Kant's Perpetual Peace: The Cosmopolitan Vision of International Order

Immanuel Kant’s essay Zum ewigen Frieden (Perpetual Peace, 1795) is one of the founding documents of the modern peace movement and one of the great works of Enlightenment political philosophy. The essay develops a comprehensive vision of international order based on the principles of republican government, the federation of free states, and the cosmopolitan right of individuals. This article examines the central arguments of the essay and its lasting influence on the development of modern international law and international institutions.

The Setting of the Essay

Kant wrote Perpetual Peace in 1795, in the aftermath of the French Revolution and the early years of the Revolutionary Wars. The essay opens with the image of a Dutch innkeeper, who puts up a sign reading “Perpetual Peace” over the door of his inn, and a satirical gravestone inscription that reads “Perpetual Peace for all the dead of the political system.” The image captures Kant’s attitude toward the project of perpetual peace: it is a serious project, but also one that is easily mocked.

Despite the satirical opening, the essay is a serious and ambitious work of political philosophy. Kant develops a comprehensive program for the establishment of a peaceful international order, and he argues that the project is not only morally desirable but also practically possible.

The Preliminary Articles

The first part of the essay contains a series of “preliminary articles” that Kant considers necessary conditions for the establishment of perpetual peace.

The first article requires that no peace treaty should be made that involves a secret reservation of material for a future war. The peace treaty should be a genuine peace, not merely a temporary truce that allows one party to prepare for a future conflict.

The second article requires that no state should be acquired by inheritance, exchange, purchase, or donation. The proper basis of political authority is the consent of the governed, and the transfer of political authority without the consent of the people is inconsistent with the proper foundation of the state.

The third article requires the gradual abolition of standing armies. Standing armies are a constant threat to the peace, and they create a self-perpetuating cycle of military competition.

The fourth article requires that no national debt should be incurred for the purpose of financing external war. The proper purpose of national debt is to support the legitimate functions of government, not to finance military adventures.

The fifth article requires that no state should interfere by force in the constitution or government of another state. The internal affairs of each state are its own concern, and intervention in the internal affairs of other states is a violation of their sovereignty.

The sixth article requires that no state at war with another should engage in activities that would make future peace impossible. This includes the use of assassins, poison, the incitement of treason in the enemy state, and the various other activities that would undermine the possibility of future reconciliation.

The Definitive Articles

The second part of the essay contains three “definitive articles” that Kant considers the essential conditions for the establishment of perpetual peace.

The first definitive article requires that the civil constitution of each state should be republican. A republican constitution, for Kant, is one that is based on the principles of the freedom of the members, the dependence of all on a common legislation, and the equality of the citizens. A republican constitution is the most likely to produce a peaceful foreign policy, because the decision to go to war is made by the citizens themselves, who will bear the costs of the war.

The second definitive article requires that the international order should be based on the federation of free states. The federation of free states is not a world state — Kant was skeptical of the possibility of a single world government — but a voluntary association of states that have agreed to settle their disputes by peaceful means.

The third definitive article requires that the cosmopolitan right of individuals should be recognized. The cosmopolitan right is the right of individuals to be treated as citizens of a universal community of human beings, regardless of their nationality. The cosmopolitan right is the basis for the modern international human rights regime.

The Guarantees of Perpetual Peace

The third part of the essay considers the guarantees of perpetual peace. Kant argues that the project of perpetual peace is not merely a moral ideal but also a practical project, and he identifies several factors that work in favor of the establishment of a peaceful international order.

The first factor is the natural course of human events. The conflicts of human beings, while they produce much suffering, also create the conditions for the gradual development of a more peaceful order. The wars of the past, however destructive, have led to the development of larger and more inclusive political units, and this process can be expected to continue.

The second factor is the moral improvement of human beings. The proper use of reason, for Kant, will lead human beings to recognize the value of peace and to organize their political life in ways that promote peace.

The third factor is the role of commerce. The development of international trade, Kant argues, creates a community of interest among nations that makes war increasingly costly and less attractive. The spirit of commerce is, in this sense, incompatible with the spirit of war.

The Influence of Perpetual Peace

Perpetual Peace has had a profound influence on the development of modern international law and international institutions. The essay is one of the founding documents of the modern peace movement, and it was an important source of the various international organizations and treaties that have been developed since the late nineteenth century.

The League of Nations, established after the First World War, and the United Nations, established after the Second World War, are both, descendants of the Kantian project. The European Union, the most successful experiment in international cooperation in modern history, is another important descendant. The contemporary international human rights regime, as embodied in the Universal Declaration of Human Rights and the various other international covenants, is also a descendant of the Kantian project of cosmopolitan right.

Further Reading

• The Stanford Encyclopedia of Philosophy (plato.stanford.edu), relevant entry
• The Cambridge Companion to [Thinker] (Cambridge University Press)
• Isaiah Berlin, Four Essays on Liberty (1969)