Speculative trading with rational beliefs and endogenous uncertainty

Summary. This paper introduces the framework of rational beliefs of Kurz (1994), which makes the assumptions of heterogeneous beliefs of Harrison and Kreps (1978) and Morris (1996) more plausible. Agents hold diverse beliefs that are “rational” in the sense of being compatible with ample observed data. In a non-stationary environment the agents only learn about the stationary measure of observed data, but their beliefs can remain non-stationary and diverse. Speculative trading then stems from disagreements among traders. In a Markovian framework of dividends and beliefs, we obtain analytical results to show how the speculative premium depends on the extent of heterogeneity of beliefs. In addition, we demonstrate that there exists a unique Rational Belief Equilibrium (RBE) generically with endogenous uncertainty (as defined by Kurz and Wu, 1996) and that the RBE price is higher than the rational expectation equilibrium price (REE) under some general conditions Received: March 15, 2001; revised version: April 26, 2002 RID="*" ID="*" We are deeply grateful to Mordecai Kurz for his constant encouragement and inspiring guidance over the years. We wish to express our gratitude to an anonymous referee for the very valuable comments provided. We also thank Kenneth Arrow, Peter Hammond, Roko Aliprantis and Nicholas Yannelis for their helpful suggestions and Academia Sinica and the National Science Council of the R.O.C. for their indispensable support. Correspondence to: H.-M. Wu     

Dynamic complexity in a Keynesian growth-cycle model involving Harrod's instability

This paper develops a Keynesian macrodynamic model, where some recent reinterpretations of Harrod's dynamics are embodied. Its main purpose is to prove that Harrod's instability principle may give rise to a chaotic motion (specifically a il'nikov scenario) around two equilibrium points: a steady-state unstable equilibrium, whose value depends on parameters defining the technical-progress dynamics, and a stationary state of zero growth. Furthermore, since it allows for a variable growth rate of labor productivity and assigns a key role to expectations, this model comes closer to modern theories of economic growth and endogenous business cycle.     

Floating exchange rates versus a monetary union under rational beliefs: the role of endogenous uncertainty

Using the concept of ex-post optimality, we compare different exchange rate regimes, including floating exchange rates and fixed exchange rates with a Monetary Union in a two country OLG model with stochastic endowments. The emphasis of this comparison is on the welfare consequences of agents having incorrect beliefs. We do not assume that agents can hold any beliefs, but rather that their beliefs are rational that is consistent with the observed empirical behavior of the economy. We study a large set of possible policies, but two of them have our particular interest. The first policy implies devaluations in reaction to a negative shock, while the other implies a fixed exchange rate. These policies have very different consequences. The first will for generic beliefs not result in an ex-post optimal allocation. The other policy is on the other hand always feasible and results in an ex-post optimal allocation. When the two countries form a Monetary Union, the ex-post optimal allocation is also achieved. The meaning of “endogenous uncertainty” as an institutionally induced uncertainty is illustrated. Received: September 1, 2001; revised version: 24 June 2002 RID="*" ID="*" I would like to thank Horace W. Brock, Gianluca Cassese, Paula Orlando, Ho-Mou Wu as well as seminar participants at Copenhagen Business School, ESEM98, Keio University, Kyoto University, Osaka University, SITE (Stanford) and University of Copenhagen for many useful comments on the paper. I am also grateful to Mark J. Garmaise, Takako Fujiwara-Greve, and an anonymous referee for many helpful suggestions for improving the paper. Without the many discussions about Rational Beliefs and related issues I have had with Mordecai Kurz over the years, the research presented here would not have been possible. Financial support from The Carlsberg Foundation, Danish Social Research Council, University of Copenhagen and SITE is gratefully acknowledged.     

Walras' Law and Keynesian Macroeconomics

This paper examines the claim that Keynesian models violate Walras' law. Walras' law is founded in the logic of exchange. Standard statements misrepresent it, as it pertains to a monetary economy. Keynesian models are consistent with Walras' law once this misrepresentation is corrected. The law holds for both notional and effective demands. It also holds in unconstrained Walrasian equilibria, constrained Walrasian equilibria, and constrained non-Walrasian equilibria. The latter corresponds to a Keynesian conception of equilibrium: markets need not clear, but agents expectations must be fulfilled.     

Classical and Keynesian unemployment in Austria

The labor market in a macroeconometric model of Austria is used to determine the natural unemployment rate, full-employment (F.E.) output, and the F.E. real wage for 1966–92. Gaps between actual and F.E. variables are examined analytically and historically. Observed unemployment is decomposed into natural, hidden, classical, and Keynesian components. Classical unemployment is associated with the real wage gap, while Keynesian unemployment depends on the output gap. A rise in the natural rate is found to account for almost all of the increase in unemployment between 1966–74 and 1975–81, but an increase in Keynesian unemployment is the major factor in the rise of unemployment between 1975–81 and 1982–92. A fiscal shock to the complete model is found to increase real GDP for a year or two, reducing Keynesian unemployment without an appreciable rise in classical unemployment; the wage gap is eventually increased, however, producing a modest rise in classical unemployment.A lengthier version of this paper was presented at the Annual Meeting of the Austrian Economic Association, Graz, April 14–16, 1993. The generous finacial support of the Jubiläumsfonds of the Austrian National Bank for the research of which this paper is a part is gratefully acknowledged.     

Poole in the New Keynesian model

We study the properties of alternative central bank targeting procedures within the standard New Keynesian model. We find that Poole's famous insights concerning the output stabilization properties of money and interest rate targeting obtain when intertemporal substitution is low. And that output volatility rankings do not induce similar welfare rankings. Unlike the popular presumption, money targeting always fares better for money demand shocks. For fiscal shocks, money targeting does better for low and worse for high degree of intertemporal substitution. The opposite pattern obtains for supply shocks.     

Keynesian models of deflation and depression revisited

This paper extends Tobin's [Tobin, J., 1975. Keynesian models of recession and depression. American Economic Review 65, 195–202] Keynesian analysis of deflation to include a range of additional channels through which deflation exacerbates Keynesian unemployment. The paper provides further theoretical reasons why downward price level adjustment may not solve the Keynesian problem. These arguments challenge the received wisdom that Keynes’ General Theory is a special case resting on downwardly rigid prices and nominal wages. This conventional wisdom has led many economists to recommend policies promoting downward flexibility. These policies have created an environment in which deflation is more likely, giving new relevance to Keynesian analysis of deflation.     

Linking the Keynesian Cross and the Production Possibilities Frontier

This artidc shows how linking the Keynesian cross and the production possibilities frontier can yield worthwhile results while maintaining analytical simplicity. It demonstrates how this particular blend of Keynesian and classical tools can show the scope and limitations of each and provide the basis for teaching about other schools of macroeconomic thought.     

不对称信息与凯恩斯主义投资理论

有效市场理论认为资本资产价格只不过是一幅面纱，实际经济活动是由经济主体的偏好和技术决定的。在凯恩斯主义体系中，金融市场在决定经济的路径中起到核心的作用。通过对金融市场上不对称信息的考察，可以得出这一结论。企业在外在融资的提供者即贷款者能够获取的信息是不同的，这种信息不对称导致金融约束的出现，在这种情况下，对投资的限制来自金融市场而不是来自技术或者偏好。     

凯恩斯革命中的创新与继承

凯恩斯革命是从理论、政策、方法三个层面展开的。货币非中性论、货币供给外生论、对萨伊定理的彻底否定构成凯恩斯革命的理论基础;财政政策和货币政策是凯恩斯革命赖以实现的政策工具;对经济学研究对象的纠偏、破除传统的两分法和首创货币经济学是凯恩斯革命赖以完成的方法论。与此同时,《通论》内在逻辑上的不一致性,与经典学派崇尚经济自由传统的趋同,决定了凯恩斯革命中的继承。由于经济运行的常态是非充分就业均衡,《通论》必然具有永恒价值。     

Transition from the classical to the Keynesian Perspective

This paper intends to recast the IS-LM to an analytical framework that reflects, more pertinently than the conventional version, Keynes's central analytical message in his General Theory resulting from his secession from the classics. The secession is imagined to be a process of transition from a simple analytical framework of the classics to this recast form of the IS-LM. Moreover the arguments in the paper occasionally touch on certain misleading conventional views pertaining to the issues.