Judgment Aggregation with Rationality and Feasibility Constraints

I introduce a model of judgment aggregation that allows for an explicit distinction between rationality and feasibility constraints. The former are assumed to be satisfied by the individual agents; the latter must be met by the collective decision returned by the aggregation rule in use. Using this model, I characterise the class of combinations of rationality and feasibility constraints for which the majority rule can guarantee feasible outcomes and I propose several majoritarian aggregation rules that, in some sense, approximate the ideal of the majority when using the majority rule itself is not feasible. Finally, to illustrate the power and flexibility of the model, I show how it can be used to simulate several common voting rules in a simple and elegant manner. This includes the well-known Borda rule, for which finding a natural counterpart in judgment aggregation has long been an elusive quest.