It is the aim of this paper to examine certain aspects of a point of view which has attracted much attention in physical methodology. This is the standpoint known as operationalism. We wish to discuss its significance in the construction and interpretation of physical theories.

The essential meaning of operationalism in physics is that physical concepts should be defined in terms of actual physical operations. On this view there is no meaning to a concept unless it represents an operation which can be performed in the laboratory. Thus the term “pressure of a gas” signifies nothing until an operation is described which constitutes the measurement of pressure. When one thinks of pressure one must think. of some actual apparatus, such as, for example, some glass and rubber tubing and some mercury and certain operations performed using these until finally one gets a pointer reading which one calls the pressure of the gas. The same stand is taken with respect to length, time, velocity, acceleration, temperature, etc.