Scientific method does not depend on such chance conjunctions of circumstance, but controls its observations or experimentally arranges conditions so as to discover what are the conditions necessary to produce given effects, or what effects invariably follow from given causes. It does not accept a chance conjunction as evidence of an invariable relation, but seeks, under regulated conditions, to discover what the genuinely invariable relations are. This method of controlling our generalizations about the facts of experience, we shall presently examine in some detail.
Curiosity and scientific inquiry. Curiosity, the instinctive basis of the desire to know, is the basis of scientific inquiry. Without this fundamental desire, there could be no sustaining motive to deep and thoroughgoing scientific research, for theoretical investigations do not always give promise of immediate practical benefits. The scientific interest is a development of that restless curiosity for a knowledge of the world in which they are living which children so markedly exhibit. Beginning as a kind of miscellaneous and omnivorous appetite for facts of whatever description, it grows into a desire to understand the unsuspected and hidden relations between facts, to penetrate to the unities discoverable beneath the mysteries and multiplicities of things.
The scientific mood is thus in the first place a sheer instinctive curiosity, a basic passion for facts. It is this which sustains the scientific worker in the sometimes long and dreary business of collecting specimens, instances, details. Many of the most notable scientific advances, as Lord Kelvin pointed out, must be attributed to the most protracted and unmitigated drudgery in the collection of facts, a thoroughgoing and trying labor in which the scientific worker could persist only when fortified by an eager and insistent curiosity. This "hodman's work" is the basis of the great generalizations which constitute the framework of the modern scientific systems. "The monotonous and quantitative work of star-cataloguing has been continued from Hipparchus, who began his work more than a century before Christ, work which is continued even to the present day. This work, uninspiring as it seems, is yet an essential basis for the applications of astronomy, the determination of time, navigation, surveying. Furthermore, without good star places, we can have no theory of the motions of the solar system, and without accurate catalogues of the stars we can know nothing of the grander problems of the universe, the motion of our sun among the stars, or of the stars among themselves."[1]
[Footnote 1: Hinks: Astronomy, p. 162.]
Not only is curiosity a sustaining motive in the drudgery of collection and research incident and essential to scientific generalization; it alone makes possible that suspense of judgment which is necessary to fruitful scientific inquiry. This suspense is, as we have already seen, difficult for most men. Action demands immediate decision, and inquiry deliberately postpones decision. It is only a persistent desire to "get at the bottom of the matter" that will act as a check upon the demands of social life and of individual impatience which rush us to conclusions. In most men, as earlier noted, the sharp edge of curiosity becomes easily blunted. They are content, outside their own immediate personal interests, "to take things for granted." They glide over the surfaces of events, they cease to query the authenticity of facts, or to examine their relevance and their significance, or to be concerned about their completeness. For an example, one has but to listen to or partake in the average discussion of any political or social issue of the present day. There are few men who retain, even as far as middle life, a genuinely inquiring interest in men and affairs. Their curiosity is dulled by fatigue and the pressure of their own interests and preoccupations, and they allow their prejudices and formulas to pass for judgments and conclusions. The scientist is the man in whom curiosity has become a permanent passion, who, as long as he lives, is unwilling to forego inquiry into the processes of Nature, or of human relations.
Thinking begins with a problem. While the general habit of inquiry is developed in the satisfaction of the instinct of curiosity, any particular investigation begins with a felt difficulty. By difficulty is not meant one of an imperative and practical kind, but any problem whether theoretical or practical. For many men, it is true, thinking occurs only when instinct and habit are inadequate to adjust them to their environment. Any problem of daily life affords an example. To borrow an illustration from Professor Dewey:
A man traveling in an unfamiliar region comes to a branching of the roads. Having no sure knowledge to fall back upon, he is brought to a standstill of hesitation and suspense. Which road is right? And how shall the perplexity be resolved? There are but two alternatives. He must either blindly and arbitrarily take his course, trusting to luck for the outcome, or he must discover grounds for the conclusion that a given road is right.[1]
[Footnote l: Dewey: How We Think, p. 10.]
To the inquiring mind, purely theoretical difficulties or discrepancies will provoke thought. To the astronomer an unaccounted-for perturbation in the path of a planet provokes inquiry; the chemist is challenged by a curious unexplained reaction of two chemical elements, the biologist, anterior to the discovery of micro-organisms, by the putrefaction of animal tissues. The degree to which curiosity persists and the extent of training a man has had in a given field largely determine the kind of situations that will provoke inquiry. "A primrose by the river's brim" may be simply a primrose to one man, while to another, a botanist, it may suggest an interesting and complex problem of classification.
But however remote and recondite thinking becomes, however far removed from immediate practical concerns, it occurs essentially in a situation analogous to the "forked-road situation" described above. The situation as it stands is confused, ambiguous, uncertain. In a practical problem, for example, there are two or more courses of action open to us, all of them giving promise as solutions of our difficulties. We aim through reflection to reduce the uncertainty, to clarify the situation, to discover more clearly the consequences of the various alternatives which suggest themselves to us. When action is unimpeded, suggestions flow on just as they arise in our minds. This is illustrated best in the reveries of a day-dream when casual and disconnected fancies follow each other in random and uncontrolled succession. But when there is a problem to be settled, an ambiguity to be resolved, suggestions are held in check and controlled with reference to the end we have in view; each suggestion is estimated with regard to its relevance to the problem in hand. Every idea that arises is, so to speak, queried: "Is it or is it not a solution to our present difficulty?"