When Should Political Scientists Use the Self-Confirming Equilibrium Concept? Benefits, Costs, and an Application to Jury Theorems

Many claims about political behavior are based on implicit assumptions about how people think. One such assumption, that political actors use identical conjectures when assessing others’ strategies, is nested within applications of widely-used game theoretic equilibrium concepts. When empirical research calls this assumption into question, the self-confirming equilibrium (SCE) concept is an alternate criterion for deriving theoretical claims. Using a series of examples, we examine opportunities and challenges inherent in applying the SCE concept. Our main example focuses on Feddersen and Pesendorfer’s (1998) claim that unanimity rules can lead juries to convict innocent defendants. Using SCE, we show that the claim depends on the assumption that jurors have identical beliefs about one another’s strategies. When juror beliefs vary in ways that follow from empirical jury research, we show that fewer false convictions can occur in equilibrium. Generally, the SCE confers advantages when actors have different conjectures about one another’s strategies.