Despite the importance of social dilemmas, a single unified and well-accepted formal definition of social dilemma has yet to be presented. This diculty stems from the fact that, even though it is commonly accepted that a social dilemma arises when there can be a conflict between individual and collective interest, authors seem to di er in the formalization of the notions of individual and collective interest.

This resulted in the existence of multiple conflicting and sometimes non-precise definitions of a social dilemma leading to certain games being considered social dilemmas by some authors but not by others.

We contend that a non-cooperative game is a social dilemma if there is a rationalizable strategy profile which is Pareto inefficient. By proposing this definition, we are applying the broadest and most well-accepted notions of collective rationality and the less stringent requirement for the exercise of individual rationality. With this definition, we argue that social dilemmas should be perceived as social settings prone to conflict instead of settings in which conflict is certain. Furthermore, we hold that if conflict can arise in a single interaction of a set of iterated iteractions, then the entire situation must be forcedly considered a social dilemma.

An interesting result of the proposed definition, is that social dilemmas can arise in situations (such as some iterated deadlock games) in which players are propelled to choose strategies which are the only possible individual and collectively rational choices in the immediate best interest of both the individual and society but the consecutive pursuit of such short-term reasoning derives in an inecient outcome in the long-run for all individuals in society.

Accordingly, under our definition, situations which do not pose dilemmas to society in the short-term may in fact pose a conflict in the long run.

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