This course offers a critical evaluation of the causes of international conflict. It begins by surveying some of the classic contributions to the study of war and peace by Thucydides, Aquinas, Hobbes, Machiavelli, Kant and Keohane and Nye. The course then examines the historical development of the modern system of states from its origins in the Peace of Westphalia in 1648 until the end of the nineteenth century. The final section of the course looks at the origins of the major international conflicts of the twentieth and twenty-first century, considering the First World War, the Second World War, the Cuban Missile Crisis, and the crisis in trans-Atlantic relations that developed during the 2003 Iraq War. The emphasis throughout the course is on the relevance of the theoretical and empirical material for issues facing contemporary American foreign policy.