This paper develops a positive theory of credibility, ambiguity, and inflation under discretion and asymmetric information. The monetary policymaker maximizes his own (politically motivated) objective function that is positively related to economic stimulation through monetary surprises and negatively related to monetary growth. The relative importance he assigns to each target shifts stochastically through time. His current preference trade-off is known to him but not to the public. When choosing the (state contingent) path of money growth for the present and the future, the policymaker compares the benefits from current stimulation with the costs associated with higher future inflation expectations. Current monetary growth conveys information to the public about future money growth because there is persistence in the policymaker's objectives. Although expectations are rational, information is imperfect because monetary control procedures are imprecise. As a result the public cannot correctly distinguish persistent changes of emphasis on different policy objectives from transitory monetary control errors. The public becomes aware of changes gradually by.observing past monetary growth. Credibility is defined in terms of the speed with which the public recognizes changes in the objectives of the policymaker. Credibility is lower the noisier monetary control and the more stable the objectives of the policymaker. Looser monetary control and a higher degree of time preference on the part of the policymaker induce him to produce higher and more variable monetary growth. When the policymaker is free to determine the accuracy of monetary control he does not always choose the most effective control available in spite of the fact that monetary surprises always have an expected value of zero. The reason is that ambiguous control procedures enable the policymaker to generate positive surprises when he cares more than on average about economic stimulation. He leaves the inevitable negative surprises for periods in which he cares more about inflation prevention. This result provides an explanation for the Fed's preference for ambiguity, recently documented by Goodfriend (1986). The policymaker is more likely to pick more ambiguous control procedures the more uncertain his objectives and the higher his time preference. The paper also provides a theoretical underpinning for the well documented crosscountry positive correlation between the level and the variability of inflation.

Explanations of inflation can be subdivided into two major groups. "Sociological theories" assert that movements of prices and wages proceed independently of market conditions. Economic theories on the other hand elaborate the essential dependence of price-wage movements on evolving market conditions. Sociological theories, dominant in Europe, emphasize the role of a wide array of institutional arrangements. In contrast, according to economic theory all forces and events affect inflation via market processes

The Future of the IMF and World Bank: Panel Discussion by Stanley Fischer, Allan H. Meltzer, Jeffrey D. Sachs and Nicholas Stern. Published in volume 93, issue 2, pages 45-50 of American Economic Review, May 2003

I wish to dedicate the paper to Mark Perlman, who guided this Journal until now. Perlman's help and encouragement in preparing this paper were characteristically vigorous and scholarly. I wish to express appreciation to the Hoover Institution where an early draft was written and to E. S. Shaw for his comments on that draft. Alex Cukierman, Brian Kantor, Scott Richard, and E. Roy Weintraub made several helpful suggestions, and Karl Brunner suffered through many discussions about Keynes and Keynesians. Many people read and commented on the previous draft, and their suggestions and criticisms have helped me to see points I would have missed. I am grateful especially to Paul Davidson and Donald Moggridge. Davidson commented generously and helpfully on almost every page. Moggridge helped me to strengthen my argument and graciously made available sections of volume 27 of Keynes's Collected Writings that had not been published at the time.

Charles F. Walker, Allan H. Meltzer, Edgar Peske, Bion B. Howard, John P. Shelton, Ragnar D. Naess, Developments in the Curriculum and Teaching of Finance: Discussion, The Journal of Finance, Vol. 21, No. 2, Papers and Proceedings of the Twenty-Fourth Annual Meeting of the American Finance Association, New York, New York, December 28-30, 1965 (May, 1966), pp. 423-434

Myths and legends about the Great Depression have dominated the public's perception of the business cycle. They have shaped government policy and, until recently, they have even held powerful sway among economists. In the immediate aftermath of the Great Depression, many economists came to question the fundamental concept of economic equilibrium. Velocity was thought to be highly unstable -as in the case of the liquidity trap-so that the quantity of money supplied was consistent with any level of nominal income. In the real sector, there was the frightening specter of underemployment