Everything we were taught about the monetary base is wrong in a world with interest on reserves (IOR). A large base can sit there forever. The price level is not proportional to the base, changes in the base, etc. It just isn’t. The broader aggregates, such as M2, haven’t grown so rapidly.
But consider the scenario that worries me. Our debt continues to increase. Nominal interest rates rise, so the government has to borrow more just to finance the debt. Congress wants to avoid having to cut spending elsewhere, and the Fed is asked to do its part.
Tyler points out that the Fed could increase its purchases of Treasuries without increasing the money supply. However, the mechanism for doing this is to raise the interest rate that it pays on reserves. That mechanism does not solve the problem of lowering the government’s interest costs, which is what I think is the nub of the scenario that I am talking about.
My guess is that in practice, for a variety of reasons, when the cost of government debt starts to rise, the Fed is not going to be willing/able to sterilize its funding of the debt, through IOR or any other means. We are going to see both intended and unintended monetary expansion, and that will produce inflation.
As usual, let me say that I am not blaming the Fed or saying that inflation is just around the corner. When really out-of-control inflation emerges, it is a fiscal phenomenon.