Moral Bias in Large Elections: Theory and Experimental Evidence

We argue that large elections may exhibit a moral bias (i.e., conditional on the distribution of preferences within the electorate, alternatives understood by voters to be morally superior are more likely to win in large elections than in small ones). This bias can result from ethical expressive preferences, which include a payoff voters obtain from taking an action they believe to be ethical. In large elections, pivot probability is small, so expressive preferences become more important relative to material self-interest. Ethical expressive preferences can have a disproportionate impact on results in large elections for two reasons. As pivot probability declines, ethical expressive motivations make agents more likely to vote on the basis of ethical considerations than on the basis of narrow self-interest, and the set of agents who choose to vote increasingly consist of agents with large ethical expressive payoffs. We provide experimental evidence that is consistent with the hypothesis of moral bias.