Michal Kalecki swam into my ken just after the publication of the General Theory of Employment, Interest and Money, in 1936. The small group who had been working with Maynard Keynes during the gestation of the book understood what it was about, but amongst the public as a whole it was still a mystery. Kalecki, however, knew it all. He had taken a year’s leave from the institute where he was working in Warsaw to write the theory of employment but Keynes’ book came out, and got all the glory. Michal never made any claim for himself and I made it my business to blow his trumpet for him, but most of the profession (including Keynes) just thought that I was being kind to a lame duck. Only since the publication of his essays written in Polish from 1933 to 1935 has it been generally recognized that he had already worked out all the essentials of what became known as Keynes’ theory (Selected Essays on the Dynamics of the Capitalist Economy, Cambridge University Press, 1971). He showed that it is investment, not private saving, that brings about capital accumulation; that a government deficit, in a slump, will increase employment; that cutting wages only makes the slump worse; that the rate of interest depends upon supply and demand of the stock of money, not on the flow of saving, and that it is the forward-looking expectation of profits that induces firms to accumulate.
The question of glory did not seem to me to be important. As Michal was the first to admit, his ideas would have taken a long time to establish while with Keynes they burst upon the world as a revolution. But I was deeply impressed by the fact that two thinkers of such different background and habits of thought could arrive at the same diagnosis of the economic situation. Logic is the same for everybody; the same logical structure, if it is not fudged, can support quite different ideologies, but for most social scientists ideology leaks into the logic and corrupts it.
In the natural sciences, it is common enough for the same discovery to come almost simultaneously from two independent sources. The general development of a subject throws up a new problem and two equally original minds find the same answer, which turns out to be validated by further work. In the history of economic thought, the case of the discovery of the theory of employment by Keynes and Kalecki is unique.
– Joan Robinson in PORTRAIT: Michal Kalecki, Challenge, Vol. 20, No. 5, November/December, 1977, pp. 67-69, http://www.jstor.org/stable/40719591