Potentials and Solutions of Cooperative Games

This study considers strategic communication before voting. Voters have partially conflicting interests rather than common interests. That is, voters cannot tell whether a collective decision is a matter of truth, such as guilty or innocent, or a matter of taste, such as left or right. A set of imperfectly informed voters communicates before casting their votes. From a statistical perspective, truth-telling by all voters in deliberation, coupled with majority rule, may lead to desirable outcomes asymptotically as the population of voters increases. Thus, from a statistical perspective, increasing the population of voters is desirable. This study, however, shows that truthful communication is not incentive-compatible with equilibrium behavior when the size of the electorate is sufficiently large. In particular, truthful communication by all voters is inconsistent with equilibrium for any voting rule and any degree of conflict when the population of voters becomes arbitrarily large. On the other hand, truthful communication might be an equilibrium for a small population of voters. Under these circumstances, voting rules matter. This study shows that majority rule most promotes truthful communication before voting.