The difference between two colourful bits of rectangular paper

David Andolfatto had a provocative and open-ended tweet a few days back:

The difference between money and debt. pic.twitter.com/CSQuLzUJPU

— David Andolfatto (@dandolfa) April 26, 2019

We see two coloured pieces of paper, both with an old dead President on it. They each have a face value of $500. Both are issued by a branch of the government, the $500 McKinley banknote (at right) by the Federal Reserve while the $500 Treasury bond (at left) by the Treasury. Both are bearer instrument: anyone can use them.

So why do we bestow one of them the special term "money" while the other is "credit"? I mean, they seem to be pretty much the same, right?

The word money is an awful word. It means so many different things to different people that any debate invoking the term is destined to go off-track within the first fifty characters. So I'm going to try and write this blog post without using the term money. Why are the two instruments that David has tweeted about fundamentally and categorically different from each other?

One of them is the medium of account, the other isn't

Being a veteran of the monetary economics blogosphere, David's tweet immediately made me think of the classical debates between Scott Sumner and Nick Rowe about the the medium-of-exchange vs medium-of-account functions of assets like banknotes and deposits and coins. (For those who don't remember, here are some posts.)

As Scott Sumner would probably say, one of the fundamental differences between the two bits of paper is that the McKinley $500 Federal Reserve note has been adopted as the U.S.'s medium-of- account. The $500 Treasury bond  hasn't.

Basically, if Jack is selling his car for $500, this price is represented by the $500 note (and other sub-denominations like the $50, $20 etc), not a $500 bond. Put differently, the bill is used as the medium for describing the accounting unit, the $. The bond does not have this special status. Now it could be that Jack is willing to accept bonds as payment, but since he doesn't use bonds to describe his sticker prices, he'll have to do some sort of calculation to convert the price into bond terms. When something is the medium of account, the entire language of prices is dictated by that instrument.

So why has society generally settled on using banknotes and not the bonds as our medium of account?

First, let's learn a bit more about the bond in question. The image that David has provided us with isn't actually a bond, it's a bond coupon. A coupon is a small ticket that the bond owner would periodically detach from the larger body of the bond in order to claim interest payments. The full bond would have looked more like this:

This format would have hobbled the bond's usefulness as a medium of exchange. The bond principal of $100 is represented by the largest sheet of paper. Attached to it are a bunch of coupons (worth $1.44 each) that haven't yet been stripped off. To compute the purchasing power of the bond, the $100 principal and all of the coupons would have to be added up. Complicating this summation is the time value of money. A coupon that I can clip off tomorrow is more valuable than the one I can clip off next year.

So if Jack is selling a car, and Jill offers him a $500 Treasury bond rather than a banknote, he'll have to spend a lot more time puzzling out the bond's value. A $500 McKinley note, which pays 0%, is much easier on the brain, and thus less likely to hit some sort of mental accounting barrier. (Larry White wrote a paper on this a while back).

Another hurdle is that there are many vintages of $500 Treasury bonds. A $500 bond that has been issued last year will be worth more than one that has been issued ten years ago and has had most of its coupons  stripped off. Put differently, Treasury bonds are not fungible. Banknotes, on the other hand, don't come in vintages. They are perfectly interchangeable with each other. So in places like stores and markets where trade must occur quickly, banknotes are far more convenient.

Further complicating matters is capital gains tax. Each time the $500 Treasury bond changes hands its owner must go back into their records to find the original price at which they received the bond, compute the profit, and then submit all this information to the tax authority. The $500 note doesn't face a capital gains tax. Better to use hassle-free banknotes, and not taxable bonds, to make one's day-to-day purchases.

Which finally gets us to why notes and not bonds are the medium-of-account. Since banknotes are such a convenient medium of exchange, everyone will have a few on hand. And this makes it convenient to set our prices in terms of notes, not Treasury bonds.

Why is it convenient? Say that Jack were to set the price of the car he is selling at $500, but tells his customers that the sticker price is in terms of Treasury bonds. So the $500 Treasury bond will settle the deal. But which Treasury bond does he mean? As I said earlier, at any point in time there are many vintages of $500 bonds outstanding. The 1945 one? The 1957 one? So confusing!

Jack's customers will all have a few notes in their wallet, having left their bonds locked away at home. But if Jack sets prices in terms of bonds, that means they'll have to make some sort of foreign exchange conversion back to notes in order to determine how many note to pay Jack. What a hassle!

If Jack sets the sticker price in terms of fungible notes he avoids the "vintages problem". And he saves the majority of his customers the annoyance of making a forex conversion from bond terms back into note terms. Since it's better to please customers than anger them, prices tend to be set in terms of the most popular payments instrument. Put differently, the medium-of-account tends to be married to the medium-of-exchange.

Alpha leaders vs beta followers

There is another fundamental difference between the two pieces of paper. Say that the Treasury were to adopt a few small changes to the instruments it issues. It no longer affixes coupons to Treasury bonds. And rather than putting off redemption for a few years, it promises to redeem them on demand with banknotes at any point in time. This new instrument would look exactly like the McKinley note. Without the nuisances of interest calculations, Treasury bond transactions should be just as effortless as the those with Federal Reserve notes.

But a fundamental difference between the two still exists. Since the Treasury promises to redeem the bond with banknotes, the Treasury is effectively pegging the value of the Treasury bond to the value of Federal Reserve notes. However, this isn't a reciprocal relationship. The Federal Reserve doesn't promise to redeem the $500 note with bonds (or with anything for that matter).

This means that the purchasing power of the bond is subservient to that of the banknote. Or as Nick Rowe tweets, "currency is alpha leader, bonds are beta follower."

Bonds promise to pay currency. Currency does not promise to pay bonds.
There's an asymmetric fixed (future) exchange rate between bonds and currency. Issuers of bonds peg to currency; issuers of currency do not peg to bonds.
So currency is alpha leader, bonds are beta follower.

— Nick Rowe (@MacRoweNick) April 26, 2019

This has much larger implications for the macroeconomy. In the long-run, the US's price level is set by the alpha leader, the Federal Reserve, not by the beta follower, the Treasury.

The Treasury could remove the peg. Now both instruments would be  0% floating liabilities of the issuer. Without a peg, their market values will slowly diverge depending on the policy of the issuer. For instance, a few years hence the $500 Treasury bond might be worth two $500 Federal Reserve notes. We could imagine that in certain parts of the U.S., custom would dictate a preference for one or the other as a medium of exchange. Or maybe legal tender laws nudge people into using one of them. And so certain regions would set price in terms of Treasury bonds while others will use Federal Reserve notes as the medium of account.

The Treasury's monetary policy would drive the price level in some parts of the U.S., whereas the Fed's monetary policy would drive it in the rest. This would be sort of like the 1860s. Most American states adopted Treasury-issued greenbacks as the medium of exchange during the Civil War, but California kept using gold coins issued by the US Mint. And thus prices in California continued to be described in terms of gold, and held steady, whereas prices in the East inflated as the Treasury printed new notes. (I wrote about this episode here.)

In conclusion...

So in sum, the two instruments in David's tweet are fundamentally and categorically different because one is the medium of account and the other isn't. Treasury bonds just aren't that easy to transact with, so people don't carry them around, and thus shopkeepers don't set sticker prices in terms of Treasury bonds. But even if the Treasury were to modify its bonds to be banknote look-alikes, they are still fundamentally different. Treasury paper is pegged to notes, but not vice versa.

This peg can be severed. But for convenience's sake, one of the two instruments will come to be used as the medium-of-account within certain geographical areas. And thus in its respective area, the issuer of that medium-of-account will dictate monetary policy.