The Logic of Modern Physics.

The Logic of Modern Physics is a 1927 philosophy of science book by American physicist and Nobel laureate Percy Williams Bridgman. The book was widely read by scholars in the social sciences, in which it had a huge influence in the 1930s and 1940s, and its major influence on the field of psychology in particular surpassed even that on methodology in physics, for which it was originally intended. The book is notable for explicitly identifying, analyzing, and explaining operationalism for the first time, and coining the term operational definition.

Operationalism can be considered a variation on the positivist theme, and, arguably, a very powerful and influential one. Sir Arthur Eddington had discussed notions similar to operationalization before Bridgman, and pragmatic philosophers had also advanced solutions to the related ontological problems. Bridgman's formulation, however, became the most influential.