"The production function has been a powerful instrument of miseducation. The student of economic theory is taught to write Q = f (L, K ) where L is a quantity of labor, K a quantity of capital and Q a rate of output of commodities. are instructed to assume all workers alike, and to measure L in man-hours of labor; [they are told something about the index-number problem in choosing a unit of output; and then are hurried on to the next question, in the hope that [they will forget to ask in what units K is measured. Before ever do ask, [they have become a professor, and so sloppy habits of thought are handed on from one generation to the next".