Cosmopolitanism and Plans for Perpetual Peace

Europe fought almost constant wars in the 18th century, and Enlightenment thinkers asked whether reason could end them. In 1713, during peace talks at Utrecht, the Abbé de Saint-Pierre proposed a permanent league of European states with a court to settle disputes. Rousseau later summarized and critiqued the plan, doubting that rulers would ever accept it.

In 1795 Immanuel Kant published Toward Perpetual Peace, arguing that lasting peace required states with republican constitutions, in which citizens who bear the costs of war must consent to it; a federation of free states; and a 'cosmopolitan right' of hospitality for visitors. Kant also criticized European conduct in the colonies as a violation of that right.

Many philosophes described themselves as citizens of the world, valuing humanity above national loyalty; critics called such plans utopian. Yet the ideas foreshadowed later international institutions, and Kant's claim that republics rarely fight each other inspired modern 'democratic peace' theory.