Question:

How should we understand a commodity's exchange-value? How should we understand its value? What is the relationship between the two?

Answer:

A commodity's exchange-value and value, and their relationship, can be understood from the following perspectives.

1 The definition of exchange-value. Marx says: “Exchange-value first appears as a quantitative relation, the proportion in which use-values of one kind exchange for use-values of another kind, a relation constantly changing with time and place. (49)” For example, if I can exchange five jin of rice for two of your garments, we can say that two garments are the exchange-value of five jin of rice.

2 The definition of value. For rice and garments to be exchangeable, they must have something in common: the undifferentiated human labor congealed in the commodities, which is value. Apart from their natural properties, their only common feature is that both are products of labor.

“The common element that manifests itself in the exchange relation, or exchange-value, of commodities is their value. (51)”

3 The relationship between exchange-value and value. Value is the basis of exchange-value. Value is a commodity's inherent property, while exchange-value is merely its form of expression.

4 The dual character of commodities. A commodity can therefore be said to possess two properties—the two factors of a commodity—use-value and value. It is a unity of use-value and value.

“Commodities appear in the form of use-values, or commodity-bodies, such as iron, linen, wheat, and so on. This is their ordinary, natural form. However, they are commodities only because they are something twofold: both useful objects and bearers of value. They therefore appear as commodities, or possess the commodity form, only insofar as they possess a double form, a natural form and a value-form. (61)”

5 Value is a social property peculiar to commodities, so products and services that do not enter the market have no value. For instance, services performed through household labor are not commodities and have no value because they do not enter the market or serve exchange; they possess only use-value. Paid domestic services, by contrast, are commodities possessing both value and use-value. Of course, “value” here is simply a term in Marxist political economy, carrying no moral implications.

6 A commodity's value is a social property and can therefore manifest itself only in social relations between commodities. Thus, we cannot study individual commodities and individual people metaphysically, in isolation.

“No producer, whether in industry or agriculture, produces value or commodities when considered in isolation. His product becomes value and a commodity only within particular social connections. (Volume III, 719)”