The time has long passed when it was necessary to explain or to justify philosophy of science to a convention of scientists. The growing intent among philosophers and scientists to clarify and perhaps to unify the programs, methods, and results of the disciplines of philosophy and science is matched by a growing determination among the special sciences to cooperate in the examination of fundamental concepts and presuppositions in the light of the positive results of science, to cooperate in the systematic doubting of these positive results, and to cooperate in the thoroughgoing analysis and critique of logic and of language,—all of which are projects which can be carried out only by the joint effort of philosophers and scientists. In short, it has long since been realized that the special sciences cannot safely be abandoned to their devotees, exclusively. It was only twenty-five years ago that Santayana was able to say “I would gladly learn more of contemporary thinkers if they would only learn more of each other.” The implication that lies in that statement is hardly the case today, when the synoptic enterprise of philosophy-of-science is helping the scientific thinker to recognize the limitations of his task and the assumptions with which he starts, and to save him from being too easygoing in the criticism of his categories.

More and more, natural scientists are becoming aware that they must consider the human element as one of the variables in physical measurement. Its measure has usually been hidden in what has been called the error of measurement. Part of its measure has been qualitative for we often hear that Mr. Soandso is a good or a poor experimenter or observer. As we go to engineering research or to any applied field, we become more conscious of the human element. Here, an attempt is made to design apparatus and measuring equipment that will operate or make measurements with minimum variability associated with people. Some problems, such as those dealing with what consumers want, require an even more complete knowledge about the behavior of people. It is not possible to define or to specify a product that will be satisfactory to the consumer if we do not know what the consumer wants. Hence, it is our first observation that the natural scientist needs information about the human element that is always present to some degree in his work.

The explosion of the first atomic bomb at the Alamagordo Bombing Range, New Mexico, on July 16, 1945, was the start of a new era, the dawn of the atomic age. The preliminary work on atomic fission was done before the last world war, and as military leaders visioned its great destructive possibilities, several countries entered the race to be the first to harness atomic fission for military purposes. Our own country gambled two billion dollars, and with the aid of certain European scientists and in collaboration with England and Canada, succeeded in developing a fission chain reaction that made possible the atomic bomb.

The very juxtaposition of the terms “physical science” and “social sciences” in the same sentence is indicative of the definitive trend now present in both physical science and in the thinking of the physical scientist. The two fields of human interest represented by physical science and the social sciences have drawn closer together, have coalesced at least in those areas of implication deducible from the fields themselves and this conjunction is fraught with consequences important to both fields.

The purpose of my remarks is to draw some conclusions about the conditions which must be realized if physical, biological and social scientists are to work effectively in reaching common goals. I shall draw these conclusions on the basis of my experience as a psychologist whose participation in the war effort found him a member of a team composed principally of physicists and research engineers. I may say that while my experiences were largely at the level of the lower echelons of the working fraternity, the conclusions appear to me to have application without regard to the extent of the brass which, in a figurative sense, decorates the scientist's hat.

Today a failure of the physical sciences accompanies a failure of the social sciences; and the failure of both consists in part in this: in the lack of a fully-developed and implemented sense of social responsibility. Both have denied guilt for their shortcomings in this respect: advancing rationalizations to the effect that social reform is not the task of science; that objectivity suffers if such motivations are allowed to become involved; and that science makes its most valuable contributions to social welfare rather by maintaining a strict laboratory manner of impartiality. Implied often, as well, is the conclusion that not science itself but the misuse of science; not the patience and care of science itself but the impatience and carelessness of non-scientists is responsible for the miscarriage of its contributions.

As I understood it, the general aim of the symposium was exploratory. Is there need of cooperation between the two divisions? And in what respects? Granting the fullest measure of autonomy, in what way, if any, can there still be mutual assistance?

What I am going to say here may be thought by some to be more appropriate to science as a whole, rather than “what sociology has to offer to the physical sciences.” The main point of my remarks has to do with objectivity and values in science. Great masses of people are today in doubt as to whether science is a friend or an enemy of theirs. They do not see it as a means to continued material progress, as objectively measured in such things as the level of living, and morbidity and death rates. To them it is, for example, a means for spreading mass misery through depressions due to technological unemployment. Or, it is the means for the production of ever more destructive weapons in continually more destructive wars.

The papers given at this symposium have been directed to two problems:

1. (1) the needs of the physical sciences which the social sciences should fulfill, and

2. (2) the capacity of contemporary social science to satisfy these needs.

Consideration of the first problem divided itself into two parts: (a) the needs involved in the process of answering questions in the physical sciences, and (b) the needs involving application of information gained by questions in physical science. The role of social science with respect to (b) is generally recognized, but the role with respect to (a) is not. Many, in science and philosophy, still hold to the notion of a non-evaluative, non-normative, purely objective, or what-have-you physical science. Professor Littauer, however, raised a critical problem in this regard: on what basis is the decision made to accept or reject a scientific hypothesis? We are in a position today to assert that such decisions do involve an evaluative judgment. Recent developments in mathematical statistics, as represented in Wald's On the Principles of Statistical Inference, indicate that the selection of the best statistical testing procedure involves at least a knowledge of the social consequences for the various mistakes one might make in using any specific testing procedure. The introduction of the “weight function” into the method for selecting among alternative hypotheses points in a striking way to one door through which knowledge and evaluation of possible social phenomena enters physical science. The social scientist is badly needed here. It is true that today this aspect of experimental method is seldom self-consciously faced. Where it is, the evaluations are generally intuitive and are not based on sound sociological knowledge. But it is becoming increasingly clear that the continued development of experimental methods in all sciences depends on our reducing the question of what constitutes a “best” test to experimental terms.

A theory in natural science is a comprehensive formula or doctrine which describes and correlates in a unified abstract form of statement the general determining factors of some special group of natural facts. It is at once inclusive, realistic and understandable. If a theoretical statement holds good, the existence and characteristics of many individual events can be inferred deductively from it. It thus gives a logical basis for empirical fact. But it is based on experience of nature, and must conform to the facts of nature; these are primary, and a valid theory, no matter how broad it may be, is to be considered as itself a statement of fact, i.e., a true description of some condition which has a real and stable existence in the natural world. In its scientific usage, the term “fact” refers primarily to some datum of experience having the special character of permanence or regular recurrence; this is why scientific facts are verifiable; in this respect they differ from the passing individual events of history. Any scientific theory presupposes the stability and unequivocality of the natural facts. Hence if a theory is sound, it furnishes a reliable basis for prediction, discovery and invention. Scientific or technological creation then becomes possible; modern engineering and medicine could never have become what they are without a background of theoretical physics and biology. Obviously any natural science must always have at its disposal an ample body of observational and experimental data, but in most cases the work of collecting and verifying these is carried out under the guidance of theory.

To explain the phenomena in the world of our experience, to answer the question “why?” rather than only the question “what?”, is one of the foremost objectives of all rational inquiry; and especially, scientific research in its various branches strives to go beyond a mere description of its subject matter by providing an explanation of the phenomena it investigates. While there is rather general agreement about this chief objective of science, there exists considerable difference of opinion as to the function and the essential characteristics of scientific explanation. In the present essay, an attempt will be made to shed some light on these issues by means of an elementary survey of the basic pattern of scientific explanation and a subsequent more rigorous analysis of the concept of law and of the logical structure of explanatory arguments.