 Kant thinks that human faculties can reach their fullest expression only in free and peaceful circumstances (1784, 50), which in turn require a particular set of institutions.  A federation of republics will mark the final stage of human development.  A republic is a state based on the rule of law whose members are free and equal citizens (1795, 99).  A federation is a group of nations who have agreed to observe rules of peaceful conduct in their mutual relations (1795, 98ff).  Kant argues that the domestic and international features of this institutional constellation will reinforce each other.  Republics will not go to war with each other because a declaration of war requires the consent of the public, who are reluctant to pay a war's price (1795, 100).  In turn, domestic conditions will be improved in the absence of a state's constant involvement in wars (1784, 49). 