 Operationalism is based on the intuition that we do not know the meaning of a concept unless we have a method of measurement for it. It is commonly considered a theory of meaning which states that “we mean by any concept nothing more than a set of operations; the concept is synonymous with the corresponding set of operations” (Bridgman 1927, 5). That drastic statement was made in The Logic of Modern Physics, published in 1927 by the American physicist P. W. Bridgman. The operationalist point of view, first expounded at length in that book, initially found many advocates among practicing physicists and those inspired by the tradition of American pragmatism or the new philosophy of logical positivism. It is highly doubtful that Bridgman intended to advance a precise and universal theory of meaning, or any systematic philosophical theory at all. His writings were primarily “reflections of a  physicist”[1]  rooted in experimental practice and aimed at articulating the scientific method from a first-person point of view. However, as Bridgman’s ideas gained currency they were shaped into a general philosophical doctrine of “operationalism” or “operationism”, and in that form became very influential in many areas, especially in methodological debates in psychology. Both in philosophy and in psychology operationalism is nowadays commonly regarded as an extreme and outmoded position, but that is not to say that the potential of the early ideas has been exhausted.