NEWTON, ISAAC (b. Woolsthorpe, England, 25 December 1642; d. London, England, 20 March 1727), mathematics, dynamics, celestial mechanics, astronomy, optics, natural philosophy.

    pleasantly” said to Samuel Clarke that “He had broke Leibnitz's Heart with his Reply to him.”

Newton's later London years were marked by creative scientific efforts. During this time he published the Opticks, with the two mathematical tracts, and added new queries for its later editions. He also produced, with Roger Cotes's aid, a second edition of the Principia, including the noteworthy general scholium, and, with assistance from Henry Pemberton, a third edition. In the last, however, Newton altered the scholium to lemma 2, book II, to prevent its being read as if Leibniz were entitled to a share of credit for the calculus—although Leibniz had been dead for nearly twelve years.

Newton died on Monday, 20 March 1727,188 at the age of eighty-five, having been ill with gout and inflamed lungs for some time. He was buried in Westminster Abbey.

Newton's Philosophy: The Rules of Philosophizing, the General Scholium, the Queries of the “Opticks.”

Like others of his day, Newton believed that the study of natural philosophy would provide evidence for the existence of God the Creator in the regularities of the solar system. In the general scholium at the end of book III of the Principia, he said “it is not to be conceived that mere mechanical causes could give birth to so many regular motions,” then concluded his discussion with observations about God, “to discourse of whom from phenomena does certainly belong to Natural Philosophy” (“Experimental Philosophy” in the second edition). He then went on to point out that he had “explained the phenomena of the heavens and of our sea, by the power of Gravity” but had not yet “assigned the cause of this power,” alleging that “it is enough that Gravity does really exist, and act according to the laws which we have explained” and that its action “abundantly serves to account for all the motions of the celestial bodies, and of our sea.” The reader was thus to accept the facts of the Principia, even though Newton had not “been able to discover the cause of those properties of gravity from phenomena.” Newton here stated his philosophy, “Hypotheses non fingo.”189

Clearly, Newton was referring here only to “feigning” a hypothesis about the cause of gravitation, and never intended that his statement should be applied on all levels of scientific discourse, or to all meanings of the word “hypothesis.” Indeed, in each of the three editions of the Principia, there is a “hypothesis” stated in book II. In the second and third editions there are a “Hypothesis I” and a “Hypothesis II” in book III. The “phaenomena” at the beginning of book III, in the second and third editions, were largely the “hypotheses” of the first edition. It may be that Newton used these two designations to imply that these particular statements concerning planetary motions are not mathematically true (as he proved), but could be only approximately “true,” on the level of (or to the limits of) phenomena.

Newton believed that his science was based upon a philosophy of induction. In the third edition of the Principia, he introduced rule 4, so that “the argument of induction may not be evaded by hypotheses.” Here he said that one may look upon the results of “general induction from phenomena as accurately or very nearly true,” even though many contrary hypotheses might be imagined, until such time as the inductive result may “either be made more accurate or liable to exceptions” by new phenomena. In rule 3, in the second and third editions, he stated his philosophical basis for establishing general properties of matter by means of phenomena.

Newton's philosophical ideas are even more fully developed in query 31, the final query of the later editions of the Opticks, in which he argued for both the philosophy of induction and the method of analysis and composition (or synthesis). In both mathematics and natural philosophy, he said, the “Investigation of difficult Things by the method of Analysis, ought ever to precede the Method of Composition.” Such “Analysis consists in making Experiments and Observations, and in drawing general Conclusions from them by Induction, and admitting of no Objections against the Conclusions, but such as are taken from Experiments, or other certain Truths.”

In both the Principia and the Opticks, Newton tried to maintain a distinction among his speculations, his experimental results (and the inductions based upon them), and his mathematical derivations from certain assumed conditions. In the Principia in particular, he was always careful to separate any mathematical hypotheses or assumed conditions from those results that were “derived” in some way from experiments and observations. Often, too, when he suggested, as in various scholiums, the applicability of mathematical or hypothetical conditions to physical nature, he stated that he had not proved whether his result really so applies. His treatment of the motion of small corpuscles, in book I, section 14, and his static model of a gas composed of mutually repulsive particles, in book II, proposition 23, exemplify Newton's use of mathematical models of physical reality for which he lacked experimental evidence sufficient for an unequivocal statement.

Perhaps the best expression of Newton's general philosophy of nature occurs in a letter to Cotes (28 March 1713), written during the preparation of the second edition of the Principia, in which he referred