Date
2011-01
Dewey
Microéconomie
Sujet
capacities; Ambiguity; No-Trade Theorem; Choquet expected utility theory; unambiguous events; Agreement Theorem; common knowledge; asymmetric information
JEL code
D81; D82; D70
Conference name
TARK XIII
Conference date
07-2011
Conference city
Groningen
Conference country
Pays-Bas
Book title
TARK XIII : Proceedings of the 13th Conference on Theoretical Aspects of Rationality and Knowledge
Publisher
ACM
Publisher city
New York
Year
2011
ISBN
978-1-4503-0707-9
Author
Lefort, Jean-Philippe
Dominiak, Adam
Type
Communication / Conférence
Item number of pages
35
Abstract (EN)
In this paper we show that unlike in Bayesian frameworks asymmetric information does matter and can explain differences in common knowledge decisions due to ambiguous character of agents' private information. Agents share a common-but-not-necessarily-additive prior beliefs represented by capacities. It is shown that, if each agent's information partition is made up of unambiguous events in the sense of Nehring (1999, Mat. Soc. Sci. 38, 197-213), then it is impossible that the agents disagree on their commonly known decisions, whatever these decisions are : whether posterior beliefs or conditional expectations. Conversely, an agreement on conditional expectations, but not on posterior beliefs,
implies that agents' private information must consist of Nehring-unambiguous
events. The results obtained allow to attribute the existence of a speculative
trade to the presence of agents' diverse and ambiguous information.