The notion that inflation is (mainly) a monetary phenomenon is new to many students and going through the history of inflation and monetary policy regimes is a very rewarding exercise for a teacher.
But there is a problem with the way we teach inflation: in many countries inflation has been under control for decades now. And this control does not come from the fact that monetary policy was anchored to a physical commodity such as gold but from the actions and credibility of the central bank. Here is a nice chart from recent work from Jan Groen and Menno Middeldorp that measures inflation expectations in the US going back to 1970.
After the early 90s the line becomes flat, there is very little to say about either the level or the volatility of inflation. In this environment, inflation is almost constant and the correlation between money supply and inflation is inexistent. But we leave this fact for the last five minutes of the class given how much fun it was to talk about Germany in 1923, Hungary in 1946 and Zimbabwe in 2008.
So given the way we have been teaching about inflation it is not that surprising that for the last five years some have been worrying so much about inflation or even hyperinflation as central banks balance sheets have grown very fast. [There is, of course, the mistake that many do of not understanding the difference between the monetary base and the money supply but I will leave that for another post.]
Next time I teach my macroeconomics course I will spend less time talking about inflation and if I talk about it, I will not show the picture of the one hundred trillion dollars note from Zimbabwe, instead I will spend more time about the incredible stability of inflation in many countries. And I will use the extra time to talk about long recessions and even longer recoveries.
Antonio Fatás