We provide a generalization of Harsanyi (1955)'s aggregation theorem to the case of incomplete preferences at the individual and social level. Individuals and society have possibly incomplete expected utility preferences that are represented by sets of expected utility functions. Under Pareto...

We provide possibility results on the aggregation of beliefs and tastes for Monotone, Bernoullian and Archimedian preferences of Cerreia-Vioglio, Ghirardato, Maccheroni, Marinacci and Siniscalchi (2011). We propose a new axiom, Unambiguous Pareto Dominance, which requires that if the unambiguous...

We analyze the aggregation problem without the assumption that individuals and society have fully determined and observable preferences. More precisely, we endow individuals ans society with sets of possible von Neumann-Morgenstern utility functions over lotteries. We generalize the classical...

We provide a generalization of Harsanyi (1995)'s aggregation theorem to the case of incomplete preferences at the individual and social level. Individuals and society have possibly incomplete expected utility preferences that are represented by sets of expected utility functions. Under Pareto...

The evaluation of social risk equity for alternative probability distributions over the potential sets of fatalities is analyzed axiomatically. Fishburn and Straffin [Equity considerations in public risks valuation, Operatons Research 37 (1999), 229-239] have identified a necessary and...

This paper assesses the quantitative impact of ambiguity on the historically observed financial asset returns and prices. The single agent, in a dynamic exchange economy, treats the conditional uncertainty about the consumption and dividends next period as ambiguous. We calibrate the agent's...

We investigate the empirical relation between ambiguity aversion, risk aversion and portfolio choices. We match administrative panel data on portfolio choices with survey data on preferences over ambiguity and risk. We report three main findings. First, conditional on participation, ambiguity...

Nous proposons une revue de la littérature récente centrée sur les effets de l'ambiguïté (ou incertitude non probabilisée) sur les comportements des acteurs sur les marchés financiers et sur le fonctionnement de ces derniers. Nous exposons les mécanismes théoriques de choix de...

This chapter of a collective book aims at presenting the basics of decision making under risk. We first define notions of risk and increasing risk and recall definitions and classifications (that are valid independently of any representation) of behavior under risk. We then review the classical...

We report in this paper the result of three experiments on risk, ambiguity and time attitude. The first two differed by the population considered (students vs general population) while the third one used a different protocol and concerned students and portfolio managers. We find quite a lot of...