NATURAL LIGHT. See DOUBT; INTUITION.
NATURAL PHILOSOPHY. In the early modem period, philosophy was not distinguished as sharply from the empirical sciences as it is today. In the Aristotelian tradition, natural philosophy included the study not only of local motion, but also of the generation and corruption of living things and even of theological issues relevant to an account of the material world. Descartes inherited this broader notion of natural philosophy, but sometimes suggested that it needs to be revised in two important ways. First, he tried at times to purge natural philosophy of the study of topics that belong to the domain of theology (but see transubstantiation). Second, he sometimes spoke as if natural philosophy is reducible to physics and physics, in turn, to mathematics. This departure from Aristotelian orthodoxy is explained by Descartes’s view that all material change is due to local motion and that matter itself is identical to extension. However, in an interview with Frans Burman he was reported as holding that though the object of mathematics is a “true and real entity,” the object of physics is a real being that is “something specifically existing” (AT, vol. V, p. 160). In the preface to the French translation of the Principles, moreover, Descartes indicated that natural philosophy includes not only physics, but also the three sciences that derive from physics, namely, medicine, mechanics, and morals.
NATURE. In the Sixth Meditation, Descartes held that “nature considered in its general aspect” is nothing other than “God himself or the ordered system of created things established by God” (AT, vol. VII, p. 80). In speaking of created things, he further distinguished in this text between nature defined in terms of certain purposes, which is merely a “label that depends on my thought” and that is “quite extraneous to the things to which it is applied,” and nature defined in terms of laws of nature, which is “really to be found in the things themselves.” Thus, a badly made clock runs contrary to nature understood in the first sense, but is perfectly in accord with nature understood in the second sense (AT, vol. VII, pp. 84–85). Here, Descartes was rejecting the Aristotelian view that the natures of material objects are determined by the teleological ends that derive from the forms of those objects. In his view, such natures were to be explicated rather in entirely mechanistic terms.
In the early The World, Descartes also noted that he used the term nature to denote not “some goddess or other sort of imaginary power,” but rather “matter itself, insofar as I am considering it taken together with all the qualities I have attributed to it, and under the condition that God continues to conserve it in the same way that he has created it” (AT, vol. XI, p. 37). The suggestion here seems to be that God brings about effects in the material world by means of his continual conservation of matter. However, Descartes showed some sympathy for the Aristotelian view that God produces such effects by means of his concurrence with actions in secondary causes that are determined by their natures. In contrast, Nicolas Malebranche protested that the view that bodies have causal powers deriving from their natures constitutes “the most dangerous error of the philosophy of the ancients.” The error is dangerous since it attributes to creatures a power that should be reserved for God alone. Malebranche offered the occasionalist alternative that bodily events serve merely as passive “occasional causes” that prompt God to produce effects by means of his efficacious will.
NEWTON, ISAAC (1642–1727). Newton was the foremost mathematician-scientist of the late 17th century. He attended Trinity College, Cambridge, 1661–64, receiving his B.A. in 1665. In 1669 he succeeded Isaac Barrow as Lucasian Professor of Mathematics at Cambridge. He was elected to the Royal Society in 1672 and became its President in 1703. He was knighted in 1705.
Newton’s initial interest was in mathematics, which he taught himself in 1664, in part by reading Descartes’s Geometry; he then undertook intensive mathematical research in 1665–66, culminating in an unpublished treatise on the calculus. His exposure to mechanical philosophy also dates from this period: he read the works of Descartes, Pierre Gassendi, and Robert Boyle, and composed a notebook, Quaestiones quaedam philosophicae (1664) dealing with issues such as motion, gravity, and light. Newton became a critic of Descartes’s natural philosophy. His principal work, Principia mathematica philosophiae naturalis (“Mathematical Principles of Natural Philosophy,” 1687, an expansion of his unpublished 1684 treatise De motu), can be considered as an argument against Descartes’s cosmology, namely, that the Cartesian vortices of Principles, Part III, cannot account for Johannes Kepler’s three laws of astronomy.
In the Principia, Newton proposed his law of universal gravitation, in accordance with which every body attracts every other body with a force directly proportional to the masses and inversely proportional to the square of the distances. In this way, he offered an explanation for why the planets move about the sun in the particular path they follow, according to Kepler’s laws. But, for mechanists such as Gottfried Wilhelm Leibniz, Newton’s explanation was not sufficient. Leibniz thought that an account of what causes the gravitational pull between the sun and Earth was also needed; and for the account to be intelligible, he believed that it should be given in terms of the communication of motion from one body to another body by collision. He attempted a Cartesian-style mechanical explanation of the phenomena, that is, a vortex theory of planetary motion, the planets being carried around the sun in a huge whirlpool of subtle matter, using two vortices to account for the astronomical observations upon which Newton based his theory.
NOËL, ETIENNE (1581–1659). A French Jesuit and teacher of philosophy and theology at Descartes’s old school at La Flèche. Noël taught at La Flèche when Descartes was a student and, 20 years later, he was the rector of La Flèche to whom Descartes sent copies of the Discourse on Method. He published some physical treatises in which he deviated from strict Aristotelianism and he disputed the conclusions of Blaise Pascal’s experiments concerning the void.
NOTES AGAINST A PROGRAM (NOTAE IN PROGRAMMA QUODDAM). The Notes Against a Program must be explained against the background of Descartes’s relation with Henricus Regius. Regius, who had earned his Utrecht chair in medicine by giving very successful private lessons in philosophy, thought of publishing his views as early as 1641. Descartes, who was obviously less keen on having someone publish ideas he considered his own, dissuaded him from doing so. But by 1645, after Descartes had published the Meditations (1641) and the Principles (1644), Regius wanted to publish a book, called Foundations of Physics (Fundamenta physices, 1646), containing a synthesis of his philosophical views. When he submitted the manuscript to Descartes, Descartes was particularly unhappy with the last chapter, which contains not only ideas on the relation between body and mind (the nature of which Regius finds uncertain), but also a few remarks on innate ideas (which he denies) and the knowledge of God (whose idea he derives from the idea we have of human perfection). Descartes urged his friend to withdraw the book or at least to suppress a few passages (which Regius did eventually). For Descartes this was not enough. He publicly dissociated himself from his former friend in the preface to the French edition of the Principles (1647), even to the point of accusing him of plagiarism.
That in turn seems to have been the reason why one of Regius’s students, Petrus Wassenaer (d. 1680), undoubtedly with the cooperation of Regius himself, submitted for disputation a series of corollaries to the last chapter of Regius’s book, including those Regius had suppressed at the request of Descartes. The rector of the university canceled the disputation with the added reason that it was dedicated to a Remonstrant minister. Wassenaer and Regius then took the unusual step of having the corollaries printed as a broadsheet (a programma) and it is in that form that they reached Descartes. Descartes replied to them in a detailed fashion, insisting on the dangerous implications of these views, but he was in doubt whether he should publish his response. Others took the trouble—presumably Adriaan Heereboord, who added a preface of his own in which he dealt with his adversaries, the theologian Jacobus Revius and the philosopher Adam Steuart (1591–1654); it was published at the beginning of 1648. Although the Notae do not break new ground, they are interesting in that they contain a clear formulation of Descartes’s views on innate ideas, the relation between reason and faith, and a reaffirmation of mind-body dualism.