This article presents comments of the author on a paper by Bruce W. Knight related to the fair return on fair value doctrine which was published in the February 1930 issue of "The Quarterly Journal of Economics." In his paper, Knight makes a vigorous attack upon the "fair return on fair value " doctrine. He states that the doctrine would not be able bring about the desirable amount of investment. According to him, the doctrine rests on the untenable assumption that regulation which secures a competitive return would secure what he calls competitive production. His attack on the doctrine fails on two grounds. Firstly he makes use of contradictory assumptions. Secondly, another of his assumptions comes dose to begging the question. His first contradictory assumption is contained in his definition of competitive production. In his definition, he assumes that additional investment in any branch of industry lowers the value product per unit of investment. An additional amount of the factors of production, if applied to an under-invested branch of industry, will add more to the value product of that branch than it would add in a branch which is not under-invested.