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Abstract:
In traditional reputation theory, reputation is good for the long-run player. In "Bad Reputation," Ely and Valimaki give an example in which reputation is unambiguously bad. This paper characterizes a more general class of games in which that insight holds, and presents some examples to illustrate when the bad reputation effect does and does not play a role. The key properties are that participation is optional for the short-run players, and that every action of the long-run player that makes the short-run players want to participate has a chance of being interpreted as a signal that the long-run player is "bad." We also broaden the set of commitment types, allowing many types, including the "Stackelberg type" used to prove positive results on reputation. Although reputation need not be bad if the probability of the Stackelberg type is too high, the relative probability of the Stackelberg type can be high when all commitment types are unlikely.

Abstract:
In traditional reputation theory, reputation is good for the long-run player. In "Bad Reputation," Ely and Valimaki give an example in which reputation is unambiguously bad. This paper characterizes a more general class of games in which that insight holds, and presents some examples to illustrate when the bad reputation effect does and does not play a role. The key properties are that participation is optional for the short-run players, and that every action of the long-run player that makes the short-run players want to participate has a chance of being interpreted as a signal that the long-run player is "bad". We also broaden the set of commitment types, allowing many types, including the "Stackelberg type" used to prove positive results on reputation. Although reputation need not be bad if the probability of the Stackelberg type is too high, the relative probability of the Stackelberg type can be high when all commitment types are unlikely.

Abstract:
We propose that a simple 'dual-self' model gives a unified explanation for several empirical regularities, including the apparent time-inconsistency that has motivated models of hyperbolic discounting and Rabin's paradox of risk aversion in the large and small. The model also implies that self-control costs imply excess delay, as in the O'Donoghue and Rabin models of hyperbolic utility, and it explains experimental evidence that increased cognitive load makes temptations harder to resist. Finally, the reduced form of the base version of our model is consistent with the Gul-Pesendorfer axions.

Abstract:
We propose that a simple "dual-self" model gives a unified explanation for several empirical regularities, including the apparent time-inconsistency that has motivated models of hyperbolic discounting and Rabin's paradox of risk aversion in the large and small. The model also implies that self-control costs imply excess delay, as in the O'Donoghue and Rabin models of hyperbolic utility, and it explains experimental evidence that increased cognitive load makes temptations harder to resist. Finally, the reduced form of the base version of our model is consistent with the Gul-Pesendorfer axioms.

Abstract:
This paper discusses the implications of learning theory for the analysis of Bayesian games. One goal is to illuminate the issues that arise when modeling situations where players are learning about the distribution of Nature's move as well as learning about the opponents' strategies. A second goal is to argue that quite restrictive assumptions are necessary to justify the concept of Nash equilibrium without a common prior as a steady state of a learning process.

Abstract:
A security design model shows that multinational firms needing to finance their operations should issue different securities to investors in different countries in order to aggregate their disparate information about domestic and foreign cash flows. However, if the firm becomes bankrupt, investors may face uncertain costs of reorganizing assets in a foreign country and thus may value foreign assets at their average value. This penalizes superior firms with low reorganization costs. Such firms minimize the adverse selection penalty by designing securities that allocate all the cash flow in bankruptcy to investors for which the adverse selection costs are the smallest given the exchange rate. We show that this sharing rule can be implemented with currency swaps because these instruments allow the priorities of claims in bankruptcy to switch depending on the exchange rate.

Abstract:
We argue that some but not all superstitions can persist when learning is rational and players are patient, and illustrate our argument with an example inspired by the code of Hammurabi. The code specified an appeal by surviving in the river as a way of deciding whether an accusation was true, so it seems to have relied on the superstition that the guilty are more likely to drown than the innocent. If people can be easily persuaded to hold this superstitious belief, why not the superstitious belief that the guilty will be struck dead by lightning? We argue that the former can persist but the latter cannot by giving a partial characterization of the outcomes that arise as the limit of steady states with rational learning as players become more patient. These 'subgame-confirmed Nash equilibria' have self-confirming beliefs at information sets reachable by a single deviation. According to this theory a mechanism that uses superstitions two or more steps off the equilibrium path, such as 'appeal by surviving in the river', is more likely to persist than a superstition where the false beliefs are only one step off of the equilibrium path.

Abstract:
The code of Hammurabi specified a "trial by surviving in the river" as a way of deciding whether an accusation was true. This system is puzzling for two reasons. First, it is based on a superstition: We do not believe that the guilty are any more likely to drown than the innocent. Second, if people can be easily persuaded to hold a superstitious belief, why such an elaborate mechanism? Why not simply assert that those who are guilty will be struck dead by lightning? We attack these puzzles from the perspective of the theory of learning in games. We give a partial characterization of patiently stable outcomes that arise as the limit of steady states with rational learning as players become more patient. These "subgame-confirmed Nash equilibria" have self-confirming beliefs at certain information sets reachable by a single deviation. We analyze this refinement and use it as a tool to study the broader issue of the survival of superstition. According to this theory Hammurabi had it exactly right: his law uses the greatest amount of superstition consistent with patient rational learning.

Abstract:
We examine the role of off-path "superstitions" in macro-economics, and show how a false belief about off-path play is the key element underlying both the Lucas Critique and the game-theoretic concept of self-confirming equilibrium. However, the impact of false beliefs in these two cases is different: In the Lucas case, a policy maker's incorrect beliefs about off-path play can lead to the adoption of mistaken policy innovation. However, the consequences of such an innovation provide evidence that the belief that motivated them was wrong. In contrast, play may never escape an undesirable self-confirming equilibrium, as the action implied by the mistaken belief does not generate data that contradicts it; escape from the self-confirming equilibrium requires that players do a sufficient amount of experimentation with off-path actions.

Abstract:
The limit set of perfect public equilibrium payoffs of a repeated game as the discount factor goes to one is characterized, with examples, even when the full-dimensionality condition fails.

Economic Theory, Game Theory, Repeated Games, Perfect Public Equilibrium, Folk Theorem

Abstract:
We use the theory of learning in games to show that no-trade results do not require that gains from trade are common knowledge nor that play is a Nash equilibrium.

Abstract:
According to a common argument, the presence of strong intellectual property rights spurs innovation, which then leads to fiercer competition, higher economic growth and increasing benefits for the average consumers. We argue that, in the case of intellectual property rights, this has lead to misconceptions and abuses. Current legislation on intellectual property confuses the protection of property rights on objects in which ideas are embodied with the attribution of monopoly power on the idea itself and, furthermore, with restrictions on the usage of such goods on the part of the buyers. This implies that both patent and copyright laws should be dramatically altered. To back up our claim we provide theoretical arguments, even for the most extreme case in which goods are produced at a positive fixed cost and zero marginal cost.

Intellectual property, monopoly power, patents and copyrights

Abstract:
In the modern theory of innovation, monopoly plays a crucial role both as a cause and an effect of creative economic activity. Innovative firms, it is argued, would have insufficient incentive to innovate should the prospect of monopoly power not be present. This theme of monopoly runs throughout the theory of growth, international trade, and industrial organization. We argue that monopoly is neither needed for, nor a necessary consequence of innovation. In particular, intellectual property is not necessary for, and may hurt more than help, innovation and growth. We show that, in most circumstances, competitive rents allow creative individuals to appropriate a large enough share of the social surplus generated by their innovations to compensate for their opportunity cost. We also show that, as the number of pre-existing and IP protected ideas needed for an innovation increases, the equilibrium outcome under the IP regime is one of decreasing probability of innovation, while this is not the case without IP. Finally, we provide various examples of how competitive markets for innovative products would work in the absence of IP and critically discuss a number of common fallacies in the previous literature.

Intellectual Property, Allocation, Surplus

Abstract:
Intellectual property (IP) protection involves a trade-off between the undesirability of monopoly and the desirable encouragement of creation and innovation. Optimal policy depends on the quantitative strength of these two forces. We give a quantitative assessment of current IP policies. We focus particularly on the scale of the market, showing that as it increases, due either to growth or to the expansion of trade, IP protection should be reduced.

Abstract:
We construct a competitive model of innovation and growth under constant returns to scale. Previous models of growth under constant returns cannot model technological innovation. Current models of endogenous innovation rely on the interplay between increasing returns and monopolistic markets. In fact, established wisdom claims monopoly power to be instrumental for innovation and sees the nonrivalrous nature of ideas as a natural conduit to increasing returns. The results here challenge the positive description of previous models and the normative conclusion that monopoly through copyright and patent is socially beneficial.

Innovation, Patents, Endogenous Growth, Intellectual Property

Abstract:
We construct a competitive model of innovation and growth under constant returns to scale. Previous models of growth under constant returns cannot model technological innovation. Current models of endogenous innovation rely on the interplay between increasing returns and monopolistic markets. In fact, established wisdom claims monopoly power to be instrumental for innovation and sees the non-rivalrous nature of ideas as a natural conduit to increasing returns. The results here challenge the positive description of previous models and the normative conclusion that monopoly through copyright and patent is socially beneficial.

Innovation, endogenous technological change, monopoly power

Abstract:
This article discusses the paper by Green and Zhou "Money as a Mechanism in a Bewley Economy" as presented at the second Karaken Conference.

Abstract:
A model of security design based on the principle of information aggregation and alignment is used to show that (i) firms needing to finance their operations should issue different securities to different groups of investors in order to aggregate their disparate information and (ii) each security should be highly correlated (closely aligned) with the private information signal of the investor to whom it is marketed. This alignment reduces the adverse selection penalty paid by a firm with superior information. Adverse selection costs are often contingent on ex post publicly observable and contractible state variables such as exchange rates. In such cases, debt contracts are dominated by currency swaps. Moreover, optimal securities are derivative contracts that are contingent on state variables that influence adverse selection costs. This is because the netting of cash flows in these derivative contracts, in effect, alters the state-by-state seniority of different claims in a desirable way.

Abstract:
When considering the incentive of a monopolist to adopt an innovation, the textbook model assumes that it can instantaneously and seamlessly introduce the new technology. In fact, firms often face major problems in integrating new technologies. In some cases, firms have to (temporarily) produce at levels substantially below capacity upon adoption. We call such phenomena switchover disruptions, and present extensive evidence on them. If firms face switchover disruptions, then they may temporarily lose some unit sales upon adoption. If the firm loses unit sales, then a cost of adoption is the foregone rents on the sales of those units. Hence, greater market power will mean higher prices on those lost units of output, and hence a reduced incentive to innovate. We introduce switchover disruptions into some standard models in the literature, show they can overturn some famous results, and then show they can help explain evidence that firms in more competitive environments are more likely to adopt technologies and increase productivity.

Innovation, Productivity, Monopoly

Abstract:
When considering the incentive of a monopolist to adopt an innovation, the textbook model assumes that it can instantaneously and seamlessly introduce the new technology. In fact, firms often face major problems in integrating new technologies. In some cases, firms have to (temporarily) produce at levels substantially below capacity upon adoption. We call such phenomena switchover disruptions, and present extensive evidence on them. If firms face switchover disruptions, then they may temporarily lose some unit sales upon adoption. If the firm loses unit sales, then a cost of adoption is the foregone rents on the sales of those units. Hence, greater market power will mean higher prices on those lost units of output, and hence a reduced incentive to innovate. We introduce switchover disruptions into some standard models in the literature, show they can overturn some famous results, and then show they can help explain evidence that firms in more competitive environments are more likely to adopt technologies and increase productivity.

Abstract:
Typical models of bankruptcy and collateral rely on incomplete asset markets. In fact, bankruptcy and collateral add contingencies to asset markets. In some models, these contingencies can be used by consumers to achieve the same equilibrium allocations as in models with complete markets. In particular, the equilibrium allocation in the debt constrained model of Kehoe and Levine (2001) can be implemented in a model with bankruptcy and collateral. The equilibrium allocation is constrained efficient. Bankruptcy occurs when consumers receive low income shocks. The implementation of the debt constrained allocation in a model with bankruptcy and collateral is fragile in the sense of Leijonhufvud's corridor of stability, however: If the environment changes, the equilibrium allocation is no longer constrained efficient.

Abstract:
In the modern theory of growth, monopoly plays a crucial role both as a cause and an effect of innovation. Innovative firms, it is argued, would have insufficient incentive to innovate should the prospect of monopoly power not be present. This theme of monopoly runs throughout the theory of growth, international trade, and industrial organization. We argue that monopoly is neither needed for, nor a necessary consequence of innovation. In particular, intellectual property is not necessary for, and may hurt more than help, innovation and growth. We argue that, as a practical matter, it is more likely to hurt.

Abstract:
It has been argued that concave models exhibit less 'endogeneity of growth' than models with increasing returns to scale. Here we study a simple model of factor saving technological improvement in a concave framework. Capital can be used either to reproduce itself, or, at some additional cost, to produce a higher quality of capital, which requires less labour input. If better quality capital can be produced quickly, we get a model of exogenous balanced growth as a special case of ours. If, however, better quality capital can be produced slowly, we get a model of "endogenous growth" in which the growth rate of the economy and the rate of adoption of new technologies is determined by preferences, technology and initial conditions. Moreover, in the latter case, the process of growth is necessarily uneven, exhibiting a natural cycle with alternating periods of high and slow growth. Growth paths and technological innovations also exhibit dependence upon initial conditions. The model provides a step toward a theory of endogenous innovation under conditions of perfect competition.

One, two and multisector growth models, aggregate productivity, choices and consequences, innovation and invention, measurement of economic growth, processes and incentives, technological change

Abstract:
This book brings together the joint work of Drew Fudenberg and David Levine (through 2008) on the closely connected topics of repeated games and reputation effects, along with related papers on more general issues in game theory and dynamic games. The unified presentation highlights the recurring themes of their work.

Long-Run Players, Limit Games, Robustness, Equilibrium, Reputation Effects, Repeated Games

Abstract:
Intellectual property (IP) protection involves a trade-off between the undesirability of monopoly and the desirable encouragement of creation and innovation. Optimal policy depends on the relative strength of these two forces. We give a quantitative assessment of current IP policies. We focus particularly on the scale of the market, showing that as it increases, due either to growth or to the expansion of trade, IP protection should be reduced.

Abstract:
We show that with common knowledge and a common rate of time preference, the potential loser can always avoid wasteful conflict through a time-consistent series of small concessions. We examine how the failure of each of these assumptions may explain why conflicts arise. We also debate which actions may be helpful in such unfortunate circumstances.

Abstract:
Market booms are often followed by dramatic falls. To explain this requires an asymmetry in the underlying shocks. A straightforward model of technological progress generates asymmetries that are also the source of growth cycles. Assuming a representative consumer, we show that the stock market generally rises, punctuated by occasional dramatic falls. With high risk aversion, bad news causes dramatic increases in prices. Bad news does not correspond to a contraction of existing production possibilities, but to a slowdown in their rate of expansion. This economy provides a model of endogenous growth cycles in which recoveries and recessions are dictated by the adoption of innovations.

Technological Revolutions, Stock Market Value, Growth Cycles

Abstract:
In the modern theory of growth, monopoly plays a crucial role both as a cause and an effect of innovation. Innovative firms, it is argued, would have insufficient incentive to innovate should the prospect of monopoly power not be present. This theme of monopoly runs throughout the theory of growth, international trade, and industrial organization. We argue that monopoly is neither needed for, nor a necessary consequence of, innovation. In particular, intellectual property is not necessary for, and may hurt more than help, innovation and growth. We argue that, as a practical matter, it is more likely to hurt.

Innovation, Capital Accumulation, Growth, Trade, Intellectual Property

Abstract:
Innovations and their adoption are the keys to growth and development. Innovations are less socially useful, but more profitable for the innovator, when they are adopted slowly and the innovator remains a monopolist. For this reason, rent-seeking, both public and private, plays an important role in determining the social usefulness of innovations. This paper examines the political economy of intellectual property, analyzing the trade-off between private and public rent-seeking. While it is true in principle that public rent-seeking may be a substitute for private rent-seeking, it is not true that this results always either in less private rent-seeking or in a welfare improvement. When the public sector itself is selfish and behaves rationally, we may experience the worst of public and private rent-seeking together.

Intellectual Property, Patent, Trade Secrecy, Rent-Seeking Innovation

Abstract:
Innovation and the adoption of new ideas are fundamental to economic progress. Here we examine the underlying economics of the market for ideas. From a positive perspective, we examine how such markets function with and without government intervention. From a normative perspective, we examine the pitfalls of existing institutions, and how they might be improved. We highlight recent research by ourselves and others challenging the notion that government awards of monopoly through patents and copyright are "the way" to provide appropriate incentives for innovation.

Economic Theory, Game Theory

Abstract:
Intellectual property protection involves a trade-off between the undesirability of monopoly and the desirable encouragement of creation and innovation. As the scale of the market increases, due either to economic and population growth or to the expansion of trade through treaties such as the World Trade Organization, this trade-off changes. We show that, generally speaking, the socially optimal amount of protection decreases as the scale of the market increases. We also provide simple empirical estimates of how much it should decrease.

Intellectual Property, International Trade, Innovation, Harmonization, Monopoly

Abstract:
A security design model shows that multinational firms needing to finance their operations should issue different securities to investors in different countries in order to aggregate their disparate information about domestic and foreign cash flows. However, if the firm becomes bankrupt, investors may face uncertain costs of reorganizing assets in a foreign country and thus may value foreign assets at their average value. This penalizes superior firms with low reorganization costs. Such firms minimize the adverse selection penalty by designing securities that allocate all the cash flow in bankruptcy to investors for which the adverse selection costs are the smallest given the exchange rate. We show that this sharing rule can be implemented with currency swaps because these instruments allow the priorities of claims in bankruptcy to switch depending on the exchange rate.