The criterion of the empirical : a critical and historical review of three theories

Between, roughly, 1920 and 1935, there appeared on the philosophical scene a number of currents which, though independent in origin (at least in the sense of lack of direct and conscious intellectual affiliations), and differing in several important aspects, may be said to have had as a minimum common element the aim of defining; the domain of natural science or "the empirical", and in particular, of demarcating it from, on the one hand, logic and mathematics, and on the other (and especially) a body of assertions collectively called "metaphysics". These currents were, broadly speaking, "operationism" (first expounded as such by P.W. Bridgman); the "principle of verifiability" which was the central idea of "logical positivism" (put forward first by a number of German philosophers, chiefly Schlick and Carnap); and a "logic of scientific discovery" based on the central concept of falsifiability (K.R. Popper). These ideas - and especially the first two - were very vigourously and widely discussed during the period mentioned above and the ensuing years; frequently the discussions took the form of what Feigl hardly exaggerates in calling "intense disputes". A prolonged and widespread dispute over a philosophical doctrine is not a new phenomenon. What is more unusual here, however, is the nature and extent of disagreement with regard to it. Leading representatives - not to speak of lesser lights - of each of the trends in question have asserted that the idea at least is of great, and even of fundamental importance. Others who have written on the problem dispute this, some going so far as to deny it any real importance at all. Now, as Dingle (the chief English representative of operationism) says, in remarking this situation, "when men who are neither fools nor liars agree that a certain idea is either the greatest discovery of a generation or the silliest nonsense imaginable, but cannot agree which it is, it is clear that there is more than a difference of opinion: there must be some defect of understanding also. Intelligent men do not thus differ about that which they comprehend equally." This diagnosis is further confirmed, by the complaints by exponents of the doctrines in question that their views are wholly or partially misunderstood, and by critics that these views suffer from insufficiently clear and exact definition. The trouble is indeed a real one. But apart from the inadequacies in the formulations of the various individual doctrines, a very important source of confusion is the failure to take sufficiently into account the differences between, on the one hand, the three main approaches already mentioned, and, on the other, the differences due to the fact that formulations of the doctrine on the basis of a particular approach have undergone (sometimes frequent) revisions and/or the fact that individual philosophers have presented individual, and hence more or less widely differing formulations. A satisfactory study of the three types of theory in question and hence of the problem(s) which they are designed to resolve can only be undertaken if both the similarities and differences, external and internal, between them are constantly kept in view. This situation constituted primary stimulus to the studios summarised in the following essay which attempts to present the relevant doctrines - or representative versions of them - as clearly as possible (what may, in principle, be lost in generality, by taking into consideration only views which have been actually held by philosophers being, it is suggested, amply compensated for by the advantage of definiteness) and, in the closest connection with this, to examine them critically in a number of important respects. In the latter connection as full a use as possible has been made of the very considerable critical literature which has accumulated around the question. A more exact delimitation of subject-matter would presuppose a preliminary clarity with regard to the exact systematic structure of the problem. But precisely this fundamental question is one of those which has been left very unclear. hence the separating out of this problem, of the philosophical questions involved, and of their ramifications will be one of the first tasks undertaken. Such a preliminary analysis is all the more necessary insofar as the doctrines in question have frequently penetrated far outside the professional philosophical world - especially, of course, into the world of the special sciences, and many do not seem to have realised the philosophical implications of some of their statements. or the necessity of a philosophical justification for them. The very facts that the philosophical views in question did find an almost immediate echo in scientific spheres and in other domains not philosophical in a specialised sense of the word, and that, independent in origin as regards personal influence, these doctrines did tend to similar ends by means very similar in many respects - this suggests that such ideas corresponded to intellectual currents already present, however latent, since an idea can usually only exercise influence where there is a previously present susceptibility. Thus these ideas must have originated and developed rather as foci of tendencies already present end stretching beyond them, then as originators of such tendencies (however much the latter may have been influenced by those ideas after the event). In fact it is essentially the broadness of this influence which lends to the doctrines in question an importance and significance greater than might be accorded the views of relatively specialised and isolated schools of philosophy. Thus, a more exact delimitation of the subject-matter of the following essay also demands a preliminary general view of the historical background of the above doctrines - the background from which they have arisen and which, partly at least, lends to them their significance. Thus, in sum, the first task is to gain a map, as accurate as possible within the scale available, of the whole country, both historically and systematically; after this it will be possible to indicate what part of it is to be more intensively explored in the remainder of the essay. These first problems will form the subject-matter of the Introduction and Part One