Theories of international relations—and explanations of state behavior—rise and fall with the geopolitical tide. What we now call “realism” emerged during and after World War II. The events of the 1930s and 1940s had shown that the world was rough and lawless and created an opening for an intellectual paradigm that emphasized the primacy of power and the ruthlessness of geopolitics. The end of the Cold War, by contrast, dealt a sharp blow to realism, by seeming to shatter its core premise. How, in a world ruled by power and self-interest, could a country as mighty as the Soviet Union simply acquiesce in its own decline and destruction?
