Information, Rationality and Aggregation of Competences : Condorcet's Jury Theorem (Information, Rationalite et Agregation des Competences: Le Theoreme du Jury de Condorcet)

The jury theorem states that based on the aggregation of competences, a group of agents will be the most capable of making the right decisions rather than one individual. However, the jury theorem is based on two restrictive hypotheses, the first being the stochastic independence of decisions. And yet because certain information comes from common knowledge and that behaviour can be mimetic, agents' choices can be correlated and dependent. The true expression of preferences is the second hypotheses. Nevertheless, this condition supposes that everyone acts in a parametric and non strategic manner. After presenting the initial formulation of the jury theorem, we shall show that collective competence arises even if individual choices are correlated, but is confronted with the constraint of individual rationality