Philosophical sketch of Immanuel Kant (1724-1804) on the primary conditions for Peace and co-existence between states is reflected in his Perpetual Peace. In Kant's view, three primary conditions of perpetual peace of a republican government in every country are based on a civil constitution, establishment of a federation of free states, and cosmopolitan right of individuals as world citizens. The foundations of republican system, i.e. freedom for all members of the society as human beings, belonging of each individual to a public code of law as subject, and equality before law as a citizen, are important in Kant's political philosophy. Two primary responsibilities for Kant's federation of free states, i.e. non-interference in the internal affairs of member states, and upholding of a unified front against extraterritorial aggression, suffer from ambiguity and inadequacy, and is therefore vulnerable. Kant's formulation of "a unified world government" is cautionary and conditional; for it can be ended to despotism and decline.
