The impossibility of non-manipulable probability aggregation

Franz Dietrich (1, 2, 3) , Christian List (4)

1 CNRS - Centre National de la Recherche Scientifique
2 PSE - Paris School of Economics
3 CES - Centre d'économie de la Sorbonne
4 LMU - Fakultät für Physik - Ludwig-Maximilians-Universität [München/Munich]

A probability aggregation rule assigns to each profile of probability functions across a group of individuals (representing their individual probability assignments to some propositions) a collective probability function (representing the group's probability assignment). The rule is "non-manipulable" if no group member can manipulate the collective probability for any proposition in the direction of his or her own probability by misrepresenting his or her probability function ("strategic voting"). We show that, except in trivial cases, no probability aggregation rule satisfying two mild conditions (non-dictatorship and consensus preservation) is non-manipulable.

Domaines: Economies et finances; Statistiques [math.ST]; Gestion et management

Franz Dietrich, Christian List. The impossibility of non-manipulable probability aggregation. 2024. ⟨halshs-04405495⟩