Inconsistency on Multimember Courts

Appellate courts sometimes issue inconsistent decisions. Individual judges are sometimes inconsistent too. We argue that making judges more consistent could exacerbate the problem of inconsistent courts. We do so through a variant of Arrow’s model of preference aggregation in which preferences are complete but need not be transitive. We introduce an ordinal rationality measure to compare preference relations. Using this measure, we introduce a new axiom, monotonicity in rationality, which requires the collective preference to become more rational when individuals’ preferences become more rational. We show that no collective choice rule satisfies monotonicity in rationality and the standard Arrovian assumptions: unrestricted domain, weak Pareto, independence of irrelevant alternatives, and nondictatorship.