I shall be concerned in this paper with the consideration of panpsychism and of materialism in new forms as alternatives. Extended reference will be made to C. S. Peirce's view of perception as realistic in intention and yet not quite clear as to its mechanism and how it attains objective import. I shall say little about Whitehead as a representative of panpsychism as I have just finished a detailed criticism of his epistemological framework. I shall, however, make comments on William James's radical empiricism as tied in with his view of perception as direct and immediate—roughly speaking, the alternative to Locke's representation of “unperceived things”—and bring in my own theory of sensations as guiding perceiving. Russell's neutral monism, connected historically with James's radical empiricism, will be touched on here in connection with his rejection of materialism. Phenomenalism and materialism exclude each other. Materialism, as an ontology, requires a realistic epistemology. I shall also make some comments on Dewey's biological experientialism. One can often best explain a perspective by means of contrasts.

It is helpful for any enterprise to stop occasionally and examine itself. Science has done this rather infrequently in its long and eventful history, and there has not been, in general, any continuity in these self-examinations. As a result the history of the philosophy of science has been a rather spotty affair. My belief is that the philosophy of science should also, at times, become self-critical. When a study is concerned primarily with methods of other disciplines it tends to underemphasize the role played by the methods which it itself uses. What is the method of the philosophy of science, and is it justifiable? Can there be a satisfactory study of science and can this be scientific?

Part I is concerned with the tenet of modern Emperical Realism that while the theoretical concepts employed in science obtain their meanings entirely from the connections their usage establishes with the data language, the referents of such terms may be “unobservables,” that is, entities which cannot be discussed within the data language alone. Such a view avoids both the restrictive excesses of logical positivism and the epistemic laxity of transcendentalism; however, it also necessitates a break with classical semantics, for it follows from the empirical realistic position that a theoretical term must in principle be capable of simultaneously designating not just one entity, but indefinitely many.

Drawing upon the Carnapian explication of “analytic truth,” Part II examines a possible axiomatic basis for the empiricist theory of scientific meaningfulness to demonstrate that even if theoretical terms are able to designate entities inaccessible to the observation language, as held by Empirical Realism, so long as the meanings of theoretical terms derive from their connections with the observation language, the meaning content of a theory is exhausted by its observational consequences.

It is claimed that 'Do x!“ means 'Then you will do x'. Answering a “Why?” question concerning the former may take either of two forms, viz., 'Because ——' or 'If you wish to ——'. The second answer completes the truncated hypothetical. “Ought” sentences are treated as a species of imperatives involving universality in the “if” clause ('If anyone wished to ——'). Moral “ought” sentences involve a double universality, viz., the one mentioned above and universality connecting the action with social harmony (e.g., “If everyone were to do x, then there would be social harmony').

At this juncture, we must not minimize grave concerns which remain. As Jeffreys [28, 29] and Carnap [10] have candidly admitted, and as Fisher [20] has strenously insisted in his luminous assessment of the meaning and limitations of Bayes' theorem, there apparently must exist for the possibility of the successive application of Bayes' theorem to a hypothesis on the basis of a sequence of experimental observations, an initial evidence or judgment base, say e′, which is not itself compounded out of new observation and a prior evidence base. For e′, Pr(H) must be estimated for the first time, so to speak. Setting aside any investigation here as to whether an epistemology [52, 53, 54] which looks to Carneades as well as Plato-Aristotle, and to Hegel as well as Locke, must be bound eternally to the notion of unreconstructible “first” terms in the sequences of controlled inquiry, it must in any case be admitted that attainability of the initial estimate Pr(H/e′) is a task of enormous difficulty, as one may for example, notice in Peirce's [44] very bitter struggle with it. To assume that “initial” prior probabilities are impossible of achievement is an a priori dispair which is, as usual, no more warranted than a priori optimism. There do exist interesting proposals for making the required kind of “first” estimates in Carnap, Wald, and Jeffreys; in Jeffreys [28] the entire situation is vividly characterized and the ingenious suggestion offered that even for an infinite number of relevant hypotheses each of them may be assigned positive probabilities “even on no observational information at all” by ordering these positive probabilities in a converging series, whose sum is equal to 1, by judgments of comparative (mathematical) simplicity. Those like myself who have never encountered, even in Einstein [18], an independent or simple criterion of simplicity of laws will not, of course, consider Jeffreys' proposal to be even nearly definitive; yet it serves well to challenge the dogmatic despair concerning the usefulness and relevance of Bayes' theorem.

I wish to examine the “justification” or “vindication” of inductive procedure that has been set forth in various places by the late Professor Reichenbach and by Professor Feigl, most recently by the latter. Although Professor Feigl has explicitly referred to this kind of a “vindication” as “trivial,” it is nevertheless evident, from the stress placed upon and the space devoted to this proposal, that both Professors Feigl and Reichenbach attach considerable importance to it. Thus Professor Feigl says: