Newton, employing mathematical methods which are the admiration of adepts, but which no one but himself appears to have been able to use with ease, not only answered this question in the affirmative, but stayed not his constructive genius before it had founded modern physical astronomy.
The historians of mechanical and of astronomical science appear to be agreed that he was the first person who clearly and distinctly put forth the hypothesis that the phenomena comprehended under the general name of "gravity" follow the same order throughout the universe, and that all material bodies exhibit these phenomena; so that, in this sense, the idea of universal gravitation may, doubtless, be properly ascribed to him.
Newton proved that the laws of Kepler were particular consequences of the laws of motion and the law of gravitation—in other words, the reason of the first lay in the two latter. But to talk of the law of gravitation alone as the reason
of Kepler's laws, and still more as standing in any causal relation to Kepler's laws, is simply a misuse of language. It would really be interesting if the Duke of Argyll would explain how he proposes to set about showing that the elliptical form of the orbits of the planets, the constant area described by the radius vector, and the proportionality of the squares of the periodic times to the cubes of the distances from the sun, are either caused by the "force of gravitation" or deducible from the "law of gravitation." I conceive that it would be about as apposite to say that the various compounds of nitrogen with oxygen are caused by chemical attraction and deducible from the atomic theory.
Newton assuredly lent no shadow of support to the modern pseudo-scientific philosophy which confounds laws with causes. I have not taken the trouble to trace out this commonest of fallacies to its first beginning; but I was familiar with it in full bloom more than thirty years ago, in a work which had a great vogue in its day—the "Vestiges of the Natural History of Creation"—of which the first edition was published in 1844.
It is full of apt and forcible illustrations of pseudo-scientific realism. Consider, for example, this gem serene. When a boy who has climbed a tree loses his hold of the branch, "the law of gravitation unrelentingly pulls him to the ground,
and then he is hurt," whereby the Almighty is quite relieved from any responsibility for the accident. Here is the "law of gravitation" acting as a cause in a way quite in accordance with the Duke of Argyll's conception of it. In fact, in the mind of the author of the "Vestiges," "laws" are existences intermediate between the Creator and His works, like the "ideas" of the Platonisers or the Logos of the Alexandrians.[27] I may cite a passage which is quite in the vein of Philo:—
We have seen powerful evidences that the construction of this globe and its associates; and, inferentially, that of all the other globes in space, was the result, not of any immediate or personal exertion on the part of the Deity, but of natural laws which are the expression of His will. What is to hinder our supposing that the organic creation is also a result of natural laws which are in like manner an expression of His will? (p. 154, 1st edition).
And creation "operating by law" is constantly cited as relieving the Creator from trouble about insignificant details.