So much for the theory; now to its disappearance. Nyland's explanation for the disappearance of Chapman's theory was that Robbins and Hicks, in 1929 and 1932 respectively, had each introduced a simplifying assumption that the given length of the working day was optimal for output. According to Nyland (1989), the requirement for such a move arose because the variability of both the duration and intensity of working time made it difficult – if not impossible – to calculate returns to the various factors of production. Subsequently, in Nyland's account, Robbins's and Hicks's simplification came to be regarded as the way things were in reality.
However, a re-examination of the texts by Robbins and Hicks fails to detect the simplifications that Nyland identified. Both authors made statements that may seem to announce such a simplification. But a careful re-reading of the wording and context of those statements challenges Nyland's interpretation. In Robbins's article (1929), the context for the statement Nyland takes to be a simplifying assumption involved, first, acknowledgements to Chapman for his theoretical analysis of the hours of labour and to Philip Sargant Florence for the empirical confirmation of Chapman's theoretical insights. Second, Robbins offered the disclaimer that in his discussion, he wasn't examining what factors might lead to a reduction of the hours of labour but only the effects that would proceed from it, assuming such a reduction to take place. Finally, came the alleged simplifying assumption itself: "If we are to predict the effect of a given variation in hours we must conceive of it in relation to a working day of maximum productiveness" (p. 27). Robbins's working day of maximum productiveness is thus not posited as the given working day but only a point of reference to which any given variation in hours must be related. If the given day was longer than the hypothetical day of maximum productiveness, then a reduction in hours would induce an increase in production. If the day was already shorter than optimal, then a further shortening would lead to an decrease in production. Such an analysis remained in accord with Chapman's theory.
Abstract: Sidney Chapman's theory of the hours of labour, published in 1909 in The Economic Journal, was acknowledged as authoritative by the leading economists of the day. It provided important insights into the prospects for market rationality with respect to work time arrangements and hinted at a profound immanent critique of economists’ excessive concern with external wealth. Chapman's theory was consigned to obscurity by mathematical analyses that reverted heedlessly to outdated and naïve assumptions about the connection between hours and output. The Sandwichman is serializing "Missing: the strange disappearance of S. J. Chapman’s theory of the hours of labour" on EconoSpeak in celebration of the centenary of publication of Chapman's theory. (To download the entire article in a pdf file, click on the article title.)