In the October 1937 number of Philosophy of Science Lindsay has made certain criticisms of the adequacy of the “operational method” of analyzing and giving meaning to the concepts of physics, documenting his criticisms chiefly from my own writings. In these criticisms he has made statements as to the method which I would by no means accept. This is not characteristic of his paper only, for I have seldom indeed seen a printed discussion of the method which I would accept as being an adequate or sometimes even fair representation of what I understand by it. It will perhaps pay therefore if I attempt to state what I conceive it to be all about, particularly since I have never attempted such a comprehensive statement and since my own ideas on the subject have been developing since I first wrote in the Logic of Modern Physics. For one reason I have hesitated to do this, for fear of seeming to subscribe to the not uncommon idea that we are dealing with some elaborate and profound new theory of the nature of knowledge or of meaning. I believe that I myself have never talked of “operationalism” or “operationism”, but I have a distaste for these grandiloquent words which imply something more philosophic and esoteric than the simple thing that I see. What we are here concerned with is an observation and description of methods which at least some physicists had already, perhaps unconsciously, adopted and found successful—the practise of the methods already existed. What I have attempted is to analyze these successful methods, not to set up a philosophical system and a theory of the properties that any method must have if it hopes to be successful. Since I was concerned with a technique already extant, my principal method of getting others to see what the technique involved has been to exhibit examples of the technique in action, rather than to attempt any exhaustive characterization of the technique itself.

When the layman reads a book or two of popularized physics and then moves solemnly forth, as occasionally happens, to expound some comprehensive doctrine purporting to be built directly out of the materials he has picked up, the type of comment which the physicist will make is plain enough in advance. But why does it so rarely occur to the physicist that others may think of his epistemologizing much what he is sure to think of their quantizing?

The concept of causality as it appears in a specific scientific theory involves two factors: (1) the relation of necessary connection between the states of a system at different times, and (2) the definition of state at a given time.

Mr. E. J. Nelson, in “The Inductive Argument for an External World,” treats of fundamental topics with erudition and urbanity, but his essay remains inconclusive, I believe, with respect to its purpose of discrediting the argument. He agrees with Mr. Savery, Mr. Pratt, and me, as against the positivists, that the question of the existence of an external world is meaningful (249) and indeed of paramount importance for both metaphysics and logic. But he argues against us that it cannot be inductively established by its supposed power of “saving the appearances.” He is not sure that any induction is valid; but even if other inductions are valid, he thinks this one can not be (240, 245, 247), for the following reasons. (1) By the multiplicative axiom of probability-theory, evidence for a hypothesis can only multiply its antecedent probability, and can increase the probability only when the latter is finite, while the hypothesis of an external world has and can have no finite antecedent probability (241, 245). (2) By the same axiom, even granted an antecedent probability for the hypothesis itself, no experience can act as evidence to increase the probability of a hypothesis except in so far as the hypothesis implies, makes probable, or “explains” the evidence, and this the hypothesis of an external world cannot do (244, 245, 247).

It is the thesis of this paper that the term scientific law can and should mean in the social sciences exactly what it means in any of the other sciences. There seems to be considerable agreement among scientists as well as others that a scientific law is a generalized and verifiable statement, within measurable degrees of accuracy, of how certain events occur under stated conditions. If I were to attempt a more specific statement I would say that a law is (1) a group of verbal or mathematical symbols (2) designating an unlimited number of defined events in terms of a limited number of reactions (3) so that the performance of specified operations always yields predictable results within measurable limits.

Few words appear more frequently in the literature of contemporary social science than “culture.” Not only does it occur frequently, but with such a multitude of meanings that a single definition of the term becomes almost impossible. Even a cursory examination of social scientific writing discloses that its signification varies with the contexts in which it appears and with most individuals who use it. As long as words are single exhibits of the versatility and variety of language, no fault can be found with a plurality of meanings which may come to adhere to them. But when words are designed for and used in discussions of a supposedly technical character in any of the social science disciplines, the time for literary and philological speculation has past. Words intended for such use must conform to certain standards of conceptual validity, must be used consistently in analogous contexts, and must never be torn from the universe of discourse of which they are a part.

The article by Mr. David L. Miller, called ‘Purpose, Design and Physical Relativity', in the July 1936 issue of Philosophy of Science, consists mainly of a commentary on the development of Whitehead's thought from the Enquiry Concerning the Principles of Natural Knowledge to Process and Reality. Now most criticisms of Whitehead so far published have been from realists of the anti-metaphysical Cambridge school, complaining that his later works retract the teaching of his earlier works on the philosophy of natural science; and this complaint is raised quite unjustly, because a careful reading of the earlier works will show that there is nothing in them that precludes the logical possibility of a metaphysics of nature such as Whitehead expounded later. We should be grateful for any comment on Whitehead which does not repeat this hoary error. But unfortunately two opposed misinterpretations do not together make a correct interpretation. The opposite distortion of Whitehead is effected by those readers who, having found that the earlier books showed genius but were, alas, too much under the influence of ill-advised realist dogma, proceed to construe the succession of later books as the gradual self-correction of the great man towards a mature judgment which is in full accord with the reader's own. Of this distortion, I am afraid, Mr. Miller has given us an example.