All agreed: Aumann meets DeGroot

Jan-Willem Romeijn*, Olivier Roy

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

4 Citations (Scopus)
113 Downloads (Pure)


We represent consensus formation processes based on iterated opinion pooling (DeGroot in J Am Stat Assoc 69:118-121, 1974; Lehrer and Wagner in Rational consensus in science and society: a philosophical and mathematical study. Springer, Berlin, 1981) as a dynamic approach to common knowledge of posteriors (Aumann in Ann Stat 4(6):1236-1239, 1976; Geanakoplos and Polemarchakis in J Econ Theory 28:192-200, 1982). We thus provide a concrete and plausible Bayesian rationalization of consensus through iterated pooling. The link clarifies the conditions under which iterated pooling can be rationalized from a Bayesian perspective, and offers an understanding of iterated pooling in terms of higher-order beliefs.

Original languageEnglish
Pages (from-to)41-60
Number of pages20
JournalTheory and Decision
Issue number1
Publication statusPublished - Jul-2018


  • Iterated pooling
  • Dynamic agreement theorem
  • Social epistemology

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