The study of social dilemmas is the study of the tension between individual and collective rationality. In a social dilemma, individually reasonable behavior leads to a situation in which everyone is worse off. The first part of this review is a discussion of categories of social dilemmas and how they are modeled. The key two-person social dilemmas (Prisoner’s Dilemma, Assurance, Chicken) and multiple-person social dilemmas (public goods dilemmas and commons dilemmas) are examined. The second part is an extended treatment of possible solutions for social dilemmas. These solutions are organized into three broad categories based on whether the solutions assume egoistic actors and whether the structure of the situation can be changed: Motivational solutions assume actors are not completely egoistic and so give some weight to the outcomes of their partners. Strategic solutions assume egoistic actors, and neither of these categories of solutions involve changing the fundamental structure of the situation. Solutions that do involve changing the rules of the game are considered in the section on structural solutions.
