The disappearance and formation of states and nations after the end of the Cold War have proved puzzling to both theorists and policymakers. Lars-Erik Cederman argues that this lack of conceptual preparation stems from two tendencies in conventional theorizing. First, the dominant focus on cohesive nation-states as the only actors of world politics obscures crucial differences between the state and the nation. Second, traditional theory usually treats these units as fixed. Cederman offers a fresh way of analyzing world politics: complex adaptive systems modeling. He provides a new series...