Equal rights to trade and mediate

摘要

Consider any exchange economy with a fixed finite set of traders whose preference orderings and feasible sets of net trades satisfy standard convexity and continuity assumptions. Suppose these traders are granted equal rights to choose net trade vectors within a common convex cone. This property, when combined with Pareto efficiency, characterizes Walrasian equilibrium without lump-sum transfers in two special cases: when there are only two goods; or when at least one trader has unique supporting prices. In general, even without imposing Pareto efficiency explicitly, conferring an additional right to mediate mutually beneficial transactions with other traders will characterize Walrasian equilibrium.An early version was presented to the Conference on Axiomatic Resource Allocation Theory in Namur, July 1999, in honour of Louis Gevers, with whom I have had many enjoyable and fruitful exchanges since we first met in 1971. A later version was presented at the conference of the Society for Social Choice and Welfare in Alicante, June/July 2000. It is a pleasant duty to acknowledge helpful discussions at these conferences with Marc Fleurbaey, François Maniquet, and Yves Sprumont, as well as subsequently with Karl Vind. Further very helpful suggestions came from two anonymous referees, as well as François Maniquet acting in an editorial role. Finally, my gratitute to the Institute of Economic Research at Hitotsubashi University, to the Japanese Ministry of Education, and to my host Kotaro Suzumura, for making possible a visit in Autumn 1998 during which preliminary research for this paper was conducted.