The impossibility of unbiased judgment aggregation

F.K. Dietrich, C. List

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Standard impossibility theorems on judgment aggregation over logically connected propositions either use a controversial systematicity condition or apply only to agendas of propositions with rich logical connections. Are there any serious impossibilities without these restrictions? we prove an impossibility theorem without requiring systematicity that applies to most standard agendas: every judgment aggregation function (with rational inputs and outputs) satisfying a condition called unbiasedness is dictatorial (or effectively dictatorial if we remove one of the agenda conditions). Our agenda conditions are tight. When applied illustratively to (strict) preference aggregation represented in our model, the result implies that every unbiased social welfare function with universal domain is effectively dictatorial.
Original languageEnglish
Pages (from-to)281-299
Number of pages19
JournalTheory and Decision
Volume68
Issue number3
DOIs
Publication statusPublished - 1 Jan 2010

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