Rethinking the Neutrality Axiom in Judgment Aggregation

When aggregating the judgments of a group of agents, an important consideration concerns the fairness of the aggregation process. This is the fundamental idea behind the neutrality axiom in social choice theory: if two judgments enjoy the same support amongst the agents, either both or neither of them should be part of the collective decision. This is a reasonable requirement in many scenarios, but we argue that for scenarios in which agents are asked to judge very diverse kinds of propositions, the classical neutrality axiom is much too strong. We thus propose a family of weaker neutrality axioms, parametrised by binary relations between the propositions.