This paper focuses on the justice of income distribution in a system of private property rights. Milton Friedman argued that the “ethical principle that would directly justify the distribution of income in a free society is ‘to each according to what he and the instruments he owns produces’” (1962: 161–2). In this paper we (a) show that the winning of pure entrepreneurial profit cannot be justified on the basis of Friedman’s ethical principle, and (b) argue that a fuller understanding of the meaning of “pure entrepreneurial profit” reveals that Friedman’s universal ethic is of little relevance to capitalism, properly understood as a free enterprise system. To pass ethical judgment on pure entrepreneurial profit, it is necessary to supplement Friedman’s ethical principle with additional ethical insights. This paper does not argue directly in favor of any one such possible additional insight; it will simply demonstrate how one such additional insight might, if it passes final ethical screening, serve as the ethical defense of pure capitalism, which, we argue, Friedman’s ethical principle is unable to do.