Surplus value
central concept in Karl Marx's theory of value and critique of political economy
In Marxian economics, surplus value is the difference between the amount raised through a sale of a product and the amount it cost to manufacture it: i.e. the amount raised through sale of the product minus the cost of the materials, plant and labour power. The concept originated in Ricardian socialism, with the term "surplus value" itself being coined by William Thompson in 1824; however, it was not consistently distinguished from the related concepts of surplus labour and surplus product. The concept was subsequently developed and popularised by Karl Marx. Marx's formulation is the standard sense and the primary basis for further developments, though how much of Marx's concept is original and distinct from the Ricardian concept is disputed (see § Origin). Marx's term is the German word "Mehrwert", which simply means value added (sales revenue minus the cost of materials used up), and is cognate to English "more worth".
It is a major concept in Karl Marx's critique of political economy, underpinning a variety of his theories related to the function of capitalism and the exploitation of the working class. Conventionally, value-added is equal to the sum of gross wage income and gross profit income. However, Marx uses the term Mehrwert to describe the yield, profit or return on production capital invested, i.e. the amount of the increase in the value of capital.
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