What is (not) money? Medium of exchange [not equal to] means of payment.

Yang, Bill Z.

1. Introduction

What is money? In economics, it is unanimously defined as the medium of exchange. But its interpretation varies from author to author. Some authors refer to medium of exchange as "anything that is generally accepted as payment for goods and services or in the settlement of debts" (Hubbard, 2005, p. 14), (1) while others use it as a synonym of means of payment (e.g., Thomas, 2006, p. 21). These treatments, however, are not only pedagogically troublesome but also conceptually incorrect. For example, almost all students get very confused when told check is not money, in particular, right after they had just learnt that "money is anything that is generally accepted as payment." The standard argument in most textbooks is that "check is not money but the checking deposits are" without explaining why a check is not money. Mumbles from students would often be "A check is indeed generally accepted as payment, by definition, why isn't it money? If a check is not money, then what is it?" To our knowledge, no textbook has directly answered these questions. Therefore, it is necessary to define money correctly so that one can easily judge whether a commonly-used "means of payment" is money, by definition.

This note is intended to provide such a formulaic definition of money. We define money as medium of exchange--the set of assets in an economy that people regularly exchange for goods and services from others. There are two key points in this definition. First, money must be an asset that signifies a part of what its holder owns. Second, people normally convert their assets from other forms to this specific one before exchanging for goods and services, implying that this set of assets are generally accepted in transactions. By definition, currency and demand deposits are money, while checks, credit and debit cards are not. This is because currency and checking deposits are their owner's assets, whereas a check or a credit/debit card is not a part of its owner's assets.

Then, what is check if it is not money? Why is it "generally accepted in transactions?" Checks as well as debit cards, credit cards and money orders, etc., are a means of payment, referred to as a generally accepted (institutional) arrangement or method that facilitates delivery of money from one to another. For example, a (signed) check essentially serves as a "standardized permit" that authorizes the recipient to claim a certain amount of checkable deposits from the check writer's bank account, but the check itself does not signify any part of the writer's assets. That is, a check is a means of payment and hence generally accepted in transactions, though it is not a medium of exchange.

Conceptually, medium of exchange should NOT be used as a synonym of means of payment; the medium of exchange stands for "what" (is paid) and the means of payment concerns "how" (to deliver it). Once such a distinction is clarified, one can uniformly explain why currency, checkable deposits, and stored-value cards are money, and why checks, debit/credit cards, or money orders are not money. It is because the former are a medium of exchange, whereas the latter are a means of payment but not a medium of exchange.

2. Medium of exchange [not equal to] means of payment

Characterized by its primary function, (2) money in economics is defined as medium of exchange. This definition is perhaps universally adopted by all economists. Interpretations for "medium of exchange" differ, however. For example, many authors refer to medium of exchange as "anything that is generally accepted as payment," (3) and others treat medium of exchange as a synonym of means of payment. (4) These treatments have caused lots of confusion in the classroom: following the definition students would conclude that a check is money, because a check is a means of payment and "generally accepted as payment." But they were immediately told that a check is not money! Confused? Of course! Such confusion stems from the above interpretations for medium of exchange; they are conceptually incorrect!

We now provide a correct and formulaic definition of money; following it one can directly judge whether or not a means of payment is money, by definition. We also articulate why "medium of exchange" and "means of payment" are two different concepts, and hence why money should be exclusively defined as a medium of exchange but not a means of payment.

As illustrated in Figure 1, the term "medium of exchange" is sufficiently self-explanatory; when one plans to trade something for something else from another, she first converts it to a medium of exchange, and then trades the medium of exchange for what she wants to buy. A medium of exchange has two key features: First, it represents a part of its owner's assets; second, it is commonly accepted in transactions. We refer to medium of exchange as the set of assets in an economy that people regularly exchange for goods and services. (5)

[FIGURE 1 OMITTED]

In a modern payment system, an exchange process essentially takes two steps. At step 1, potential buyers allocate a part of their assets in the form of, or directly exchange their goods or services for, a specific type of assets that is ready to make payment. For example, when one works and gets paid she actually trades her labor service for bank deposits or currency. At step 2, buyers exchange their bank deposits or currency for goods and services from sellers. Clearly, checkable deposits and currency are a part of people's assets and serve as a medium of exchange in transactions. By definition, checkable deposits and currency are money.

A related question is: How do buyers deliver money to sellers? In other words, how to make payment? In the real world, people have gradually developed a variety of means of payment--generally accepted institutional arrangements or methods that facilitate delivery of money from one to another. For example, a buyer may withdraw currency from her bank account or ATM and then hand-to-hand deliver it to make payment. In this case, currency also serves as the ultimate means of payment; when cash changes hands, payment is made and exchange is completed.

To deliver cash hand to hand is not the only means of payment, however. Writing checks is another very popular method to make payment. Unlike cash, a signed check itself does not carry any value of the check writer. In fact, it only plays a role of a standardized permit that authorizes the recipient to claim a certain amount of checkable deposits from the check writer's bank account. As a signed check changes hands, payment is not really completed until the recipient has finally received the funds, as illustrated in Figure 2. That is, writing a check is an institutional arrangement that facilitates transfer of demand deposits from one's account to another's, but the check itself is not a medium of exchange. By definition, check is a means of payment but not money.

In general, money serves as the ultimate means of payment (Shiller, 2003, p. 206), but not every means of payment must be money. This is because, by definition, a medium of exchange conveys a part of one's assets ready to be traded for goods and services from other people, whereas a means of payment (e.g., checks) may not carry any value and only help deliver money. In other words, medium of exchange is a concept of "what is to be paid", while means of payment is a notion of "how to deliver it." Hence, "medium of exchange" and "means of payment" are NOT synonymous. Therefore, we should not refer to money as a means of payment, or "anything that is generally accepted as payment." Rather, money should be exclusively defined as medium of exchange--the set of assets in an economy that people regularly exchange for goods and services.

Pedagogically, a good definition (of money) should be formulaic; following it one can conclude correctly what is money and what is not money. By definition, a means of payment is generally accepted in transactions, because it is institutionally backed by the current payment system. To determine whether a specific means of payment is money, a simple criterion is to see whether it carries value, physically or digitally. With such a criterion, for example, one can elucidate why e-cash and store-valued cards are also money, because they convey their holders' assets digitally. Likewise, one can explain for why debit cards, e-checks, money orders, bank checks, traveler's checks, credit cards, etc. are not money, because they do not carry any part of payers' assets and only help deliver money under a commonly accepted institutional arrangement. (6)

[FIGURE 2 OMITTED]

3. Functions of some often-used means of payment

In the previous section, we compared a check to a "standardized permit." What about other non-money means of payment? Since debit cards and e-checks are just electronic version of checks, they can be interpreted as e-permit. Similarly, money order, cashier's check and traveler's check essentially serve as "standardized receipts." Their issuer plays a role of "general cashier," working for all recipients. For example, when one buys a money order from post office with cash, the money is paid to this "cashier" (the post office), while the money order is the receipt with which the recipient will claim the payment from the issuer later.

Table 1 lists some often-used means of payment and their functions.

4. Conclusion

This note is intended to provide a correct and formulaic definition of money; with it that one can easily determine what is money and what is not money. We emphasize two points: First, medium of exchange and means of payment are not synonymous; medium of exchange is the set of assets in an economy that people regularly exchange for goods or services, while a means of payment is a generally accepted institutional arrangement or method that facilitates delivery of money from one to another. Second, money should be exclusively defined as medium of exchange but not means of payment or "anything that is generally accepted as payment." With such a distinction established, one can explain consistently whether or not a specific means of payment is money and why. It may help to better understand the concept of money in economics and avoid unnecessary confusions caused by the conventional but incorrect definitions of money.

References

Baumol, William J., and Alan S. Blinder, 1999. Economics: Principles and Policy, 8th Edition, Dryden.

Bade, Robin, and Michael Parkin, 2002. Foundations of Macroeconomics, Addison Wesley.

Burton, and Lombra, 2006. The Financial System and the Economy: Principles of Money and Banking, 4th Edition, Thomson South-Western

Frank, Robert H. and Ben S. Bernanke, 2004. Principles of Economics, 2nd Edition, Irwin McGraw Hill.

Hubbard, Glenn, 2004. Money, the Financial System, and the Economy, 5th Edition, Pearson Addison Wesley.

Mankiw, N. Gregory, 2004. Brief Principles of Macroeconomics, 3rd Edition, Thomson South-Western.

Mishkin, Frederic S., 2004. The Economics of Money, Banking, and Financial Markets, 7th Edition, Pearson Addison Wesley.

Shiller, Robert, 2003. The New Financial Order, Princeton: Princeton University Press.

Thomas, Lloyd B., 2006. Money, Banking and Financial Markets, Thomson South-Wester.

Footnotes

(1.) Similar interpretations for medium of exchange can also be found in, for example, Mishkin (2004, p. 45), Thomas (2006, p. 19), and Bade and Parkin (2002, p. 253), among others.

(2.) Money has three (or four) functions: Medium of exchange (the primary one), Unit of account and Store of value (some authors add the fourth --Standard of deferred payment). We use an acronym MUSt to help our students remember these functions with ease.

(3.) For example, see Hubbard (2004, p. 14), Mishkin (2004, p. 44), Thomas (2006, p. 19), and Burton and Lombra (2005, p. 24), among others.

(4.) For example, see Burton and Lombra (2006, p. 24), Miller and VanHoose (2004, p.6), and Baumol and Blinder (1999, p. 626), among others.

(5.) Our definition for money is very close to Mankiw's (2003, p. 220): "Money is the set of assets in the economy that people regularly use to buy goods and services from other people." Frank and Bernanke (2004, p. 596) also share a very similar definition. We replace "use [it] to buy" by "exchange [it] for" to emphasize the difference between a medium of exchange and means of payment. For example, when people use checks to buy goods and services from other people, they do not exchange checks for goods and services; rather, they mean to exchange their checking deposits for goods and services.

(6.) A practical way to judge whether a means of payment carries value is whether you can have your "money" back with an institutional arrangement through the payment system, if you happen to lose it.

Bill Z. Yang, School of Economic Development, Georgia Southern University, Statesboro, GA 30460-8152, E-mail: [email protected]. The author would like to thank an anonymous editor for helpful comments.

TABLE 1
Functions of some often-used means of payment

 Does it
 carry one's Is it
Means of payment Functions assets? money?

Currency Medium of exchange Yes Yes
Checking deposits Medium of exchange Yes Yes
E-cash E-briefcase Yes Yes
Stored-value cards E-wallet Yes Yes
Checks Permit No No
E-checks E-Permit No No
Debit cards ID/Permit No No
Credit cards ID/IOU No No
Money orders Receipts No No
Cashier checks Receipts No No
Traveler's checks Receipts No No