Strategy-proof judgment aggregation

Dietrich, Franz and List, Christian (2005) Strategy-proof judgment aggregation. PEPP, 9. Suntory and Toyota International Centres for Economics and Related Disciplines, London School of Economics and Political Science, London, UK.

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Abstract

In the theory of judgment aggregation on logically connected propositions, an important question remains open: Which aggregation rules are manipulable and which are strategy-proof? We define manipulability and strategy-proofness in judgment aggregation, characterize all strategy-proof aggregation rules, and prove an impossibility theorem similar to the Gibbard-Satterthwaite theorem. Among other escape-routes from the impossibility, we discuss weakening strategy-proofness itself. Comparing two prominent aggregation rules, we show that conclusion-based voting is strategy-proof, but generates incomplete judgments, while premise-based voting is only strategy-proof for "reason-oriented" individuals. Surprisingly, for "outcome-oriented" individuals, the two rules are strategically equivalent, generating identical judgments in equilibrium. Our results introduce game-theoretic considerations into judgment aggregation and have implications for debates on deliberative democracy.

Item Type:	Monograph (Discussion Paper)
Official URL:	http://sticerd.lse.ac.uk
Additional Information:	© 2005 the authors
Library of Congress subject classification:	H Social Sciences > HB Economic Theory
Sets:	Departments > Government Departments > Philosophy, Logic and Scientific Method Collections > Economists Online Research centres and groups > Centre for Philosophy of Natural and Social Science (CPNSS) Research centres and groups > Suntory and Toyota International Centres for Economics and Related Disciplines (STICERD) Research centres and groups > LSE Choice Group
Identification Number:	9
Date Deposited:	11 Jul 2008 09:53
URL:	http://eprints.lse.ac.uk/19299/

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