Cumulative Record: Definitive Edition (1999). Chapter 7: Are Theories of Learning Necessary. Quote 6

A science of behavior must eventually deal with behavior in its relation to certain manipulable variables. Theories—whether neural, mental, or conceptual—talk about intervening steps in these relationships. But instead of prompting us to search for and explore relevant variables, they frequently have quite the opposite effect. (pp. 70-71)