Hayek on Keynes' Third Fundamental Error: Keynes' Macroeconomic Approach Hides from Economists the Fundamental Mechanisms of Change in the Market

Keynes’ model is clearly macroeconomic. According to Hayek, though, this approach is wrong, as it hides the fundamental mechanisms of change in the market from the economist. In his view, in order to understand the market process, economists need to study the economy from the point of view of the actors involved. Therefore, the relevant things are relative prices and the investment structure, and not concepts such as aggregate investment or the level of wages. Thus, Keynes’ theory would not be enough to explain the market process.

--David Sanz Bas, "Hayek's Critique of The General Theory: A New View of the Debate between Hayek and Keynes," Quarterly Journal of Austrian Economics 14, no. 3 (Fall 2011): 296.