Path independent choice and the ranking of opportunity sets

The indirect utility principle provides an instrumentalist basis for ranking opportunity sets, given an underlying preference ranking on alternatives. Opportunity set A is weakly preferred to B if A includes at least one preference-maximising element from A⋃B. We introduce the Plott consistency principle as a natural extension of this logic to decision-makers who choose amongst alternatives according to a path independent choice function. Such choice functions need not be rationalisable by a preference order. Plott consistency requires that A is an acceptable choice from {A, B} if A includes at least one element from the set of acceptable choices from A⋃B. We explore necessary and sufficient conditions (imposed on a choice function defined on collections of opportunity sets) for Plott consistency.