 The typical game in which following a norm would provide a better solution (than the one attained by self-centered agents) is a mixed-motive game such as the prisoner’s dilemma or the trust game. In such games the unique Nash equilibrium represents a suboptimal outcome. It should be stressed that—whereas a convention is one among several equilibria of a coordination game—a social norm can never be an equilibrium of a mixed-motive game. However, Bicchieri (2006) has argued that when a norm exists it transforms the original mixed-motive game into a coordination one. As an example, consider the following prisoner’s dilemma game  (Figure 1),  where the payoffs are B=Best, S=Second, T=Third, and W=Worst. Clearly the only Nash equilibrium is to defect (D), in which case both players get (T,T), a suboptimal outcome. Suppose, however, that society has developed a norm of cooperation; that is, whenever a social dilemma occurs, it is commonly understood that the parties should privilege a cooperative attitude. Should, however, does not imply “will”, therefore the new game generated by the existence of the cooperative norm has two equilibria: either both players defect or both cooperate.