The possibility of judgment aggregation under subjunctive implications

The new …eld of judgment aggregation aims to …nd group judgments on logically interconnected propositions. Recent impossibility results have established limitations on the possibility to vote independently on the propositions, hence notably on the possibility to use quota rules (rules with acceptance thresholds for the propositions). I show that, fortunately, the impossibilities fail to apply to a wide class of realistic agendas once connection rules (like “if a then b”) are adequately modelled, namely as subjunctive rather than material implications. For these agendas, I characterise the set of all consistent quota rules, and I suggest ways to choose the acceptance thresholds. I also prove a characterisation result valid for arbitrary agendas in most logics. Key words: judgment aggregation, material implication, subjunctive implication, possibility theorems. JEL Classi…cation Numbers: D70, D71, D79