Let X be a set of “personal states”; any person, in any circumstance, is at some point in X. A social state assigns an element of X to every person in society. Suppose it is sometimes possible to make ordinal interpersonal comparisons of well-being. We represent this with a (possibly...

Let X be a set of social alternatives, and let V be a set of ‘votes’ or ‘signals’. (We do not assume any structure on X or V.) A variable population voting ruleF takes any number of anonymous votes drawn from V as input, and produces a nonempty subset of X as output. The rule F satisfies...