The "placebo" effect of psychotherapy: a moose in the rabbit stew.

The placebo concept, essential for pharmacology, is inappropriate for psychotherapy. "Common," "nonspecific," or "relationship" factors have not been satisfactorily differentiated from "specific," "intended," or "characteristic" factors in psychotherapy. This paper analyzes the placebo from historic, heuristic, semantic, and theoretical standpoints with reference to its misuse regarding psychotherapy.