The aim of this article is to discuss the teleological principle of living beings in Kant ́s moral philosophy. What Kant calls On the Principle for Judging Intrinsic Purposiveness in Organized Beings is described at § 66 of Kritik der Urteilskraft (AA 05 376) as: an organized product of nature is one in which everything is a purpose and reciprocally also a means. In such a product nothing is gratuitous, purposeless, or to be attributed to a blind natural mechanism. I intend to show here that when Kant questions the idea of good will in the Grundlegung zur Metaphysik der Sitten ,he appeals to the teleological principle of living beings to arrive at the conclusion that the idea of good will is not a chimera, a fantasy, namely, it is reasonable to believe in good will, i.e. it is reasonable to believe that there are moral actions done from duty and not merely done in conformity with duty. With the presupposition of the teleological principle, acting from duty, acting morally, will not be a chimera anymore, as there will be good reasons to believe in good will , which will be then produced by reason in its practical use, despite the fact that the existence of good will continues not proven in Kant ́s view, because for him it is impossible to prove that we actually act morally (from duty) given that no one is able to know either his/her own intentions or the intentions of others (ignorance of our intentions).
