On the Philosophy of Discovery, Chapters Historical and Critical

by William Whewell

2. I would now further observe, that in this progression from fact to theory, we advance (when the theory is complete and completely possessed by the mind) from the apprehension of truths as actual to the apprehension of them as necessary; and thus Facts which were originally observed merely as Facts become the consequences of theory, and are thus brought within the domain of Ideas. That which was a part of the objective world becomes also a part of the subjective world; a necessary part of the thoughts of the theorist. And in this way the progress of true theory is the Idealization of Facts.

Thus the Progress of Science consists in a perpetual reduction of Facts to Ideas. Portions are perpetually transferred from one side to another of the Fundamental Antithesis: namely, from the Objective to the Subjective side. The Centre or Fulcrum of the Antithesis is shifted by every movement which is made in the advance of science, and is shifted so that the ideal side gains something from the real side.

3. I will proceed to illustrate this Proposition a little further. Necessary Truths belong to the Subjective, Observed Facts to the Objective side of our knowledge. Now in the progress of that exact speculative knowledge which we call Science, Facts which were at a previous period merely Observed Facts, come to be known as Necessary Truths; and the attempts at new advances in science generally introduce the representation of known truths of fact, as included in higher and wider truths, and therefore, so far, necessary.

We may exemplify this progress in the history of the science of Mechanics. Thus the property of the lever, the inverse proportion of the weights and arms, was known as a fact before the time of Aristotle, and known as no more; for he gives many fantastical and inapplicable reasons for the fact. But in the writings of Archimedes we find this fact brought within the domain of necessary truth. It was there transferred from the empirical to the ideal side of the Fundamental Antithesis; and thus a progressive step was made in science. In like manner, it was at first taken by Galileo as a mere fact of experience, that in a falling body, the velocity increases in proportion to the time; but his followers have seen in this the necessary effect of the uniform force of gravity. In like manner, Kepler's empirical Laws were shown by Newton to be necessary results of a central force attracting inversely as the square of the distance. And if it be still, even at present, doubtful whether this is the necessary law of a central force, as some philosophers have maintained that it is, we cannot doubt that if now or hereafter, those philosophers could establish their doctrine as certain, they would make an important step in science, in addition to those already made.

And thus, such steps in science are made, whenever empirical facts are discerned to be necessary laws; or, if I may be allowed to use a briefer expression, whenever facts are idealized.

4. In order to show how widely this statement is applicable, I will exemplify it in some of the other sciences.

In Chemistry, not to speak of earlier steps in the science, which might be presented as instances of the same general process, we may remark that the analyses of various compounds into their elements, according to the quantity of the elements, form a vast multitude of facts, which were previously empirical only, but which are reduced to a law, and therefore to a certain kind of ideal necessity, by the discovery of their being compounded according to definite and multiple proportions. And again, this very law of definite proportions, which may at first be taken as a law given by experience only, it has been attempted to make into a necessary truth, by asserting that bodies must necessarily consist of atoms, and atoms must necessarily combine in definite small numbers. And however doubtful this Atomic Theory may at present be, it will not be questioned that any chemical philosopher who could establish it, or any other Theory which would produce an equivalent change in the aspect of the science, would make a great scientific advance. And thus, in this Science also, the Progress of Science consists in the transfer of facts from the empirical to the necessary side of the antithesis; or, as it was before expressed, in the idealization of facts.

5. We may illustrate the same process in the Natural History Sciences. The discovery of the principle of Morphology in plants was the reduction of a vast mass of Facts to an Idea; as Schiller said to Göthe when he explained the discovery; although the latter, cherishing a horror of the term Idea, which perhaps is quite as common in England as in Germany, was extremely vexed at being told that he possessed such furniture in his mind. The applications of this Principle to special cases, for instance, to Euphorbia by Brown, to Reseda by Lindley, have been attempts to idealize the facts of these special cases.

6. We may apply the same view to steps in Science which are still under discussion;—the question being, whether an advance has really been made in science or not. For instance, in Astronomy, the Nebular Hypothesis has been propounded, as an explanation of many of the observed phenomena of the Universe. If this Hypothesis could be conceived ever to be established as a true Theory, this must be done by its taking into itself, as necessary parts of the whole Idea, many Facts which have already been observed; such as the various form of nebulæ;—many Facts which it must require a long course of years to observe, such as the changes of nebulæ from one form to another;—and many facts which, so far as we can at present judge, are utterly at variance with the Idea, such as the motions of satellites, the relations of the material elements of planets, the existence of vegetable and animal life upon their surfaces. But if all these Facts, when fully studied, should appear to be included in the general Idea of Nebular Condensation according to the Laws of Nature, the Facts so idealized would undoubtedly constitute a very remarkable advance in science. But then, we are to recollect that we are not to suppose that the Facts will agree with the Idea, merely because the Idea, considered by itself, and without carefully attending to the Facts, is a large and striking Idea. And we are also to recollect that the Facts may be compared with another Idea, no less large and striking; and that if we take into our account, (as, in forming an Idea of the Course of the Universe, we must do,) not only vegetable and animal, but also human life, this other Idea appears likely to take into it a far larger portion of the known Facts, than the Idea of the Nebular Hypothesis. The other Idea which I speak of is the Idea of Man as the principal Object in the Creation; to whose sustenance and development the other parts of the Universe are subservient as means to an end; and although, in our attempts to include all known Facts in this Idea, we again meet with many difficulties, and find many trains of Facts which have no apparent congruity with the Idea; yet we may say that, taking into account the Facts of man's intellectual and moral condition, and his history, as well as the mere Facts of the material world, the difficulties and apparent incongruities are far less when we attempt to idealize the Facts by reference to this Idea, of Man as the End of Creation, than according to the other Idea, of the World as the result of Nebular Condensation, without any conceivable End or Purpose. I am now, of course, merely comparing these two views of the Universe, as supposed steps in science, according to the general notion which I have just been endeavouring to explain, that a step in science is some Idealization of Facts.

7. Perhaps it will be objected, that what I have said of the Idealization of Facts, as the manner in which the progress of science goes on, amounts to no more than the usual expressions, that the progress of science consists in reducing Facts to Theories. And to this I reply, that the advantage at which I aim, by the expression which I have used, is this, to remind the reader, that Fact and Theory, in every subject, are not marked by separate and prominent features of difference, but only by their present opposition, which is a transient relation. They are related to each other no otherwise than as the poles of the fundamental antithesis: the point which separates those poles shifts with every advance of science; and then, what was Theory becomes Fact. As I have already said elsewhere, a true Theory is a Fact; a Fact is a familiar Theory. If we bear this in mind, we express the view on which I am now insisting when we say that the progress of science consists in reducing Facts to Theories. But I think that speaking of Ideas as opposed to Facts, we express more pointedly the original Antithesis, and the subsequent identification of the Facts with the Idea. The expression appears to be simple and apt, when we say, for instance, that the Facts of Geography are identified with the Idea of globular Earth; the Facts of Planetary Astronomy with the Idea of the Heliocentric system; and ultimately, with the Idea of Universal Gravitation.