Let me recount my experience with the study of world politics. More than fifty years ago, when I was earning my doctorate in political science, the field focused mainly on diplomats and heads of state. That was the prime way in which individuals were considered relevant to international affairs. Since then, I have watched-and helped-my discipline expand beyond the interaction of states and their diplomats: today most scholars focus on nation-states, organizations, and institutions. For a long time, this seemed a reasonable and rational approach to the study of world politics.