The Legacy of High Inflation on Monetary Policy Rules

This paper shows the key, yet overlooked, role played by the legacy of a high inflation history on the strength of the monetary policy response to inflationary shocks. To rationalize this, we propose a New Keynesian model that diverges from the existing workhorse model by adding path-dependence (to a forward-looking model) and potentially imperfect central bank credibility. We show that achieving low inflation (hitting the target) requires more aggressive monetary policy reactions, and is costlier from an output point of view, when individuals’ past inflationary experiences shape their inflation expectation formation. In turn, we provide empirical evidence of the need for these two theoretical additions. Countries that experienced a high level of inflation before adopting the IT regime tend to respond more aggressively to deviations of inflation expectations from the central bank’s target. We also point to the existence of a credibility puzzle, whereby the strength of a central bank’s monetary policy response to deviations from the inflation target remains broadly unchanged even as central banks gain credibility over time. Put differently, a country’s inflationary past casts a long and persistent shadow on central banks.