Perpetual Peace: A Philosophical Sketch

These three articles form the moral and political architecture of Kant’s peace project and outline his argument for Republican Constitutions as a Framework for Peace. Republican constitutions establish justice within states, the federation of free states ensures lawful relations among them, and cosmopolitan right extends respect to all individuals as members of a single moral community. Therefore, peace is more than the absence of war: It is the presence of law at every level.

The first definitive article—republican constitutions—anchors peace in domestic justice. For Kant, republicanism guarantees that citizens, who are those who bear the costs of war, decide whether it occurs. This institutionalizes moral autonomy, as the same rational self-legislation that governs individuals becomes a civic process. This is reflective of Kant’s larger ideology that the moral framework of governments should mirror the innate moral framework of human reason. Comparing Kant to his contemporaries, Locke and Rousseau, helps to clarify how innovative Kant’s ideas were. Locke’s social contract protects property, and Rousseau’s writing about the “general will” demotes the position of the individual. Kant mediates between the two by grounding sovereignty in universal law.

The second article—federation of free states—extends this reasoning internationally. Kant rejects the idea that peace requires a global monarchy. He proposes a voluntary federation in which states retain sovereignty but agree to resolve disputes through law. This design anticipates later institutions, such as the League of Nations and the United Nations. However, Kant’s version is moral, not administrative.

The third article sets up the theme of Universal Hospitality and Cosmopolitan Ethics. Cosmopolitan right and universal hospitality complete the triad by giving legal status to the individual as a world citizen. By elevating the rights of the individual, Kant shows the far-reaching effects of this approach: “[A] transgression of rights in one place in the world is felt everywhere” (18). Kant proposes that the rights of every individual impacts the rights of everyone else. Hospitality converts the moral maxim of the golden rule, which pervades different cultures and religions. Kant limits it to a right of visitation, not settlement, but the principle still undermines colonial logic that prevailed during his lifetime. Commerce and travel must operate on equality rather than domination.

Together, these articles create a three-tiered moral architecture—republics at home, federation abroad, and cosmopolitan ethics individually and globally. Each level mirrors the moral law’s demand for autonomy and respect. Peace is achieved when the internal, external, and universal orders of right are harmonized.

Modern international-relations scholars see the roots of liberal institutionalism in Kant’s works, while critics such as Michel Foucault and Achille Mbembe read his universalism as entangled with colonial power. Some researchers argue that Kant’s conditional hospitality excludes those whom Europe never recognized as equals. Nevertheless, Kant’s logic provides the language through which later generations could demand inclusion. His definitive articles imagine peace as the moral unfolding of reason through law.