ILLUSTRATIONS:
(1) The hypothesis is advanced that the fire started from the coal range in the kitchen. After the incendiary is caught, this supposition ceases to be an hypothesis.
(2) It is suspected, that my insomnia is due to the three cups of strong coffee indulged in at the evening meal. As soon as this supposition is proved by experimental means (law of difference), it ceases to be an hypothesis and becomes an unpopular inductive truth.
8. HYPOTHESIS AND THEORY.
In common parlance hypothesis and theory are used interchangeably. We refer to the “nebular hypothesis” or the “nebular theory”; to the “hypothesis of the sun’s heat” or “the theory of the sun’s heat.” On the other hand, we say “the theory of gravitation,” “the theory of evolution,” etc., with certain uniformity. From these observations we may infer that hypothesis and theory may be used interchangeably when the facts are of a low probability; but when the facts have undergone cogent verification, it is more correct to use theory in their designation rather than hypothesis. “A theory is a partially verified hypothesis.” It has been remarked that theory has a second signification of being a term which stands for “any body of acquired truth.” It is unfortunate that its use could not be confined to this latter conception.
9. THE REQUIREMENTS OF A PERMISSIBLE HYPOTHESIS.
Any hypothesis should be made to conform to the following requisites: (1) The hypothesis must be conceivable. The hypothetic generalizations of primeval days were mere fancy. For example, the loud noise from theclouds on dark days was the angry voice of the God of the skies. Even in this day when a complex situation cannot be explained there comes the temptation to draw entirely upon the imagination, and advance an hypothesis which is absurd in every sense of the word. The permissible hypothesis demands that there be some ground for the conjecture. A fact or two at least must be used as the foundation for whatever the constructive imagination may build. On the other hand the past has taught us that we cannot afford to be too exacting in the enforcement of this rule. The ideas of Copernicus, Newton, Harvey, Darwin, and many another of the world’s best thinkers, were looked upon at first as being ridiculous. There is always a bare possibility of a “lurking truth” in the conjecture, and no broad minded and sanely educated man can afford to scoff blindly at something which may seem to him mere fancy. Prejudice and a willful blindness to truth, have ever been imminent stumbling blocks in the path of progress.
(2) The hypothesis must be capable of proof or disproof. This means, that where it is possible the hypothesis should touch, in one form or another, our experience. If the hypothesis is wholly unlike any experience we may have had, it becomes impossible to ascertain, whether it agrees or disagrees with the facts, which it is supposed to explain. A legitimate hypothesis must furnish some opportunity for securing facts to prove or disprove it. For example, to advance an hypothesis relative to the conditions of the next world is hardly permissible, as “spirit-facts” are entirely without our fieldof experience. Surely, one returning from Heaven could give us no conception of it; because there is nothing in the carnal mind that may be used to interpret the experiences that must function in the Celestial City.
(3) The hypothesis must be adequate. It should take into consideration all the known facts. It stands to reason that, if one known fact is ignored, the entire procedure is thus vitiated. It would be absurd to suppose the moon to be inhabited without giving heed to the fact of its having no atmosphere.
(4) The hypothesis must be as simple as possible. We must, of course, recognize situations which in themselves are too complex to admit of simple conjectures. The purport of the fourth rule is, that the hypothesis should not be made unnecessarily complex.