Judgment aggregation and agenda manipulation

Journal article: When individual judgments ('yes' or 'no') on some propositions are aggregated into collective judgments, outcomes may be sensitive to the choice of propositions under consideration (the agenda). Such agenda-sensitivity opens the door to manipulation by agenda setters. I define three types of agenda-insensitivity ('basic', 'full', and 'focal') and for each type axiomatically characterize the aggregation procedures satisfying it. Two axioms turn out to be central for agenda-insensitivity: the familiar independence axiom, requiring propositionwise aggregation, and the axiom of implicit consensus preservation, requiring the respect of any (possibly implicit) consensus. As the paper's second contribution, I prove a new impossibility theorem whereby these two axioms imply dictatorial aggregation for almost all agendas.

Author(s)

Franz Dietrich

Journal
  • Games and Economic Behavior
Date of publication
  • 2016
Keywords JEL
D70 D71
Keywords
  • Characterization theorems
  • Impossibility theorems
  • Agenda manipulation
  • Description-sensitivity
  • Multiple issues
  • Judgment aggregation
Pages
  • 113-136
Version
  • 1
Volume
  • 95