Introduction to Judgment Aggregation

Davide Grossi (1) , Gabriella Pigozzi (2)

1 ILLC - Institute for Logic, Language and Computation
2 LAMSADE - Laboratoire d'analyse et modélisation de systèmes pour l'aide à la décision

The present notes serve as material for the course Introduction to Judgment Ag- gregation to be given at the 23rd European Summer School on Logic, Language and Information (ESSLLI'11, Ljubljana). The notes are structured as follows: Section 1 introduces the field of judgment aggregation, its relations to preference aggregation and some formal preliminaries. Section 2 shows that the paradox that originated judgment aggregation is not a problem limited to propositionwise majority voting but a more general issue, illustrated by an impossibility theorem of judgment aggregation that is here proven. The relaxation of some conditions used in impossibility results in judgment aggregation may lead to escape routes from the impossibility theorems. These escape routes are explored in Section 3. Section 4 presents the issue of manipulation that arises when voters strategically misrepresent their true vote in order to force a different outcome in the aggregation process. Finally, we conclude by sketching a list of on-going research in the field of judgment aggregation (Section 5)

Mots clés: judgment aggregation; preference aggregation

Domaines: Mathématiques [math]

Davide Grossi, Gabriella Pigozzi. Introduction to Judgment Aggregation. ESSLLI 2011, Aug 2011, Ljubljana, Slovenia. pp.160-209, ⟨10.1007/978-3-642-31485-8_5⟩. ⟨hal-01497075⟩