An overview of economic applications of David Schmeidler`s models of decision making under uncertainty

This paper surveys some economic applications of the decision theoretic framework pioneered by David Schmeidler to model effects of ambiguity. We have organized the discussion principally around three themes: financial markets, contractual arrangements and game theory. The first section discusses papers that have contributed to a better understanding of financial market outcomes based on ambiguity aversion. The second section focusses on contractual arrangements and is divided into two sub-sections. The first sub-section reports research on optimal risk sharing arrangements, while in the second sub-section, discusses research on incentive contracts. The third section concentrates on strategic interaction and reviews several papers that have extended different game theoretic solution concepts to settings with ambiguity averse players. A final section deals with several contributions which while not dealing with ambiguity per se, are linked at a formal level, in terms of the pure mathematical structures involved, with Schmeidler`s models of decision making under ambiguity. These contributions involve issues such as, inequality measurement, intertemporal decision making and multi-attribute choice.Ellsberg Paradox, Ambiguity aversion, Uncertainty aversion

Interim Efficient Allocations under Uncertainty

This paper considers an exchange economy under uncertainty with asymmetric information. Uncertainty is represented by multiple priors and posteriors of agents who have either Bewley's incomplete preferences or Gilboa-Schmeidler's maximin expected utility preferences. The main results characterize interim efficient allocations under uncertainty; that is, they provide conditions on the sets of posteriors, thus implicitly on the way how agents update the sets of priors, for non-existence of a trade which makes all agents better off at any realization of private information. For agents with the incomplete preferences, the condition is necessary and sufficient, but for agents with the maximin expected utility preferences, the condition is sufficient only. A couple of necessary conditions for the latter case are provided.multiple priors; interim efficiency; no trade; dynamic consistency; rectangular prior set

Speculation in Financial Markets: A Survey

This survey covers the microeconomic theory of speculation in financial markets, since the development of the economics of uncertainty. It starts with a description of Walrasian exchange economies, both in general equilibrium –the Arrow-Debreu model and its extensions– and in partial equilibrium. Speculation, it is explained, is an incomplete-market phenomenon. It proceeds by analyzing more general voluntary trade environments, with a focus on whether or not differences in information are a valid source for belief heterogeneity. The role of common priors in the no-trade theorem is discussed. Finally, heterogeneous priors models are considered.

Contagion through Learning

We study learning in a large class of complete information normal form games. Players continually face new strategic situations and must form beliefs by extrapolation from similar past situations. We characterize the long-run outcomes of learning in terms of iterated dominance in a related incomplete information game with subjective priors. The use of extrapolations in learning may generate contagion of actions across games even if players learn only from games with payoffs very close to the current ones. Contagion may lead to unique long-run outcomes where multiplicity would occur if players learned through repeatedly playing the same game. The process of contagion through learning is formally related to contagion in global games, although the outcomes generally differ.Similarity, learning, contagion, case-based reasoning, global games, coordination, subjective priors.

Bargaining Versus Fighting

I examine the determinants of conflict and settlement by embedding probabilistic contests in a bargaining framework. Different costly enforcement efforts (e.g., arming, litigation expenditures) induce different disagreement points and Pareto frontiers. After examining the incentives for settlement, I demonstrate how different division rules and bargaining norms have real, economic effects. I then analyze some sources of conflict. I emphasize long-term, strategic considerations by examining an illustrative model and discussing particular historical examples.Conflict; Negotiation; War; Settlement; Arming; Litigation