Surplus value

Surplus value is a central concept in Karl Marx's critique of political economy. Marx did not himself invent the term: he developed the concept. "Surplus value" is a translation of the German word "Mehrwert", which simply means value added (sales revenue less the cost of materials used up). Conventionally, value-added is equal to the sum of gross wage income and gross profit income. However, Marx's use of this concept is different, because for Marx, the Mehrwert refers to the yield, profit or return on production capital invested, i.e. the amount of the increase in the value of capital. Hence, Marx's use of Mehrwert has always been translated as "surplus value", distinguishing it from "value-added". According to Marx's theory, surplus value is equal to the new value created by workers in excess of their own labor-cost, which is appropriated by the capitalist as profit when products are sold.

Marx thought that the gigantic increase in wealth and population from the 19th century onwards was mainly due to the competitive striving to obtain maximum surplus-value from the employment of labor, resulting in an equally gigantic increase of productivity and capital resources. To the extent that increasingly the economic surplus is convertible into money and expressed in money, the amassment of wealth is possible on a larger and larger scale (see capital accumulation and surplus product).

The problem of explaining the source of surplus value is expressed by Friedrich Engels as follows:

"Whence comes this surplus-value? It cannot come either from the buyer buying the commodities under their value, or from the seller selling them above their value. For in both cases the gains and the losses of each individual cancel each other, as each individual is in turn buyer and seller. Nor can it come from cheating, for though cheating can enrich one person at the expense of another, it cannot increase the total sum possessed by both, and therefore cannot augment the sum of the values in circulation. (...) This problem must be solved, and it must be solved in a purely economic way, excluding all cheating and the intervention of any force — the problem being: how is it possible constantly to sell dearer than one has bought, even on the hypothesis that equal values are always exchanged for equal values?"

Marx's solution was to distinguish between labor-time worked and labor power. A worker who is sufficiently productive can produce an output value greater than what it costs to hire him. Although his wage seems to be based on hours worked, in an economic sense this wage does not reflect the full value of what the worker produces. Effectively it is not labour which the worker sells, but his capacity to work.

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