Political science has had difficulty handling rapid change; it prefers the static (stable political systems) to the dynamic. If historians are stuck in the past, political scientists are often captives of the present. For some the collapse of the Soviet Union showed that the theories and methods of political science are of only limited utility. Despite decades of gathering data and theorizing, political science was unable to anticipate the defining event of the post-World War II era. Critics charged that political science could describe what is but could never discern what was likely to be. Others, however, maintained that this criticism was unfair, arguing that such upheavals can be predicted, given sufficient data. Still, the demise of the Soviet Union spurred some political scientists to develop theories to explain political changes and transformations. Examining the collapse of authoritarian regimes and their replacement with democratic governments in Greece, Spain, Portugal, Latin America, eastern Europe, and the Soviet Union during the last three decades of the 20th century, they sought to develop a theory of transitions to democracy. Others argued that no such universal theory is possible and that all democratic transitions are unique.