Fairness or Foresight: Why is Majority Rule Stable?

Social choice theory shows that majority rule is generically unstable. Contrary to this theoretical prediction, however, large policy shifts are rare events in politics. Hence, why is majority rule stable? The uncovered set is the dominant preference-based explanation for the stability of majority rule. Its underlying logic assumes that voters act strategically considering the ultimate consequences of their actions instead of choosing myopically. However, there is vast experimental evidence showing that subjects only exhibit low levels of rationality. Therefore, I argue that the uncovered set rests on implausible behavioral assumptions. Instead, social preferences such as a concern for distributional fairness offer a better explanation for the stability of majority rule. In this study I test my claim in a series of committee decision-making experiments. In the experiments, I systematically vary the fairness properties of the policy space while keeping the location of the uncovered set constant. The experimental results overwhelmingly support the fairness explanation. When the UCS coincides with the fair alternatives it correctly predicts about 94 percent of all decisions. When all fair alternatives are located outside the UCS its success rate drops to four percent. This finding is important for the further development of democratic theory calling for the development of a behavioral approach to the theory of collective decision making.