Marxists tend to like the labor theory of value because it provides a vivid account of exploitation and highlights a basic antagonism at the core of capitalism: capitalists and workers are locked in a battle over the appropriation of the surplus that workers produce. But many commentators assume it is either internally inconsistent or hopelessly outdated.

The theory is thus hotly contested but arguably poorly understood by both critics and advocates alike. The debate has also sometimes been mired in arcane mathematical issues. As a consequence, interesting philosophical and empirical questions have received less attention. Jacobin put a number of these questions to Duncan Foley, author of Understanding Capital: Marx’s Economic Theory.