Kant's project in the Groundwork is “the search for and establishment of the supreme principle of morality” (G 4:392). The establishment of the moral principle apparently relates to only one of its formulations, the third main formula, the formula of autonomy. The search results in formulating the principle in three ways. Two of them have significant variants that are supposed to bring the moral principle “closer to intuition, and thus to feeling” and thereby to “provide entry and durability for its precepts” (G 4:405, 436). The First Section, beginning from “common rational moral cognition,” arrives only at the first and most provisional formulation of the law, while the Second Section (proceeding more philosophically from an account of the will and carrying the search to completion) arrives at all three. The argument of this section follows a progressive development proceeding from the concept of a categorical imperative. Here are the different formulations of the moral law as Kant presents them:

First formula:

1. FUL Formula of Universal Law: “Act only in accordance with that maxim through which you at the same time can will that it become a universal law” (G 4:421; cf. G 4:402); with its variant,

2. FLN Formula of the Law of Nature: “So act, as if the maxim of your action were to become through your will a universal law of nature” (G 4:421; cf. 4:436).

Second formula:

1. FH Formula of Humanity as End in Itself: “So act that you use humanity, as much in your own person as in the person of every other, always at the same time as an end and never merely as a means” (G 4:429; cf. 4:436).