STABILITY-CRITERIA FOR SOCIAL NORMS WITH APPLICATIONS TO THE PRISONERS-DILEMMA

This article introduces four criteria for characterizing social norms in both cooperative and noncooperative games. The criteria are hybrids of von Neumann and Morgenstern's notion of stability and Greenberg's theory of social situations. When applied to the three-player prisoner 's dilemma, these criteria illustrate that Nash and strong Nash equili brium behavior do not rule out the possibility of unilateral defection as a social norm. We conclude with a new type of equilibrium behavior that induces coalition building and leads to social norms that rule o ut unilateral defection and allow for cooperation.