II. The Bare Elements of Scientific Methods

First, not even the “exact” sciences like astronomy or physics are exact in the sense of “absolute” or “infallible.” Their firmest laws or uniformities are to be regarded as tentative. They may be upset at any time by further work. But at any given moment they are not to be tampered with unless they prove unreliable in relation to observed facts. A few mystics, inhibited in our crass society from the delights of navel-gazing, have made too much of the contemporary revolution in physics. Newton’s laws have not been “disproved”; nor has the principle of indeterminacy been so firmly established as to make all men equally good at the game of poker. What has happened in modern physics, as far as a layman can judge, is that the physicist has been sharply reminded that even his neatest uniformities are not absolutes, but are subject to correction, that he is safer in regarding these uniformities as based on observations rather than on the will of God, or the nature of things, or on reality.

This brings us easily to the second point. Science makes no attempt to study or describe reality—certainly not ultimate reality. Science is not even concerned with truth, in the sense that word has for theologians, for most philosophers, and for a good many other people. The desire to find a final cause, an unmoved mover, a Ding an sich, seems to be so common in men that we have no grounds for believing that this search is not, in one form or another, a fairly constant element in human society. Only, scientists as scientists can have no part in such a search. This by no means need be taken as indicating that the search is silly, and ought to be stopped. Some scientists have lately been, as private persons, very active in the search, and indeed, after the manner of such searches, successful. Faith has long since found God in unlikelier places than the atom. But such discoveries are not the discoveries of science. That discipline is based, not on faith, but on skepticism, on a skepticism that will not even worry itself over its status in the universe. And so the scientist works on serenely, undisturbed by the philosopher’s final thrust: that to be constantly skeptical is to believe in doubt, which is after all a form of faith.

Third, the scientist by no means confines himself to “the facts and nothing but the facts.” Dangerous metaphysical depths yawn at this point, but we shall have to try and go ahead in spite of them. The popularization of Baconian ideas on induction is probably the chief source of the erroneous notion that the scientist does nothing to the facts he laboriously and virtuously digs up, except to let them fall neatly into a place they have made for themselves. Actually the scientist cannot work without a conceptual scheme; and though the relation between facts and conceptual schemes is not by any means clear it is at least clear that a conceptual scheme involves something besides facts.

Let no one be frightened of the technical term “conceptual scheme.” It is really very simple: thunder and lightning impinge on our senses of hearing and sight—probably the mere differentiating of this sound and this flash from other sounds and flashes means that we are employing a conceptual scheme; certainly when we think of Jupiter with his bolts, Thor with his hammer, or the electrical discharge of modern physics, we have clearly arranged our sense-perceptions in accordance with definite conceptual schemes. We possess, indeed, the basic elements of three different theories of thunder and lightning, three different uniformities in these phenomena. But the only important reasons why we should prefer our electrical discharge to Jupiter or Thor as a conceptual scheme is that it is more useful, and that we can by using it get on better also with other conceptual schemes we use for similar purposes. But in the sense which the word true has for the theologian, and most moralists and philosophers, our electrical discharge is not a bit truer than the old notions about Jupiter and Thor.

We may even use two contradictory conceptual schemes, choosing one or the other at convenience, or from habit. We are all of us educated out of the old Ptolemaic conceptual scheme, which saw the sun moving about a stationary earth, into the Copernican conceptual scheme, which sees the earth moving about a stationary sun. Einstein, of course, used a conceptual scheme different from both of these, but most of us are not yet up to Einstein; in daily life we all, however, contentedly say “the sun rises,” and should be very pedantic indeed if we insisted on saying in Copernican terms “the earth has revolved into sight of the sun.” More important is the present situation in respect to conceptual schemes in modern physics. We learn, as far as laymen can learn in such matters, that physicists find it convenient in the study of certain problems to regard the electron as a particle, or at least a point, and in the study of other problems to regard it as a wave. Some physicists, many of them of very great distinction indeed, are troubled by this contradiction, and have sought to work out a single conceptual scheme which will make the electron a nice logical unity again. One suspects, however, that these physicists have left in them a little of the philosopher, and that it is their philosophical selves that demand unity in the electron. For other physicists get on admirably with this logically impossible electron, wave when they want it to be a wave, particle when they want it to be a particle. As scientists, they are quite content to solve their problems, which deal wholly with this world and can be solved in this world, though no doubt not in the next, without regard for ultimate truth.

The scientist, then, goes to work roughly in some such fashion as this: he starts with a conceptual scheme of some sort, and questions, or even hypotheses, he frames in terms of that scheme; he then hunts for a suitable supply of facts—and a fact in the natural sciences we define with Professor L. J. Henderson as “an empirically verifiable statement about phenomena in terms of a conceptual scheme”; these facts he seeks to arrange in uniformities or theories which will answer his questions, and perhaps suggest other questions; he then immerses himself again in the hunt for facts, and emerges with new or modified uniformities. The scientist is not interested in where his conceptual scheme came from, or whether it preceded or followed on facts, or whether it is “subjective” and the facts “objective.” These questions he leaves to the philosophers, who have not settled them yet after two thousand years of debate. But the scientist does, by his recognition that a conceptual scheme is as essential to his activity as are observed facts, emancipate himself completely from self-styled “scientific” materialists, positivists, empiricists, who naively assert that our sense-perceptions are somehow in themselves an orderly and sole reality, or a “reflection” of such a reality. For, note particularly, the facts with which the scientist deals are not phenomena, sense-perceptions, the “external world,” those dear absolutes of innocent positivists, but merely statements about phenomena. A properly verifiable statement about Cromwell is then as much a fact as the reading of a thermometer in a laboratory.

Fourth, though the scientist is very careful indeed about matters of definition, and is as disdainful of sloppiness and bad thinking as any logician can be, he distrusts rigidity and attempts at perfection here as elsewhere. He is interested less in beauty and neatness of definition than in having his definitions fit not his sentiments and aspirations, but the facts. Above all, he does not dispute over words. He is less interested in the accurate theoretical distinction between a mountain and a hill than he is in making sure that he is dealing with concrete elevations on this earth. He does not expect class-terms to be perfect, mutually exclusive; when he distinguishes between a plant and an animal, he is not at all offended if you call his attention to a living thing that seems to belong to both his classes at once. He sets to work studying the living thing and will, if necessary, modify his class-terms. But he is quite willing also, if it proves more convenient, to set up a new class-term of borderline plant-animals. This simple willingness to be guided by convenience is of course one of the amazing things about the scientist and one of the most difficult for us who have not had a scientific training to adapt ourselves to. Most of us are early trained to prefer our opinions to our convenience.

Finally, scientific thinking cannot be, except perhaps in suggesting problems, what nowadays most of us know well enough as wishful thinking. The scientist’s own hopes and fears, his own standards of what he would like to have prevail on this earth, must be kept as far as possible out of his work, and especially out of his observations of, or dealings with, facts. How far such hopes and fears and standards enter into his choice of conceptual schemes, how far they influence the kind of questions he asks, are difficult problems we may perhaps be permitted to dodge. Sufficient that the techniques of most of the established sciences provide a very effective check on the cruder forms of wishful thinking. History—because it has been so long an art and a craft perhaps the most respectable of the social sciences—provides in the technical training undergone by most professional historians a surprisingly effective and not wholly dissimilar check on the more violent forms of partisan writing and thinking.

All in all, there is no reason why we should feel that the natural scientist uses methods, sets standards, forever quite unattainable by the social scientist. Natural science as the more innocent materialists of the last century saw it—exact, infallible, a cosmos built on induction—must seem remote to a struggling economist or sociologist. But natural science as it has always been understood by its ablest practitioners and is now widely understood—natural science as expounded methodologically by a Poincaré—is no such thin substitute for Divine Providence, no such metaphysical abstraction. Only God is exact, infallible, omniscient, unchanging, and modern science has been content to leave the search for God to disciplines fitted by long success for such a search.