For the past four decades, political theorist Jon Elster has sought to reduce the ambiguities and hubris of social scientists by insisting that their explanations meet two minimal criteria. The first criterion is methodological individualism, or the necessity of accounting for aggregate social phenomena, such as the unemployment rate or a revolution, in terms of individual desires, beliefs, preferences, and actions. The second criterion requires clarification of the mechanisms, or the individual-level motivations and decisions, by which specific causes yield particular social effects. Because social life is so complex and thus the range of possible mechanisms so diverse, Elster argues, aspirations to general theory in the social sciences are ill advised. However, he believes specification of a causal mechanism in every case will increase our confidence in the resulting, more tightly knit explanations of social action.