The Natural Motion of Matter in Newtonian and Post-Newtonian Physics

Abstract

The Thomist 71 (2007): 529-54 THE NATURAL MOTION OF MATTER IN NEWTONIAN AND POST-NEWTONIAN PHYSICS ]OHNW. KECK Institute for the Study ofNature Washington, D.C. IN THE CENTURIES since Isaac Newton delivered modern science into an astonished world, the great unanswered question remains: what do its suppositions and abstractions mean in terms of common human experience? The critical problem remains how to incorporate science's valid insights into a well-grounded philosophy of nature. Certainly the rise of modern science has been the most jarring intellectual movement in history. The dislocations sprung from this science originate not only in its technology, but even more in its concepts and discoveries that are ostensibly at odds with traditional natural philosophy. Natural philosophy is the basis of Aristotelian-Thomistic metaphysics and ethics, "because it is through the senses that we are open to things, and something enters us, according to our natural mode of knowing. "1 As theology makes use of philosophy, natural philosophy also makes an indirect contribution to theology.2 Modern science and Aristotelian-Thomistic philosophy claim the same sensible world as their home territory.3 Science's tremendous successes advertise 1 Jacques Maritain, Science and Wisdom, trans. Bernard Wall (New York: Charles Scribner's Sons, 1954), 35. 2 Jacques Maritain, An Introduction to Philosophy, trans. E. I. Watkin (New York: Sheed and Ward, 1962), 87. 3 Benedict M. Ashley, The Way toward Wisdom: An Interdisciplinary and Intercultural Introduction to Metaphysics (Notre Dame, Ind.: University of Notre Dame Press, 2006), 9091 . 529 530 JOHNW. KECK that it has some real claim to truth about this world, so 1t 1s difficult to blame the world for failing to take seriously a philosophy that, while claiming to be grounded in sense experience, fails to account for the real aspects of nature that modern science has discovered. In the absence of such an accounting, inferior philosophy readily occupies the vacancy. It is incumbent on the perennial philosophy to provide an adequate account of the sensible world-all of it. The task of the present inquiry is to begin to pay part of this centuries-old debt by resolving Newtonian and post-Newtonian physics in terms of traditional natural philosophy. The chasm that separates science from natural philosophy runs between their understandings of nature. At the beginning of book 2 of the Physics, Aristotle defines nature as "a source or cause of being moved and of being at rest in that to which it belongs primarily."4 Nature is an inherent source of motion and rest. In his discussion of chance, Aristotle emphasizes the purposefulness of nature's acts: "action for an end is present in things which come to be and are by nature."5 In stark contrast, modern physics6 restricts itself to the mathematical principles of nature. Since quantity is most closely related to matter, which is inactive and undetermined insofar as it is material, modern physics is blind to purpose, as well as to closely related substantial form.7 It is instructive to examine how modern physics treats Aristotle's four kinds of causal explanation. Nature, as Aristotle wrote, includes four causes and "it is the business of the physicist to know about them all."8 Modern physics, by reducing all of nature to the quantifiable and measurable, has effectively 4 Aristotle, Physics 2.1.192b21-22 (trans. R. P. Hardie and R. K. Gaye, ed. Mortimer]. Adler, in GreatBooks ofthe Western World 8 [Chicago: Encyclopaedia Britannica, Inc., 1952], 257-355; this translation is used throughout this article). 5 Ibid., 2.8.199a6-7. 6 Modern physics here means (modern) mathematical natural philosophy, not quantum mechanics. 7 David L. Schindler, "Introduction: The Problem of Mechanism," in David L. Schindler, ed., Beyond Mechanism: The Universe in RecentPhysics and Catholic Thought (Lanham, Md.: University Press of America, 1986), 4. 8 Aristotle, Physics 2.7.198a23. THE NATURAL MOTION OF MATTER 531 eliminated all but one of the four causes. Matter exists not as analogical potency, but (since quantity is the only recognized accident) univocally as the ultimate actuality beneath all things.9 Formal causality persists but accidentally through mathematics (e.g., the form of "roundness" makes a ball round). Substantial form is...