Just How Much Do We Really Know?

Dewey B. Larson

Physical science stands today in a highly anomalous position. On the one hand, no branch of knowledge has ever occupied a higher place in general public esteem. The spectacular way in which the abstract ideas of the theoretical scientist and the discoveries of his colleagues in the laboratories have been applied to the fashioning of ingenious devices that have drastically changed the whole world picture has made a profound impression on the man in the street, and the word “scientific” has acquired an unparalleled prestige. To some degree, at least, these sentiments are shared by the rank and file of the professional scientists, and the confident words “We know...” continually echo and reecho through the halls of learning.

But this unbounded confidence is completely lacking among the “insiders” of the profession, the relatively small group of theorists who bear the burden of keeping scientific theory equal to the growing demands upon it: demands which continually become more urgent as the pace of discovery quickens in the laboratories and in the observatories. These men make no secret of their dissatisfaction with present-day theory and their grave concern over the future of physical science. P.A.M. Dirac, for instance, tells us flatly that after many years of intensive research the efforts of the world’s physicists to find a satisfactory theory have been a failure.² Coming as it does from one who has had a prominent part in the development of those modern theories which he characterizes as failures, this statement stands in marked contrast to the complacent attitude of the scientific profession in general with regard to the adequacy of the underpinnings of their theoretical structure.

Nor is Dirac alone in his opinion. Practically all of the most prominent leaders in theoretical science have expressed somewhat the same thought, explicitly or tacitly, at one time or another during recent years. Erwin Schrödinger, another of the developers of current theory, fervently hoped for some upheaval of old beliefs which in the end will lead to something better than the mess of formulas which now surrounds our subject.³ P.W. Bridgman aimed many a sharp barb at the most cherished doctrines of modern science. Is this honestly... a very impressive performance? he asks, referring to wave mechanics, Is it not exactly the sort of compromise that we should have predicted in advance would be the only possible one if it should prove that we were incapable of inventing any vitally new way of thinking about small-scale things?⁴ And he sums up his impressions of the General Theory of Relativity in these words: ...It seems to me that the arguments that have led up to the theory and the whole state of mind of most physicists with regard to it may some day become one of the puzzles of history.⁵ Even Werner Heisenberg, whose attitude toward present-day theory is particularly sympathetic because of his close personal identification with some of the outstanding features of the system of thought currently in vogue, reveals his true appraisal of the existing situation when he admits, It is obvious that at the present state of our knowledge it would be hopeless to try to find the correct theory of elementary particles.⁶ Such comments and admissions by some of the principal architects of currently accepted theory are particularly significant, but there is no lack of confirmation from other sources. Some theorists are beginning to doubt whether an adequate theory can ever by constructed. C.N. Yang of Princeton, for example, was quoted in a recent news release as expressing some doubts about the ability of the human brain in general, and his in particular, to accomplish this task.⁷ Truly, as Philip M. Morse characterized the existing situation, It is an unhappy time for theory.⁸

The question Why? naturally suggests itself. Why do the acknowledged leaders in the field take such a pessimistic view of the theoretical structure that is regarded so highly by the rand and file of the scientific profession: a structure that enjoys an acceptance so complete that even the most extravagant claims in its behalf are received without demur? The answer to this question is not at all difficult to find; on the contrary, it is almost immediately evident that these leading theorists are appraising currently popular theory much less favorably because they are applying more rigid standards in judging the validity of current claims to knowledge. The scientist who attempts to clarify or improve the structure of theory cannot afford to follow the general practice of accepting today’s best guess as the equivalent of fact; he has to do his best to make certain of the solidity of his foundation before he attempts to build anything upon it. All too often that foundation crumbles in spite of all of the care that is taken to check it thoroughly; anything less than this maximum care would simply invite disaster.

To those who look upon present-day scientific “knowledge” from this critical viewpoint it is obvious that much of it is not knowledge at all. Such a statement may seem incredible on first consideration, since it is generally understood that physical science is an “exact” science and that it draws a clear line of demarcation between factual and non-factual material. In theory this is true. Speculation and hypothesis play and important part in scientific research, but the products of such activity are not supposed to be considered in any way authoritative unless and until they are verified by experiment or observation. The most distinctive feature of science is that its acceptance of the established facts as the ultimate authority. As it happens, however, scientists are not only scientists, they are human beings, and in this latter capacity they are subject to the ordinary weaknesses of the human race, including a strong bias in favor of familiar and commonly accepted ideas, a totally unscientific reliance on presumably authoritative pronouncements, and a distinct reluctance to admit ignorance. All of these add up to a marked tendency to regard general acceptance as equivalent to proof, a tendency that has the effect of diluting the firmly established factual material of science with a larger admixture of matter of an unproved and uncertain character.

It is generally conceded that physical science is faced with a difficult and formidable task in readjusting its basic concepts to enable overcoming the obstacles that now stand in the way of further progress. Here are some of the recent comments on the subject: from J.R. Oppenheimer, It is clear that we are in for one of the very difficult, probably very heroic, and at least thoroughly unpredictable revolutions in physical understanding to physical theory⁹; from Freeman J. Dyson, For the last ten years it has been clear to most physicists that a basic conceptual innovation will be needed in order to come to grips with the properties of elementary particles¹⁰; from David Bohm, Moreover, physics is now faced with a crisis in which it is generally admitted that further changes will have to take place, which will probably be as revolutionary compared to relativity and the quantum theory as these theories are compared to classical physics¹²; from Norwood R. Hanson, The whole [quantum] theory may topple; in places the foundations seem far from secure¹³; from Ernest Hutten, Most physicists feel that the time is ripe, again, for a radical change in our ideas, and for a new theory.¹⁴

But what happens if the hopes of Schoedinger, Hutten, et al., materialize and the revolutionary new theory which they anticipate so eagerly actually does appear? As matters now stand, such a theory will be summarily rejected, as it will inevitably conflict with many of the ideas and concepts that we are not permitted to question because they are part of the basic dogma of present-day science, even though they may owe that standing merely to general acceptance rather than to any factual support. The fate of these new ideas is all the more certain because the task of appraising them is normally left to a small group of individuals who, although they may be willing to concede the necessity for radical changes in principle, are strongly opposed to any change in the general lines of thought to which they are now committed. The average scientist does not normally feel that he can take the time to examine basic scientific concepts thoroughly. As Bridgman points out, many of the old ideas to which he subscribes have not been thought through carefully but are held in the comfortable belief that some one must have examined them at some time.¹⁵

The objective of this memorandum is to bring out that under present conditions the scientific profession cannot afford to rely on this indefinite some one to put its theoretical house in order;