Perpetual Peace: A Philosophical Sketch

In Kant’s book Groundwork of the Metaphysics of Morals, the philosopher establishes the categorical imperative—the supreme principle of morality. Kant sees freedom and morality as intrinsically linked. Reason commands humans to live according to a universal and unconditional morality merely because moral acts are the rational thing to do. Kant argues that moral action is the only complete expression of freedom. In Perpetual Peace, Kant describes moral laws as categorical imperatives.

Kant views a government’s constitution as a rational framework through which a state organizes the moral and political life of its citizens. A constitution expresses the relationship between freedom and law—two central pillars of Kant’s moral philosophy. Kant argues that a “republican constitution” is the only legitimate form of government because it aligns political authority with the autonomy of individuals.

Cosmopolitan right, in Kant’s Perpetual Peace, is the third category of law in his moral-political framework, alongside civil and international rights. It governs the relationship between individuals and foreign nations, emphasizing a minimal but universal moral obligation for respect and hospitality. For the philosopher, cosmopolitan right emerges from the shared ownership of the earth’s surface. Thus, every human being has the “right to visit” other lands without hostility, so long as they act peaceably.