The Genesis of the Only Diagram in the General Theory: A Comment

Abstract

Roy Harrod (1951, p. 453) explicitly states that he “supplied a diagram purporting to reconcile the classical theory [of interest] with [Keynes's] theory, and he incorporated it in the [General Theory]-the only diagram in it!” (italics added). John M. Keynes (1936, p. 180n) himself writes: “This diagram was suggested to me by Mr. R.F. Harrod.” Furthermore, Harrod, in a letter to Ralph Hawtrey (19 June 1951) also says: “I was myself responsible for the diagram on page 180 which was an attempt to demonstrate to Maynard that his theories were not quite so out of line with the classical position as he supposed” (quoted in Warren Young 1987, p. 136). Now Rod O'Donnell (1999) claims that Harrod never supplied a diagram but only suggested how one could be drawn. Thus both Harrod and Keynes have misled us about the genesis of the only diagram in the General Theory. O'Donnell advances arguments in support of his claim which do not appear convincing.