Title: The Will of the People — How do Individuals Aggregate Ordinal Preferences? (with B.D. Bernheim)
Abstract: Famous impossibility results (Arrow, 1950, Sen, 1970) show that there is no single best rule for aggregating ordinal preferences. Yet, in domains ranging from political economy to market design, preference aggregation problems abound, raising the question of how individuals believe normatively appealing aggregation should occur. In our experiment, individuals in the role of Social Architects make a choice for a group they are not part of, knowing only group members’ ordinal preferences over the alternatives, in two contexts: assigning tasks to workers, and donating money to a political party. We find that the vast majority of Social Architects aggregate ordinal preferences like utilitarians, after imputing cardinal utility information from ordinal rankings. Subjects find little normative appeal in the celebrated Condorcet pairwise majority rule and in any other procedures that require ignoring information about preference intensity. Multi-stage procedures, which are frequently used in practice, also find vanishing empirical support. Using a clustering method, we show that subjects do not systematically employ any aggregation procedure outside the set of rules we consider. Our results also fill a gap in the literature on other-regarding preferences which exclusively considers cardinally comparable outcomes.
