One of modernity's central puzzles has been whether global politics can be organized so as to improve on the seemingly limited and contingent possibilities of human freedom available in a sovereign states system. That is to say, the corollary of state sovereignty, established to provide security and freedom within the state, was international anarchy, which delimited and threatened that very security and freedom through recreating the state of nature – which for Hobbes and Kant was a state of war – in relations between states. A vital reason for Kant's enduring influence among scholars of International Relations, and the basis for his status as a classic thinker in this field, is that he addressed this conundrum in such a way as to promise both security and freedom.

Whilst his seminal essay ‘Perpetual Peace’ (1795) did not offer any guarantees (beyond the unsatisfying recourse to nature's irresistible will), his schema can at least muster sufficient empirical support in the form of the Democratic Peace and related research agendas to have taken it beyond the realm of political philosophy into that of empirical enquiry and practical politics. Indeed, the Democratic Peace has emerged as the major ‘Kantian’ research agenda in the contemporary study of International Relations and it is for this reason that this chapter concentrates upon the reading of Kant that it has produced.