Groundwork of the Metaphysics of MoralsImmanuel Kant

The Groundwork is Kant's attempt to isolate the supreme principle of morality. It is short (under a hundred pages), architecturally precise, and relentless in its exclusions. Kant strips away everything empirical, everything contingent, everything that depends on what human beings happen to desire, until only the pure form of moral obligation remains.

Section I begins from common moral knowledge. The only thing good without qualification is a good will. Talents, temperament, and fortune can all be used badly; only a will that acts from duty has unconditional worth. Duty is not inclination. The shopkeeper who gives honest change because honesty is good for business acts in accordance with duty but not from it. Moral worth attaches only to actions done because the moral law requires them.

Section II formulates the categorical imperative. "Act only according to that maxim through which you can at the same time will that it become a universal law." Kant gives four examples: lying promises, suicide, neglect of talents, refusal to help others. Each fails the universalizability test. He then offers a second formulation: treat humanity, in your own person and in others, always as an end and never merely as a means.

Section III grounds the categorical imperative in the idea of freedom. A rational will is autonomous: it legislates the moral law for itself rather than receiving it from outside. This self-legislation is not arbitrary; it is the expression of reason's own nature. Morality and freedom, Kant argues, stand or fall together.