The expressive power of voting rules

Different voting rules are commonly used to settle collective decisions. A promising way to assess voting rules, for which little is known, is to compare the expressive utility that voters derive from voting with each rule. In this paper, we first propose a simple ordinal model of expressive voting that allows us to compare voting rules in terms of the expressive utility that voters can derive from voting (their expressive power). Our model provides a novel testable implication according to which expected turnout increases with expressive power. We then ran an online experiment testing this implication in a controlled environment. We find that if voters are made aware of alternative voting rules, turnout is higher in voting rules with higher expressive power. Our results also show that higher expressive power is associated with a better representation of voters’ actual preferences and, according to our model, higher expressive utility. This suggests that the expressive power of voting rules is a relevant criterion when choosing between voting rules for economic and political decisions.