Solidarity and Efficiency in Preference Aggregation: A Tale of Two Rules
University of Milan Bicocca Department of Economics, Management and Statistics Working Paper No. 390
38 Pages Posted: 26 Nov 2018
Date Written: November 15, 2018
Abstract
This paper is concerned with preference-aggregation rules satisfying desirable efficiency and solidarity requirements. We formulate weaker versions of existing solidarity axioms and show how they imply, in conjunction with strategy-proofness, the existence of reference outcomes holding privileged status. We propose a new class of rules, fixed order status-quo rules, that can be productively contrasted to their closest counterparts in the literature, status-quo rules based on the least upper bound of a lattice. Fixed order status-quo rules satisfy stronger efficiency requirements than lattice status-quo rules but have weaker, though still significant, solidarity properties. A subfamily based on lexicographic orders is analyzed further. Fixed order status-quo rules are characterized by strategy-proofness, strong efficiency, and a third axiom, unanimity-basedness.
Keywords: social choice, preference aggregation, solidarity, efficiency, strategy-proofness, status quo rules
JEL Classification: D71, C70
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