We study approval voting in a setting with a fixed profile of individuals choices and variable societies. Four properties each linking choices made by a group of individuals to choices by its various subgroups are introduced, and are used for characterizing approval voting

In this paper we axiomatically characterize two recursive procedures for defining a social group. The first procedure starts with the set of all individuals who are defined by everyone in the society as group members, while the starting point of the second procedure is the set of all individuals...