Before it was hijacked by Paul Krugman, Scott Sumner and I were having a friendly little argument about whether Milton Friedman repackaged the Keynesian theory of the demand for money as the quantity theory of money transmitted to him via a fictitious Chicago oral tradition, as I, relying on Don Patinkin and Harry Johnson, claim, or whether Friedman was a resolute anti-Keynesian, as Scott claims. We have been trading extended quotations from the literature to try to support our positions.
I now offer some additional quotations, all but one from Axel Leijonhufvud’s wonderful essay “The Wicksell Connection: Variations on a Theme,” published in Leijonfuvud’s volume Information and Coordination (Oxford University Press, 1981). By some coincidence, the quotations tend to support my position, but, more importantly, they shed important light on problems of interpreting what Keynes was really talking about, and suggest a way of thinking about Keynes that takes us beyond the sterile ideological debates into which we tend lapse at the mere mention of the name John Maynard Keynes, or for that matter, Milton Friedman. Of course, the main lesson that readers should take away is: read the whole essay.
Herewith are a few extracts in which Leijonhufvud comments on Friedman and his doctrinal relationship with Keynes.
Milton Friedman has emphatically denied that the elasticity of LM is at issue [in the Monetarist v. Keynesian controversies]. At the same time his use of what is basically an IS-LM structure in presenting his own theory, and his oft-repeated insistence that no theoretical issues but only questions of empirical magnitudes within this shared theoretical frame separate him from his opponents, have apparently fortified others in their belief that (whatever he says) this elasticity must be crucial. Furthermore, Friedman has himself played around with elasticities, for example in advancing the notion of a horizontal IS curve. (p. 144, fn. 22)
The troubles with keeping track of the Wicksellian theme in its Keynesian guises and disguises go far back in time. The original “Savings-equals-Investment” debate did not reach a clear-cut collective verdict. As Lipsey ["The Foundations of the Theory of National Income: An Analysis of Some Fundamental Errors"] has recently shown, confusion persists to the present day. The IS-LM framework did not lend itself too well to a sharp characterization of the question whether the excess demand for bonds or the excess demand for money governs the interest rate. It was concluded that the distinction between the Loanable Funds and Liquidity Preference hypotheses was probably either pointless or misleading and that, in either case, the issue could safely be left unresolved. Correspondingly, Hansen found, Keynes’ insistence that saving and investment determine income while money stock and liquidity preference determine the rate of interest (rather than the other way around) makes no sense once you realize that, in IS-LM, everything simultaneously determines everything.
In Hansen’s reading Keynes’ interest theory was “indeterminate” – money supply and demand could not determine the interest rate, as Keynes would have it, but only give you the LM curve, etc. This way of looking at it missed the issue of which excess demand governs the interest rate.
One is reminded of Hansen’s indeterminacy charge by Friedman’s more recent argument that Keynes’ theory suffered from a “missing equation” – and should be completed by adding an exogenously determined price level. Keynes’ theory . . . was of the dynamic-historical variety. In describing the state of the system at some point in the sequential process, such theories make use of information about the system’s initial (historical) state. Static models do not use historical information, of course, but have to have equations for all endogenous variables. Reading a dynamic-historical theory on the presumption that it is static, therefore, is apt to lead to the mistaken impression that it lacks equations and is indeterminate. (pp. 180-81 and fn. 84)
Friedman, like so many others, filters Keynes and Keynesian theory through the IS-LM model and, consequently, ends up where everyone else ends up: bogged down in the Neoclassical Synthesis, which is to say, with the conclusion that exogenous fixity of money wages was Keynes’ explanation of unemployment. His discussion is notable for a sophisticated treatment of Keynes’ demand for money function and for its sweeping endorsement of the Pigou-effect. . . . (p. 189)
I break off from the final quotation, which is just a small part of an extended discussion of Friedman, because the argument is too dense to summarize adequately, and the entire lengthy passage (pp. 187-94) has to be read to grasp its full import. But I close with one final quotation from Leijonhufvud’s essay “Schools, ‘Revolutions,’ and Research Programmes in Economic Theory,” also contained in Information and Coordination (pp. 291-345).
The most widely known “monetarist,” Professor Milton Friedman, has for a long time consistently voiced the position that “monetarists” and “(neo)-Keynesians” share essentially the same theory and that their differences all derive from contrasting hypotheses concerning certain crucial empirical magnitudes. (He has also, however, persistently denied that the issues can be defined as a “simple” matter of the magnitude of the interest-elasticity of the excess demand for money – an otherwise oft-repeated contention in the debate.) In his recent attempts to provide an explicit representation for his theory, accordingly, Friedman chose ot use the “Keynesian” so-called “IS-LM” framework as his language of formal discourse.
In my opinion, there are “hard core” differences between the two theories and ones, moreover, that the “IS-LM” framework will not help us define. Not only are these differences at the “cosmological” level not accurately represented by the models used, but they will also lead to divergent interpretations of empirical results. (pp. 298-99, fn. 10)
The last paragraph, I suspect, probably sums up not just the inconclusiveness of the debate between Monetarists and Keynesians, but also the inconclusiveness of the debate about whether Friedman was or wasn’t a Keynesian. So be it.