Here is McCraw discussing and quoting Schumpeter’s notes for the Walgreen Lectures that he was preparing to deliver just before he died.
(p. 475) In notes he prepared in 1949 for the prestigious Walgreen Lectures, Schumpeter headed one entire section “The Personal Element and the Element of Chance: A Principle of Indeterminateness.” Here, he wrote that the time had come for economists to face a problem they had long tried to dodge:
the problem of the influence that may be exerted by exceptional individuals, a problem that has hardly ever been treated without the most blatant preconceptions. Without committing ourselves either to hero worship or to its hardly less absurd opposite, we have got to realize that, since the emergence of exceptional indi-(p. 476)viduals does not lend itself to scientific generalization, there is here an element that, together with the element of random occurrences with which it may be amalgamated, seriously limits our ability to forecast the future. That is what is meant here by “a principle of indeterminateness.” To put it somewhat differently: social determinism, where it is nonoperational, is a creed like any other and entirely unscientific.
McCraw, Thomas K. Prophet of Innovation: Joseph Schumpeter and Creative Destruction. Cambridge, Mass.: Belknap Press, 2007.