INTRODUCTION

The Second Section of the Groundwork of the Metaphysics of Morals contains three arguments that have the form: if there were a categorical imperative, this is what it would have to be like. Each of these arguments leads to a new set of terms in which the categorical imperative can be formulated. In summarizing these arguments, Kant tells us that universality gives us the form of the moral law; rational nature or humanity as an end in itself gives us the material of the law; and autonomous legislation in a kingdom of ends represents a complete determination of maxims and a totality of ends. The Formula of the Universal Law is to be used in actual decision making, we are told; the other two, which bring the moral law “closer to intuition” and “nearer to feeling” can be used to “gain a hearing for the moral law” (G 436).

Attention to these remarks about the relations among the three formulas has perhaps obscured the fact that the three formulas represent a progression in the argument that leads from “popular moral philosophy” into “the metaphysics of morals.” I think that it is sometimes supposed that Kant's claim that the categorical imperative is a principle of reason rests squarely on the Formula of Universal Law – i.e., on that formula's “formality.” The claims of the other two formulas to be rational principles are then taken to be based upon their presumed equivalence to the Formula of Universal Law.