Conventional wisdom in international relations maintains that democracies are only peaceful when encountering other democracies. Using a variety of social scientific methods of investigation ranging from statistical studies and laboratory experiments to case studies and computer simulations, Rousseau challenges this conventional wisdom by demonstrating that democracies are less likely to initiate violence at early stages of a dispute. Using multiple methods allows Rousseau to demonstrate that institutional constraints, rather than peaceful norms of conflict resolution, are responsible for...