Originally Posted by David Gordon, in "Requiem for Marx"
Marx assumed that an exchange is an equality: in our earlier example, 1 house = 2 cars. In sharp contrast, in the Austrian view, an exchange takes place only if there is a double inequality: each person must value what he gains more than what he gives up. This view seems to me far-reaching in its importance. It exposes a presupposition of classical economics which, once questioned by the Austrian, appears the very reverse of obvious. Why is an exchange an equality? Neither Marx nor any other defender of the labor theory has given an explanation for this assumption.
Further, Marx assumed that an exchange involves a very strong sense of equality. In his view, the equality constituting an exchange must be explained by a common element on both sides of the equality. In other words, for Marx an exchange was an identity, in the same way that the two sides of an equation in mathematics designate the same quantity. If 1 house = 2 cars, then both '1 house' and '2 cars' share some common quantity. To those not enmeshed in the Marxist metaphysics of value, this step seems if anything even more wrongheaded than its predecessor, the postulate of equality. And if even, per absurdum, one accepted identity, Marx offers no argument for the contention that the common quantity must be labor.
Still another problem arises from the fact that, as Marx well knew, market prices differ from labor values. Marx dealt with this by trying to show that labor values could somehow be transformed into price. Those interested in the technical details of this issue should consult Bohm-Bawerk, who, pace Thomas Sowell, understood Marx perfectly well. It seems to me that one fact is often overlooked in the details of simple and expanded reproduction, Divisions I and II, and other elements of the Marxist architectonic. Suppose that Marx could show that market prices can be derived from labor values, by using a formula that gives the 'correct' results. In what way would this prove that labor values are the explanation of price? Marx's assumption that labor value was 'ultimate' would remain just that-an assumption. Given these and other difficulties, it is small wonder that most of the recent 'analytical Marxists,' a group which has attempted to revivify Marxism by applying to it the techniques of analytic philosophy and modern economics, dispense altogether with the labor theory. But what of Marx's much vaunted explanation of profit? This too fails, even if one grants Marx the labor theory of value. Sometimes, first thoughts are best; and the phrase "the labor value of labour" is indeed unmeaning. Labor is the measure of value: if so, it cannot at the same time have a value. Marx quite correctly noted that one can on his theory obtain the labor value of a laborer. But laborers are not for sale on the capitalist market: this, on the contrary, is the situation that obtains in a slave society. The laborer sells exactly what the capitalist buys-his labor power. Marx's explanation of profit through labor exploitation goes wrong at its first step.