  Thus the concern over methodological individualism began to fade away, and might have disappeared completely had it not been for the sudden explosion of interest in game theory (or “rational choice theory”) among social scientists in the 1980s. The reason for this can be summed up in two words (and an article): the prisoner’s dilemma. Social scientists had always been aware that individuals in groups are capable of getting stuck in patterns of collectively self-defeating behavior. Paul Samuelson’s “The Pure Theory of Public Expenditure” (1954), Garrett Hardin’s “The Tragedy of the Commons,” (1968), and Mancur Olson’s The Logic of Collective Action (1965), had all provided very clear examples of cases where the mere existence of a common interest among individuals nevertheless failed to provide them with an incentive to perform the actions necessary to realize that interest. What the story of the prisoner’s dilemma – and more importantly, the accompanying game matrix – provided was a simple yet powerful model that could be used to represent the structure of all these interactions (see R. Hardin 1982).