Solidarity in Terms of Reciprocity

In this paper we introduce a new concept of solidarity in terms of reciprocity and characterize the set of social choice functions that are reciprocate (in both a strong and a weak sense), anonymous and efficient in a standardpublic good provision model when the agents have single-peaked preferences on the amount of the good provided. The resulting procedures are the well-known Generalized Condorcet Winner Solutions, and therefore,we provide an alternative characterization of that class of social choice functions based in new ethical properties regarding solidarity.