One of the central tenets of Marxism is the "labor theory of value," which is the idea that the economic value of something is determined by the number of hours that it took to make it. It should be acknowledged that labor really is (at least partially) relevant in determining the value of something. Nonetheless, it seems safe to say that Karl Marx takes this theory far beyond the evidence. It is his extreme form of this theory that will receive a response here. He introduces this theory early in his work, in the very first section of the very first chapter of "Das Kapital" (his longest book):
Karl Marx
Quote from Marx about "labor theory of value"
"A use value, or useful article, therefore, has value only because human labour in the abstract has been embodied or materialised in it. How, then, is the magnitude of this value to be measured? Plainly, by the quantity of the value-creating substance, the labour, contained in the article. The quantity of labour, however, is measured by its duration, and labour time in its turn finds it standard in weeks, days, and hours." (Source: Karl Marx's "Das Kapital," Part 1, Chapter 1, Section 1, as translated into English at Marxists.org)
Marx and Engels
Even Marx presented some qualifications to his theory ...
There are several problems with this theory, and much has been written describing the many flaws of using it to describe value. I will not touch on all of these problems, but only on one of them - the one that I find the most interesting. It can be demonstrated with a qualification that Marx himself made to this theory. Even Karl Marx, the greatest proponent of the labor theory of value, qualified his theory with the idea that only those labor hours that were "socially necessary" should be counted as adding value. Marx's concept of "socia[l] necess[ity]" is not very well-defined, but his definition's meaning is clear enough to show that it contradicts his labor theory of value, attacking its very basis as an explanation.
Iron and Coal, painting from 1855-1860 (during Marx's lifetime) about the Industrial Revolution













