Immanuel Kant, a German philosopher, created "perpetual peace" in his 1795 work.

A situation where peace has been achieved over a specific territory permanently is referred to as perpetual peace. In the 18th century, while serving as the Treaty of Utrecht's chief negotiator, Charles-Irénée Castel de Saint-Pierre wrote his article "Project for Perpetual Peace" under an assumed name. The concept, meanwhile, was not well understood until the late 18th century. Immanuel Kant, a German philosopher, coined the phrase "perpetual peace" in his 1795 article Perpetual Peace: A Philosophical Sketch, which led to its acceptance.

Although there are many differences between Kant's article and contemporary democratic peace philosophy, there are some similarities. Instead of speaking of democratic states, he refers to republican (Republikanisch) states, which he defines as having representative governments with a wall separating the legislative branch from the executive. Universal suffrage, which is crucial to contemporary democracy and significant to certain contemporary thinkers, is not discussed by him; his critics disagree as to whether it is indicated by his terminology. Most crucially, he does not believe that republican governments can bring about peace on their own. He believes that a league of nations is required to consciously implement his six-point programme, as well as freedom of movement, though not necessarily migration.