That is, of course, a chart of the American, rather than UK, money supply. But much the same has happened to our own money supply under the same QE program. And it's also telling us that it would be better to reverse QE than it would be to raise interest rates. So the idea that that debt could just be cancelled doesn't fly we're afraid. We all know that at some point we're going to have decent economic growth again, unemployment will fall to a minimum (that frictional unemployment that reflects people changing jobs, not involuntary unemployment) and that then inflation will start to rise again. We all also know, because Milton Friedman told us so, that inflation is always a monetary phenomenon. And, finally, we all also know that base money creation is more inflationary than credit creation: or boosting M1 leads to more inflation than the same boosting of M4 would cause.
It's putting those all together that tells us that we should reverse QE. Think through the future: so, we get out of this liquidity trap, this zero lower bound. The velocity of money returns to something like normal. At which point we've got two choices as to how to reduce the accompanying inflation. One is to raise interest rates, the standard response. But that works on M4, it slows credit creation. We could also reduce that money supply by reducing M1: reversing QE. And as above, we think that shrinking M1 would have more effect on reducing inflation than reducing M4 would.
Another way of saying the same thing is that the amount we'd have to raise interest rates to choke off inflation will be higher if we don't reverse QE than if we do. And this will be true for decades to come as we gradually get back to the right sort of relationship in size between M1 and M4. Or, not reversing QE means that we have to accept more economic pain to reduce inflation than if we reverse QE. For decades.
Which rather puts the kibosh on that idea so trendy over on hte left. Which is that as one part of the government owns the debt of the government we could just cancel that debt and reduce the debt burden. But doing that permanently increases that base money supply and thus permanently increases the interest rates we'll need to slay inflation in the future.
So, reverse QE before raising interest rates.