Thibault Gajdos

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We develop an axiomatic approach to decision under uncertainty that explicitly takes into account the information available to the decision maker. The information is described by a set of priors and a reference prior. We define a notion of imprecision for this informational setting and show that a decision maker who is averse to information imprecision(More)
shop on decision under uncertainty are gratefully acknowledged. Comments by an anonymous referee and the associate editor have been useful to improve the paper. Financial support from the French Ministry of Research (Action concertée incitative) and the Ministry of Environment (S3E) is gratefully acknowledged. Abstract This paper presents an axiomatic model(More)
We provide a general impossibility theorem on the aggregation of preferences under uncertainty. We axiomatize in the Anscombe-Aumann setting a wide class of preferences, called rank-dependent additive preferences that includes most known models of decision under uncertainty as well as state-dependent versions of these models. We prove that aggregation is(More)
We reconsider the principles of diminishing transfer (introduced by Kolm (1976)) and dual diminishing transfer (introduced by Mehran (1976)). It appears that if a Rank Dependent Expected Utility (RDEU) maximizer respects the principle of diminishing (resp. dual diminishing) transfer, then he behaves in accordance with the Expected Utility model (resp.(More)
The most usual procedure when facing decisions in complex settings consists in consulting experts, aggregating the information they provide, and deciding on the basis of this aggregated information. We argue that such a procedure entails a substantial loss, insofar as it precludes the possibility to take into account simultaneously the decision maker's(More)
In this paper, we provide an axiomatic characterization of social welfare functions for uncertain incomes. Our most general result is that a small number of reasonable assumptions regarding welfare orderings under uncertainty rule out pure ex ante as well as pure ex post evaluations. Any social welfare function that satisfies these axioms should lie(More)
The axioms that characterize the generalized Gini social evaluation orderings for one-dimensional distributions are extended to the multidimensional attributes case. A social evaluation ordering is shown to have a two-stage aggrega-tion representation if these axioms and a separability assumption are satisfied. In the first stage, the distributions of each(More)
The (generalized) Gini indices rely on the social welfare function of a decision maker who behaves in accordance with Yaari's model, with a function f that transforms frequencies. This SWF can also be represented as the weighted sum of the welfare of all the possible coalitions in the society, where the welfare of a coalition is defined as the income of the(More)
  • Marie-Louise Leroux, Gregory Ponthiere, David De La Croix, Louis Eeckhoudt, Marc Fleurbaey, Thibault Gajdos +7 others
  • 2010
This paper reexamines a counterintuitive corollary of utilitarianism under unequal longevities: the tendency to redistribute resources from short-lived towards long-lived agents, against any intuition of compensation. It is shown that this corollary prevails not only under time-additive lifetime welfare, but, also, in general, under non-additive lifetime(More)
We provide a model of decision making under uncertainty in which the decision maker reacts to imprecision of the available data. Data is represented by a set of probability distributions. We axiomatize a decision criterion of the maxmin expected utility type, in which the set of priors explicitly depends on the available data. The central axiom is one of(More)