Assessing Rational Expectations

The rational expectations hypothesis (REH) dominates economic modeling in areas ranging from monetary theory, macroeconomics, and general equilibrium to finance. In this book, Roger Guesnerie continues the critical analysis of the REH begun in his Assessing Rational Expectations: Sunspot Multiplicity and Economic Fluctuations, which dealt with the questions raised by multiplicity and its implications for a theory of endogenous fluctuations. This second volume emphasizes "eductive" learning: relying on careful reasoning, agents must deduce what other agents guess, a process that differs from the standard evolutionary learning experience in which agents make decisions about the future based on past experiences. A broad "eductive" stability test is proposed that includes common knowledge and results in a unique "rationalizable expectations equilibrium." This test provides the basis for Guesnerie's theoretical assessment of the plausibility of the REH's expectational coordination, emphasizing, for different categories of economic models, conditions for the REH's success or failure. Guesnerie begins by presenting the concepts and methods of the eductive stability analysis in selected partial equilibrium models. He then explores to what extent general equilibrium strategic complementarities interfere with partial equilibrium considerations in the formation of stable expectations. Guesnerie next examines two issues relating to eductive stability in financial market models, speculation and asymmetric price information. The dynamic settings of an infinite horizon model are then taken up, and particular standard and generalized saddle-path solutions are scrutinized. Guesnerie concludes with a review of general questions and some "cautious" remarks on the policy implications of his analysis. Roger Guesnerie is Professor at Collège de France, Directeur d'études at EHESS (L'École des Hautes Études en Sciences Sociales), and Director of Federation Paris-Jourdan."Roger Guesnerie has made a truly seminal contribution to the modeling of 'eductive' learning, which is based on reasoning from all available knowledge and information. This book collects his key papers in the area. It is essential for all economists interested in the implications of learning in macroeconomics, microeconomics, and finance." -- Seppo Honkapohja, University of Cambridge, author of Learning and Expectations in Macroeconomics