political change. Particularly Skocpol's States and Social Revolutions became one of the most widely recognized works of the third generation; Skocpol defined revolution as "rapid, basic transformations of society's state and class structures [...] accompanied and in part carried through by class-based revolts from below", attributing revolutions to a conjunction of multiple conflicts involving state, elites and the lower classes. From the late 1980s, a new body of scholarly work began questioning the dominance of the third generation's theories. The old theories were also dealt a significant blow by new revolutionary events that could not be easily explained by them. The Iranian and Nicaraguan Revolutions of 1979, the 1986 People Power Revolution in the Philippines and the 1989 Autumn of Nations in Europe saw multi-class coalitions topple seemingly powerful regimes amidst popular demonstrations and mass strikes in nonviolent revolutions. Defining revolutions as mostly European violent state versus people and class struggles conflicts was no longer sufficient. The study of revolutions thus evolved in three directions, firstly, some researchers were applying previous or updated structuralist theories of revolutions to events beyond the previously analyzed, mostly European conflicts. Secondly, scholars called for greater attention to conscious agency in the form of ideology and culture in shaping revolutionary mobilization and objectives. Third, analysts of both revolutions and social movements realized that those phenomena have much in common, and a new 'fourth generation' literature on contentious politics has developed that attempts to combine insights from the study of social movements and revolutions in hopes of understanding both phenomena. Further, social science research on revolution, primarily work in political science, has begun to move beyond individual or comparative case studies towards large-N empirical studies assessing the causes and implications of revolution. Initial studies generally rely on the Polity Project's data on democratization. Such analyses, like those by Enterline, Maoz, and Mansfield and Snyder, identify revolutions based on regime changes indicated by a change in the country's score on Polity's autocracy to democracy scale. More recently, scholars like Jeff Colgan have argued that Polity, which measures the degree of democratic or autocratic authority in a state's governing institutions based on the openness of executive recruitment, constraints on executive authority, and political competition, is inadequate because it measures democratization, not revolution, and fails to account for regimes which come to power by revolution but fail to change the structure of the state and society sufficiently to yield