A Robust Folk Theorem for the Prisoner's Dilemma

We prove the folk theorem for the Prisoner’s dilemma using strategies that are robust to private monitoring. From this follows a limit folk theorem: when players are patient and monitoring is sufficiently accurate, (but private and possibly independent) any feasible individually rational payoff can be obtained in sequential equilibrium. The strategies used can be implemented by finite (randomizing) automata. ∗Thanks to Görkem Celik for valuable research assistance. †Economics Department, Northwestern University. [email protected] ‡Economics Department, University of Southamption. [email protected]