Is majority consistency possible?

Eyal Baharad, Shmuel Nitzan

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

The most well-known approaches to decision rules are inspired by “majority-based” and “ranking-based” utilitarianism. The long lasting discussion on the appropriate collective decision mechanism is based on the merits of the rules consistent with these two approaches. Focusing on conformity with qualified majority, we propose single-approval multiple-rejection (SAMR) as a plausible flexible scoring rule narrowing the gap between the two approaches. Given k alternatives, such a mechanism permits approval of a single alternative and rejection of at most (Formula presented.) alternatives allowing any relative significance of the approved vs. the rejected alternatives. SAMR is the unique type of rule that spans the whole spectrum of the qualified majority-based utilitarian rules, independent of k. Our first characterization result exposes the relationship between its consistency with any predetermined (Formula presented.) -majority based rule, (Formula presented.) , and the best/worst (approval/rejection) relative weight p. Our second result establishes that the plurality rule is the unique scoring rule consistent with any (Formula presented.) -majority, (Formula presented.). These results imply the impossibility of universal scoring-rule consistency with any ideal or real (Formula presented.) -majority.

Original languageEnglish
Pages (from-to)287-299
Number of pages13
JournalSocial Choice and Welfare
Volume46
Issue number2
Early online date7 Sep 2015
DOIs
StatePublished - 1 Feb 2016

Bibliographical note

Publisher Copyright:
© 2015, Springer-Verlag Berlin Heidelberg.

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