1. Foreword. Man's every act is an act of faith; generally, an unconscious faith; seldom, an examined faith; never, a faith that by taking thought could have been replaced by assured certainties. All this appears whenever we stop to “rationalize” our conduct. Whatever that conduct may have been, it can be made to appear reasonable only if some propositions are taken to be true, others false. Or, perhaps the more experienced and less exacting mind would feel the reasonableness of its actions to have been as well established as might be, if it could show the premises with which its acts were consistent to be more likely true than false; those with whose truth they were inconsistent, more likely false than true. Either way of putting it points to the one moral; namely, that, apart from incalculable chance, there is nothing but one's judgment in the matter of premises to determine all that one's life can come to know of fruition or frustration. Nothing, then, can be more important to any man than to do all he can to assure the soundness of his reasons for the faith that is in him; i.e. to test the weight of evidence supporting the working hypotheses on which he is willing to act. But to have considered the evidence for the hypotheses on which he has acted or is prepared to act, could be practically useful only to one who had in one way or another come by a sound idea of the evidence on which one should act, if one's actions are not to end in disappointment. The result at which a man's thought on this matter of evidence may have arrived, will constitute his theory of evidence; and the task of constructing the soundest possible theory of evidence is the undertaking of philosophy.

Biological science does not try to distinguish between health and disease. Biology is concerned with the interaction between living organisms and their environment. What we call health or disease is quite irrelevant.

These reactions between the individual and his environment are complex. The individual and his surroundings form an integrated system which we can arbitrarily divide into two parts. There is an “external” component, by which we mean such factors as light, heat, percentage of oxygen in the air, quantity of minerals or vitamins in food, micro-organisms in food or air, and so on. These can induce changes in what we arbitrarily call the “internal” component. Here we include such crude factors as anatomical structures, or finer details like composition of intercellular fluid, or secretions of glands, or changes of electrical potential in nerve or muscle.

1. It seems plausible to say that a language is a system of expressions the use of which is subject to certain rules. It would seem, thus, that learning to use a language is learning to obey the rules for the use of its expressions. However, taken as it stands, this thesis is subject to an obvious and devastating refutation. After formulating this refutation, I shall turn to the constructive task of attempting to restate the thesis in a way which avoids it. In doing so, I shall draw certain distinctions the theoretical elaboration of which will, I believe, yield new insight into the psychology of language and of what might be called “norm conforming behavior” generally. The present paper contains an initial attempt along these lines.

1. Some Preliminary Distinctions. The relation between the natural and the social sciences, as it bears on their respective subject-matters, methods, and propositions, has long been a source of problems for the philosophy of science. The title of this paper is intended to indicate one of the most basic of these problems. Before developing my point, however, I wish to guard against a possible misinterpretation. I am not questioning the accepted fact that as knowledge in any field advances men may come to recognize the incorrectness of what they had previously regarded as “laws” in that field, and may consequently “change” these laws to take account of such increased knowledge. Let me call this kind of change of laws doctrinal change. The kind of change about which I am asking is rather a change in the subject-matter itself insofar as it is subject to laws—i.e., a change in the causal relations among the facts, objects, properties, events, or whatever they may be called, with which the science deals. Let me call this kind of change of laws factual change. Now, without inquiring more fully at the moment into the nature of scientific laws as such, we may say that the history of science shows that men can and do effect doctrinal changes in the laws of any science, natural as well as social, and formal as well as empirical. And it is recognized also, with minor exceptions to be noted later, that men cannot effect factual changes in the laws of the natural sciences, since these are independent of human volition or decision. The question I am asking, then, is whether men can effect factual changes in the laws of the social sciences.

What sort of subject is the philosophy of science? It would be difficult to find any sort of agreement on the answer to this question. There are a large number of physicists who have promoted the idea that the subject is a kind of cosmic journalism: any new major discoveries in physics warrant an up-to-the-minute, catch-as-catch-can analysis of the boundaries of scientific knowledge. On the other hand, the Oxonian sirens of ordinary language tell us that any careful scrutiny of technical scientific matters is not proper philosophical activity. I want to argue that the philosopher of science need be neither a journalist of science nor merely an acute man of common sense eternally restricted to contemplating the general meaning of such notions as those of mind, free will, cause and determinism.

1. Introduction. The germ of the clock paradox was contained in Einstein's fundamental paper on the special theory of relativity, where he declares that the retardation of a moving clock “still holds good if the clock moves from A to B in any polygonal line, and also when the points A and B coincide.” This remark soon gave rise to a criticism which was to play a prominent role in the discussions of the consistency of the theory of relativity. It was charged that this theory allows the paradoxical conclusion that at the instant of the return of a moving clock U1 to its point of departure A, the time shown by Ul is both earlier and later than the corresponding reading of a clock U2 which has remained stationary at A during U1's journey. Critics based this contention on the following assumptions, for which they claimed the sanction of relativity: (i) The relative motion of U1 and U2 is such that the kinematic process seen by an observer on one of these clocks is of the same character as that seen by an observer on the other, and this symmetry allows each of these two clocks to be used as a reference frame from which to describe the motion of the other, and (ii) there is reciprocity between these two reference frames such that in each of them, the moving clock must be slow upon returning to the stationary one.

It has been shown by several authors that in operations involving information a quantity appears which is the negative of the quantity usually defined as entropy in similar situations. This quantity ℜ = − KI has been termed “negentropy” and it has been shown that the negentropy of information and the physical entropy S are mirrorlike representations of the same train of events. In physical terminology the energy is degraded by an increase in entropy due to an increased randomness in the positions or velocities of components, wave functions, complexions in phase space; in informational terminology some information about the same components has been lost or the negentropy has been decreased. In equilibrium the system has for a given energy content maximum randomness (or minimum information is required). One consequence of this dual aspect was the idea to apply the methods of statistical mechanics to problems of communication and Brillouin showed that Fermi-Dirac statistics or generalized Fermi statistics are applicable for example to a transmission of signals such as telegrams.

When the terms ‘control’ and ‘experiment’ are used in reference to the methodological procedures of the social sciences, frequently the question is raised as to whether or not the investigator uses the terms in the same sense as the natural scientist. The purpose of this paper is to show that the social scientist has good reason to use them in the same sense and that in fact this usage is consistent with a long tradition of social research. This will be shown by an investigation of some common assumptions in the social sciences, such as, (a) the claim that the social sciences are younger than the natural sciences and that the former have depended upon the latter for methodological cues, (b) that human behavior is ultimately inexplicable and unpredictable, and (c) that the social scientist is unable to observe human behavior under controlled, experimental conditions except in trivial instances. Of course, not all social scientists make these assumptions but they occur in the literature and their significance is considerable when the scientific status of the social sciences is being discussed.