ACCOUNTING FOR THE TRAGEDY IN THE PRISONERS-DILEMMA

The Prisoner's Dilemma (PD) exhibits a 'tragedy' in this sense: if the players are fully informed and rational, they are condemned to a join tly dispreferred outcome. In this essay I address the following questi on: What feature of the PD's payoff structure is necessary and suffici ent to produce the tragedy? In answering it I use the notion of a ''tr embling-hand equilibrium''. In the final section I discuss an implicat ion of my argument, an implication which bears on the persistence of t he problem posed by the PD.