STABILITY AND COORDINATION IN DUVERGERS LAW - A FORMAL MODEL OF PREELECTION POLLS AND STRATEGIC VOTING

This paper investigates the dynamics of the ''wasted vote'' phenomenon and Duverger's Law. I construct a theoretical model in order to consi der how preelection polls serve to inform the electorate about the rel ative chances of the candidates and how that information acts over tim e to decrease the support of the trailing candidate. The results shed light on how public opinion polls can aggregate information in the ele ctorate and coordinate voters on the viable candidates in the election . Specifically, I show that in a Bayesian game model of strategic voti ng there exist non-Duvergerian equilibria in which all three candidate s receive votes (in the limit). These equilibria require extreme coord ination, however, and any variation in beliefs leads voters away from them to one of the Duvergerian equilibria. Thus, non-Duvergerian equil ibria are unstable, while two-party equilibria are not. In addition, I describe how preelection polls provide information to voters about th e viability of candidates and can thus be used by voters to coordinate on a Duvergerian outcome.