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[This DISC is preceded by several responses to Daniele Besomi's posting with the subject
"WWW -- Harrod home-age." -- RBE]
 
I have just taken a look at some, but not all, of the papers associated with the origins
of the multiplier-accelerator model (I do not have all of
them available at the moment, although I have read most of them before).   
 
1)  The argument that Giblin invented the multiplier looks to me to be a hard one to make,
based on reading his lecture.  It certainly is not the multiplier
as it is usually formulated, although there are hints of it there, surely.  In any case,
Giblin does not have an accelerator model in his lecture that I could spot, so he is not
in the running on having developed the multiplier-accelerator model.
 
2)  Although one reads frequently that R.F. Kahn "discovered" or "invented" the multiplier
(according to Keynes, anyway), I do not know where he published that result, if he even
did.
 
3)  Although he did not work out a mathematical model, J.M. Clark not only had the idea of
the accelerator, but understood that it was associated with a multiplier effect as well
prior to both Kalecki and Harrod.  The source
is J.M. Clark, "Capital Production and Consumer-taking: A Further Word," Journal of
Political Economy, Oct. 1932, pp. 692-93.  In particular, although he sees an initiation
of a change in investment from a decrease in consumer demand, he then notes that the
decrease in investment, "in turn reduces purchasing power, unless offset by opposite
movements elsewhere, and results in a positive decrease in consumers' demand."
 
If that is not the multiplier effect interacting with the accelerator effect, I do not
know what is.
 
4)  The Kalecki model has certain mathematical problems. It is a sort of multiplier-
accelerator model, but not a full blown one.
 
5)  In his original paper in REStat in 1939, Samuelson only mentions Alvin Hansen (who
wrote in 1938) as an influence on him.  He reiterates this in a piece in 1959 in REStat.
However, he discusses Harrod's role in his less well known paper from later in that year,
"A Synthesis of the Principle of Acceleration and the Multiplier," Journal of Political
Economy, 1939, Dec. 1939, pp. 786-797.  He provides the quote from Clark in there that I
just noted.  He gives a lot of credit to Harrod (and does not mention Kalecki), but also
declares that "Upon rigorous analysis his exposition will be found to abound with non
sequiturs and oversimplifications. On the whole Harrod's intuition surpasses his reasoned
conclusions."
 
In short, Harrod clearly played a very important role.  But, he would appear to be neither
the inventor of the idea of combining a multiplier with an accelerator, credit for which
should probably go to J.M. Clark, nor of producing a fully consistent and rigorous model
that does so.
 
Barkley Rosser 
 
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