Logic of Modern Physics is an admirable attempt to carry out this program for all concepts of physics.) I am not writing for those who think that Einstein’s philosophical opponents were right.
II
Professor C. I. Lewis, in a remarkable address on “Experience and Meaning” (published in this Review, March 1934), has justly stated that the view developed above (he speaks of it as the “empirical-meaning requirement”) forms the basis of the whole philosophy of what has been called the “logical positivism of the Viennese Circle”. He criticizes this basis as inadequate chiefly on the ground that its acceptance would impose certain limitations upon “significant philosophic discussion” which, at some points, would make such discussion altogether impossible and, at other points, restrict it to an intolerable extent.
Feeling responsible as I do for certain features of the Viennese philosophy (which I should prefer to call Consistent Empiricism), and being of the opinion that it really does not impose any restrictions upon significant philosophizing at all, I shall try to examine Professor Lewis’s chief arguments and point out why I think that they do not endanger our position — at least as far as I can answer for it myself. All of my own arguments will be derived from the statements made in section I.
Professor Lewis describes the empirical-meaning requirement as demanding “that any concept put forward or any proposition asserted shall have a definite denotation; that it shall be intelligible not only verbally and logically but in the further sense that one can specify those empirical items which would determine the applicability of the concept or constitute the verification of the proposition” (loc. cit. 125). Here it seems to me that there is no justification for the words “but in the further sense ...”, i.e., for the distinction of two (or three?) senses of intelligibility. The remarks in section I. show that, according to our opinion, ‘verbal and logical’ understanding consists in knowing how the proposition in question could be verified. For, unless we mean by ‘verbal understanding’ that we know how the words are actually used, the term could hardly mean anything but a
