The circuit approach has done much to reawaken interest in Keynes's monetary theory of production and to extend it in new directions. Yet, it appears to remain confined within the limits of the industrial circulation of Keynes's Treatise; it thus does not deal with the determination of investment goods prices nor can it deal with the differential determination of the prices of assets and liabilities introduced in the General Theory in terms of the marginal efficiency of capital and liquidity preference. Since the impor¬tance of money in Keynes's theory is intimately linked with these concepts, it leads us to conclude that circuit theory needs further development in order to capture Keynes's views on the dominance of money over the real sector in a capitalist economy.

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The Cambridge-based Keynesian theories of growth and distribution developed in the 1950s and 1960s were presented as extensions or ‘generalizations’ of Keynes's General Theory. While they were sharply criticized by neoclassical economists, their develop¬ment was also accompanied by ‘internal’ criticism which only became externally evi¬dent sometime after the ‘Cambridge Debates’ had come to be classified as a history of economic thought. The first of these internal criticisms was associated with neo-Ricard¬ian economists who emphasized the differences between capital theory based on the generalization of Keynes's General Theory and on Sraffa's Production of Commodities. The second came from American post Keynesians such as Davidson and Minsky, as well as from Austrian economists such as Ludwig Lachmann, who criticized the emphasis on static or steady-state analysis when it was the process of history that the theory was trying to explain. Both of these criticisms concerned the role of uncertainty and expec-tations in the theory, the former was critical because it was too great, the latter because it was too small.

A third line of criticism, usually, but not always linked to the second, came from economists who considered Keynes's revolution to have been primarily concerned with monetary theory and considered the long-run models of steady growth in which money played no active role as unacceptable, if not unKeynesian. They argued that Keynes's conception of liquidity should play a crucial role in long-period analysis or else such analysis should be abandoned.