Why do people behave the way they do in politics? What causes conﬂicts such as those in Bosnia, Rwanda, or Northern Ireland? Is racism inevitable? Why do presidents make the decisions they do? Why did 9/11 happen? These and many other questions about politics are of great concern to all of us, whether we are directly aﬀected or are only eyewitnesses through the news. So much of political behavior seems to defy explanation and seems incomprehensible when looked at with hindsight: People start wars that are, in the end, thought of as pointless and futile, such as World War I or the war in Vietnam; civil wars erupt among people who have lived together harmoniously for years, but then commit hideous acts of barbaric violence against one another, as in the former Yugoslavia, Liberia, or Sierra Leone; groups commit acts of terrorism that kill numerous innocent civilians each year; or a scandalplagued president who cannot resist tempting fate by engaging in an extra-marital aﬀair when he knows full well the extent of the scrutiny of those looking for more scandals. Unless one understands the thoughts and feelings of the people who make the decisions to commit those acts, one cannot fully understand why those things occurred. But an exploration of the psychology-the personalities, thought processes, emotions, and motivations-of people involved in political activity provides a unique and necessary basis for understanding that activity.