Group identification: An integrated approach

Abstract Consider social decision rules identifying two or more groups by aggregating individual opinions on who belong to which group. We search for rules respecting cross-group independence in the aggregation process. This independence axiom or its variants, together with other implicit constraints in the two models by Miller (2008) and Cho and Ju (2017) , characterize a restricted family of rules; the only “democratic” rule in this family is the liberal rule. Our new framework provides a unified perspective on the main results of the two papers and uncovers implicit constraints in their modeling. Once those constraints are weakened, there emerge a richer family of independent rules including the consent rules ( Samet and Schmeidler, 2003 ). The standard majority rule and many other democratic rules lying between the majority and liberal rules are examples. We also provide a characterization of the consent rules.