What makes a central bank special?

Nick Rowe over at WCI has an interesting post asking what makes a central bank special; see Currency, Interest, and Redeemability.

According to Nick, what makes a central bank special is not that it can borrow and lend, create money, and set interest rates. All of us can do these things in principle; and in practice, many large private financial institutions do do these things. The difference, as Nick explains, is what he calls "asymmetric redeemability." The Bank of Montreal, for example, issues money redeemable in BoC liabilities; but the reverse is not true.

I think that's right; but let me expand with a few related thoughts of my own.

If one looks at history, a recurring property of monetary economies is the emergence of a "base money" that serves as the redemption object for "broad money" objects. Frequently, the broad money is made redeemable, on demand, and at par, with the base money. (We might even call base money "central" money, as it serves as the focal point for all other monies.)

In modern economies, the demandable liabilities created by chartered banks (M1, say) constitute broad money made redeemable, on demand, and at par, with government cash (small denomination paper). In the antebellum US, private banknotes were made redeemable on demand at par for specie (gold and silver coin). And so on throughout much of recent monetary history.

Now, there are a lot of interesting questions that arise here that are not the main focus of my post here. For example, why do banks embed their liabilities with what amounts to be an American put option (liabilities made redeemable on demand at a fixed strike price)? Is it the byproduct of a legal restriction, or is it an equilibrium phenomenon?

Either way, it seems obvious that the agency in control of the supply of base money (the object of redemption) is going to be in a position to implement "monetary policy." Whether this is a good or bad thing is the subject of much debate of course (let's not get into that here). And so, I have to agree with Nick's conclusion:

There is something very seriously wrong with any approach to monetary theory which says we can assume central banks set interest rates and ignore currency. It is precisely those irredeemable monetary liabilities of the central bank (whether they take the physical form of paper, coin, electrons, does not matter) that give central banks their special power.

(He is, however, not quite right about private agencies not being able to issue irredeemable objects and get them to be used them as money; see Bitcoin).

Scott Sumner, who runs a very nice blog himself, has an interesting take on Nick's post; see: The Bank of Canada is Important Precisely Because it is not a Bank.  Here is Scott:

Now let’s consider a different monetary system.  Imagine a gold standard and a monopoly producer of gold.  The gold mine company would reduce short term interest rates by increasing the supply of gold.  Like currency, gold is irredeemable.  But no one would call this gold mining company a “bank” because it possesses no bank-like qualities.  Banks don’t create irredeemable assets, gold mines do.

Scott is trying to tell us that a central bank is not a bank; it is the monopoly supplier of base money. He also says that "banking has nothing to do with monetary policy."

I find it difficult to evaluate this view because he does not define "bank" or "monetary policy" here (although I'm sure he does elsewhere). Permit me once again to give my 2 cents worth.

A financial intermediary is an asset transformer. An insurance company, for example, takes "deposits" (premiums), purchases assets, and creates a set of state-contingent liabilities backed by these assets. A pension fund, as another example, takes "deposits" (contributions), purchases assets, and creates a set of time-contingent liabilities backed by these assets. A bank, finally, takes "deposits", purchases (or finances) assets, and creates a set of demandable liabilities backed by these assets.

So a bank is a special kind of intermediary. It is special because the demandable liabilities created by banks are used widely as payment instruments; i.e., money (and the demandable property of these liabilities probably goes a long way to enhancing their acceptability as money, but that's another story).

When a bank accepts your land as collateral for a money loan, it performs an asset swap. It is transforming your illiquid land into a liquid asset (the liability created by the bank). Banks are in the business of transforming illiquid assets into liquid assets. This leads us to ask what the Fed is doing when it purchases (say) MBS or UST assets? In my view it is transforming (relatively) illiquid assets into a very liquid asset (Fed cash). QE is banking; and it falls under the category of monetary policy, in my books at least.

So in some sense, all banks (private and public) are engaged in a form of  "monetary policy." But it still remains true that a central bank with legislated monopoly control over the economy's base money object is "special" precisely for this reason. And any theoretical framework that is to have any hope of ever understanding the role of money and banking in society is going to have to model these objects explicitly; the way this guy does, for example.