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The impossibility of unbiased judgment aggregation

Dietrich, Franz and List, Christian (2007) The impossibility of unbiased judgment aggregation. Department of Government, London School of Economics and Political Science, London, UK. (Unpublished)

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Standard impossibility theorems on judgment aggregation over logically connected propositions either use a controversial systematicity condition or apply only to agen- das of propositions with rich logical connections. Are there any serious impossibilities without these restrictions? We prove an impossibility theorem without systematicity that applies to most standard agendas: Every judgment aggregation function (with rational inputs and outputs) satisfying a condition called unbiasedness is dictatorial (or e¤ectively dictatorial if we remove one of the agenda conditions). Our agenda conditions are tight. Applied illustratively to (strict) preference aggregation repres- ented in our model, the result implies that every unbiased social welfare function with universal domain is e¤ectively dictatorial.

Item Type: Monograph (Working Paper)
Official URL:
Additional Information: © 2007 Franz Dietrich and Christian List
Divisions: Government
Philosophy, Logic and Scientific Method
Subjects: B Philosophy. Psychology. Religion > BC Logic
Sets: Departments > Government
Departments > Philosophy, Logic and Scientific Method
Research centres and groups > Centre for Philosophy of Natural and Social Science (CPNSS)
Date Deposited: 29 Jul 2008 08:33
Last Modified: 07 May 2015 10:18

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