论预期在现代宏观经济学中的地位

THE ROLE OF EXPECTATIONS IN MODERN MACROECONOMICS

预期假定在西方现代宏观经济学中一贯占有异常突出的位置。到七十年代，在美国甚至出现了以其预期假定的特征来命名的学派——理性预期学派，这是人所共知的。但是，我们在分析和评论各个学派所提出的命题和政策主张时，却很少同它们特定的预期假定联系起来，从而影响了我们分析的准确性和批评的力量。另一方面，当我们分析社会主义宏观经济运行的规律时，也从未涉及经济活动者的预期问题，尽管我们十分强调人们在进行经济活动时对经济规律认识的重要性。

After fifties, it is the American economists, such as Phillip Cagan, Robert Lucas, etc, who have made path breaking contributions to the development of expectations hypothesis, bringing forth the two revolutions in macroeconomics. Assimilating Cagan＇s theory to his own macro-monetaristic model, Friedman brought forward his new idea-unemployment can temporarily be brought down below the natural rate but only at the expense of a higher permanent inflation ratel in the long run, the stable policies suggested by Keynesians can only cause the economy more unstable. Later on, in the light of Muth＇s ＂Rational Expectations Hypothesis＂, Lucas and Sargent established the famous theory known as ＂The School of Rational Expectations＂. It shows that there is no ＂trade-off＂ between inflation and unemployment and the discretionary monetary and fieal policya re practically ineffective even in the short run. The adaptive and especially the rational expectations hypothesis embody the rebirth of liberalism and demoeratism in the current economic thought America. In this paper, the author suggests developed by American economists throw that the expectations hypothesese a light on China＇s macroeconomic analysis and policy choices. The issues in discusion are of greate interest and essential to the regulation of China＇s planned commodity economy and his policy decisions as well.