The aim of Immanuel Kant’s Groundwork for the Metaphysics of Morals is to ascertain and justify the categorical imperative.1 I will concentrate on the third part of the Groundwork. Here, Kant wants to show why the categorical imperative is binding for us. The purpose of this part of the Groundwork is to show that we have the faculty of practical reasoning—that we are able to establish ends independent of sensual impulses.
Before taking the pains of establishing and justifying the moral principle, Kant has to clarify why it should be binding for human beings. After all, it could be possible that man cannot act autonomously because he is a slave of his passions / genes / brain structures. The categorical imperative applies only to beings whose actions stem from their own free will. According to Kant, a free will is the “ability to control how [one] behaves in conformity with the representation of certain laws” (GMM, p. 28). Therefore, only rational beings have a free will, for only they can act according to self-assigned laws (recall the Greek roots of “autonomy”: autos, self; nomos, law). In other words, rational beings can act autonomously and hence are free. Kant contrasts this kind of causality with absolute necessity, which is the causality of unreasoning beings—of creatures that cannot act autonomously because they are completely bound by their biological necessities and urges.
However, Kant points out that even though rational beings act freely, this doesn’t mean that their will is anarchical. After all, autonomy is the [End Page 259] causality of reasonable beings, and causality implies the law of cause and consequence. Kant underlines: “Although freedom is not a property of the will according to laws of nature, it doesn’t follow that freedom is lawless!… The ‘concept’ of lawless free-will would be an absurdity” (GMM, p. 41). The freedom of the will consists in its autonomy—its “property of itself being a law” (GMM, p. 41). Kant reminds us that the locution “the will itself is a law in all its actions” denotes the formulation of the categorical imperative: “Act only on a maxim that can also have itself as a universal law for its object” (p. 41, emphasis in original). He concludes: “Therefore a free will and a will under moral laws are identical.” Hence, to assume a free will ultimately leads to the moral principle.
So far, Kant has only shown why and to what extent the moral principle is binding for autonomous beings. On what grounds could man be ranked among them? In that respect, Kant proves himself quite pragmatic: to avoid giving a theoretical proof of man’s free will (an issue that is still unsolved), he proves it practically, and declares: “Any being who can’t act otherwise than under the idea of freedom is, just for that reason, really free in his conduct—i.e. all laws that are inseparably bound up with freedom hold for him just as if his will were validly pronounced free in itself as a matter of theoretical philosophy” (GMM, p. 42). Assuming that we are free has the same consequences for our moral conduct as if we were free. This is a necessary condition for us, as human beings, to legitimately claim that we have a will of our own. If we didn’t, we would have to suppose that our moral judgment doesn’t stem from reason, but from mere impulse. This, however, runs counter to the way we see ourselves. We therefore have to consider ourselves as free agents.
To summarize, Kant claims that we have to follow the categorical imperative because we are free, and that we are free because we are able to develop moral principles like the categorical imperative. Kant concedes that this does indeed sound strange: “It has to be admitted that there is a kind of circle here from which there seems to be no escape. We take ourselves to be free in the order of effective causes so that we can think of ourselves as subject to moral laws in the order of ends; and then we think of ourselves...