Passion over Reason? Mixed Motives and the Optimal Size of Voting Bodies∗

We study a Condorcet jury model where voters are driven by instrumental as well as expressive motives. We show that arbitrarily small amounts of expressive motives significantly affect equilibrium behavior and the optimal size of voting bodies. Increasing the size of voting bodies always reduces accuracy over some region. Unless conflict between expressive and instrumental preferences is very low, information does not aggregate in the limit. In that case, large voting bodies are no better than a coin flip at selecting the correct outcome. Thus, even when adding informed voters is costless, smaller voting bodies often produce better outcomes.