The causes and challenges of low interest rates: insights from basic principles and recent literature

What causes the downward trend of real interest rates in major developed economies since the 1980s? What are the challenges of the near-zero interest and inflation rates for monetary policy? What can the policymakers learn from the latest developments in the monetary and interest rate theory? This paper aims to answer these questions by reviewing both basic principles of interest rate determination and recent academic and policy debates.

The paper critically reviews the explanations for the downward trend of real interest rates in recent decades and monetary policy options in a near-zero interest rate environment.

The decline of real interest rates is likely an outcome of multiple technological, social and economic factors including diminished productivity growth, changing demographics, elevated tail-risk concerns, time-varying convenience yields of safe assets, increased global demand for safe assets, rising wealth and income inequality, falling relative price of capital, accommodative monetary policies, and changes in industry structure that alter the investment and saving behaviors of the corporate sector. The near-zero interest rate limits the space of central banks' response to economic crises. It also challenges some conventional wisdoms of monetary theory and sparks radically new ideas about monetary policy.

This survey differs from the existing work by taking a broader view of both economics and finance literature. It critically assesses the economic forces driving the global decline of real interest rates through the lens of basic principles and empirical evidence and discusses the merits and limitations of each proposed explanation. The study emphasizes the importance of a better understanding of economic forces driving diverging trends of corporate investment and saving behaviors. It also discusses the implications of the neo-Fisherism and the fiscal theory of price level for monetary policy in a low interest rate environment.