Majority-preserving judgment aggregation rules

The literature on judgment aggregation has now been moving from studying impossibility results regarding aggregation rules towards studying specific judgment aggregation rules. Here we focus on a family of rules that is the natural counterpart of the family of Condorcet-consistent voting rules: majority-preserving judgment aggregation rules. A judgment aggregation rule is majority-preserving if whenever issue-wise majority is consistent, the rule should output the majoritarian opinion on each issue. We provide a formal setting for relating judgment aggregation rules to voting rules and propose some basic properties for judgment aggregation rules. We consider six such rules some of which have already appeared in the literature, some others are new. For these rules we consider their relation to known voting rules, to each other, with respect to their discriminating power, and analyse them with respect to the considered properties. Gabriella Pigozzi and Srdjan Vesic benefited from the support of the project AMANDE ANR-13-BS02-0004 of the French National Research Agency (ANR). J. Lang LAMSADE, CNRS Université Paris-Dauphine Place du Maréchal de Lattre de Tassigny 75775 Paris Cedex 16 Tel: +33 1 44 05 40 21 Fax: +33 1 44 05 40 91 E-mail: [email protected] G. Pigozzi LAMSADE Université Paris-Dauphine M. Slavkovik University of Bergen Leendert van der Torre University of Luxembourg Srdjan Vesic CRIL CNRS 2 Jérôme Lang et al.