The Taylor Principle and Indeterminacy Under a Financial Market Imperfection

This paper investigates the impact of a financial market imperfection on the conditions that monetary policy rules must satisfy for the determinacy of a rational-expectations equilibrium. A financial market imperfection can disturb intertemporal substitution in certain cases. If a financial market is sufficiently imperfect, this imperfection can cause the real interest rate elasticity of aggregate demand to become positive. In this case, the Taylor principle is not the unique necessary and sufficient condition for monetary policy rules to ensure determinacy. If the central bank responds to current inflation, then the Taylor principle is a sufficient, but not a necessary, condition. Moreover, if the bank responds to expected inflation, the Taylor principle is neither a necessary nor a sufficient condition. Our calibration results suggest that it may be dangerous for a central bank to adhere solely to the Taylor principle when real financial markets are immature or bankrupt, as was the case for the Japanese market during the 1990s