In a recent article C. Jackson Grayson, Jr. [Grayson, Jackson C., Jr. 1973. Management science and business practice. Harvard Bus. Rev. (July–August) 41–48.] states that he used absolutely none of the management science tools explicitly. Yet, to the question whether he might have done better by using some management science models his answer is no. How does he know? That question is the main subject of this note. Can a decision maker do better without science, models, computers etc.? In other words, can we rely exclusively on experience, intuition, expert judgement, hunch or genius? The answer is no. Or, more precisely, it all depends on the decision maker, the problem and the environment.