It is essentially a truism that the natural sciences have little or no place for dogmatism; to the contrary, there is an underlying skepticism pervading all scientific propositions. Any philosophy which pretends to provide an adequate philosophy of science, should, it seems to me, exhibit epistemologically a corresponding skepticism. At the very least, such a philosophy should demonstrate a skepticism in its views of the “truth” of scientific statements.

Here we will discuss the necessary relationship between both prediction and human behavior and meaning and human behavior. The main assumption upon which our thesis rests is that knowing is for the sake of acting and that, consequently, the symbolic process is continuous with overt bodily behavior and with the environment of the knower. A corollary to this assumption is: the locus of meaning is in behavior. Possibly after reading the article it will be clear that meanings presuppose conduct of which we can take cognizance, and that there is a difference between behaving and taking cognizance of behavior (both actual and possible). And although the locus of meaning is in behavior, meanings emerge only in relation to the symbolic process. In a sense we suffer, endure, live through behavior, but in the bare suffering of it there may be no meaning, for meaning requires also the symbolic process.

The death of Alfred North Whitehead late in 1947 was a double loss. Those who knew Whitehead, even slightly, feel keenly the loss of a warm and stimulating personality, which in the last years of his retirement had mellowed to a benign radiance. The wider circle of students and teachers of philosophy who knew him through his writing alone regret the passing of the man who, many thought, was the most capable cosmologist of our time.

Comments on Professor Feigl's very comprehensive review of the problem of existential hypotheses may take one of two forms. One may accept the problem in Feigl's own terms and either sympathize or criticize the realistic empiricism to which he subscribes. Or, one may feel that the entire approach is ill-founded, and hence that the distinctions in viewpoints which he draws are comparable to splits in a political party whose basic tenets are incompatible with one's own. This comment takes the second course, and as a commentary can do little more than point out the more serious of the differences which separate Feigl's views from those of the writer.

The issue “realism vs. phenomenalism” or “realism vs. positivism” has been widely discussed during the last fifty years. The issue has even become a political and social one in Lenin's Materialism and Empiriocricism, which is built entirely around this topic. He calls “positivism” bluntly a “reactionary philosophy” because it supposedly denies the reality of the world which is described by science. M. Schlick devoted to this issue the paper “Realism and Positivism” which was published recently (in English) with an introduction by D. Rynin. It should, therefore, be welcomed, that Professor Feigl attacked this problem by the methods of modern semantics. This is an attempt to solve a question by precise logical argument which has been frequently treated in a way that provided more heat than light. It is certainly very desirable to scrutinize Feigl's argument carefully and to find out exactly its contribution to our conception of scientific method.

Professor Feigl's admirably lucid and concise appraisal of the major considerations which are still significant in the controversy between realism and phenomenalism includes the important reminder that the problem at hand should be viewed as concerning, not the truth or falsity of two conflicting hypotheses, but rather the comparative adequacy of two alternative proposals for the rational reconstruction of scientific knowledge. Feigl advocates the approach of semantic realism in preference to a phenomenalistic type of reconstruction on the grounds that in his critical examination, the latter has been “found wanting,” whereas semantic realism—and only semantic realism—can provide a satisfactory systematic account of the meaning and the experiential foundation of scientific hypotheses. While I fully agree with Feigl's general appraisal of the issues involved, I have doubts as to the superiority of the proposed realistic interpretation, and I should like to state these here in outline.

A special merit of Professor Feigl's stimulating essay lies in the clarity with which he draws the issue between phenomenalistic and realistic interpretations of science as one concerned entirely with the evaluation of their relative adequacy as analytic reconstructions of empirical knowledge. Responsible and fruitful discussion of these interpretations cannot therefore be a debate over the truth or falsity of scientific theories. For as he carefully notes, the differences between these alternative analyses are not “pragmatic differences” of the ordinary sort, since no differences in regard to any observable consequences that could weigh for or against a scientific theory can be associated with them. Feigl's own rejection of phenomenalism and his espousal of semantic realism must in consequence also be judged in terms of the standard he himself has recognized as alone relevant in this discussion.

The literature of science speaks of many things in the heavens and on earth that neither the man in the street nor the scientist in his laboratory, can directly see with his eyes or touch with his fingers. Scientific hypotheses refer to atoms and genes, cosmic rays and electrostatic charges. No one can deny the importance of these hypothetical constructions; without them we could neither understand nor manage the world which we directly experience. They simplify the system of laws that relate observable variables to one another. They suggest further research and enable us to predict what will be found if certain operations are carried out. The sporadic and disjointed collection of observed objects and events, and the occurrence of the unusual ones which we call illusions, are explained by correlating them with a hypothetical physical or physiological state of affairs that has order and spatio-temporal continuity.

In this rejoinder to the critical comments elicited by my essay “Existential Hypotheses,” I propose to deal first with the challenge coming from the avowedly different philosophical outlook of Professor Churchman. My other critics, Professors Frank, Hempel, Nagel and Ramsperger, on the whole, share my basic conception of the tasks of philosophy of science and epistemology, even if they dissent in one important respect or another from the special solution I suggested. But since I discern even in Professor Nagel's remarks (and possibly also between the lines of Professor Ramsperger's comments) a pragmatist or instrumentalist strain akin to the major contentions of Professor Churchman, it will be well to begin with a defense and further clarification of my underlying point of view. Only after this restatement of my platform will I undertake to defend semantic realism against the specific criticisms advanced by the last four authors.