On the Robustness of Majority Rule and Rule by Consensus†

We show that simple majority rule satisfies the Pareto property, anonymity, neutrality, and (generic) transitivity on a bigger class of preference domains than any other voting rule. If we replace neutrality in the above list of properties with independence of irrelevant alternatives, then the corresponding conclusion holds for unanimity rule (rule by consensus). * Faculty of Economics and Politics, University of Cambridge ** School of Social Science, Institute for Advanced Study and Department of Economics, Princeton University † This research was supported by grants from the Beijer International Institute of Ecological Economics and the U.S. National Science Foundation. We thank Salvador Barberá, François Maniquet, and William Thomson for helpful comments on an earlier version.