Kant’s Structure of the Justification of Practical Reason

The research deals with the burning problem of Kant’s justification of practical reason. For in the second Critique Kant asserts that the deduction of the principles of practical reason is impossible , since the objective reality of the moral law cannot be proven by any deduction. How does Kant confirm the entire sphere of practical reason and what stages does he go through in this process? The aim of the article is to explicate and reconstruct the systematic elements and stages of Kant’s justification of practical reason. The aim of the article is to explicate and reconstruct the systematic elements and stages of Kant’s justification of practical reason. Indeed, justification is impossible if we understand deduction as a purely theoretical procedure, which Kant carried out in the Critique of Pure Reason . Yet, Kant himself points out that “ deduction is the justification (Rechtfertigung) of its objective and universal validity”. This justification of the principles of practical reason can be found in Kant’s works and has a certain structure. Firstly, in the Critique of Pure Reason, he justifies the existence of an intelligible world where the determining ground of causality is freedom. In the intelligible domain, the principles of pure reason, based on spontaneity, have objective reality. Thus, in the first Critique , Kant justifies the existence of an intelligible world, freedom as the ground of causality and the ought as a reason for practical action. Secondly, in the Groundwork of the Metaphysics of Morals , Kant demonstrates that freedom carries one to an intelligible world where the good will resides. The good will rests upon freedom and brings forth human autonomy. And it is the good will from which the categorical imperative and morality in general emanate. Thirdly, it is explicated in the second Critique that freedom is the keystone ( Schlußstein ) of practical reason. Here, the moral law (= a “fact of reason”) is instrumental in deducing transcendental freedom itself. This means that the reality of transcendental freedom manifests itself through the moral law. The moral law exists and is effective; therefore, there is transcendental freedom behind it. Thus, the structure of the transcendental deduction of practical reason consists of a step-by-step justification of: the intelligible world, the spontaneity of reason, transcendental freedom, good will, duty (the categorical imperative), the moral law as a “fact of reason”.