in common human reason: when we make moral judgments, we rely on this criterion, although invariably we do not articulate it as such.