The greatest works of political and social theory are often the shortest, and none more so than the text of Immanuel Kant, Idea for a Universal History, written just over two hundred years ago in 1784: it is all of thirteen pages long, and advances a thesis that should concern us all. In essence, it argues that history can, and to some degree does, move in a progressive direction—one in which the domestic organisation of states on an increasingly legal, constitutional, basis will lead to greater cooperation between states and ultimately to some form of world government. Kant's hope was ‘that after many reformative revolutions, a universal cosmopolitan condition, which Nature has as her ultimate purpose, will come into being as the womb wherein all the original capacities of the human race can develop’. There are many readings of Professor Kant, not least when this text is combined with others. Yet to put it in modern terms, not entirely traducing his meaning, his work can be read as envisaging a world of constitutional regimes and liberal democracies, one that will be without war. This is a bold thesis with many unproven assumptions: but it is not entirely implausible, on either theoretical or historical grounds. Abused as it may have been by the twin menaces of a modish post-1989 triumphalism, and a postmodernist pessimism, it nonetheless sets us a goal that can, and should, command attention. Two centuries later, the goals of Enlightenment, and a measured concept of progress, retain an, albeit chastened, validity in international as in domestic affairs.