Two-stage majoritarian choice
We propose a class of decisive collective choice rules that rely on an exogenous linear ordering to partition the majority relation into two acyclic relations. The first relation is used to obtain a shortlist of the feasible alternatives while the second is used to make a final choice. In combination with faithfulness to the underlying majority relation, rules in this class are characterized by two desirable rationality properties: Sen’s expansion consistency and a version of Manzini and Mariotti’s weak WARP. The rules also satisfy natural adaptations of Arrow’s independence of irrelevant alternatives and May’s positive responsiveness.
Majority rule Decisiveness IIA Monotonicity Rational shortlist methods