Decision making and trade without probabilities

This paper studies trade in a first-price sealed-bid auction where agents know only a range of possible payoffs. The setting is one in which a lemons problem arises, so that if agents have common risk preferences and common priors, then expected utility theory leads to a prediction of no trade. In contrast, we develop a model of rational non-probabilistic decision making, under which trade can occur because not bidding is a weakly dominated strategy. We use a laboratory experiment to test the predictions of both models, and also of models of expected utility with heterogeneous priors and risk preferences. We find strong support for the rational non-probabilistic model.     

Risk perceptions,voluntary contributions and environmental policy

This article studies the effect of uncertainty on agents’ voluntary contributions to environmental quality. There is uncertainty in future environmental quality and we consider a heterogeneity in individuals’ risk perception. In this context, the social optimum can be decentralized by means of tax-financed government subsidies to private provision. We distinguish the case of a government that represents perfectly agents’ preferences from the case of a government with its own risk preferences. In the two cases, we show that neutrality still holds.     

Status,Risk-Taking and Intertemporal Substitution in an Endogenous Growth Model

This paper examines intertemporal risk-taking in a stochastically growing economy with externalities in human capital accumulation where agents have preferences for social status. In order to isolate the effects of status concerns on long-run expected growth, the analysis is embedded in a non-expected utility setting, which disentangles the effects from risk aversion and intertemporal substitution. We examine the interaction between status desire and risk, risk aversion and intertemporal substitution. The externalities generated by the status game are able to correct the allocative distortions from the knowledge spillovers.Acknowledgement The author would like to thank an anonymous referee for his valuable comments.     

Intertemporal equilibria with Knightian uncertainty

We study a dynamic and infinite-dimensional model with incomplete multiple prior preferences. In interior efficient allocations, agents share a common risk-adjusted prior and subjective interest rate. Interior efficient allocations and equilibria coincide with those of economies with subjective expected utility and priors from the agents? multiple prior sets. A specific model with neither risk nor uncertainty at the aggregate level is considered. Risk is always fully insured. For small levels of ambiguity, there exists an equilibrium with inertia where agents also insure fully against Knightian uncertainty. When the level of ambiguity exceeds a critical threshold, full insurance no longer prevails and there exist equilibria with inertia where agents do not insure against uncertainty at all. We also show that equilibria with inertia are indeterminate.     

WHY SOCIAL PREFERENCES MATTER – THE IMPACT OF NON-SELFISH MOTIVES ON COMPETITION, COOPERATION AND INCENTIVES

A substantial number of people exhibit social preferences, which means they are not solely motivated by material self-interest but also care positively or negatively for the material payoffs of relevant reference agents. We show empirically that economists fail to understand fundamental economic questions when they disregard social preferences, in particular, that without taking social preferences into account, it is not possible to understand adequately (i) effects of competition on market outcomes, (ii) laws governing cooperation and collective action, (iii) effects and the determinants of material incentives, (iv) which contracts and property rights arrangements are optimal, and (v) important forces shaping social norms and market failures.     

Redistribution,taxes, and the median voter

We study a simple model of production, accumulation, and redistribution, where agents are heterogeneous in their initial wealth, and a sequence of redistributive tax rates is voted upon. Though the policy is infinite-dimensional, we prove that a median voter theorem holds if households have identical, Gorman aggregable preferences; furthermore, the tax policy preferred by the median voter has the “bang-bang” property.     

The relevance of private information in mechanism design

Recent results in mechanism design show that as long as agents have correlated private information and are sufficiently risk neutral, it is possible to design mechanisms that leave agents with arbitrarily small information rents. We show that these full-rent-extraction results hinge on the implicit assumption that the agents’ beliefs uniquely determine their preferences. We present an example of the voluntary provision of a public good in which this assumption is relaxed, and consequently, even in highly correlated environments, if agents’ beliefs do not uniquely determine their preferences, then the extraction of the agents’ entire information rents is impossible.     

Wealth inequality, preference heterogeneity and macroeconomic volatility in two-sector economies

We explore the link between wealth inequality, preference heterogeneity and macroeconomic volatility in a two-sector neoclassical growth model. First we prove that, if agents have homogeneous preferences, when the absolute risk tolerance is a strictly convex (concave) function, sufficiently high (low) levels of wealth inequality may lead to endogenous fluctuations in the neighborhood of the steady state. Second, we consider the effects of preference heterogeneity when agents are homogeneous with respect to their wealth. We show that when the utility function belongs to the HARA class, sufficiently high levels of preference heterogeneity may lead to endogenous fluctuations in the neighborhood of the steady state if the elasticity of intertemporal substitution in consumption is greater than one.     

Childhood preventive care,adult healthcare and economic growth: The role of healthcare financing

We analyze the impact of healthcare financing on economic growth, focusing on the issue of the joint public–private financing of healthcare (co-payment). We use an overlapping-generations model with endogenous growth based on health human capital accumulation, where families pay for childhood preventive care and the government can either fully finance or co-finance adulthood curative care. From a growth maximizing perspective, distortionary taxes give an advantage to co-financing. Nevertheless, we prove that, if agents are assumed to be heterogeneous in preferences, full financing can become the best option.     

Global equilibrium dynamics with stationary recursive preferences

We study the global dynamics of capital accumulation for a general two-sector model which is not necessarily convex and where preferences of an infinitely-lived agent are stationary but not additively separable. We obtain monotonicity and convergence results for capital under ‘normality’ assumptions on preferences and factor intensity assumptions on technology. We then derive results on oscillatory dynamics under alternative factor-intensity conditions or under the assumption of inferiority of ‘future utilities’. Finally, in an exchange model with two agents we show that utilities will be monotonic or oscillatory depending on the normality or inferiority of the preferences.     

Should the Good and the Selfish be Taxed Differently?*

In this paper, we consider an environment where individual actions have externalities and two types of agents exist: agents with social preferences (the good) and selfish agents. Selfish agents have pay‐off functions that do not take into account social welfare. The pay‐off of an agent is a linear combination of social welfare and the pay‐off of a selfish agent. We demonstrate that the corrective tax rates that maximize social welfare do not depend on the degree of social preferences. Hence, the good and the selfish should not be taxed differently.     

Efficient allocations under ambiguity

Important implications of the expected utility hypothesis and risk aversion are that if agents have the same probability belief, then consumption plans in every efficient allocation of resources under uncertainty are comonotone with the aggregate endowment, and if their beliefs are concordant, then the consumption plans are measurable with respect to the aggregate endowment. We study these two properties of efficient allocations for models of preferences that exhibit ambiguity aversion using the concept of conditional beliefs, which we introduce in this paper. We provide characterizations of such conditional beliefs for the standard models of preferences used in applications.     

Preference shocks from aggregation: time series data evidence

Abstract.  We investigate the impact of preference shocks on the aggregate dynamics of the U.S. economy in the context of a neoclassical growth model derived from aggregation. The aggregation result we use is as follows: if markets are complete and if agents have identical preferences of the addilog type, then the heterogeneous‐agent economy where agents are subject to idiosyncratic productivity shocks behaves as if there was a representative consumer who faces shocks to preferences and technology. We estimate the parameters in the aggregation‐based model from the aggregate time‐series data and compute the numerical solution. We find that the preference shocks play an important role in the aggregate labour‐market fluctuations. JEL classification: C73, D90, E21     

Coalitions, agreements and efficiency

If agents negotiate openly and form coalitions, can they reach efficient agreements? We address this issue within a class of coalition formation games with externalities where agents’ preferences depend solely on the coalition structure they are associated with. We derive Ray and Vohra's [Equilibrium binding agreements, J. Econ. Theory 73 (1997) 30-78] notion of equilibrium binding agreements using von Neumann and Morgenstern [Theory of Games and Economic Behavior, Princeton University Press, Princeton, 1944] abstract stable set and then extend it to allow for arbitrary coalitional deviations (as opposed to nested deviations assumed originally). We show that, while the extended notion facilitates the attainment of efficient agreements, inefficient agreements can nevertheless arise, even if utility transfers are possible.     

Implementation with partial provability

We extend implementation theory by allowing the social choice function to depend on more than just the preferences of the agents and allowing agents to support their statements with hard evidence. We show that a simple condition on evidence is necessary for the implementation of a social choice function f when the preferences of the agents are state independent and sufficient for implementation for any preferences (including state dependent) with at least three agents if the social planner can perform small monetary transfers beyond those called for by f. If transfers can be large, f can be implemented in a game with perfect information when there are at least two players under a boundedness assumption. For both results, transfers only occur out of equilibrium. The use of evidence enables implementation which is robust in the sense that the planner needs little information about agents? preferences or beliefs and agents need little information about each others? preferences. Our results are robust to evidence forgery at any strictly positive cost.     

Solidarity and Probabilistic Target Rules

We consider a probabilistic approach to collective choice problems where a group of agents with single-peaked preferences have to decide on the level or location of a public good. We show that every probabilistic rule that satisfies Pareto efficiency and "solidarity" (population-monotonicity or replacement-domination) must equal a so-called target rule.     

Wealth inequality and dynamic stability

We explore the link between wealth inequality and stability in a two-sector neoclassical growth model with heterogeneous agents. We show that when the inverse of absolute risk aversion (or risk tolerance) is a strictly convex function, wealth inequality is a factor that favors instability. In the opposite case, inequality favors stability. Our characterization also shows that whenever absolute risk tolerance is linear, as when preferences exhibit hyperbolic absolute risk aversion (HARA), wealth heterogeneity is neutral.     

Asset pricing in a production economy with Chew–Dekel preferences

In this paper we provide a thorough characterization of the asset returns implied by a simple general equilibrium production economy with Chew–Dekel risk preferences and convex capital adjustment costs. When households display levels of disappointment aversion consistent with the experimental evidence, a version of the model parameterized to match the volatility of output and consumption growth generates unconditional expected asset returns and price of risk in line with the historical data. For the model with Epstein–Zin preferences to generate similar statistics, the relative risk aversion coefficient needs to be about 55, two orders of magnitude higher than the available estimates. We argue that this is not surprising, given the limited risk imposed on agents by a reasonably calibrated stochastic growth model.     

Bargaining and Boldness

We study a multiperson bargaining problem with general risk preferences through the use of Shaked's game of cycling offers with exogenous breakdown. If preferences are “smooth,” then as the risk of breakdown vanishes, the limiting outcome is one in which bargainers are equally marginally bold; where a bargainer's marginal boldness measures his willingness to risk disagreement in return for a marginal improvement in his position. Under smoothness, any (ordinal-)Nash solution is an equally marginally bold outcome. However, unlike the concept of the (ordinal-)Nash solution, a unique equally marginally bold outcome exists in natural cases—in particular, if all bargainers have risk-averse preferences of the rank-dependent expected utility type. For these preferences, the equally marginally bold outcome maximizes a “bargaining power”-adjusted (asymmetric) Nash product where the degree of asymmetry is determined by the disparity in the marginal valuation of certainty among bargainers. Journal of Economic Literature Classification Numbers: C72, C78, D81.     

Incomplete preferences and rational intransitivity of choice

Do violations of classical rationality theory imply that agents are acting against their self-interest? To answer this question, we investigate whether completeness and transitivity necessarily hold when agents choose outcome rationally—that is, their choice sequences do not lead to dominated outcomes. We show that, because of the danger of money pumps and other manipulations, outcome rationality implies that agents must have transitive psychological preferences. Revealed preferences, on the other hand, must be complete since agents can be forced to choose from any set of options. But these justifications of transitivity and completeness cannot be combined. We show that if psychological preferences are incomplete then revealed preferences can be intransitive without exposing agents to manipulations or violating outcome rationality. We also show that a specific case of nonstandard behavior, status quo maintenance, is outcome-rational in the simple environments considered in the experimental literature, but not in more complex settings.