In reply to Steve Kates, and in this case not really disagreeing with him, I will note that for all of his advocacy of Keynesian ideas, for many of the edtions of his influential Principles text, Paul Samuelson had a section on business cycle theories in which he reproduced the full list (or nearly) of those presented by Haberler in his book, with a pretty similar explanation. Of course Samuelson was a student of Haberler as well as having been influenced by Keynes. It would appear that he did not see Keynes as replacing Haberler's set of listed theories so much as augmenting it. Barkley Rosser