The Practical Purposiveness in the Determination of a Free Will. The Paradoxical Character of Kant’s A Priori

Since the lectures on metaphysics of the last 1770s and first 1780s, Kant’s treatment of the pure concepts of understanding deals not only with the traditional analytical method, but also with a synthetic one. The synthetic method aims to establish how the principles of understanding can be derived from the pure concepts of understanding. Although the sources of these concepts are totally independent from experience, their application as principles is necessarily linked to an empirical matter. This paradox is intrinsic to the critique of reason, which searches for the legitimacy of our use of the rational concepts and finds out that the only possibility we have to deal with the whole of these concepts concerns the object of experience. Kant clearly states that we cannot know how this paradox can be possible. In the Critique of the Power of Judgement this kind of principles—which are necessarily linked to the empirical data—will be defined by Kant as metaphysical, that is principles which represent the only a priori conditions under which objects whose concept must be given empirically can be further determined a priori. In this sense they are opposed to the transcendental principles, through which the only universal a priori condition under which things can become objects of our cognition at all is represented. The dialectic between the a priori determination of an object and the necessary empirical giveness of its concept can be well assessed by one of the metaphysical principles, the practical purposiveness [praktische Zweckmäßigkeit] which must be thought in the determination of a free will. Indeed the concept of a faculty of desire [Begehrungsvermögen] as a will must be given empirically. The proposed paper aims to analyze this practical principle in order to show that it expresses one of the highest theoretical tension within Kant’s concept of a priori. The moral side of Kant’s thought seems the most suitable to appreciate the paradoxical features of this complex notion.