The view, or doctrine, that all theoretical concepts or propositions in science must be amenable to operational definitions. Thus, the truth of a concept or proposition rests on the demonstration that it can be tested by a logically based procedure, or by a finite sequence of operations. As such, operationalism rejects any concept that cannot be tested in this way as a legitimate subject for scientific investigation. Operationalism as a guiding principle of the scientific method was brought to the fore by Percy W. Bridgman (1882-1961), winner of the Nobel Prize for Physics (1946), in the 1920s. He did so in order to improve his ability to communicate ideas to his students and colleagues by means of couching them in terms of procedures that one can actually perform. It soon found its advocates in logical positivism, as well as in the behaviorism of John B. Watson (1878-1958) and Burrhus F. Skinner (1904-1990). However, the impossibility of eliminating metaphors and metaphysics from science spelt the downfall of an all-embracing operationalism, and with it the demise of logical positivism. Its legacy is the undisputed practical value of operational definitions, but they too can be sometimes problematic. For example, Edwin G. Boring (1886-1968), the historian of experimental psychology, defined intelligence as what an intelligence test measures, which is a tautology. It is important to bear in mind that the provision of operational definitions does not eliminate the use of metaphors, as such definitions ultimately rest on one or more of these underlying figures of speech.
See Behaviorism, Canon of parsimony, Intelligence, Logical positivism, Metaphor, Ockham’s (or Occam’s) razor, Tautology