Louis Gevers : une carrière dédiée au choix collectif et au bien-être social

Nous présentons les principales contributions à l'économie normative de Louis Gevers, récemment décédé. Il a principalement contribué à la théorie du choix social, où ses travaux sur la base informationnelle du choix social ont été déterminants. Il a également contribué à l'analyse théorique et empirique des limites politiques et positives à la redistribution, à la théorie de l'équité et de l'implémentation, à l'évaluation empirique des politiques sociales, et, finalement, aux aspects politiques de l'équité intergénérationnelle. Nous montrons en quoi ces contributions à des champs différents de la discipline procèdent en réalité d'une préoccupation commune.We briefly review the main contributions to welfare economics by Louis Gevers, who recently passed away. His most famous papers are on social choice theory where his work on the informational basis of social choice has been most influential. He also contributed to the theoretical and empirical analysis of the political and positive limits to redistribution, to the theory of fairness and implementation, to the empirical evaluation of social policies, and, finally, to the political aspects of intergenerational equity. We show how all those contributions to different fields were actually connected to each other

No Profitable Decomposition in Quasi-Linear Allocation Problems

We study the problem of allocating a bundle of perfectly divisible private goods from an axiomatic point of view, in situations where compensations can be made through monetary transfers. The key property we impose on the allocation rule requires that no agent should be able to gain by decomposing the problem into sequences of subproblems. Combined with additional standard properties, it leads to a characterization of the rule that shares the total surplus equally. Hence a traditional welfarist rule emerges as the unique consequence of our axioms phrased in a natural economic environment.Social Choice; Axiomatic Bargaining; Welfarism; Egalitarianism

Social choice and the indexing dilemma

This paper distinguishes an index ordering and a social ordering function as a simple way to formalize the indexing problem in the social choice framework. Two main conclusions are derived. First, the alleged dilemma between welfarism and perfectionnism is shown to involve a third possibility, exemplified by the fairness approach to social choice. Second, the idea that an individual is better off than another whenever he has more (goods, functionings...) in all dimensions, which is known to enter in conflict with the Pareto principle, can be partly salvaged by adopting the fairness approach.social choice, indexing, Pareto, well-being

Social Choice Theory and the Informational Basis Approach

For over a quarter of a century, the use of utility information based upon interpersonal comparisons has been seen as an escape route from the Arrow Impossibility Theorem. This paper critically examines this informational basis approach to social choice. Even with comparability of differences and levels, feasible social choice rules must be insensitive to a range of distributional issues. Also, the Pareto principle is not solely to blame for the inability to adopt rules combining utility and non-utility information: if the Pareto principle is not invoked then there is no way of combining utility and non-utility information in a ranking of states unless levels of utility are comparable; with only level comparability, information must be combined in restrictive ways and the notion of giving different independent weight to different considerations is ruled out. If informational bases are viewed as the restriction on information that is available, rather than a theoretical limit on information, then there exist methods to estimate richer informational structures and overcome some of these difficulties.

Two Criteria for Social Decisions

This paper studies the ethical underpinnings of two social criteria which are prominent in the literature dealing with the problem of evaluating allocations of several consumption goods in a population with heteregenous preferences. The Pazner-Schmeidler criterion (Pazner-Schmeidler 1978) and the Walrasian criterion (Fleurbaey and Maniquet 1996) are prima facie quite different. But it is shown here that these criteria are related to close variants of the fairness condition that an allocation is better when every individual bundle in it dominates the average consumption in another allocation. In addition, the results suggest that the Pazner-Schmeidler criterion can be viewed as the best extension of the Walrasian criterion to non-convex economies.social welfare, social choice, fairness

Axiomatic Bargaining on Economic Enviornments with Lott

Most contributions in axiomatic bargaining are phrased in the space of utilities. This comes in sharp contrast with standards in most other fields of economic theory. The present paper shows how Nash’s original axiomatic system can be rephrased in a natural class of economic environments with lotteries, and how his uniqueness result can be recovered, provided one completes the system with a property of independence with respect to preferences over unfeasible alternatives. Similar results can be derived for the Kalai-Smorodinsky solution if and only if bargaining may involve multiple goods. The paper also introduces a distinction between welfarism and cardinal welfarism, and emphasizes that the Nash solution is ordinally invariant on the class of von Neumann-Morgensterm preferences.Bargaining; Welfarism; Nash; Kalai-Smorodinsky; Expected Utility

Social Choice and Just Institutions:New Perspectives

It has become accepted that social choice is impossible in absence of interpersonal comparisons of well-being. This view is challenged here. Arrow obtained an impossibility theorem only by making unreasonable demands on social choice functions. With reasonable requirements, one can get very attractive possibilities and derive social preferences on the basis of non-comparable individual preferences. This new approach makes it possible to design optimal second-best institutions inspired by principles of fairness, while traditionally the analysis of optimal second-best institutions was thought to require interpersonal comparisons of well-being. In particular, this approach turns out to be especially suitable for the application of recent philosophical theories of justice formulated in terms of fairness, such as equality of resources.social choice, theories of justice

Utilitarianism with and without expected utility

We give two social aggregation theorems under conditions of risk, one for constant population cases, the other an extension to variable populations. Intra and interpersonal welfare comparisons are encoded in a single ‘individual preorder’. The theorems give axioms that uniquely determine a social preorder in terms of this individual preorder. The social preorders described by these theorems have features that may be considered characteristic of Harsanyi-style utilitarianism, such as indifference to ex ante and ex post equality. However, the theorems are also consistent with the rejection of all of the expected utility axioms, completeness, continuity, and independence, at both the individual and social levels. In that sense, expected utility is inessential to Harsanyi-style utilitarianism. In fact, the variable population theorem imposes only a mild constraint on the individual preorder, while the constant population theorem imposes no constraint at all. We then derive further results under the assumption of our basic axioms. First, the individual preorder satisfies the main expected utility axiom of strong independence if and only if the social preorder has a vector-valued expected total utility representation, covering Harsanyi’s utilitarian theorem as a special case. Second, stronger utilitarian-friendly assumptions, like Pareto or strong separability, are essentially equivalent to strong independence. Third, if the individual preorder satisfies a ‘local expected utility’ condition popular in non-expected utility theory, then the social preorder has a ‘local expected total utility’ representation. Fourth, a wide range of non-expected utility theories nevertheless lead to social preorders of outcomes that have been seen as canonically egalitarian, such as rank-dependent social preorders. Although our aggregation theorems are stated under conditions of risk, they are valid in more general frameworks for representing uncertainty or ambiguity

Haag as a How-To Theorem

Haag's theorem is a classic no-go theorem. It rigorously demonstrates there is a logical problem with the interaction picture (IP), one of the most widely used modeling tools in quantum field theory (QFT). The significance of the theorem for the use of the IP in QFT has been the subject of long-running debate, focused around how ``worried'' we should be. In this paper, we argue for an alternative and opposite perspective on Haag's theorem, rejecting the `worry' framing in favor of emphasizing the no-go theorem's implications for model development

Two criteria for social decisions

1ères lignes : La distribution de la presse est un sujet d’actualité. Un projet de loi réformant la loi Bichet de 1947 sera discuté ce printemps. L’enjeu est de taille : il s’agit de « moderniser l’environnement législatif, sans casser les fondamentaux qui font le succès du système de distribution de la presse », a déclaré le ministre de la Culture, Franck Riester. La formule est pour le moins biaisée dans un contexte de crise où, durant ces dix dernières années, les ventes ont baissé de 50 %, le chiffre d’affaires de 40 %, et où la principale messagerie (Presstalis) a été au bord de la faillite en 2017