The Unity of Kant’s Metaphysics of Morals: Capital Punishment as a Case Study

The present paper aims to assess the articulated relationship between ethics and right in Kant’s Metaphysics of Morals. This will be done by discussing Kant’s argument in favor of the capital punishment against C. Beccaria, as it is formulated in the paragraph On the Right to Punish and to Grant Clemency of this text. Our first goal is to emphasize Kant’s thesis that the capital punishment is able to punish any offender « in terms of his sensibilities » [nach seiner Empfindungsart] (MS-RL, AA 06 : 332, 334). This could sound strange, since Kant clearly states that ethics cannot penetrate the deep darkness of the human heart and discover his real dispositions (MS-TL, AA 06 : 392). Therefore, the obligation of the ethical duty can only be wide, whereas the juridical obligation can be narrow just because the moral disposition of the subject does not matter here. Although the expression « in terms of his sensibilities » cannot be referred to the thorny concept of « disposition » [Gesinnung], it nonetheless draws attention to the subject’s inner dimension also in the domain of criminal law. The second goal of the paper consists in showing that the foregoing does not weaken the distinction between ethics and right, but it rather bears witness to their peculiar organization within the Sittenlehre. Indeed, such a distinction develops – but does not contradict – the assessment provided by Kant in his previous moral writings. This is aptly exemplified by Kant’s distinction between homo phaenomenon and homo noumenon in the same paragraph in which he rejects Beccaria’s argument. The final part of the paper tests the consistency of the first two points by analyzing the way Kant deals with the case of suicide, and the way he judges the self-murderer.