WELFARE IMPLICATIONS OF THE INTERACTION BETWEEN HABITS AND CONSUMPTION EXTERNALITIES*

We analyze the welfare properties of the equilibrium path of a growth model where both habits and consumption externalities affect the utility of consumers. Our analysis highlights the crucial role played by complementarities between externalities and habits in order to generate an inefficient dynamic equilibrium. In particular, we show that the competitive equilibrium is inefficient when consumption externalities and habit‐adjusted consumption are not perfect substitutes.     

Consumption Externalities,Habit Formation and Equilibrium Efficiency*

We analyze the welfare properties of the competitive equilibrium in a capital accumulation model where individual preferences are subject to both habit formation and consumption spillovers. Using an additive specification for preferences, according to which the argument in the utility function is a linear combination of present and past values of own consumption and consumption spillovers, we analyze the circumstances under which these spillovers are a source of inefficiency. It is shown that consumption externalities have to interact with habits in order to generate an inefficient dynamic equilibrium. Finally, we characterize optimal tax policies aimed at restoring efficient decentralized paths.     

Equilibria in incomplete assets economies with infinite dimensional spot markets

The paper studies the two period incomplete markets model where assets are claims on state contingent commodity bundles and there are no bounds on portfolio trading. The important results on the existence of equilibrium in this model assume that there is a finite number of commodities traded in each spot market and that preferences are given by smooth utility functions. With these assumptions an equilibrium exists outside an “exceptional” set of assets structures and initial endowments. The present paper extends these results by allowing for general infinite dimensional commodity spaces in each spot market. These include all the important commodity spaces studied in the literature on the existence of Walrasian equilibrium—in each spot market the consumption sets are the positive cone of an arbitrary locally solid Riesz space or of an ordered topological vector space with order unit or of a locally solid Riesz space with quasi-interior point. The paper establishes that even with our very general commodity spaces there exists an equilibrium for a “very” dense set of assets structures. Our approach is in the main convex analytic and the results do not require that preferences be smooth or complete or transitive. The concepts and techniques studied in this paper have important finite as well as infinite dimensional applications. This paper has benefited from the comments of Martine Quinzii, Wayne Shafer, Manuel Santos and Yeneng Sun. The research of C. D. Aliprantis is supported by the NSF Grants SES-0128039, DMS-0437210, and ACI-0325846. The research of R. Tourky is funded by the Australian Research Council Grant A00103450.     

Consumption externality, efficiency and optimal taxation in one-sector growth model

In an economy with consumption externalities, existing studies find that a competitive equilibrium is efficient in the long run and remains efficient in transitions if preferences are homothetic. This paper revisits the efficiency issue in an otherwise standard one-sector growth model where consumption externalities affect a utility via their effects on the time preference. We find that even if preferences are homothetic, the externality changes the marginal rate of substitution between now and future and leads to a disparity in the intertemporal elasticity of substitution between the centrally planned economy and a decentralized economy. As a result, a competitive equilibrium is inefficient in transition dynamics. We characterize an optimal tax/subsidy structure that enables the allocation in a decentralized economy to replicate the social optimum.     

Adaptive behavior and the existence of Weizsäcker's long-run indifference curves

Suppose that past consumptions of the first r commodities (r < n) influence present consumption. Then, the long-run demand function to which demand converges maximizes the equilibrium short-run utility function only under very restrictive conditions. The long-run demand functions can be rationalized by a utility function, different from the equilibrium short-run utility function, if and only if the short-run utility function is such that past consumptions of any good that experience, learning, or taste changes is separable from all other goods. The class of such utility functions has been found.     

Search, Nash bargaining and rule-of-thumb consumers

This paper analyses the effects of introducing two typical Keynesian features, namely rule-of-thumb (RoT) consumers and consumption habits, into a standard labour market search model. RoT consumers use the margin that hours and wage negotiation provides them to improve their lifetime utility, by narrowing the gap in utility with respect to Ricardian consumers. This margin for intertemporal optimisation has not been studied yet, because this class of restricted agents has been mainly used in models with no equilibrium unemployment. Our approach allows for a deeper study of the effects of shocks on vacancies, unemployment, hours, wages and how they interact. As habits increase, RoT consumers find it optimal, after a positive technology shock, to negotiate lower hours and higher wages, and this mechanism reduces the simulated correlation between the real wage (or productivity) and total hours to values closer to those obtained empirically. Thus, with the interaction of RoT consumers and consumption habits, the labour market search model improves significantly in reproducing some of the stylised facts characterising the US labour market.     

Relative deprivation,wealth inequality and economic growth

This paper presents an endogenous growth model where utility depends on relative deprivation as well as consumption. It is shown that a negative relationship exists between wealth inequality and equilibrium growth rate. In addition, if the concern for relative deprivation is strong enough, instantaneous utility decreases while aggregate income increases.      

Information Structure and the Tragedy of the Commons in Resource Extraction

Synopsis This paper considers the well-known Levhari-Mirman discrete-time model of resource extraction, and investigates the effects of the information structure of the dynamic game – open-loop, Markovian or history-dependent – on the equilibrium consumption path and the overall utility of the agents. Due to the special structure of the model, the open-loop regime yields a Pareto-optimal outcome. The Markovian regime leads to the most pronounced version of the tragedy of the commons. History-dependent behavior yields an outcome set that is intermediate between the other two cases, and that may include the Pareto-optimal outcome in some cases. The level of efficiency of equilibrium behaviour is thus U-shaped as a function of the level of information the agents’ extraction strategies are based on. The analysis suggests that in environments characterized by a dynamic (and no market) externality, forcing agents to commit to open-loop behavior would constitute welfare-improving regulation.     

A bargaining model in general equilibrium

The goal of the paper is to present a simple model of rational endogenous household formation in a general equilibrium framework in which Pareto optimality at the economy level is not necessarily obtained. The simplest example of household formation is the case in which pairs of individuals engage themselves in a bargaining process on the division of some wealth: if an agreement on the distribution is (not) reached, we can say that the household is (not) formed. The vast majority of existing bargaining models predicts agreements on an efficient outcome. A seminal paper by Crawford (Econometrica 50:607–637, 1982) describes a very simple game with incomplete information in which, even with rational agents, disagreement causes welfare losses. We embed that model in a general equilibrium framework and present some results on equilibria both in the bargaining game and the associated exchange economy. Crawford’s results support Schelling’s intuition on the reasons of disagreement: it may arise if players’ commitments are reversible. Crawford shows that high probabilities of reversibility tend to favor the bargaining impasse, in fact with low probability. We prove that even if those probabilities are arbitrarily close to zero, disagreement is an equilibrium outcome, with high probability. That conclusion seems to be an even stronger support to Schelling’s original viewpoint. In the exchange economy model with that noncooperative bargaining game as a first stage, we present significant examples of economies for which equilibria exist. Because of disagreement, Pareto suboptimal exchange economy equilibria exist for all elements in the utility function and endowment spaces and they may coexist with Pareto optimal equilibria even at the same competitive prices.     

Profit maximization mitigates competition?

Summary. We consider oligopolistic markets in which the notion of shareholders’utility is well-defined and compare the Bertrand-Nash equilibria in case of utility maximization with those under the usual profit maximization hypothesis. Our main result states that profit maximization leads to less price competition than utility maximization. Since profit maximization tends to raise prices, it may be regarded as beneficial for the owners as a whole. Moreover, if profit maximization is a good proxy for utility maximization, then there is no need for a general equilibrium analysis that takes the distribution of profits among consumers fully into account and partial equilibrium analysis suffices.     

Note on the non-existence of sunspot equilibrium

In this note, we emphasize the role of consumers’ risk aversion in the non-existence of sunspot equilibria in incomplete market economies. We prove that there are no sunspot equilibria if the fundamentals of the underlying economy admit a unique equilibrium for any distribution of endowments. This substantiates Mas-Colell’s (Economic analysis of markets and games: essays in honor of Frank Hahn. MIT, Cambridge, 1992) conjecture. We also prove that, in a two-consumer economy, no sunspot equilibrium exists under the more relaxed condition that the underlying economy admits a unique equilibrium for the initial endowment. This is a generalization of Corollaries 1 and 2 of Hens and Pilgrim (Econ Theory 24:583–602, 2004).      

RECURSIVE EQUILIBRIA IN AN AIYAGARI‐STYLE ECONOMY WITH PERMANENT INCOME SHOCKS

We prove existence of a recursive competitive equilibrium (RCE) for an Aiyagari‐style economy with permanent income shocks and derive important economic implications. We show that there exist equilibria where borrowing constraints are never binding and establish a nontrivial lower bound on the equilibrium interest rate. These results imply distinct consumption dynamics compared to existing studies. We present a new approach to solve the agent's problem that uses lattices of consumption functions to deal with permanent income shocks and an unbounded utility function. The approach provides a theoretical foundation for convergence of the time iteration algorithm widely used in applied work.     

Signaling bargaining power: Strategic delay versus restricted offers

Summary. I study the first-round separating equilibrium of a buyer-seller bargaining game, extended to allow for asymmetric information, strategically delayed offers and offers restricted to a portion of the good. When bargaining is over a consumption good, in equilibrium the “strong” buyer uses a restricted offer if his optimal consumption path is conservative relative to the “weak” buyer. A pure restricted offer may even be a costless, efficient signal. When the good is durable, a pure strategic delay is involved in signaling a strong bargaining position if the discount factor is high. Received: June 24, 1998; revised version: May 30, 1999     

Detrimental externalities, pollution rights, and the “Coase theorem”

This paper, which builds on Chipman (The economist’s vision. Essays in modern economic perspectives, 131–162, 1998), analyzes a simple model formulated by Hurwicz (Jpn World Econ 7:49–74, 1995) of two agents—a polluter and a pollutee—and two commodities: “money” (standing for an exchangeable private good desired by both agents) and “pollution” (a public commodity desired by the polluter but undesired by the pollutee). There is also a government that issues legal rights to the two agents to emit a certain amount of pollution, which can be bought and sold with money. It is assumed that both agents act as price-takers in the market for pollution rights, so that competitive equilibrium is possible. The “Coase theorem” (so-called by Stigler (The theory of price, 1966) asserts that the equilibrium amount of pollution is independent of the allocation of pollution rights. A sufficient condition for this was (in another context) obtained by Edgeworth (Giorn Econ 2:233–245, 1891), namely that preferences of the two agents be “parallel” in the money commodity, whose marginal utility is constant. Hurwicz (Jpn World Econ 7:49–74, 1995) argued that this parallelism is also necessary. This paper, which provides an exposition of the problem, raises some questions about this result and provides an alternative necessary and sufficient condition.     

Decoupling in electric utilities

Distributing electricity to users has been covered through the charge per kilowatt-hour for electricity used. Conservation advocates have promoted policies that “decouple” distribution revenues or profits from the amount of electricity delivered, claiming that usage-based pricing leads utilities to encourage use and discourage conservation. Because decoupling separates profits from conduct, it runs against the dominant finding in regulatory economics in the last 20 years—that incentive-based regulation outperforms rate-of-return profit guarantees. Even if distribution costs are independent of use, some usage charges can be efficient. Price-cap regulation may distort incentives to inform consumers about energy efficiency—getting more performance from less electricity. Utilities will subsidize efficiency investments, but only when prices are too low. If consumers fail to adopt energy efficiency measures that would be individually beneficial, decoupling can increase welfare, but only if all energy revenues are separated from use, not just those associated with distribution.     

Intellectual property rights and R&amp;D subsidies: are they complementary policies?

IPR protection and R&D subsidy are simultaneously implemented in many economies. Are they complementary policies for improving the welfare of consumers? We address this question in a dynamic general equilibrium model with innovation-driven growth. Under concave utility, the answer is yes for two cases: (1) the economy does not begin from steady state and the elasticity of intertemporal substitution (EIS) is relatively large; (2) the economy begins from steady state with either a sufficiently small initial consumption and a relatively large EIS or a sufficiently big initial consumption and a relatively small EIS. Under linear utility, the answer is yes if the discounted lifetime utility is finite in equilibrium, no matter the economy begins from the steady state or not. As empirical evidence finds cross-country heterogeneity in EIS, they are not complementary for all economies. We also identify reasonable cases whereby they are substitute policies, so we show when it is not welfare-enhancing to simultaneously implement both policies.     

Consumption taxation, social status and indeterminacy in models of endogenous growth with elastic labor supply

In this paper, we examine the effects of consumption taxation on long-run growth in an infinitely lived representative-agent model of endogenous growth with endogenous labor supply in which the desire for social status induces private agents to care about others’ wealth or consumption levels. This analysis shows that the increase in consumption taxation raises (reduces) the long-run growth rate when the equilibrium path is locally indeterminate (determinate), provided the desire for social status is not too strong in the relative wealth model. By contrast, in the consumption externalities model, the same result holds, if the Frisch labor supply and labor demand curves have the ‘normal’ slopes at their intersection point, while the result is reversed if these two curves have the ‘wrong’ slopes.     

Notes on optimal transportation

We study equilibrium in hedonic markets, when consumers and suppliers have reservation utilities, and the utility functions are separable with respect to price. There is one indivisible good, which comes in different qualities; each consumer buys 0 or 1 unit, and each supplier sells 0 or 1 unit. Consumer types, supplier types and qualities can be either discrete of continuous, in which case they are allowed to be multidimensional. Prices play a double role: they keep some agents out of the market, and they match the remaining ones pairwise. We define equilibrium prices and equilibrium distributions, and we prove that equilibria exist, we investigate to what extend equilibrium prices and distributions are unique, and we prove that equilibria are efficient. In the particular case when there is a continuum of types, and a generalized Spence–Mirrlees condition is satisfied, we prove the existence of a pure equilibrium, where demand distributions are in fact demand functions, and we show to what extent it is unique. The proofs rely on convex analysis, and care has been given to illustrate the theory with examples.     

Equilibrium binding agreements: a comment

To construct their Equilibrium Binding Agreements, Ray and Vohra (J. Econ. Theory, 73 (1997) 30-78) define a concept of an equilibrium between coalitions and prove its existence for any coalition structure. We show that this result crucially depends on the quasi-concavity of the utility functions, which in turn depends on the type of mixed strategies used by the coalitions. When coalitions use uncorrelated mixed strategies utility functions may not be quasi-concave and an equilibrium may not exist. However, if coalitions use correlated strategies, an equilibrium always exist.