Beliefs and desires incorporated

Suppose we admit for the sake of argument that "folk" explanations of human behavior--explanations in terms of beliefs and desires--sometimes succeed. They sometimes enable us to understand and predict patterns of motion that otherwise would remain unintelligible and unanticipated. Is the only explanation for such success that folk psychology is a viable proto-scientific theory of human psychology? I shall describe an analysis which yields a negative answer to that question. It was suggested by an observation and an analogy, both of which may initially seem remote from the topic at hand.