a notable difference in Polity score. Instead, Colgan offers a new data set on revolutionary leaders which identifies governments that "transform the existing social, political, and economic relationships of the state by overthrowing or rejecting the principal existing institutions of society." This most recent data set has been employed to make empirically-based contributions to the literature on revolution by identifying links between revolution and the likelihood of international disputes. Revolutions have also been approached from anthropological perspectives. Drawing on Victor Turner's writings on ritual and performance, Bjorn Thomassen has argued that revolutions can be understood as "liminal" moments: modern political revolutions very much resemble rituals and can therefore be studied within a process approach. This would imply not only a focus on political behavior "from below", but also to recognize moments where "high and low" are relativized, made irrelevant or subverted, and where the micro and macro levels fuse together in critical conjunctions. Economist Douglass North argued that it is much easier for revolutionaries to alter formal political institutions such as laws and constitutions than to alter informal social conventions. According to North, inconsistencies between rapidly changing formal institutions and slow-changing informal ones can inhibit effective sociopolitical change. Because of this, the long-term effect of revolutionary political restructuring is often more moderate than the ostensible short-term effect. While revolutions encompass events ranging from the relatively peaceful revolutions that overthrew communist regimes to the violent Islamic revolution in Afghanistan, they exclude coups d'état, civil wars, revolts, and rebellions that make no effort to transform institutions or the justification for authority (such as Józef Piłsudski's May Coup of 1926 or the American Civil War), as well as peaceful transitions to democracy through institutional arrangements such as plebiscites and free elections, as in Spain after the death of Francisco Franco. See also Age of Revolution Classless society Passive revolution Political warfare Psychological warfare Rebellion Reformism Revolutionary wave Right of revolution Social movement Subversion User revolt - A phenomenon related to the modern Internet Preference falsification Lists of revolutions List of revolutions and rebellions References Bibliography Further reading External links Arendt, Hannah (1963). IEP.UTM.edu. On Revolution. Penguin Classics. New Ed edition: February 8, 1991. . Comparative politics Social concepts Social conflict