Condorcet meets Ellsberg

The Condorcet Jury Theorem states that given subjective expected utility maximization and common values, the equilibrium probability that the correct candidate wins goes to 1 as the size of the electorate goes to infinity. This paper studies strategic voting when voters have pure common values but may be ambiguity averse—exhibit Ellsberg-type behavior—as modeled by maxmin expected utility preferences. It provides sufficient conditions so that the equilibrium probability of the correct candidate winning the election is bounded above by 1⁄2 in at least one state. As a consequence, there is no equilibrium in which information aggregates.