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, 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.”