This article shows that the law of value is axiomatic and constitutes the necessary foundation of the system of prices of production, explaining the double character of the commodities, which cost capital for capitalists and labor for workers and the society as a whole. It sustains that economics becomes a science - which does not admit any unproved hypothesis - through the theory of labor value. Given up this foundation means to break with the principle of self-found of science, clearly formulated in Marx’s Capital, which starts with the commodity as an immediate concrete and ends with the commodity as a product of capital. It means to give up the unifying principle of classical economics in favor of un-systematic theories based on ad hoc hypotheses, like those regarding profit maximization and capital accumulation. This article also shows that the neo-Ricardian proposal to determine prices and the profit rate directly from "technical coefficients" and the real wage omits the length of the working-day and the intensity of the labor process, not to say about the sociologic nature of the real wage. This means to conceal the sociologic content of those variables, beginning with the exploitation of labor. Finally, the labor theory of value furnishes not only an explanation for all economic categories of the capitalist economy (market prices; prices of production; wages; profit and the profit rate; interests and the interest rate; ground rent and the price of land; the price of the financial assets, etc.), but for the simple commodity mode of production as well, so that its abandonment means to give up on a general theory of market economies of all kind.
