That is the theme of my latest Bloomberg column. Here is one short bit:
Consider the recent spurt of 8% to 9% inflation in the US. The simple fact is that M2 — one broad measure of the money supply — went up about 40% between February 2020 and February 2022. In the quantity theory approach, that would be reason to expect additional inflation, and of course that is exactly what happened.
The quantity theory has never held exactly, one reason being that the velocity (or rate of turnover) of money can vary as well. Early on in the pandemic, spending on many services was difficult or even dangerous, and so savings skyrocketed. Yet those days did not last, and when the new money supply increase was unleashed on the US economy, there were inflationary consequences.
I do think there are plenty of indeterminacies in macro, but letting M2 rise at such a pace is not one of them!