Intertemporal Social Evaluation

Abstract

A social-evaluation functional assigns a social ranking of alternatives to each information profile in its domain. In the classical multi-profile model of social choice, profiles are restricted to welfare information: all non-welfare information is implicitly assumed to be fixed. Because of this, the conventional approach does not allow us to discern the way in which the functional makes use of non-welfare information. For that, multiple non-welfare profiles are needed. Blackorby, Bossert and Donaldson (2005a) analyze a framework in which non-welfare information may vary across information profiles. Each information profile includes a vector of individual utility functions which represent welfare information and a vector of functions which describe social and individual non-welfare information. See also Kelsey (1987) and Roberts (1980) for approaches to social choice where non-welfare information is explicitly modelled. A social-evaluation functional is welfarist if a single ordering of utility vectors, together with the utility information in a profile, is sufficient to rank all alternatives. The ordering of utility vectors is called a social-evaluation ordering. Welfarism is a consequence of three axioms: unlimited domain, Pareto indifference and binary independence of irrelevant alternatives. Unlimited domain requires that all logically possible profiles are in the domain of the functional.

We thank Geir Asheim, Peter Vallentyne and the participants of the 2005 IEA Conference for discussions and comments. Financial support through a grant from the Social Sciences and Humanities Research Council of Canada is gratefully acknowledged.