Social choice with analytic preferences

Arrow's axioms for social welfare functions are shown to be inconsistent when the set of alternatives is the nonnegative orthant in a multidimensional Euclidean space and preferences are assumed to be either the set of analytic classical economic preferences or the set of Euclidean spatial preferences. When either of these preference domains is combined with an agenda domain consisting of compact sets with nonempty interiors, strengthened versions of the Arrovian social choice correspondence axioms are shown to be consistent. To help establish the economic possibility theorem, an ordinal version of the Analytic Continuation Principle is developed. Received: 4 July 2000/Accepted: 2 April 2001     

Dominant strategy implementation with a convex product space of valuations

A necessary and sufficient condition for dominant strategy implementability when preferences are quasilinear is that, for every individual i and every choice of the types of the other individuals, all k-cycles in i’s allocation graph have nonnegative length for every integer k ≥ 2. Saks and Yu (Proceedings of the 6th ACM conference on electronic commerce (EC’05), pp 286–293, 2005) have shown that when the number of outcomes is finite and i’s valuation type space is convex, nonnegativity of the length of all 2-cycles is sufficient for the nonnegativity of the length of all k-cycles. In this article, it is shown that if each individual’s valuation type space is a full-dimensional convex product space and a mild domain regularity condition is satisfied, then (i) the nonnegativity of all 2-cycles implies that all k-cycles have zero length and (ii) all 2-cycles having zero length is necessary and sufficient for dominant strategy implementability.     

Linear Aggregation of SSB Utility Functionals

A necessary and sufficient condition for linear aggregation of SSB utility functionals is presented. Harsanyi's social aggregation theorem for von Neumann–Morgenstern utility functions is shown to be a corollary to this result. Two generalizations of Fishburn and Gehrlein's conditional linear aggregation theorem for SSB utility functionals are also established.     

Social choice with independent subgroup utility scales

In this article, the kinds of utility comparisons that can be made may differ in distinct population subgroups. Within each subgroup, utility is either ordinally or cardinally measurable. Levels and differences of utility may or may not be interpersonally comparable within a subgroup. No utility comparisons are possible between subgroups. Given these informational assumptions, it is shown that any continuous social welfare ordering that satisfies the weak Pareto principle only depends on the utilities of one of the subgroups. The class of social welfare orderings consistent with these assumptions is determined by the scale type of the dictatorial subgroup. Received: 25 May 1999/Accepted: 4 November 1999     

Bunching properties of optimal nonlinear income taxes

Bunching is said to occur if individuals with different characteristics receive the same commodity bundle. This article analyzes bunching in a finite population optimal nonlinear income tax problem. Several easily-computed sufficient conditions for the optimality of particular bunching patterns as well as a simple necessary and sufficient condition for the optimal allocation to exhibit no bunching are presented. In addition, a characterization of the optimal allocation is provided. Is is shown that the bunching pattern obtained by S. Lollivier and J.-C. Rochet is a consequence of a convexity condition which is automatically satisfied in their continuum model but which is not generally satisfied in a finite model.Discussions with Steven Matthews and Dilip Mookherjee and the comments of two anonymous referees have been extremely helpful. The hospitality of the Center for Mathematical Studies in Economics and Management Science at Northwestern University and the research support of the Social Sciences and Humanities Research Council of Canada are gratefully acknowledged.     

Measurement theory and the foundations of utilitarianism

This article reconsiders the Harsanyi–Sen debate concerning whether Harsanyi is justified in interpreting his Aggregation and Impartial Observer Theorems as providing axiomatizations of utilitarianism. Sen's criticism and its formalization by Weymark are based on the claim that von Neumann–Morgenstern utility theory is ordinal, whereas Harsanyi's utilitarian conclusions require cardinal utility. Proposals for overcoming Sen's objection that appeal to formal measurement theory are considered. It is argued that one of these proposals due to Broome and Risse rightly points to a feature of expected utility theory that was ignored by Sen and Weymark, but that this proposal does not provide a normatively compelling justification for cardinal utility. The other proposal due to Broome is shown to make use of a strength of preference relation in addition to the axioms of expected utility theory.     

Further remarks on Harsanyi's social aggregation theorem and the weak Pareto principle

Weak Pareto versions of Harsanyi's Social Aggregation Theorem are established for mixture-preserving utility functions defined on a mixture set of alternatives.     

Generalized median social welfare functions

The article considers the construction of social welfare functions when the set of alternatives is the two-dimensional nonnegative orthant, as would be the case if there are two divisible public goods which can be consumed in any nonnegative quantities. With individual and social preferences required to be linear and strictly monotonic, but otherwise unrestricted, we characterize all of the social welfare functions which satisfy binary independence of irrelevant alternatives and anonymity and which satisfy binary independence of irrelevant alternatives, anonymity, and weak Pareto. These classes of social welfare functions are shown to be formally equivalent to the classes of social choice functions characterized by Moulin in his study of strategy-proof social choice with single-peaked preferences.We are grateful to Charles Blackorby, Hervé Moulin, and an anonymous referee for their comments.     

An informationally parsimonious impartial observer theorem

In Harsanyi's impartial observer theorem, an impartial observer determines a social ordering of the lotteries on the set of social alternatives based on a sympathetic but impartial concern for all individuals in society. This ordering is derived from a more primitive ordering on the set of all extended lotteries. An extended lottery is a lottery which determines both the observer's personal identity and the social alternative. We establish a version of Harsanyi's theorem in which the observer is only required to have preferences on the extended lotteries in which there is an equal chance of being any person in society. Received: 19 June 1996 / Accepted: 30 December 1996     

Arrow's Theorem with a fixed feasible alternative

Arrow's Theorem, in its social choice function formulation, assumes that all nonempty finite subsets of the universal set of alternatives is potentially a feasible set. We demonstrate that the axioms in Arrow's Theorem, with weak Pareto strengthened to strong Pareto, are consistent if it is assumed that there is a prespecified alternative which is in every feasible set. We further show that if the collection of feasible sets consists of all subsets of alternatives containing a prespecified list of alternatives and if there are at least three additional alternatives not on this list, replacing nondictatorship by anonymity results in an impossibility theorem.Most of the research for this article was completed while we were participants in the Public Choice Institute held at Dalhousie University during the summer of 1984. We wish to record here our thanks to the Institute Director, E.F. McClennen, and its sponsors, the Council for Philosophical Studies, the U.S. National Science Foundation, and the Social Science and Humanities Research Council of Canada. We are grateful to our referees for their comments and the Center for Mathematical Studies in Economics and Management Science at Northwestern University, where Weymark was a visitor during 1985–86, for secretarial assistance.