I think that the demand for a theory of successful thinking cannot be satisfied, and that it is not the same as the demand for a theory of creative thinking. Success depends on many things—for example on luck. It may depend on meeting with a promising problem. It depends on not being anticipated. It depends on such things as a fortunate division of one’s time between trying to keep up-to-date and concentrating on working out one’s own ideas.
But it seems to me that what is essential to “creative” or “inventive” thinking is a combination of intense interest in some problem (and thus a readiness to try again and again) with highly critical thinking; with a readiness to attack even those presuppositions which for less critical thought determine the limits of the range from which trials (conjectures) are selected; with an imaginative freedom that allows us to see so far unsuspected sources of error: possible prejudices in need of critical examination.
