利息率理论的建构研究

On the Constitution of Interest Rate Theory

建构是补充和完善的意思。利息率是一个古老而又核心的经济学研究领域,具有代表性的研究成果有魏克赛尔在1898年提出的利息率理论、凯恩斯在1936年提出的利息率理论和罗伯逊在1940年提出的利息率理论。战后,虽然法博齐和莫迪利亚尼利用最优均衡的分析方法使前人利息率理论的表达更加精确,但从总体来看关于利息率的研究没有实质上的进展。在新的历史条件下审视这些经典的利息率理论,可以发现它们在不同程度上存在欠缺:魏克赛尔的利息率理论没有能够反映信用货币制度带来的新变化,凯恩斯的利息率理论混淆了货币与借贷资金的区别,罗伯逊的利息率理论则没有考虑借贷资金的消费需求和政府需求。实际上,利息率是由借贷资金的供给和需求决定的。借贷资金的供给除了货币供给这个外生变量以外,还有储蓄这个内生变量。借贷资金的需求不仅有投资形成的借贷需求,还有提前消费和政府弥补财政赤字形成的借贷需求。因此,有必要在借贷资金的需求方面补充消费需求和政府需求两个因素,前者是利息率和预期收入的函数,后者是财政赤字的函数。利用美国宏观经济数据对新构建的借贷资金需求函数进行的计量检验表明,该借贷资金需求函数能够解释现实利息率的变化。

Constitution means complementarity and improvement.Interest rate is an ancient and essential research field in economics where representative findings include Knut Wicksell’s interest rate theory of 1898,John M.Keynes’s interest rate theory of 1936,and Dennis Robertson’s interest rate theory of 1940.After the Second World War,Frank J.Fabozzi and Franco Modigliani made the existing interest rate theories more accurate by means of optimal equilibrium,but in general there was no essential progress in this field.These classical theories,once surveyed under new historical contexts,show defects to varying degrees:Knut Wicksell’s interest rate theory could not reflect new changes of credit monetary system;John M.Keynes confused loan funds with currency;Dennis Robertson did not consider consumption demand and government demand for load funds.Actually,interest rate is determined by supply of and demand for load funds.Besides monetary supply which acts as exogenous variable,supply of load funds is also influenced by savings which serve as endogenous variable.Demand for load funds is determined not only by investment,but also by excessive consumption and government budget deficit.Therefore,it is necessary to replenish consumption demand for load funds and government demand for load funds,of which the former is a function of interest rate and expected income,while the latter is a function of budget deficit.Based on American macroeconomic data,econometric test on this new demand function for load funds proves its validity in explaining changes of interest rate in reality.