Social Choice in the Wild

Kenneth Arrow's impossibility theorem in social choice theory is remarkable for being at once both definitive and inscrutable. It seems to disallow a rational procedure for collective choice without suggesting practical ways to reduce the probability or magnitude of the problem. To shed light on this issue, and considering the difficulties of recreating real-world political dynamics in the lab, we study a pressing social dilemma in a coastal California city. Local citizens engaged in small group deliberations over strategies to resolve an intensifying water supply shortage -an issue which had provoked sharply divided public opinion. We propose a measure of decision stability to grade the danger of a social choice paradox and find that the process of small group deliberation significantly increases this measure of stability.