Jean-Philippe Lefort

A dynamic Ellsberg urn experiment

Two rationality arguments are used to justify the link between conditional and unconditional preferences in decision theory : dynamic consistency and consequentialism. Dynamic consistency requires that ex ante contingent choices are respected by up dated preferences. Consequentialism states that only those outcomes which are still possible can matter for up dated preferences. We test the descriptive validity of these rationality arguments with a dynamic version of Ellsbergs three color experiment and that subjects act more often in line with consequentialism than with dynamic consistency.

Agreeable trade with optimism and pessimism

In this paper we extend the results on ex-ante agreeable trade of Kajii and Ui [Kajii, A., Ui, T., 2006. Agreeable bets with multiple priors. Journal of Economic Theory 128, 299–305] to the case of non-convex Choquet preferences. We discuss the economic relevance of the main result for the existence of speculative trade under ambiguity. Following Haller [Haller, H., 1990. Non-market reopening, time-consistent plans and the structure of intertemporal preferences. Economics Letters 32, 1–5] we also elaborate the relevance of updating preferences upon arrival of public information for the potential of re-contracting initial contingent claims.