Information Revelation in Constant-Sum Games: Elections and Beyond

Abstract

We study two-player constant-sum Bayesian games with type-independent payoffs. Under a "completeness" statistical condition, any "identifiable'" equilibrium is an ex-post equilibrium. We apply this result to a Downsian election in which office-motivated candidates possess private information about policy consequences. The ex-post property implies a sharp bound on information aggregation: equilibrium voter welfare is at best equal to the efficient use of a single candidate's information. In canonical specifications, politicians may "anti-pander" (overreact to their information), whereas some degree of pandering would be socially beneficial. We discuss other applications of the ex-post result.