No-envy, efficiency, and collective rationality

We consider fair collective choice functions (hereafter fair CCFs) which associate with each profile of extended preference orderings and each set of feasible social states a subset of the set of Pareto efficient and envy-free states for the preference profile. Our main objective is to examine compatibility of fair social choices with collective rationality. We formulate desirable properties of collective rationality, and look for CCFs satisfying them. Next, we show that any fair CCF violates most of collective rationality properties. Moreover, one of our results implies that no fair CCF can be rationalized by a social preference relation.