shadowy feeling of being acquainted with the words, and in a philosophical discussion it does not seem advisable to call such a feeling ‘understanding’.
Similarly, I should not advise that we speak of a sentence as being ‘logically intelligible’ when we just feel convinced that its exterior form is that of a proper proposition (if, e.g. it has the form, substantive—copula—adjective and therefore appears to predicate a property of a thing). For it seems to me that by such a phrase we want to say much more, namely, that we are completely aware of the whole grammar of the sentence, i.e., that we know exactly the circumstances to which it is fitted. Thus knowledge of how a proposition is verified is not anything over and above its verbal and logical understanding, but is identical with it. It seems to me, therefore, that when we demand that a proposition be verifiable we are not adding a new requirement but are simply formulating the conditions which have actually always been acknowledged as necessary for meaning and intelligibility.
The mere statement that no sentence has meaning unless we are able to indicate a way of testing its truth or falsity is not very useful if we do not explain very carefully the signification of the phrases ‘method of testing’ and ‘verifiability’. Professor Lewis is quite right when he asks for such an explanation. He himself suggests some ways in which it might be given, and I am glad to say that his suggestions appear to me to be in perfect agreement with my own views and those of my philosophical friends. It will be easy to show that there is no serious divergence between the point of view of the pragmatist as Professor Lewis conceives it and that of the Viennese Empiricist. And if in some special questions they arrive at different conclusions, it may be hoped that a careful examination will bridge the difference.
How do we define verifiability?
In the first place I should like to point out that when we say that “a proposition has meaning only if it is verifiable” we are not saying “... if it is verified”. This simple remark does away with one of the chief objections; the "here and now predicament", as Professor Lewis calls it, does not exist any more. We fall into the snares of this predicament only if we regard verification itself as the criterion of meaning, instead of ‘possibility of verification’ (= verifiability); this would indeed lead to a “reduction to absurdity of meaning”. Obviously the predicament arises
