Irrationality and monopolistic competition: An evolutionary approach

This paper shows that a monopolistically competitive equilibrium can evolve without purposive profit maximization. Specifically, this paper formulates a precise evolutionary dynamic model of an industry where there is continuous entry of firms that randomly select their output levels on entry and fix their output levels thereafter. Firms exit the industry if they fail to pass the survival test of making nonnegative wealth. This paper shows that the industry converges in probability to the monopolistically competitive equilibrium as the size of each firm becomes infinitesimally small relative to the market, as the entry cost becomes sufficiently small, and as time gets sufficiently large. Consequently, in the limit, the only surviving firms are those producing at the tangency of the demand curve to the average cost curve and no potential entrant can make a positive profit by entry.     

Search theory,competitive equilibrium,and the Nash bargaining solution

We investigate a canonical search-theoretic model without entry. Two agents are randomly matched with a long side being rationed. The matched agents face a pair of randomly drawn non-transferable payoffs, and then choose whether or not to form a partnership subject to a small probability of exogenous break down. As this probability and friction vanish, the Nash bargaining solution emerges as the unique undominated strategy equilibrium outcome if the mass of each party is the same. If the size of one party is larger than the other, the short side extracts the entire surplus, a sharp contrast to Rubinstein and Wolinsky (1985) [16].     

The acquisition of information in a dynamic market

Summary This paper models the information acquisition process in an intertemporal rational expectations framework. It demonstrates that equilibria do not generally exist in intertemporal economies in which agents are assumed to know the state-contingent price path and the information acquisition process is endogenous. In addition, an example of a fully revealing equilibrium in which agents pay a strictly positive amount for information is provided. Finally, we also show that it is possible for an equilibrium to exist in which agents choose to purchase information even if all agents, including the agents who purchased the information, are made strictly worse off by the purchase.The author would like to thank Kerry Back, Gerry Feltham Rich Kihlstrom, Vasant Naik, Bryan Routledge, Harald Uhlig and Josef Zechner for their comments and suggestions. A special note of thanks is due to the (anonymous) referee.     

Adverse selection in credit markets and regressive profit taxation

In many countries, taxes on businesses are less progressive than labor income taxes. This paper provides a justification for this pattern based on adverse selection that entrepreneurs face in credit markets. Individuals choose between becoming entrepreneurs or workers and differ in their skill in both of these occupations. I find that endogenous cross-subsidization in the credit market equilibrium results in excessive (insufficient) entry of low-skilled (high-skilled) agents into entrepreneurship. This gives rise to a corrective role for differential taxation of entrepreneurial profits and labor income. In particular, a profit tax that is regressive relative to taxes on labor income restores the efficient occupational choice.     

Nonlinear incentive provision in Walrasian markets: a Cournot convergence approach

The paper studies insurance with moral hazard in a system of contingent-claims markets. Insurance buyers are modelled as Cournot monopolists or oligopolists. The other agents condition their expectations on market prices, as in models of rational-expectations equilibrium with asymmetric information. Thereby they correctly anticipate accident probabilities corresponding to effort incentives induced by insurance buyers’ net trades. When there are many agents to share the insurance buyers’ risks, Cournot equilibrium outcomes are close to being second-best. In contrast, if insurance buyers are price takers, equilibria fail to exist or are bounded away from being second-best.     

Search, money, and inflation under private information

I study monetary exchange and inflation when buyers have private information about their willingness to pay for certain goods. Introducing imperfect information in the Lagos-Wright [A unified framework for monetary theory and policy analysis, J. Polit. Economy 113(3) (2005) 463-484] economy shows that the existence of monetary equilibrium is a more robust feature of the environment. In general, my model has a monetary steady state in which only a proportion of the agents hold money. Agents who do not hold money cannot participate in trade in the decentralized market. The proportion of agents holding money is endogenous and depends (negatively) on the level of expected inflation. As in Lagos and Wright's model, in equilibrium there is a positive welfare cost of expected inflation, but the origins of this cost are very different.     

R&D,free entry,and social inefficiency

We employ a three-stage game model with cost-reducing research and development (R&D) that is subject to spillovers to consider the problem of excess entry under free-entry equilibrium relative to the social optimum. Firms choose to enter or exit a market in the first stage, choose R&D in the second stage and output in the final stage. Results show that there is socially inefficient or excessive entry in equilibrium. However, we uniquely demonstrate that research spillovers hold the key to whether established results regarding socially inefficient entry hold. Specifically, excessive entry occurs as long as research spillovers are relatively small, but this is not necessarily the case with large spillovers. Some policy implications are discussed.     

The political economy of contributive pensions in developing countries

This paper sheds light on the role of public institutions as a way to reduce tax evasion through a close link between payroll taxation and pension benefits. We use a political economy model in which agents have the possibility to hide part of their earnings in order to avoid taxation and, where the public system is more efficient in providing annuitized pension benefits than the private sector. We show that in the absence of evasion costs, agents are indifferent to the tax rate level as they can always perfectly adapt compliance so as to face their preferred effective tax rate. There is unanimity in favour of the maximum tax rate and, the public pension system is found to be partially contributive in order to increase tax compliance and thus the resources collected. This, in turn, enables higher redistribution toward the worst-off agents. When evasion costs are introduced, perfect substitutability between compliance and taxation breaks down. At the majority-voting equilibrium, individuals at the bottom of the income distribution who are in favour of more redistribution, and those at the top who want to transfer more resources to the old age, form a coalition against middle-income agents, in favour of high tax rates. In addition to the previous tax base argument, the optimal level of the Bismarkian pillar is now chosen so as to account for political support.     

Influence Of Over‐ And Underconfidence On A Marriage Market*

This paper examines misconfidence (over‐ or underconfidence) and marriage proposal strategies in a two‐sided search model with non‐transferable utility. Single agents are vertically heterogeneous—there exists a ranking of marital charm (types). It is shown that there are two externalities to over‐ or underconfident behaviour: someone's over‐ or underconfidence affects: (i) the duration of search for others who directly meet over‐ or underconfident agents; and (ii) the marriage decision of others who directly or indirectly meet over‐ or underconfident agents. Furthermore, these externalities prevent the lowest‐type agents from marrying in an equilibrium.     

An impossibility result for virtual implementation with status quo

In this paper, virtual implementation is restricted to deliver, on the equilibrium path, either a socially optimal outcome or a status quo: an outcome fixed for all preference profiles. Under such a restriction, for any unanimous and implementable social choice function there is a dictator, who obtains her most preferable outcome as long as all agents prefer this outcome to the status quo. Further restrictions on the lottery space and the range of social choice functions allow the dictator to impose her most preferred outcome even when other agents prefer the status quo to this outcome.     

Aggregate information cascades

We introduce a new model of aggregate information cascades where only one of two possible actions is observable to others. Agents make a binary decision in sequence. The order is random and agents are not aware of their own position in the sequence. When called upon, they are only informed about the total number of others who have chosen the observable action before them. This informational structure arises naturally in many applications. Our most important result is that only one type of cascade arises in equilibrium, the aggregate cascade on the observable action. A cascade on the unobservable action never arises.     

Unawareness and bankruptcy: A general equilibrium model

Summary. We present a consistent pure-exchange general equilibrium model where agents may not be able to foresee all possible future contingencies. In this context, even with nominal assets and complete asset markets, an equilibrium may not exist without appropriate assumptions. Specific examples are provided. An existence result is proved under the main assumption that there are sufficiently many states that all the agents foresee. An intrinsic feature of the model is bankruptcy, which agents may involuntarily experience in the unforeseen states. Received: April 23, 1997; revised version: May 19, 1997     

Contractual distortions in a market with frictions

This paper analyses contract design in a decentralized market environment with frictions. While principals (e.g., firms) have all contractual power, their market power is constrained as agents (e.g., workers) can choose to wait and search for better offers. We find that results depend crucially on how market frictions affect agents’ utilities. With type-independent costs of search and waiting, equilibrium contracts are always first-best. If agents are impatient and discount future payoffs, however, distortions vanish only gradually. In the latter case, we also characterize equilibrium offers and show that the market exhibits two types of externalities, both of which are absent in the case of type-independent costs of search.     

Entry, exit, and imperfect competition in the long run

An infinite-horizon, stochastic model of entry and exit with sunk costs and imperfect competition is constructed. A subgame perfect Nash equilibrium for the general dynamic stochastic game is shown to exist as a limit of finite-horizon equilibria. This equilibrium has a relatively simple structure characterized by two numbers per finite history. Under very general conditions, it tends to exhibit excessive entry and insufficient exit relative to a social optimum.     

Internal rationality, imperfect market knowledge and asset prices

We present a decision theoretic framework in which agents are learning about market behavior and that provides microfoundations for models of adaptive learning. Agents are ‘internally rational’, i.e., maximize discounted expected utility under uncertainty given dynamically consistent subjective beliefs about the future, but agents may not be ‘externally rational’, i.e., may not know the true stochastic process for payoff relevant variables beyond their control. This includes future market outcomes and fundamentals. We apply this approach to a simple asset pricing model and show that the equilibrium stock price is then determined by investors? expectations of the price and dividend in the next period, rather than by expectations of the discounted sum of dividends. As a result, learning about price behavior affects market outcomes, while learning about the discounted sum of dividends is irrelevant for equilibrium prices. Stock prices equal the discounted sum of dividends only after making very strong assumptions about agents? market knowledge.     

Consumption dynamics in general equilibrium: A characterisation when markets are incomplete

We introduce a methodology for analysing infinite horizon economies with two agents, one good, and incomplete markets. We provide an example in which an agent's equilibrium consumption is zero eventually with probability one even if she has correct beliefs and is marginally more patient. We then prove the following general result: if markets are effectively incomplete forever then on any equilibrium path on which some agent's consumption is bounded away from zero eventually, the other agent's consumption is zero eventually—so either some agent vanishes, in that she consumes zero eventually, or the consumption of both agents is arbitrarily close to zero infinitely often. Later we show that (a) for most economies in which individual endowments are finite state time homogeneous Markov processes, the consumption of an agent who has a uniformly positive endowment cannot converge to zero and (b) the possibility that an agent vanishes is a robust outcome since for a wide class of economies with incomplete markets, there are equilibria in which an agent's consumption is zero eventually with probability one even though she has correct beliefs as in the example. In sharp contrast to the results in the case studied by Sandroni (2000) [29] and Blume and Easley (2006) [8] where markets are complete, our results show that when markets are incomplete not only can the more patient agent (or the one with more accurate beliefs) be eliminated but there are situations in which neither agent is eliminated.     

Trade and revelation of information

We consider an economy with asymmetric information and two types of agents, fully informed and uninformed. Uninformed agents update their information observing equilibrium prices and the equilibrium levels of other agents’ excess demand. We show that, for a generic set of economies, there are rational expectations equilibria which are partially revealing on an open, dense set of signals of positive Lebesgue measure, provided that the dimension of the signal space is sufficiently larger than the dimension of the commodity space.     

THE SECOND‐PRICE AUCTION SOLVES KING SOLOMON'S DILEMMA*

The planner wants to give k identical, indivisible objects to the top k valuation agents at zero costs. Each agent knows her own valuation of the object and whether it is among the top k. Modify the (k+ 1)st‐price sealed‐bid auction by introducing a small participation fee and the option not to participate in it. This simple mechanism implements the desired outcome in iteratively undominated strategies. Moreover, no pair of agents can profitably deviate from the equilibrium by coordinating their strategies or bribing each other.     

Bargaining foundations of the median voter theorem

We give a game-theoretic foundation for the median voter theorem in a one-dimensional bargaining model based on Baron and Ferejohn's [D. Baron, J. Ferejohn, Bargaining in legislatures, Amer. Polit. Sci. Rev. 83 (1989) 1181-1206] model of distributive politics. We prove that as the agents become arbitrarily patient, the set of proposals that can be passed in any pure strategy, subgame perfect equilibrium collapses to the median voter's ideal point. While we leave the possibility of some delay, we prove that the agents' equilibrium continuation payoffs converge to the utility from the median, so that delay, if it occurs, is inconsequential. We do not impose stationarity or any other refinements. Our result counters intuition based on the folk theorem for repeated games, and it contrasts with the known result for the distributive bargaining model that as agents become patient, any division of the dollar can be supported as a subgame perfect equilibrium outcome.     

Coalitional instability of the distributive Lindahl equilibrium

Summary Bergstrom [3] has showed that the Lindahlian approach to the analysis of public goods may also be used to analyze a model of wide-spread externalities in which agents have preferences defined on allocations rather than on individual commodity bundles. He has provided versions of the first and second welfare theorem for adistributive Lindahl equilibrium and also presented sufficient conditions for its existence. However, we shall show that, in contrast to Foley's [4] result on the core stability of a Lindahl equilibrium, a distributive Lindahl equilibrium need not satisfy coalitional stability. We will provide a robust example in which the unique, distributive Lindahl equilibrium does not belong to the -core defined either as in Scarf [11] or as in Yannelis [12].I would like to thank F. Canova, R. Serrano, M. Spagat, R. Vohra at Brown University, P. C. Padoan at University of Rome and an anonymous referee for their comments. I am also grateful to the participants at the Third Annual MeetingColloquia on Economic Research at I.G.I.E.R. in Milan, Italy, and to the participants at the Citibank Workshop in Economic Theory at Brown University.