Human behavior is predictable, but, as in physical science, accurate prediction hinges on the correctness of underlying theoretical assumptions. There is, in fact, no prediction without theory; all managerial decisions and actions rest on assumptions about behavior. If we adopt the posture of the ostrich with respect to our assumptions under the mistaken idea that we are thus "being ‘practical,” or that "management is an art,” our progress with respect to the human side of enterprise will indeed be slow. Only as we examine and test our theoretical assumptions can we hope to make them more adequate, to remove inconsistencies, and thus to improve our ability to predict.