“In the years after 1936, whilst Hayek was working on The Pure Theory of Capital, most economists were convinced by Keynes, whose theory had an elegance and simplicity that Hayek’s did not. Keynes’ theory lacked Hayek’s theoretical rigor in that it was not based on equilibrium (on individual rationality), and there were places in the argument where Keynes relied on loose, informal arguments, preferring to put his trust in intuition rather than formal theory. Keynesians did not solve the problems with capital theory that Hayek had identified: they just bypassed or ignored them. According to Hayek’s methodological criteria, Keynes’ theory was decidedly inferior. Against this, Keynes’ theory provided opportunities for mathematical and statistical analysis that Hayek’s did not. Indeed, though Hayek paid some attention to data, he did so only minimally: he certainly made no attempt to test his theory against statistical data. The choice of Keynesian theory was, at least in part, a methodological one.”

"Hayek on money and the business cycle", 2006