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 dier 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.