Hayek Found Keynes Ignorant of Capital Theory and Real-Interest Theory

F.A. Hayek subjected J.M. Keynes’s early Treatise on Money (now relatively forgotten amid the glow of his later General Theory) to a sound and searching critique, much of which applies to the later volume. Thus, Hayek pointed out that Keynes simply assumed that zero aggregate profit was just sufficient to maintain capital, whereas profits in the lower stages combined with equal losses in the higher stages would reduce the capital structure; Keynes ignored the various stages of production; ignored changes in capital value and neglected the identity between entrepreneurs and capitalists; took replacement of the capital structure for granted; neglected price differentials in the stages of production as the source of interest; and did not realize that, ultimately, the question faced by businessmen is not whether to invest in consumer goods or capital goods, but whether to invest in capital goods that will yield consumer goods at a nearer or later date. In general, Hayek found Keynes ignorant of capital theory and real-interest theory, particularly that of Böhm-Bawerk, a criticism borne out in Keynes’s remarks on Mises’s theory of interest.

--Murray N. Rothbard, America's Great Depression, 5th ed. (Auburn, AL: Ludwig von Mises Institute, 2000), 37n.