Abstract

In the 17th and 18th centuries, the doctrine of just war was one of the most popular theories in international law. According to this doctrine, the right to war is an integral part of natural law and, under specific circumstances, morally justified. To my mind, Kant was a fervent critic of the theory of just war. He critically reformulates the rational and normative principles of right in a way that leaves no place for war as a legitimate procedure to resolve a conflict between states. In section, I shall analyze the fundamental principles of ius gentium, in particular, the duty to leave the state of nature at the international level and the juridical form that the association between states must adopt. The exit of the state of nature between nations must generate an international legal framework that not only protects human rights but also safeguards the sovereignty of the peoples. In section, I shall examine Kant’s critique of the doctrine of just war in Zum ewigen Frieden and in the Rechtslehre, exploring why the idea of an ius ad bellum is incompatible with the critical reformulation of the right of nations proposed there.