Public Information and Electoral Bias

We present a theory of strategic voting that predicts elections are more likely to be close and voter turnout is more likely to be high when citizens possess better public information about the composition of the electorate. These findings are disturbing because they suggest that providing more information to potential voters about aggregate political preferences (e.g., through polls, political stock markets, or expert forecasts) may actually undermine the democratic process. We show that if the distribution of preferences is common knowledge, then strategic voting leads to a stark neutrality result in which the probability that either alternative wins the election is 12. This occurs because membersof the minority compensate exactly for their smaller group size by voting with higher frequency. By contrast, when citizens are symmetrically ignorant about the distribution of types, the majority is more likely to win the election and expected voter turnout is lower. Indeed, when the population is large and voting costs are small, the majority wins with probability arbitrarily close to one in equilibrium. Welfare is, therefore, unambiguously higher when citizens possess less information about the distribution of political preferences.