Update: It’s obvious that many commenters don’t get the distinction between the proposition that banks create money — which every economics textbook, mine included, says they do (that’s what the money multiplier is all about) — and the proposition that their ability to create money is not constrained by the monetary base. Sigh.

A bit of a followup on my previous post.

As I read various stuff on banking — comments here, but also various writings here and there — I often see the view that banks can create credit out of thin air. There are vehement denials of the proposition that banks’ lending is limited by their deposits, or that the monetary base plays any important role; banks, we’re told, hold hardly any reserves (which is true), so the Fed’s creation or destruction of reserves has no effect.

This is all wrong, and if you think about how the people in your story are assumed to behave — as opposed to getting bogged down in abstract algebra — it should be obvious that it’s all wrong.

First of all, any individual bank does, in fact, have to lend out the money it receives in deposits. Bank loan officers can’t just issue checks out of thin air; like employees of any financial intermediary, they must buy assets with funds they have on hand. I hope this isn’t controversial, although given what usually happens when we discuss banks, I assume that even this proposition will spur outrage.

But the usual claim runs like this: sure, this is true of any individual bank, but the money banks lend just ends up being deposited in other banks, so there is no actual balance-sheet constraint on bank lending, and no reserve constraint worth mentioning either.

That sounds more like it — but it’s also all wrong.

Yes, a loan normally gets deposited in another bank — but the recipient of the loan can and sometimes does quickly withdraw the funds, not as a check, but in currency. And currency is in limited supply — with the limit set by Fed decisions. So there is in fact no automatic process by which an increase in bank loans produces a sufficient rise in deposits to back those loans, and a key limiting factor in the size of bank balance sheets is the amount of monetary base the Fed creates — even if banks hold no reserves.

So how much currency does the public choose to hold, as opposed to stashing funds in bank deposits? Well, that’s an economic decision, which responds to things like income, prices, interest rates, etc.. In other words, we’re firmly back in the domain of ordinary economics, in which decisions get made at the margin and all that. Banks are important, but they don’t take us into an alternative economic universe.

Now, under current conditions — that is, in a liquidity trap — the monetary base is indeed irrelevant at the margin, because people are indifferent between zero interest public liabilities of all kinds. That’s why there are no immediate policy differences between some of the monetary heterodoxies and what IS-LMists like me are saying. But that’s not the way things normally are.

Feel free to start yelling.