DS08 - Sociétés innovantes, intégrantes et adaptatives

Coping with Heterogeneous Opinions – CHOp

Submission summary

This project tackles the issue of the diversity of opinions in a society. It is grounded in Economics but is at the intersection with several other fields: Psychology, Statistics, Decision Theory, Analytical Philosophy, Social Choice, and Political Science. It goes beyond equating individuals' opinions with their probabilistic beliefs, a standard practice in Economics, and aims at encompassing notions like unawareness, ambiguity, and competence to analyze opinion heterogeneity more broadly. The general questions we will explore are the following ones:
- How does diversity of opinions come about and how can it survive?
- What is the impact of this diversity on economic arrangements?
- How do individuals react when confronted with other's opinions?
- How can one aggregate the various opinions to make the best decisions?

These questions deserve to be treated both normatively and positively, calling for various analytical approaches (e.g. axiomatic treatment, modelling of markets, etc.) and experimental approaches (from psychophysics and social psychology). From a positive side, we will provide models explaining how individuals exposed to the same information can disagree. This requires to think outside of the usual Bayesian, common prior framework. Getting outside of this framework is also required to provide an understanding of how disagreements can survive in the long run, as we aim to show, contrary to a long-standing view in economics that "irrational" opinions get wiped out of the market. Experimentally, we will focus on how individuals integrate heterogeneous opinions when making decisions and, in particular, how social pressure affects individuals' opinions. We will finally analyze how opinion heterogeneity affects economic arrangements such as bargaining, risk sharing and financial markets, incentive provision, etc.

From a normative side, we will concentrate on the many ways different opinions can be aggregated to form a social or group opinion. A particular attention will be given to procedures that allow one to extract a measure of competence or expertise from opinions expressed by members of a society or group. These degrees of competence will then be used to weight the various opinions in order to make the best informed decision for the group. We will provide an experimental assessment of these rules, compared with other rules studied in the literature. We will also go beyond taking opinions as exogenous and will see how correlations (and, possibly, failure to recognize these) among the sources of information accessible to individuals changes the way aggregating procedures like voting work. This study will fit into a more general research question which is how to aggregate "ill-defined" or "biased" opinions.

The project's aim is mainly to advance scientific knowledge on these issues. It could lead to define practical ways of aggregating opinions or rankings that could be of interest for the private and public sectors.

The team of researchers assembled for this project have expertise in the various fields the project is touching. They have already worked, produced scientific papers published in the best international outlets and organized events together.

Project coordinator

Monsieur Eric Danan (Théorie économique, modélisation et applications)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.


CNRS DR 12 LPC Centre National de la Recherche Scientifique Délégation Provence et Corse Laboratoire de psychologie cognitive
THEMA Théorie économique, modélisation et applications

Help of the ANR 147,960 euros
Beginning and duration of the scientific project: September 2017 - 48 Months

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