In assessing efforts to analyse, to understand, or even to change the relations between countries after the First World War, we must look – if only briefly – at the preparations for the Paris Peace Conference that followed it. By the time the Conference at Versailles got underway a wealth of material awaited possible (though by no means certain) use by the respective plenipotentiaries. In the end, the peace treaty contained, in addition to traditional terms of settlement which usually follow a war, provision for a formal post-war organisation, which certainly could not have been created at short notice. In contrast to the irrelevance of Kant’s ideas at Vienna, there can be little doubt that the ideas of the peace movement, particularly societies promoting a post-war organisation of states, at least indirectly affected the outcome at Paris. It was this novel feature of the peace settlement that had most to do with the development of the study of IR, namely, the League of Nations. And the individual who had most to do with adoption of the idea in the first place was a former President of the American Political Science Association, Woodrow Wilson. Again, in contrast to Vienna, he was the only world leader who could be called an intellectual with a formula for reordering the political universe. Ironically, he overlooked the lessons of his own specialty, Congressional Government, 1 and lost the battle in Congress to bring his own country into the League.