Psychology, like any other science, seeks to describe and explain its observations, data, and phenomena through the use of rigorous cause–effect statements. Some of these causal relationship statements lead to stronger and more certain predictions concerning outcomes than others. For example, the generalized term of scientific law contains the strongest and most rigorous descriptive account of how causal variables operate. Among the other, less rigorous, descriptors or concepts of how events are connected in science in general and psychology in particular are the generalized concepts of theory, hypothesis, effect, doctrine, and principle. The term ‘‘generalized concept’’ here refers to a cause–effect descriptor (e.g., ‘‘law’’; ‘‘theory’’) that defines a particular set of events and an expected outcome (e.g., ‘‘law of effect’’; ‘‘cognitive dissonance theory’’; ‘‘serial position effect’’). The following definitions of the various descriptor generalized concepts may serve as an initial guideline, or rule of thumb, for making distinctions among these generic terms.
The term law maybedefined as ‘‘a verbal statement, supported by such ample evidence as not to be open to doubt unless much further evidence is obtained, of the way events of a certain class consistently and uniformly occur’’ (English & English, 1976, p. 288).
The term theory has been defined as ‘‘a coherent explanation (of an array of logically interrelated propositions about a set of phenomena)…which has undergone some validation and which may be applied to many data, but which does not have the status of a law’’ (Harriman, 1966, p. 201). Psychological theories are said to vary with respect to temporal duration of the target activity where theories confined to sequences of brief duration are termed ‘‘synchronic,’’ and those concerned with extended durations are termed ‘‘diachronic’’ (Gergen, 1994). Another general distinction concerning theories is shown in Royce’s (1994) two major facets of theoretical psychology: the construction of ‘‘substantive theory’’ and ‘‘metatheory.’’ Substantive theory (e.g., ‘‘scientific the-