A few weeks ago, just when I was trying to sort out my ideas on whether, and, if so, how, the Chinese engage in currency manipulation (here, here, and here), Scott Sumner started another one of his periodic internet dustups (continued here, here, and here) this one about whether the medium of account or the medium of exchange is the essential characteristic of money, and whether monetary disequilibrium is the result of a shock to the medium of account or to the medium exchange? Here’s how Scott put it (here):
Money is also that thing we put in monetary models of the price level and the business cycle. That . . . raises the question of whether the price level is determined by shocks to the medium of exchange, or shocks to the medium of account. Once we answer that question, the business cycle problem will also be solved, as we all agree that unanticipated price level shocks can trigger business cycles.
Scott answers the question unequivocally in favor of the medium of account. When we say that money matters, Scott thinks that what we mean is that the medium of account (and only the medium of account) matters. The medium of exchange is just an epiphenomenon (or something of that ilk), because often the medium of exchange just happens to be the medium of account as well. However, Scott maintains, the price level depends on the medium of account, and because the price level (in a world of sticky prices and wages) has real effects on output and employment, it is the medium-of-account characteristic of money that is analytically crucial. (I don’t like “sticky price” talk, as I have observed from time to time on this blog. As Scott, himself, might put it: you can’t reason from a price (non-)change, at least not without specifying what it is that is causing prices to be sticky and without explaining what would characterize a non-sticky price. But that’s a topic for a future post, maybe).
And while I am on a digression, let me also say a word or two about the terminology. A medium of account refers to the ultimate standard of value; it could be gold or silver or copper or dollars or pounds. All prices for monetary exchange are quoted in terms of the medium of account. In the US, the standard of value has at various times been silver, gold, and dollars. When the dollar is defined in terms of some commodity (e.g., gold or silver), dollars may or may not be the medium of account, depending on whether the definition is tied to an operational method of implementing the definition. That’s why, under the Bretton Woods system, the nominal definition of the dollar — one-35th of an ounce of gold — was a notional definition with no operational means of implementation, inasmuch as American citizens (with a small number of approved exceptions) were prohibited from owning gold, so that only foreign central banks had a quasi-legal right to convert dollars into gold, but, with the exception of those pesky, gold-obsessed, French, no foreign central bank was brazen enough to actually try to exercise its right to convert dollars into gold, at least not whenever doing so might incur the displeasure of the American government. A unit of account refers to a particular amount of gold that defines a standard, e.g., a dollar or a pound. If the dollar is the ultimate medium of account, then medium of account and the unit of account are identical. But if the dollar is defined in terms of gold, then gold is the medium account while the dollar is a unit of account (i.e., the name assigned to a specific quantity of gold).
Scott provoked the ire of blogging heavyweights Nick Rowe and Bill Woolsey (not to mention some heated comments on his own blog) who insist that the any monetary disturbance must be associated with an excess supply of, or an excess demand for, the medium of exchange. Now the truth is that I am basically in agreement with Scott in all of this, but, as usual, when I agree with Scott (about 97% of the time, at least about monetary theory and policy), there is something that I can find to disagree with him about. This time is no different, so let me explain why I think Scott is pretty much on target, but also where Scott may also have gone off track.
Rather than work through the analysis in terms of a medium of account and a medium of exchange, I prefer to talk about outside money and inside money. Outside money is either a real commodity like gold, also functioning as a medium of exchange and thus combining both the medium-of-exchange and the medium-of-account functions, or it is a fiat money that can only be issued by the state. (For the latter proposition I am relying on the proposition (theorem?) that only the state, but not private creators of money, can impart value to an inconvertible money.) The value of an outside money is determined by the total stock in existence (whether devoted to real or monetary uses) and the total demand (real and monetary) for it. Since, by definition, all prices are quoted in terms of the medium of account and the price of something in terms of itself must be unity, changes in the value of the medium of account must correspond to changes in the money prices of everything else, which are quoted in terms of the medium of account. There may be cases in which the medium of account is abstract so that prices are quoted in terms of the abstract medium of account, but in such cases there is a fixed relationship between the abstract medium of account and the real medium of account. Prices in Great Britain were once quoted in guineas, which originally was an actual coin, but continued to be quoted in guineas even after guineas stopped circulating. But there was a fixed relationship between pounds and guineas: 1 guinea = 1.05 pounds.
I understand Scott to be saying that the price level is determined in the market for the outside money. The outside money can be a real commodity, as it was under a metallic standard like the gold or silver standard, or it can be a fiat money issued by the government, like the dollar when it is not convertible into gold or silver. This is certainly right. Changes in the price level undoubtedly result from changes in the value of outside money, aka the medium of account. When Nick Rowe and Bill Woolsey argue that changes in the price level and other instances of monetary disequilibrium are the result of excess supplies or excess demands for the medium of exchange, they can have in mind only two possible situations. First, that there is an excess monetary demand for, or excess supply of, outside money. But that situation does not distinguish their position from Scott’s, because outside money is both a medium of exchange and a medium of account. The other possible situation is that there is zero excess demand for outside money, but there is an excess demand for, or an excess supply of, inside money.
Let’s unpack what it means to say that there is an excess demand for, or an excess supply of, inside money. By inside money, I mean money that is created by banks or by bank-like financial institutions (money market funds) that can be used to settle debts associated with the purchase and sale of goods, services, and assets. Inside money is created in the process of lending by banks when they create deposits or credit lines that borrowers can spend or hold as desired. And inside money is almost always convertible unit for unit with some outside money. In modern economies, most of the money actually used in executing transactions is inside money produced by banks and other financial intermediaries. Nick Rowe and Bill Woolsey and many other really smart economists believe that the source of monetary disequilibrium causing changes in the price level and in real output and employment is an excess demand for, or an excess supply of, inside money. Why? Because when people have less money in their bank accounts than they want (i.e., given their income and wealth and other determinants of their demand to hold money), they reduce their spending in an attempt to increase their cash holdings, thereby causing a reduction in both nominal and real incomes until, at the reduced level of nominal income, the total amount of inside money in existence matches the amount of inside money that people want to hold in the aggregate. The mechanism causing this reduction in nominal income presupposes that the fixed amount of inside money in existence is exogenously determined; once created, it stays in existence. Since the amount of inside money can’t change, it is the rest of the economy that has to adjust to whatever quantity of inside money the banks have, in their wisdom (or their folly), decided to create. This result is often described as the hot potato effect. Somebody has to hold the hot potato, but no one wants to, so it gets passed from one person to the next. (Sorry, but the metaphor works in only one direction.)
But not everyone agrees with this view of how the quantity of inside money is determined. There are those (like Scott and me) who believe that the quantity of inside money created by the banks is not some fixed amount that bears no relationship to the demand of the public to hold it, but that the incentives of the banks to create inside money change as the demand of the public to hold inside money changes. In other words, the quantity of inside money is determined endogenously. (I have discussed this mechanism at greater length here, here, here, and here.) This view of how banks create inside money goes back at least to Adam Smith in the Wealth of Nations. Almost 70 years later, it was restated in greater detail and with greater rigor by John Fullarton in his 1844 book On the Regulation of Currencies, in which he propounded his Law of Reflux. Over 100 years after Fullarton, the Smith-Fullarton view was brilliantly rediscovered, and further refined, by James Tobin, apparently under the misapprehension that he was propounding a “New View,” in his wonderful 1962 essay “Commercial Banks as Creators of Money.”
According to the “New View,” if there is an excess demand for, or excess supply of, money, there is a market mechanism by which the banks are induced to bring the amount of inside money that they have created into closer correspondence with the amount of money that the public wants to hold. If banks change the amount of inside money that they create when the amount of inside money demanded by the public doesn’t match the amount in existence, then nominal income doesn’t have to change at all (or at least not as much as it otherwise would have) to eliminate the excess demand for, or the excess supply of, inside money. So when Scott says that the medium of exchange is not important for changes in prices or for business cycles, what I think he means is that the endogeneity of inside money makes it unnecessary for an economy to undergo a significant change in nominal income to restore monetary equilibrium.
There’s just one problem: Scott offers another, possibly different, explanation than the one that I have just given. Scott says that we rarely observe an excess demand for, or an excess supply of, the medium of exchange. Now the reason that we rarely observe that an excess demand for, or an excess supply of, the medium of exchange could be because of the endogeneity of the supply of inside money, in which case, I have no problem with what Scott is saying. However, to support his position that we rarely observe an excess demand for the medium of exchange, he says that anyone can go to an ATM machine and draw out more cash. But that argument is irrelevant for two reasons. First, because what we are (or should be) talking about is an excess demand for inside money (i.e., bank deposits) not an excess demand for currency (i.e., outside money). And second, the demand for money is funny, because, as a medium of exchange, money is always circulating, so that it is relatively easy for most people to accumulate or decumulate cash, either currency or deposits, over a short period. But when we talk about the demand for money what we usually mean is not the amount of money in our bank account or in our wallet at a particular moment, but the average amount that we want to hold over a non-trivial period of time. Just because we almost never observe a situation in which people are literally unable to find cash does not mean that people are always on their long-run money demand curves.
So whether Nick Rowe and Bill Woolsey are right that inflation and recession are caused by a monetary disequilibrium involving an excess demand for, or an excess supply of, the medium of exchange, or whether Scott Sumner is right that monetary disequilibrium is caused by an excess demand for, or an excess supply of, the medium of account depends on whether the supply of inside money is endogenous or exogenous. There are certain monetary regimes in which various regulations, such as restrictions on the payment of interest on deposits, may gum up the mechanism (the adjustment of interest rates on deposits) by which market forces determine the quantity of inside money thereby making the supply of inside money exogenous over fairly long periods of time. That was what the US monetary system was like after the Great Depression until the 1980s when those regulations lost effectiveness because of financial innovations designed to circumvent the regulations. As a result the regulations were largely lifted, though the deregulatory process introduced a whole host of perverse incentives that helped get us into deep trouble further down the road. The monetary regime from about 1935 to 1980 was the kind of system in which the correct way to think about money is the way Nick Rowe and Bill Woolsey do, a world of exogenous money. But, one way or another, for better or for worse, that world is gone. Endogeneity of the supply of inside money is here to stay. Better get used to it.
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