Paper # Author Title
What determines which assets are used in transactions? We develop a framework where the extent to which assets are recognizable determines the extent to which they are acceptable in exchange - i.e., their liquidity. We analyze the effects of monetary policy on asset markets. Recognizability and liquidity are endogenized by allowing agents to invest in information. There can be multiple equilibria with different transaction patterns. These transaction patterns are not invariant to policy. We show small changes in information that may generate large responses in prices, allocations and welfare. We also discuss issues in international economics, including exchange rates and dollarization. Download Paper
There is a large repeated games literature illustrating how future interactions provide incentives for cooperation. Much of this literature assumes public monitoring: players always observe precisely the same thing. Even slight deviations from public monitoring to private monitoring that incorporate differences in players’ observations dramatically complicate coordination. Equilibria with private monitoring often seem unrealistically complex. We set out a model in which players accomplish cooperation in an intuitively plausible fashion. Players process information via a mental system — a set of psychological states and a transition function between states depending on observations. Players restrict attention to a relatively small set of simple strategies, and consequently, might learn which perform well. Download Paper
Different markets are cleared by different types of prices---seller-specific prices that are uniform across buyers in some markets, and personalized prices tailored to the buyer in others. We examine a setting in which buyers and sellers make investments before matching in a competitive market. We introduce the notion of premuneration values---the values to the transacting agents prior to any transfers---created by a buyer-seller match. Personalized price equilibrium outcomes are independent of premuneration values and exhibit inefficiencies only in the event of "coordination failures," while uniform-price equilibria depend on premuneration values and in general feature inefficient investments even without coordination failures. There is thus a trade-off between the costs of personalizing prices and the inefficient investments under uniform prices. We characterize the premuneration values under which uniform-price equilibria similarly exhibit inefficiencies only in the event of coordination failures. Download Paper
Social norms are often posited as an explanation of differences in economic behavior and performance of societies that are difficult to explain by differences in endowments and technology. Economists are often reluctant to incorporate social aspects into their analyses when doing so leads to models that depart from the “standard” model. I discuss ways that agents’ social environment can be accommodated in standard models and the advantages and disadvantages of doing so. Download Paper
Social norms are often posited as an explanation of differences in economic behavior and performance of societies that are difficult to explain  by differences in endowments and technology. Economists are often reluctant to incorporate social aspects into their analyses when doing so leads to models that depart from the “standard” model. I discuss ways that agents’ social environment can be accommodated in standard models and the advantages and disadvantages of doing so.  Download Paper
Different markets are cleared by different types of prices---a universal price for all buyers and sellers in some markets, seller-specific prices that are uniform across buyers in others, and personalized prices tailored to both the buyer and the seller in yet others. We introduce the notion of premuneration values---the values in the absence of any muneration (payments)---created by the buyer-seller match. We characterize the premuneration values under which uniform-price and personalized-price equilibria agree. In this case, we have efficient allocations, including pre-match investment decisions, without the costs of personalized pricing. We then examine the inefficiencies that arise when the premuneration values preclude the agreement of uniform-price and personalized-price equilibria. We view premuneration values as an important consideration in market design. Download Paper
There is a large repeated games literature illustrating how future interactions provide incentives for cooperation. Much of this literature assumes public monitoring: players always observe precisely the same thing. Even slight deviations from public monitoring to private monitoring that incorporate differences in players’ observations dramatically complicate coordination. Equilibria with private monitoring often seem unrealistically complex. We set out a model in which players accomplish cooperation in an intuitively plausible fashion. Players process information via a mental system — a set of psychological states and a transition function between states depending on observations. Players restrict attention to a relatively small set of simple strategies, and consequently, might learn which perform well. Download Paper
We find an economic rationale for the common sense answer to the question in our title - courts should not always enforce what the contracting parties write. We describe and analyze a contractual environment that allows a role for an active court. An active court can improve on the outcome that the parties would achieve without it. The institutional role of the court is to maximize the parties' welfare under a veil of ignorance.  We study a buyer-seller model with risk-neutral agents and asymmetric information. The court must decide when to uphold a contract and when to void it.  The parties know their private information at the time of contracting, and this drives a wedge between ex-ante and interim-efficient contracts. In particular, if the court enforces all contracts, inefficient pooling obtains in equilibrium. By voiding some contracts the court is able to induce them to separate, and hence improve ex-ante welfare. Download Paper
Economic theory reduces the concept of rationality to internal consistency. As far as beliefs are concerned, rationality is equated with having a prior belief over a “Grand State Space”, describing all possible sources of uncertainties. We argue that this notion is too weak in some senses and too strong in others. It is too weak because it does not distinguish between rational and irrational beliefs. Relatedly, the Bayesian approach, when applied to the Grand State Space, is inherently incapable of describing the formation of prior beliefs. On the other hand, this notion of rationality is too strong because there are many situations in which there is not sufficient information for an individual to generate a Bayesian prior. It follows that the Bayesian approach is neither sufficient not necessary for the rationality of beliefs. Download Paper
We study economies with multiple assets that are valued both for their return and liquidity. Exchange occurs in decentralized markets with frictions making a medium of exchange essential. Some assets are better suited for this role because they are more liquid - more likely to be accepted in trade - even if they have a lower return. The reason assets are more or less likely to be accepted is modeled using informational frictions, or recognizability. While everyone understands e.g. what currency is and what it is worth, some might be less sure about other claims. In our model, agents who do not recognize assets do not accept them in trade. Recognizability is endogenized by letting agents invest in information, potentially generating multiple equilibria with different liquidity. We discuss implications for asset pricing and for monetary policy. In particular, we show explicitly that what may look like a cash-in-advance constraint is not invariant to policy interventions or other changes in the economic environment. Download Paper
Many important strategic problems are characterized by repeated interactions among agents. There is a large literature in game theory and economics illustrating how considerations of future interactions can provide incentives for cooperation that would not be possible in one-shot interactions. Much of the work in repeated games assumes public monitoring: players observe precisely the same thing at each stage of the game. It is well-understood that even slight deviations from public monitoring increase dramatically the difficulty the problems players face in coordinating their actions. Repeated games with private monitoring incorporate differences in what players observe at each stage. Equilibria in repeated games with private monitoring, however, often seem unrealistic; the equilibrium strategies may be highly complex and very sensitive to the fine details of the stochastic relationship between players’ actions and observations. Furthermore, there is no realistic story about how players might arrive at their equilibrium strategies.  We propose an alternative approach to understanding how people cooperate. Each player is endowed with a mental system that processes information: a mental system consists of a number of psychological states and a transition function between states that depends on observations made. In this world, a strategy is just a function from states to actions.  Our framework has the following desirable properties: (i) players restrict attention to a relatively small set of simple strategies. (ii) the number of strategies that players compare is small enough that players might ultimately learn which perform well. We find that some mental systems allow agents to cooperate under a broad set of parameters, while others are not conducive to cooperation. Download Paper
Better informed consumers may be treated preferentially by firms since their consumption serves as a quality signal for other customers. For normal goods this results in wealthy individuals being treated better than poor individuals. We investigate this phenomenon in an equilibrium model of social learning with heterogeneous consumers and firms that act strategically. Consumers search for high quality firms and condition their choices on observed actions of other consumers. When they observe consumers who are more likely to have identified a high quality firm, uninformed individuals will optimally emulate those consumers. One group of consumers arises endogenously as “leaders” whose consumption behavior is emulated. Follow-on sales induce firms to give preferential treatment to these lead consumers, which reinforces their learning. Download Paper
Economic modeling assumes, for the most part, that agents are Bayesian, that is, that they entertain probabilistic beliefs, objective or subjective, regarding any event in question.  We argue that the formation of such beliefs calls for a deeper examination and for explicit modeling.  Models of belief formation may enhance our understanding of the probabilistic beliefs when these exist, and may also help up characterize situations in which entertaining such beliefs is neither realistic nor necessarily rational. Download Paper
Economic modeling assumes, for the most part, that agents are Bayesian, that is, that they entertain probabilistic beliefs, objective or subjective, regarding any event in question.  We argue that the formation of such beliefs calls for a deeper examination and for explicit modeling.  Models of belief formation may enhance our understanding of the probabilistic beliefs when these exist, and may also help up characterize situations in which entertaining such beliefs is neither realistic nor necessarily rational. Download Paper
We examine an economy in which the cost of consuming some goods can be reduced by making commitments that reduce flexibility. We show that such consumption commitments can induce consumers with risk-neutral underlying utility functions to be risk averse over small variations in income, but sometimes to seek risk over large variations. As a result, optimal employment contracts will smooth wages conditional on being employed, but may incorporate a possibility of unemployment. Download Paper
Economic theory reduces the concept of rationality to internal consistency. The practice of economics, however, distinguishes between rational and irrational beliefs. There is therefore an interest in a theory of rational beliefs, and of the process by which beliefs are generated and justified. We argue that the Bayesian approach is unsatisfactory for this purpose, for several reasons. First, the Bayesian approach begins with a prior, and models only a very limited form of learning, namely, Bayesian updating. Thus, it is inherently incapable of describing the formation of prior beliefs. Second, there are many situations in which there is not sufficient information for an individual to generate a Bayesian prior. It follows that the Bayesian approach is neither sufficient not necessary for the rationality of  beliefs. Download Paper
We examine an economy in which the cost of consuming some goods can be reduced by making commitments that reduce flexibility. We show that such consumption commitments can induce consumers with risk-neutral underlying utility functions to be risk averse over small variations in income, but sometimes to seek risk over large variations. As a result, optimal employment contracts will smooth wages conditional on being employed, but may incorporate a possibility of unemployment. Download Paper
We describe and analyze a contractual environment that allows a role for an active court. The model we analyze is the same as in Anderlini, Felli, and Postlewaite (2006). An active court can improve on the outcome that the parties would achieve without it. The institutional role of the court is to maximize the parties’ welfare under a veil of ignorance. In Anderlini, Felli, and Postlewaite (2006) the possibility of “menu contracts” between the informed buyer and the uninformed seller is described but not analyzed. Here, we fully analyze this case.  We find that if we maintain the assumption that one of the potential objects of trade is not contractible ex-ante, the results of Anderlini, Felli, and Postlewaite (2006) survive intact. If however we let all “widgets” be contractible ex-ante, then multiple equilibria obtain. In this case the role for an active court is to ensure the inefficient pooling equilibria do not exist alongside the superior ones in which separation occurs. Download Paper
We find an economic rationale for the common sense answer to the question in our title — courts should not always enforce what the contracting parties write.  We describe and analyze a contractual environment that allows a role for an active court. An active court can improve on the outcome that the parties would achieve without it. The institutional role of the court is to maximize the parties’ welfare under a veil of ignorance.  We study a buyer-seller multiple-widget model with risk-neutral agents, asymmetric information and ex-ante investments. The court must decide when to uphold a contract and when to void it. The parties know their private information at the time of contracting, and this drives a wedge between ex-ante and interim-efficient contracts. In particular, if the court enforces all contracts, pooling obtains in equilibrium. By voiding some contracts the court is able to induce them to separate, and hence improve ex-ante welfare. In some cases, an ambiguous court that voids and upholds both with positive probability may be able to increase welfare even further. Download Paper
It is well-known that the ability of the Vickrey-Clarke-Groves (VCG) mechanism to implement efficient outcomes for private value choice problems does not extend to interdependent value problems. When an agent’s type affects other agents’ utilities, it may not be incentive compatible for him to truthfully reveal his type when faced with CGV payments. We show that when agents are informationally small, there exist small modifications to CGV that restore incentive compatibility. We further show that truthful revelation is an approximate ex post equilibrium. Lastly, we show that in replicated settings aggregate payments sufficient to induce truthful revelation go to zero. Download Paper
We present a model incorporating both social and economic components, and analyze their interaction. The notion of a social asset, an attribute that has value only because of the social institutions governing society, is introduced. In the basic model, agents match on the basis of income and unproductive attributes. An attribute has value in some equilibrium social institutions (matching patterns), but not in others. We then show that productive attributes (such as education) can have their value increased above their inherent productive value by some social institutions, leading to the notion of the social value of an asset. Download Paper
We examine an economy in which the cost of consuming some goods can be reduced by making commitments that reduce flexibility. We show that such consumption commitments can induce consumers with risk-neutral underlying utility functions to be risk averse over small variations in income, but sometimes to seek risk over large variations. As a result, optimal employment contracts will smooth wages conditional on being employed, but may incorporate a possibility of unemployment. Download Paper
We study a contracting model with unforeseen contingencies in which the court is an active player. Ex-ante, the contracting parties cannot include the risky unforeseen contingencies in the contract they draw up. Ex-post the court observes whether an unforeseen contingency occurred, and decides whether to void or uphold the contract. If the contract is voided by the court, the parties can renegotiate a new agreement ex-post.There are two effects of a court that voids more contracts. The parties' incentives to undertake relationship-specific investment are reduced, while the parties enjoy greater insurance against the unforeseen contingencies which the ex-ante contract cannot take into account. In this context, we are able to characterize fully the optimal decision rule for the court. The behavior of the optimal court is determined by the tradeoff between the need for incentives and the gains from insurance that voiding in some circumstances offers to the agents. Download Paper
We analyze conditions under which campaign rhetoric may affect the beliefs of the voters over what policy will be implemented by the winning candidate of an election. We develop a model of repeated elections with complete information in which candidates are purely ideological. We analyze an equilibrium in which voters' strategies involve a credible threat to punish candidates who renege of their campaign promises, and all campaign promises are believed by voters, and honored by candidates. We characterize the maximal credible campaign promises and obtain that the degree to which promises are credible in equilibrium is an increasing function of the value of a candidate's reputation. Download Paper
For repeated games with noisy private monitoring and communication, we examine robustness of perfect public equilibrium/subgame perfect equilibrium when private monitoring is close to some public monitoring. Private monitoring is close. to public monitoring if the private signals can generate approximately the same public signal once they are aggregated. Two key notions on private monitoring are introduced: Informational Smallness and Distributional Variability. A player is informationally small if she believes that her signal is likely to have a small impact when private signals are aggregated to generate ate a public signal. Distributional variability measures the variation in a player's conditional beliefs over the generated public signal as her private signal varies. When informational size is small relative to distributional variability (and private signals are sufficiently close to public monitoring), a uniformly strict equilibrium with public monitoring remains an equilibrium with private monitoring and communication. To demonstrate that uniform strictness is not overly restrictive, we prove a uniform folk theorem with public monitoring which, combined with our robustness result, yields a new folk theorem for repeated games with private monitoring and communication. Download Paper
We analyze conditions under which campaign rhetoric may affect the beliefs of the voters over what policy will be implemented by the winning candidate of an election. We develop a model of repeated elections with complete information in which candidates are purely ideological. We analyze an equilibrium in which voters’ strategies involve a credible threat to punish candidates who renege of their campaign promises, and all campaign promises are believed by voters, and honored by candidates. We obtain that the degree to which promises are credible in equilibrium is an increasing function of the value of a candidate’s reputation. We also show how the model can be extended so that rhetoric also signals candidate quality. Download Paper
Conflicts of interest arise between a decision maker and agents who have information pertinent to the problem because of differences in their preferences over outcomes. We show how the decision maker can extract the information by distorting the decisions that will be taken, and show that only slight distortions will be necessary when agents are informationally small. We further show that as the number of informed agents becomes large the necessary distortion goes to zero. We argue that the particular mechanisms analyzed are substantially less demanding informationally than those typically employed in implementation and virtual implementation. In particular, the equilibria we analyze are conditionally dominant strategy in a precise sense. Further, the mechanisms are immune to manipulation by small groups of agents. Download Paper
People may be surprised by noticing certain regularities that hold in existing knowledge they have had for some time. That is, they may learn without getting new factual information. We argue that this can be partly explained by computational complexity. We show that, given a knowledge base, finding a small set of variables that obtain a certain value of R2 is computationally hard, in the sense that this term is used in computer science. We discuss some of the implications of this result and of fact-free learning in general. Download Paper
There is an increasing interest in the concept of social exclusion and the related concept of social isolation and their potential role in understanding inequality. We examine the degree to which voluntary separation from social activities during adolescence affects adult wages. It is well-known that participation in high school athletic programs leads to higher adult wages. We present empirical evidence that this premium is not primarily due to selection on predetermined characteristics valued in the labor market. Download Paper
It is understood that rational expectations equilibria may not be incentive compatible: agents with private information may be able to affect prices through the information conveyed by their market behavior. We present a simple general equilibrium model to illustrate the connection between the notion of informational size presented in McLean and Postlewaite (2002) and the incentive properties of market equilibria. Specifically, we show that fully revealing market equilibria are not incentive compatible for an economy with few privately informed producers because of the producers' informational size, but that replicating the economy decreases agents' informational size. For sufficently large economies, there exists an incentive compatible fully revealing market equilibrium. Download Paper
We present a model incorporating both social and economic components, and analyze their interaction. The notion of a social asset, an attribute that has value only because of the social institutions governing society, is introduced. In the basic model, agents match on the basis of income and unproductive attributes. An attribute has value in some equilibrium social institutions (matching patterns), but not in others. We then show that productive attributes (such as education) can have their value increased above their inherent productive value by some social institutions, leading to the notion of the social value of an asset. Download Paper
There is ample evidence that emotions affect performance. Positive emotions can improve performance, while negative ones may diminish it. For example, the fears induced by the possibility of failure or of negative evaluations have physiological consequences (shaking, loss of concentration) that may impair performance in sports, on stage or at school. There is also ample evidence that individuals have distorted recollection of past events, and distorted attributions of the causes of successes of failures. Recollection of good events or successes is typically easier than recollection of bad ones or failures. Successes tend to be attributed to intrinsic aptitudes or own effort, while failures are attributed to bad luck. In addition, these attributions are often reversed when judging the performance of others. The objective of this paper is to incorporate the first phenomenon above into an otherwise standard decision theoretic model, and show that in a world where performance depends on emotions, biases in information processing enhance welfare. Download Paper
We examine an economy in which the cost of consuming some goods can be reduced by making commitments to consumption levels independent of the state. For example, it is cheaper to produce housing services via owner-occupied than rented housing, but the transactions costs associated with the former prompt relatively inflexible housing consumption paths. We show that consumption commitments can cause risk-neutral consumers to care about risk, creating incentives to both insure risks and bunch uninsured risks together. For example, workers may prefer to avoid wage risk while bearing an unemployment risk that is concentrated in as few states as possible. Download Paper
There is an increasing interest in the concept of social exclusion and the related concept of social isolation and their potential role in understanding inequality. We examine the degree to which voluntary separation from social activities during adolescence affects adult wages. It is well-known that participation in high school athletic programs leads to higher adult wages. We present empirical evidence that this premium is not primarily due to selection on predetermined characteristics valued in the labor market. Download Paper
Taller workers receive a wage premium. Net of differences in family background, the disparity is similar in magnitude to the race and gender gaps. We exploit variation in an individual's height over time to explore how height affects wages. Controlling for teen height essentially eliminates the effect of adult height on wages for white males. The teen height premium is not explained by differences in resources or endowments. The teen height premium is partly mediated through participation in high school sports and clubs. We estimate the monetary benefits of a medical treatment for children that increases height. Download Paper