On mechanism design with expressive preferences: an aspect of the social choice of Brexit

TL;DR

This paper explores how expressive preferences influence collective decision-making, revealing that random mechanisms better handle anomalies like Brexit compared to deterministic ones.

Contribution

It introduces a framework for mechanism design with expressive preferences and analyzes the impact of such preferences on social choice, especially regarding the Brexit anomaly.

Findings

Deterministic mechanisms are vulnerable to Brexit anomaly.

Random mechanisms provide more robust outcomes.

Stringent domain restrictions do not fully mitigate the anomaly.

Abstract

We study some problems of collective choice when individuals can have expressive preferences, that is, where a decision-maker may care not only about the material benefit from choosing an action but also about some intrinsic morality of the action or whether the action conforms to some identity-marker of the decision-maker. We construct a simple framework for analyzing mechanism design problems with such preferences and present some results focussing on the phenomenon we call "Brexit anomaly". The main findings are that while deterministic mechanisms are quite susceptible to Brexit anomaly, even with stringent domain restriction, random mechanisms assure more positive results.