This interdisciplinary book provides an invaluable perspective on the causes of war, drawing on a thoughtful consideration of what war actually _is_—the key foundation for an analysis of its causes. Jeremy Black assesses the three main types of war—between cultures, within cultures, and civil—emphasizing the social and cultural factors leading to conflict. He argues that cultural factors have always been the key element, especially aggression in the shape of a willingness to kill and be killed, which alters rational assumptions of risk and overcomes deterrence. He assesses the predisposition of ideologies to think and act in terms of conflict, the functional dynamics of international relations systems, and the strengths and failures of diplomacy. Drawing on research from history, political science, and international relations, Black marshals global examples spanning the fifteenth century to the present. Contrasting wars within cultures and wars between cultures he considers the implications for ongoing and future conflict.