“Why We Fight reflects Blattman’s expertise in economics, political science, and history… Blattman is a great storyteller, with important insights for us all.” —Richard H. Thaler, winner of the Nobel Memorial Prize in Economic Sciences and coauthor of Nudge “Engaging and profound, this deeply searching book explains the true origins of warfare, and it illustrates the ways that, despite some contrary appearances, human beings are capable of great goodness.”—Nicholas A. Christakis author of Blueprint: The Evolutionary Origins of a Good Society Despite the Russian invasion of Ukraine or the fear of another American civil war, most of the time wars don’t happen, and of the millions of hostile rivalries worldwide, only a fraction erupt into violence. At this moment of crisis in world affairs, this necessary book from a seasoned peacebuilder and acclaimed expert in the field lays out the root causes and remedies for war and explain the reasons why conflict wins over compromise; and how peacemakers can turn the tides once conflict threatens to or becomes war. Its message could not be more urgent right now. Why We Fight draws on decades of economics, political science, psychology, and real-world interventions to lay out the root causes and remedies for war, showing that violence is not the norm; that there are only five reasons why conflict wins over compromise; and how peacemakers turn the tides through tinkering, not transformation. From warring states to street gangs, ethnic groups and religious sects to political factions, there are common dynamics to heed and lessons to learn. Along the way, through Blattman’s time studying Medellín, Chicago, Sudan, England, and more, we learn from vainglorious monarchs, dictators, mobs, pilots, football hooligans, ancient peoples, and fanatics. What of remedies that shift incentives away from violence and get parties back to dealmaking? Societies are surprisingly good at interrupting and ending violence when they want to—even gangs do it. Realistic and optimistic, this is a book that lends new meaning to the adage “Give peace a chance.”