The concept of purpose in Kant's metaphysical elements of justice

Abstract

Kantian philosophy of law impressed today's modern European legal systems. In his Metaphysical Elements of Justice (Doctrine of Right or Science of Right), Kant develops a legal system to ensure individual rights based upon different aspects of purpose. However, one cannot understand the concept of purpose as set out in the "Metaphysical Elements of Justice" as part of "The Metaphysics of Morals" without Kant's Doctrine of Virtue. Both are evolved in the "The Groundwork of the Metaphysics of Morals" in an intertwined way. In the latter, he not only stresses in the second and fourth formulations of the categorical imperative (the Formula of Humanity and the Kingdom of Ends Formulation) to treat humanity as an end in itself but also enables the deduction of duties. As Kantian philosophy impressed modern European legal systems, the question arises whether his concept of purpose could have any impact on the modern discourse of ratio legis-in the widest sense understood, as well as the legal consequence and purpose of a legal rule. Can Kantian philosophy hint at certain aspects of ratio legis, understood in the widest sense as legal consequence, underlying values, and purposes of rules of law, and thus shed light on the modern discussion of it? To answer this question, the different kinds of purposes as set out with respect to hypothetical, categorical and legal categorical imperatives will be defined and explained with regard to their different functions and a set of four different purposes (Sect. 1). Further, both Kant's Doctrine of Right and Doctrine of Virtue-and their intertwined interconnection-will be briefly addressed to fully understand both their functions and to systemize four classes of duties (Sect. 2). From this basis, the question of how different kinds of purposes as found in Kant's Doctrine of Right and Doctrine of Virtue might matter in modern jurisprudence can be answered (Sect. 3).