Perspectives on preference aggregation

Abstract

For centuries, the mathematical aggregation of preferences by groups, organizations or society has received keen interdisciplinary attention. Extensive 20th century theoretical work in Economics and Political Science highlighted that competing notions of “rational social choice” intrinsically contradict each other. This led some researchers to consider coherent “democratic decision making” a mathematical impossibility. Recent empirical work in Psychology qualifies that view. This nontechnical review sketches a quantitative research paradigm for the behavioral investigation of mathematical social choice rules on real ballot, experimental choice, or attitudinal survey data. The paper poses a series of open questions. Some classical work sometimes makes assumptions about voter preferences that are descriptively invalid. Do such technical assumptions lead the theory astray? How can empirical work inform the formulation of meaningful theoretical primitives? Classical “impossibility results” leverage the fact that certain desirable mathematical properties logically cannot hold universally in all conceivable electorates. Do these properties nonetheless hold in empirical distributions of preferences? Will future behavioral analyses continue to contradict the expectations of established theory? Under what conditions and why do competing consensus methods yield identical outcomes