 Marx’s theory of exploitation appears to presuppose that labor is the source of all value. But the labor theory of value to which Marx and early classical economists subscribed is subject to a number of apparently insurmountable difficulties, and has largely been abandoned by economists in the wake of the marginalist revolution of the 1870s. The most obvious difficulty stems from the fact that labor is heterogeneous. Some labor is skilled, some labor is unskilled, and there does not appear to be any satisfactory way of reducing the former to the latter and thereby establishing a single standard of measure for the value of commodities. Moreover, the labor theory of value appears to be unable to account for the economic value of commodities such as land and raw materials that are not and could not be produced by any human labor. Finally, and perhaps most fatally, Marx’s assumption that labor has the unique power to create surplus value is entirely ungrounded. As Robert Paul Wolff has argued, Marx’s focus on labor appears to be entirely arbitrary. A formally identical theory of value could be constructed with any commodity taking the place of labor, and thus a “corn theory of value” would be just as legitimate, and just as unhelpful, as Marx’s labor theory of value (Wolff 1981). Therefore, if, as some have alleged, Marx’s theory of exploitation is dependent on the truth of the labor theory of value, then a rejection of the labor theory of value should entail a rejection of Marx’s theory of exploitation as well (Nozick 1974; Arnold 1990).