Call for Contributions

Half a century after its publication, Robert Aumann's Agreement Theorem ("Agreeing to Disagree", The Annals of Statistics, 1976) has not ceased to intrigue and inspire (see, for instance, recent contributions by Di Tillio, Lehrer, and Samet 2022, Geanakoplos and Polemarchakis 2023, Gizatulina and Hellman 2019, Gonczarowski and Moses 2023, Hellman and Pintér 2022).

The Agreement Theorem states that if two individuals assign the same prior probability over the set of possible states of the world and if — thanks to the common knowledge of their information partitions — the posterior probabilities they attribute to an event are common knowledge, then these posterior probabilities must be identical.

Aumann's result builds on a conceptual innovation that is as powerful as elegant: identifying what is commonly known between the participants of an exchange with the meet — that is, the finest common coarsening — of the information partitions.

The agreement result and the formal language of modeling knowledge and beliefs introduced by Aumann (1976) have generated research in multiple directions:

• dynamic foundations in the form of Bayesian dialogues and applications of these to betting and trading scenarios (Bacharach 1979, Geanakoplos and Polemarchakis 1982, Milgrom and Stokey 1982, Sebenius and Geanakoplos 1983),
• generalizations of the result moving from partitions to σ-algebras and from knowledge of an event to knowledge of random variables (for instance, Nielsen 1984)
• notions of "almost" common knowledge (Halpern 1986, Rubinstein 1989, Halpern and Moses 1990, Fagin et al. 1995) and approximate common knowledge in the form of common belief (Geanakoplos 1994, Morris 1999, Monderer and Samet 1989),
• relaxations of the common prior hypothesis (Di Tillio, Lehrer, and Samet 2022, Gizatulina and Hellman 2019, Hellman and Pintér 2022).

With this workshop, we honor the fiftieth anniversary of the publication of "Agreeing to Disagree."

Besides the areas of research mentioned above, we invite contributions on the following topics:

• critical methodological or historical assessments of the concept of common knowledge or models of interactive knowledge or belief revision, notably in relations to similar accounts in philosophy and linguistics,
• extensions of the agreement result in new directions such as ambiguity or novel notions of almost or approximate common knowledge,
• presentations of the agreement result and its applications for larger interdisciplinary audiences,
• new applications to problems in economics, computer science, psychology, philosophy, linguistics, and literature studies.

If you would like to give a talk at this event, please send a proposal (extended abstract or working paper) to:
christina.pawlowitsch@assas-universite.fr
by January 30, 2026.

Proposals are accepted on a rolling basis between now and January 30, 2026.

Program Committee:
Galit Ashkenazi-Golan * Dietmar Berwanger * Antoine Billot * Paul Égré * Ziv Hellman * Roni Katzir
* Christina Pawlowitsch * Herakles Polemarchakis

Image: © Sylvia K. Kummer, "les blancs au milieu," 2016

Opening day
June 11
with the honorary partitipation of and talk by
Robert J. Aumann

Galit Ashkenazi-Golan
(Department of Mathematics, London School of Economics)
Mathias Beiglböck
(Department of Mathematics, University of Vienna)
John Geanakoplos (TBC)
(Yale University and Santa Fe Institute, Economics)
Alia Gizatullina
(University of St. Gallen, Economics)
Yannai A. Gonczarowski
(Harvard University, Economics & Computer Science)
Michael Greinecker
(Paris-Saclay, Centre for Economics)
Ziv Hellman
(Department of Economics, Bar-Ilan University)
Roni Katzir
(Department of Linguistics, Tel Aviv University)
Yoram Moses
(Technion - Israel Institute of Technology)
Christina Pawlowitsch
(LEMMA, Université Paris-Panthéon-Assas)
Miklós Pintér
(Corvinus University, Economics)
Herakles Polemarchakis
(University of Warwick, Economics)
Elias Tsakas
(Maastricht University, Economics)
Rafael Veiel
(University of Texas, Austin, Economics)

Past events