THE SCIENTIFIC ATTITUDE OF MIND

ANY one who has not had a rigid training in science may advantageously reflect at some length upon the meaning of true scientific induction. Various illustrations in our text are meant to convey the idea that logical thinking consists simply in drawing correct conclusions as to the probable sequence of events in nature. It will soon be evident to any one who carefully considers the subject that we know very little indeed about cause and effect in a rigid acceptance of these words. We observe that certain phenomena always follow certain other phenomena, and these observations fix the idea in our mind that such phenomena bear to one another the relation of effect and cause. The conclusion is a perfectly valid one so long as we remember that in the last analysis the words "cause" and "effect" have scarcely greater force than the terms "invariable antecedent" and "invariable consequent"—that is to say, they express an observed sequence which our experience has never contradicted.

Now the whole structure of science would be hopelessly undermined had not scientific men come to have the fullest confidence in the invariability of certain of these sequences of events. Let us, for example, take the familiar and fundamental observation that any unsupported object, having what we term weight, invariably falls directly towards the centre of the earth. We express this fact in terms of a so-called law of gravitation, and every one, consciously or unconsciously, gives full deference to this law. So firmly convinced are we that the gravitation pull is a cause that works with absolute, unvarying uniformity that we should regard it as a miracle were any heavy body to disregard the law of gravitation and rise into the air when not impelled by some other force of which we have knowledge. Thanks to Newton, we know that this force of gravitation is not at all confined to the earth, but affects the whole universe, so that every two bits of matter, regardless of location, pull at each other with a force proportionate to their mass and inversely as the square of their distance.

Were this so-called law of gravitation to cease to operate, the entire plan of our universe would be sadly disarranged. The earth, for example, and the other planets would leave their elliptical orbits and hurtle away on a tangential course. We should soon be beyond the reach of the sun's beneficent influence; an arctic chill would pervade polar and tropical regions alike, and the term of man's existence would come suddenly to a close. Here, then, is a force at once the most comprehensible and most important from a human stand-point that can be conceived; yet it cannot be too often repeated, we know nothing whatever as to the nature of this force. We do not know that there may not be other starlike clusters beyond our universe where this force does not prevail. We do not know that there may not come a period when this force will cease to operate in our universe, and when, for example, it will be superseded by the universal domination of a force of mutual repulsion. For aught we know to the contrary, our universe may be a pulsing organism, or portion of an organism, all the particles of which are at one moment pulled together and the next moment hurled apart—the moments of this computation being, of course, myriads of years as we human pygmies compute time.

To us it would be a miracle if a heavy body, unsupported, should fly off into space instead of dropping towards the centre of the earth; yet the time may come when all such heavy objects will thus fly off into space, and when the observer, could there be such, must marvel at the miracle of seeing a heavy object fall towards the earth. Such thoughts as these should command the attention of every student of science who would really understand the meaning of what are termed natural laws. But, on the other hand, such suggestions must be held carefully in check by the observation that scientific imagining as to what may come to pass at some remote future time must in no wise influence our practical faith in the universality of certain natural laws in the present epoch. We may imagine a time when terrestrial gravitation no longer exerts its power, but we dare not challenge that power in the present. There could be no science did we not accept certain constantly observed phenomena as the effect of certain causes. The whole body of science is made up solely of such observations and inferences. Natural science is so called because it has to do with observed phenomena of nature.

NATURAL VERSUS SUPERNATURAL

A further word must be said as to this word "natural," and its complementary word "supernatural." I have said in an early chapter that prehistoric man came, through a use of false inductions, to the belief in supernatural powers. Let us examine this statement in some detail, for it will throw much light on our later studies. The thing to get clearly in mind is the idea that when we say "natural" phenomena we mean merely phenomena that have been observed to occur. From a truly scientific stand-point there is no preconception as to what manner of phenomenon may, or may not, occur. All manner of things do occur constantly that would seem improbable were they not matters of familiar knowledge. The simplest facts in regard to gravitation involve difficulties that were stumbling-blocks to many generations of thinkers, and which continue stumbling-blocks to the minds of each generation of present-day children.

Thus most of us can recall a time when we first learned with astonishment that the earth is "round like a ball"; that there are people walking about on the other side of the world with their feet towards ours, and that the world itself is rushing through space and spinning rapidly about as it goes. Then we learn, further, that numberless familiar phenomena would be quite different could we be transported to other globes. That, for example, a man who can spring two or three feet into the air here would be able, with the same muscular exertion, to vault almost to the house-tops if he lived on a small planet like the moon; but, on the other hand, would be held prone by his own weight if transported to a great planet like Jupiter.

When, further, we reflect that with all our capacity to measure and estimate this strange force of gravitation we, after all, know absolutely nothing as to its real nature; that we cannot even imagine how one portion of matter can act on another across an infinite abysm (or, for that matter, across the smallest space), we see at once that our most elementary scientific studies bring us into the presence of inscrutable mysteries. In whatever direction we turn this view is but emphasized. Electricity, magnetism, the hypothetical ether, the inscrutable forces manifested everywhere in the biological field—all these are, as regard their ultimate nature, altogether mysterious.

In a word, the student of nature is dealing everywhere with the wonderful, the incomprehensible. Yet all the manifestations that he observes are found to repeat themselves in certain unvarying sequences. Certain applications of energy will produce certain movements of matter. We may not know the nature of the so-called cause, but we learn to measure the result, and in other allied cases we learn to reason back or infer the cause from observation of results. The latter indeed is the essence of scientific inquiry. When certain series of phenomena have been classified together as obviously occurring under the domination of the same or similar causes, we speak of having determined a law of nature. For example, the fact that any body in motion tends to go on at the same rate of speed in a direct line forever, expresses such a law. The fact that the gravitation pull is directly as the mass and inversely as the square of the distance of the bodies it involves, expresses another such law. The fact that the planetary bodies of the solar system revolve in elliptical orbits under the joint influence of the two laws just named, expresses yet another law. In a word, then, these so-called "laws" are nothing more than convenient formulae to express the classification of observed facts.

INDUCTIVE VERSUS DEDUCTIVE REASONING

The ancient thinkers indulged constantly in what we now speak of as deductive reasoning. They gave heed to what we term metaphysical preconceptions as to laws governing natural phenomena. The Greeks, for example, conceived that the circle is the perfect body, and that the universe is perfect; therefore, sun and moon must be perfect spheres or disks, and all the orbits of the heavenly bodies must be exactly circular. We have seen that this metaphysical conception, dominating the world for many centuries, exerted a constantly hampering influence upon the progress of science. There were numerous other instances of the same retarding influence of deductive reasoning. Modern science tries to cast aside all such preconceptions. It does not always quite succeed, but it makes a strenuous effort to draw conclusions logically from observed phenomena instead of trying to force observations into harmony with a preconeived idea. Herein lies the essential difference between the primitive method and the perfected modern method. Neither the one nor the other is intended to transcend the bounds of the natural. That is to say, both are concerned with the sequence of actual events, with the observation of actual phenomena; but the modern observer has the almost infinite advantage of being able to draw upon an immense store of careful and accurate observations. A knowledge of the mistakes of his predecessors has taught him the value of caution in interpreting phenomena that seem to fall outside the range of such laws of nature as experience has seemed to demonstrate. Again and again the old metaphysical laws have been forced aside by observation; as, for example, when Kepler showed that the planetary orbits are not circular, and Galileo's telescope proved that the spot-bearing sun cannot be a perfect body in the old Aristotelian sense.

New means of observation have from time to time opened up new fields, yet with all the extensions of our knowledge we come, paradoxically enough, to realize but the more fully the limitations of that knowledge. We seem scarcely nearer to-day to a true understanding of the real nature of the "forces" whose operation we see manifested about us than were our most primitive ancestors. But in one great essential we have surely progressed. We have learned that the one true school is the school of experience; that metaphysical causes are of absolutely no consequence unless they can gain support through tangible observations. Even so late as the beginning of the nineteenth century, the great thinker, Hegel, retaining essentially the Greek cast of thought, could make the metaphysical declaration that, since seven planets were known, and since seven is the perfect number, it would be futile to search for other planets. But even as he made this declaration another planet was found. It would be safe to say that no thinker of the present day would challenge defeat in quite the Aristotelian or Hegelian manner; but, on the other hand, it is equally little open to doubt that, in matters slightly less susceptible of tangible demonstration, metaphysical conceptions still hold sway; and as regards the average minds of our time, it is perhaps not an unfair estimate to say they surely have not advanced a jot beyond the Aristotelian stand-point. Untrained through actual experience in any field of inductive science, they remain easy victims of metaphysical reasoning. Indeed, since the conditions of civilization throw a protecting influence about us, and make the civilized man less amenable to results of illogical action than was the barbarian, it may almost be questioned whether the average person of to-day is the equal, as a scientific reasoner, of the average man of the Stone Age.

A few of the more tangible superstitions of primitive man have been banished from even the popular mind by the clear demonstration of science, but a host remains. I venture to question whether, if the test could be made in the case of ten thousand average persons throughout Christendom, it would not be found that a majority of these persons entertain more utterly mistaken metaphysical ideas regarding natural phenomena than they do truly scientific conceptions. We pride ourselves on the enlightenment of our age, but our pride is largely based on an illusion. Mankind at large is still in the dark age. The historian of the remote future will see no radical distinction between the superstitions of the thirteenth century and the superstitions of the nineteenth century. But he will probably admit that a greater change took place in the world of thought between the year 1859 and the close of the nineteenth century than had occurred in the lapse of two thousand years before If this estimate be correct, it is indeed a privilege to be living in this generation, for we are on the eve of great things, and beyond question the revolution that is going on about us denotes the triumph of science and its inductive method. Just in proportion as we get away from the old metaphysical preconceptions, substituting for them the new inductive method, just in that proportion do we progress. The essence of the new method is to have no preconceptions as to the bounds of nature; to regard no phenomenon, no sequence of phenomena, as impossible; but, on the other hand, to accept no alleged law, no theory, no hypothesis, that has not the warrant of observed phenomena in its favor.

The great error of the untrained mind of the primitive man was that he did not know the value of scientific evidence. He made wide leaps from observed phenomena to imagined causes, quite overlooking the proximal causes that were near to hand. The untrained observer of to-day makes the same mistake; hence the continued prevalence of those superstitious misconceptions which primitive man foisted upon our race. But each new generation of to-day is coming upon the field better trained in at least the rudiments of scientific method than the preceding generation, and this is perhaps the most hopeful feature of present-day education. Some day every one will understand that there is no valid distinction between the natural and the supernatural; in fact, that no such thing as a supernatural phenomenon, in the present-day acceptance of the word, can conceivably exist.

All conceivable manifestations of nature are natural, nor can we doubt that all are reducible to law—that is to say, that they can be classified and reduced to systems. But the scientific imagination, as already pointed out, must admit that any and every scientific law of our present epoch may be negatived in some future epoch. It is always possible, also, that a seeming law of to-day may be proved false to-morrow, which is another way of saying that man's classification improves from generation to generation. For a "natural law," let it be repeated, is not nature's method, but man's interpretation of that method.

LOGICAL INDUCTION VERSUS HASTY GENERALIZATION

A great difficulty is found in the fact that men are forever making generalizations—that is, formulating laws too hastily. A few phenomena are observed and at once the hypothesis-constructing mind makes a guess as to the proximal causes of these phenomena. The guess, once formulated and accepted, has a certain influence in prejudicing the minds of future observers; indeed, where the phenomena involve obscure principles the true explanation of which is long deferred, a false generalization may impress itself upon mankind with such force as to remain a stumbling-block for an indefinite period. Thus the Ptolemaic conception of the universe dominated the thought of Europe for a thousand years, and could not be substituted by the true theory without a fierce struggle; and, to cite an even more striking illustration, the early generalizations of primitive man which explain numberless phenomena of nature as due to an influence of unseen anthropomorphic beings remain to this day one of the most powerful influences that affect our race—an influence from which we shall never shake ourselves altogether free until the average man—and particularly the average woman—learns to be a good observer and a logical reasoner.

Something towards this end is being accomplished by the introduction of experimental research and scientific study in general in our schools and colleges. It is hoped that something towards the same end may be accomplished through study of the history of the development of science. Scarcely anything is more illuminative than to observe critically the mistakes of our predecessors, noting how natural the mistakes were and how tenaciously they were held to, how strenuously defended. Most of all it would be of value to note that the false inductions which have everywhere hampered the progress of science have been, from the stand-point of the generation in which they originated, for the most part logical inductions. We have seen that the Ptolemaic scheme of the universe, false though it was in its very essentials, yet explained in what may be termed a thoroughly scientific fashion the observed phenomena. It is one way of expressing a fact to say that the sun moves across the heavens from the eastern to the western horizon; and for most practical purposes this assumption answers perfectly. It is only when we endeavor to extend the range of theoretical astronomy, and to gain a correct conception of the mechanism of the universe as a whole, that the essentially faulty character of the geocentric conception becomes apparent.

And so it is in many another field; the false generalizations and hasty inductions serve a temporary purpose. Our only quarrel with them is that they tend through a sort of inertia to go forever unchanged. It requires a powerful thrust to divert the aggregate mind of our race from a given course, nor is the effect of a new impulse immediately appreciable; that is why the masses of the people always lag a generation or two behind the advanced thinkers. A few receptive minds, cognizant of new observations that refute an old generalization, accept new laws, and, from the vantage-ground thus gained, reach out after yet other truths. But, for the most part, the new laws thus accepted by the leaders remain unknown to the people at large for at least one or two generations. It required about a century for the heliocentric doctrine of Copernicus to begin to make its way.

In this age of steam and electricity, progress is more rapid, and the greatest scientific conception of the nineteenth century, the Darwinian theory, may be said to have made something that approaches an absolute conquest within less than half a century. This seems a marvellously sudden conquest, but it must be understood that it is only the crude and more tangible bearings of the theory that have thus made their way. The remoter consequences of the theory are not even suspected by the great majority of those who call themselves Darwinians to-day. It will require at least another century for these ideas to produce their full effect. Then, in all probability, it will appear that the nineteenth century was the most revolutionary epoch by far that the history of thought has known. And it owes this proud position to the fact that it was the epoch in all history most fully subject to the dominant influence of inductive science. Thanks to this influence, we of the new generation are able to start out on a course widely divergent from the path of our ancestors. Our leaders of thought have struggled free from the bogs of superstition, and are pressing forward calmly yet with exultation towards the heights.