Justifiable Group Choice
23 Pages Posted: 25 Feb 2010
Date Written: December 1, 2009
We study the judgment aggregation problem from the perspective of justifying a particular collective decision by a corresponding aggregation on the criteria. In particular, we characterize the logical relations between the decision and the criteria that enable justification of a majority decision through a proposition-wise aggregation rule with no veto power on the criteria. While the well-studied "doctrinal paradox" provides a negative example in which no such justification exists, we show that genuine possibility results emerge if there is a gap between the necessary and the sufficient conditions for the decision. This happens, for instance, if there is only a partial consensus about the appropriate criteria for the decision, if only a subset of these criteria can be elicited, or if the judgment on criteria is based on probabilistic acceptance thresholds.
Keywords: Judgement aggregation, logical aggregation, social choice, majority voting, justifying choice, (non-)truth-functionality
JEL Classification: D7, D71
Suggested Citation: Suggested Citation