Following his statement the formula of universal law as an expression of the ďcategorical imperative,Ē Kant provided four examples to illustrate its application in moral judgment. The first involves a man contemplating suicide, and Kant attempts to show why his action would be wrong, based on his maxim (Kant 1997, 31-2/4:421-2). But hardly anyone thinks the argument Kant provided here actually works.
The four examples. Kant recognized a distinction between duties to oneself and duties to others, and a distinction between perfect and imperfect duties. Combined, these two distinctions yield four classifications of duties: perfect duties to oneself and to others, and imperfect duties to oneself and to others. The suicide example is supposed to illustrate how perfect duties to oneself can be derived from the version of the categorical imperative known as the formula of universal law. The example of a perfect duty to others that follows replicates the lying promise example introduced in Groundwork I, and it is generally considered to be the best of Kantís examples illustrating applications of the universal-law formula. The remaining two examples, of imperfect duties, are the duties to develop oneís natural talents, and to aid others in need.
The suicide maxim. Kant presents the maxim of the man contemplating suicide as follows: from self-love I make it my principle to shorten my life when its longer duration threatens more troubles than it promises agreeableness. This statement can be read as including the three required parts of a maxim of action: circumstances; an action description; and the end or aim of the action, the expected result. The circumstances are the manís disappointing life prospects; the action is to shorten his life; and the end or aim is, in a word, happiness. By committing suicide the man expects to avoid suffering that will diminish present happiness without paying off in future happiness. The maxim for acting this way is supposed to fail the universalization test because, as quoted above, ďA nature whose law it would be to destroy life by means of the same feeling whose destination is to impel toward the furtherance of life would contradict itself and would therefore not subsist as nature.Ē
Why Kantís suicide example seems mistaken. For a maxim failing the universalization test it is generally expected that the agent would somehow contradict himself by willing both to act on the maxim and that everyone also act on the maxim. This is how the lying promise example seems to show that action to be wrong. If the man in that example were to want everyone to act as he does, then he would want, essentially, that it be impossible for him to get the money he needs by a lying promise. But nothing like that seems applicable to the present case. It is hard to see why everyoneís having the same suicide maxim should make it impossible for the man in the suicide example to do what he wants to do. It is hard to see why he would in any way mind if everyone were to act on his maxim also, committing suicide when their life prospects turned out to be as bad as his. From Kantís explanation of the problem with the maxim, moreover, it looks as though he finds the action to be wrong because suicide is contrary to self-loveís purpose. He seems to think that self-love is meant to promote and improve human life, and so that is why, in committing suicide from self-love, one is employing it contrary to its natural purpose. Yet if that is what Kant is thinking, then it is hard to see how this example can illustrate an application of the formula of universal law, as he intends (Korsgaard 1996, 87; Guyer 2005, 192). The action is shown to be wrong not because of some problem arising for the universalization of its maxim, but because it is in some way contrary to the nature of self-love. It may also be asked why we should think of self-love in precisely this way? Why not consider a rational personís self-love to aim instead at enjoying the most satisfying span of life, so that committing suicide in the circumstances indicated by the exampleís maxim would be entirely consistent with self-love? (Aune 1979, 59-60).
Systematic contradiction in nature. The reason Kant gave for thinking the suicide maxim fails the test of the categorical imperative has something to do with ďnature.Ē This idea harks back to his earlier statement of the formula of universal law referring to the universal law of nature. Kantís thought seems to be something like the following: universalization of the suicide maxim would introduce a law of nature to the effect that self-love, in certain circumstances, leads to the destruction of life. But nature itself, Kant assumes, aims continually at its own perpetuation. Nature is life-preserving, at least on the whole (see Kant 2000, 246/5:374). It would therefore be contradictory to introduce into nature a maxim that would elevate human happiness above the preservation of life, making happiness the condition under which life should continue. In this context it can help also to recall an argument Kant presented early Groundwork I. He suggested there that nature has made human beings practically rational, and that the end of practical reason cannot therefore be to promote human happiness. It cannot be, in other words, that nature has given us the gift of practical rationality so that we can make ourselves happy by its use. For if our happiness were natureís end or purpose, it would have used a better, more effective means to this end than making us rational. This argument, if persuasive, seems to offer a further reason for thinking that a system of nature that would prioritize human happiness over life, for beings it has made practically rational, would be inconsistent; and thus, it begins to seem less mysterious why Kant supposed that the suicide maxim fails the test of the formula of the universal law of nature.
Aune, Bruce (1979), Kantís Moral Theory (Princeton, N.J.: Princeton University Press).
Guyer, Paul (2005), Kantís System of Nature and Freedom (Oxford: Oxford University Press).
Kant, Immanuel (1997), Groundwork of the Metaphysics of Morals, trans. Mary Gregor
(Cambridge: Cambridge University Press).
_____ (2000), Critique of the Power of Judgment, trans. Paul Guyer and Eric Matthews, ed. Paul Guyer (Cambridge: Cambridge University Press).
Korsgaard, Christine M. (1996), Creating the Kingdom of Ends (Cambridge: Cambridge University Press).