DiscussionNewton’s substance monism, distant action, and the nature of Newton’s empiricism: discussion of H. Kochiras “Gravity and Newton’s substance counting problem”
Introduction
Hylarie Kochiras is to be commended for taking a fresh look at many well known Newtonian passages. In doing so she diagnoses the following two problems for Newton: i) the “causal question about gravity” turns “into an insoluble problem about apportioning active powers;” ii) “More seriously” Newton has no “means of individuating substances,” that is, “Newton’s Substance Counting Problem” (267). The final sentence of her carefully argued paper hints at a further problem: iii) Newton’s Substance Counting Problem is said to threaten “even to undermine his concept of body” (279). Kochiras appears to think the second and third problems are connected because if Newton cannot individuate substances he has no way of individuating bodies. Kochiras’ argument turns on three “principles” she discerns in Newton: 1) the “very broad reach of his empiricism” (267); 2) a “rationalist feature,” the principle “that matter cannot act where it is not”; 3) “substances of different kinds might simultaneously occupy the very same region of space” (267; see also 277).
I argue that Kochiras mistakenly attributes the second and third principles to Newton. Moreover, the first principle can only be articulated in Kochiras’ manner if one ignores the development of Newton’s views. Nevertheless, I grant that Kochiras has identified genuine tensions in Newton’s system, but I argue she fails to appreciate how Newton handles these. In what follows, I tackle Kochiras’ analysis and deployment of these principles in reverse order. In doing so, I dissolve the three problems diagnosed by Kochiras in Newton’s metaphysics. In what follows I accept Kochiras’ terminology for the sake of argument and brevity, except that when I describing my counter-arguments or proposals I substitute ‘speculative’ where she had used ‘rationalist’.
The substance counting problem is generated because for Newton all beings need to be spatially located. Newton identifies four such beings: God, minds, spirits, bodies. Beings may be material, immaterial, and, perhaps, both. Kochiras offers considerable evidence from Newton’s manuscripts that Newton accepts the “Scholastic Commonplace” that two material bodies cannot occupy the same place at the same time (267; ironically in contemporary metaphysics this commonplace is known as “Locke’s Principle” see Doepke, 1986, Simons, 1985). Newton also indicates that immaterial beings may co-occupy the same place as material beings. For example, in the “General Scholium” to the Principia Newton argues that God is omnipresent; he “will not be never or nowhere” (Newton, 2004, p. 91). Against the Cartesians, Newton insists that “created minds are somewhere,” while bodies are always at a place. Clearly, bodies and minds can co-occupy the same places all of which are also occupied by God. So, it appears there is ample evidence for Kochiras’ third principle.
Nevertheless, throughout her analysis Kochiras conflates Newton’s treatment of beings with talk of “substances.” In doing so Kochiras fails to appreciate fully Newton’s conceptual innovations. To be clear Kochiras recognizes that Newton “eliminates” the “Aristotelian Scholastic notion of prime matter” (269). She also recognizes Newton’s assertion of epistemic ignorance about the inner substance of things in the Principia’s “General Scholium” (269–270). But she fails to recognize that for Newton one can have being (or reality) without being either a substance or a property (or attribute) of a substance.1 In “De Gravitatione” Newton made this point clear in his discussion of extension (or space): “it is not substance; on the one hand, because it is not absolute in itself … on the other hand, because it is not among the proper affections that denote substance, namely actions, such as thoughts in the mind and motions in bodies” (Newton, 2004, p. 21; I omit Newton’s emanation doctrine, which—while fascinating—does not need to concern us here).2 Extension is neither a substance nor can it be the kind of thing that can be said to ‘belong to’ a substance. Moreover, as Kochiras recognizes (269) extension takes the place of the ‘eliminated’ prime matter; it contains body (Newton, 2004, p. 29). In “De Gravitatione,” the ontological difference between space and body is one of different degrees of being; bodies have more reality than space “whatever has more reality in one space than in another space belongs to body rather than to space,” (Newton, 2004, p. 27).
One might be tempted to argue on Kochiras’ behalf that while extension is removed from the ontology of substance-property/quality framework, surely bodies are not. After all, Newton appears to be claiming that we are “able to” call bodies “substances” (Newton, 2004, p. 29). So, if Kochiras conflates beings and substances, so does Newton! But in context, Newton is not asserting that bodies are substances. Rather, he is claiming that his thought experiment about “a certain kind of being similar in every way to bodies” (Newton, 2004, p. 27; the thought experiment ends on 33) permits the following inference: what can be said legitimately about bodies can be said legitimately about his imagined beings.
Even if Kochiras were to grant my reading of the passage on p. 29 of “De Gravitatione,” she might still be tempted to claim that Newton asserts that bodies are substances when he writes about bodies as “created substance” and that “substantial reality is to be ascribed to” them (Newton, 2004, p. 32). But in context Newton is making three subtly different points: first, he rejects the “atheists” who presuppose that bodies have a “complete, absolute, and independent reality in themselves.” Second Newton affirms the position that bodies have a “degree of reality” that “is of an intermediate nature between God and accident” (Newton, 2004, p. 32). Now Newton asserts the doctrine of different degrees of reality to help explain (as a kind of error-theory) the Scholastic “prejudice” in applying “the same word, substance … univocally … to God and his creatures.”3 Thus, third, bodies have some substantial reality but are not themselves substances. The third point makes sense in light of the passage quoted before (Newton, 2004, p. 21); for Newton “a substance is absolute in itself,” that is, it has full reality, and it is the kind of thing that can be the cause (or source) of actions (i.e., agent causation). The effects of these actions are thoughts in the mind and motions in bodies.
To be clear, on my reading according to Newton one is only a substance if one is both self-sufficient and the cause of actions. So, because bodies are not absolute in themselves (they presuppose space and need to be created) they are not the kind of beings that are properly or strictly speaking called “substances”. (Newton does allow a different, innocent use of “substance” to mean what we would call the (chemical) stuff or composition of matter, see Newton, 2004, p. 34.) Even if one does not find the evidence I offer for my alternative reading fully compelling, it still supports my contention that Kochiras has conflated beings with substances and has not provided detailed evidence that according to Newton material entities are substances.4
The situation is even more complex when it comes to “created minds,” which are said to be “of far more noble nature than body, so that perhaps it may eminently contain [body] in itself,” (Newton, 2004, p. 30). Newton is eager to show that “the analogy between the divine faculties and our own may be shown to be greater than has formerly been perceived by philosophers (ibid). This analogy and what we may call, “the eminent containment thesis”5 are all suggestive evidence that according to Newton minds have more reality than bodies; perhaps minds are substances, especially because there is ample evidence that for Newton created minds have ideas (e.g., Newton, 2004, pp. 21–22) and volitions (e.g., Newton, 2004, p. 27) and, thus, can be the source of actions. Even so, in virtue of being created, finite minds are dependent beings and, thus, no substance.
Thus, for Newton there is strictly speaking only one genuine substance, God.6 Extension has many of God’s attributes (eternal, indivisible, etc), but crucially lacks agency. Bodies and created minds are dependent on God (and space) and, thus, not absolute in themselves.7 This is, in fact, the main point of a passage in the Principia’s General Scholium that receives much attention from Kochiras (as evidence for the second “rationalist” principle): “In Him all things are contained and move.” All entities are contained by and, thus, dependent on the sole substance, God.
To conclude: the Substance Counting Problem is a pseudo-problem because there is only one substance. It rests on a mistaken conflation between beings and substances and it ignores the doctrine of different degrees of reality, which accounts for Newton’s use of ‘substantiality” when discussing bodies. Finally, Newton’s epistemic insistence that we are ignorant of “inner substances” of bodies or the “idea of substance of God” is, of course, quite compatible with the more radical ontological claim that there are no dependent substances at all.
Even if the letter of the Substance Counting Problem is deflated, one might well think that Kochiras has adequately identified another, related problem: can Newton determine how many entities can occupy a place? (This sounds fearfully close to the question how many angels can occupy the tip of pin.) And, related to this, can Newton individuate bodies? I address these questions in turn.
Kochiras is correct that for Newton two bodies cannot occupy the same region of space at the same time (269–270). As Kochiras notes this is an empirical result for Newton. Moreover, one of Kochiras’ crucial insights is that according to Newton “secondary causes” and not God are the source of gravitational forces (270–272). God “does not act on [all things] nor they on him” (“General Scholium,” Newton, 2004, p. 91). To be precise God’s activity plays only the two following explicit roles in Newton’s though: i) God’s ubiquity is required for the act of creation (see DeGrav, Newton, 2004, p. 26)—Newton’s God does not create the universe from outside of space and time, but from within.8 ii) Newton’s benevolent God occasionally (and miraculously) reforms the machinery of the universe (271; Newton, 1952, pp. 402–403). So, even if God is omnipresent, his activity is limited.9
But even if God is removed from the scene, Kochiras would claim that according to Newton minds and spirits, on the one hand, and bodies, on the other hand, can occupy the same space at the same time. There is no doubt that in “De Gravitatione,” the “union” of the “distinct” beings, mind and body, is left rather mysterious (31), but body is dependent on and eminently contained by (nobler) mind.10 Presumably this means that against Descartes, for Newton mind and body occupy the same place, when unified. So, there is no doubt that Kochiras could re-describe the substance counting problem in terms of the co-occupation of a space at a given time by material and immaterial beings. She might wish to call this the ‘entity counting problem.’
On Kochiras’ reading of Newton “he draws no sharp distinction between physics and metaphysics,” (270). For Kochiras this appears to imply that Newton’s metaphysical commitments threaten to undermine his natural philosophy. But four considerations suggest the situation is nowhere near as dire as suggested by Kochiras.
First the substance counting problem only becomes problematic if one wants to identify a particular (created) entity at a particular point of space and time as the cause of gravity. Kochiras argues that if we are unable to distinguish material and immaterial entities then we can never hope to establish the cause of gravity. But Kochiras never show that Newton is in no position to distinguish material and immaterial entities. For immaterial entities will have near zero mass and as such are very different from material beings. This means, of course, that in practice it will be very difficult to find a measure or quantity for immaterial beings; their being must be inferred from their effects.11 But being difficult to detect is not the same as being unable to distinguish.
Second from the point of view of Newton’s “rational mechanics,” which does not concern itself with miracles, but only aims to establish “the motions that result from any forces whatever and of the forces that are required for any motions whatever,” (“Author’s Preface,” Principia, Newton, 2004, p. 40; emphasis added), discovering the causes of these forces is not a fundamental aim. So, even if Kochiras were correct, she would be calling attention to a problem external to Newton’s rational mechanics. Newton repeatedly declared that he was unable to assign the cause of gravity; given the aims Newton articulated for his science in the first edition of the Principia (before all the controversy over action at a distance) this is completely legitimate move.
Of course, within the Principia Newton also admits an interest in the “physical causes and sites of force” (Principia, Book I, Definition 8; Newton, 2004, p. 63; emphasis added). It may be thought dogmatic that at least in the body of the Principia (but not elsewhere), Newton does not allow for immaterial causes of the forces.12 So, Kochiras’ position is really a complaint about what may be thought of as Newton’s methodological stance that rules out consideration of immaterial causes of forces in the body of the Principia.
But within the Principia Newton’s focus on physical causes has some empirical support. In discussing these matters we should distinguish among a) the force of gravity as a real cause (which is calculated as the product of the masses over the distance squared); b) the cause of gravity; b∗) “the reason for these [particular--ES] properties of gravity” (“General Scholium,” Principia, 2004, 129); and c) the medium, if any, through which it is transmitted.13 Much discussion about Newton conflates b (or b∗) with c, perhaps prompted by Newton’s treatment of the ether. Of course, if one were to be able to establish empirically an ether, one might also wish to use its known properties to try to explain the cause of gravity and its properties. But this is not required.
For in the third rule of reasoning Newton offers as Ori Belkind emphasized, “a criterion for universalizing properties. Qualities are universalizable if they are found through experience, and if they are reducible in each case to the ultimate ingredients of matter” (private communication, 5 January 2010). The third rule affirms that gravity is a real cause and a quality of matter, even though Newton is ignorant of the cause of the quality. One can be ignorant of the cause of gravity because according to Newton to be a universal property does not require it to be an essential (or in modern terminology, intrinsic) property.14 So, the methodological (dogmatic) point is affirmed by this addition to the second edition of the Principia. I return to this point in the next section.
Now, fourth, one further reason why Newton might keep b and c distinct is that in some of his works he may have been committed to action at a distance! Of course, in the context of my criticism of Kochiras this is question-begging. So, another reason why Newton would keep b and c distinct is that when Newton was drafting the first edition of the Principia he is committed to the claim that at least part of the cause of gravity is a contingent, dispositional, and relational quality of matter. Elsewhere I have argued that Newton’s posthumously published Treatise, the existence of which Newton advertised in all editions of the “preface” to Book III of the Principia, offers evidence for rich details of this view.15 Kochiras accepts that the Treatise argues for the claim that gravity is “a relational quality” (272, n. 43). She disagrees with my claim that the Treatise endorses action at a distance, but for my present argument we can ignore our differences on that score. To say that gravity is a relational quality is to accept Newton’s claim that the gravitational force is the consequence of (in Newton’s terminology) “one intermediate action” because matter that enters into the relation shares a “nature;” in the Treatise the “cause of the action,” is “the disposition of each body” (Newton, 1731, pp. 37–39). A way to capture this view is to say that a body has two dispositions: a ‘passive’ disposition to respond to impressed forces is codified in Newton’s second law of motion, whereas an ‘active’ disposition to produce gravitational force is treated as a distinct interaction codified in Newton’s third law of motion.16 The Treatise presents a kind of speculation that on the whole Newton confined to queries and the “General Scholium.”
In the last line of her paper Kochiras suggests that the substance counting problem threatens to undermine Newton’s concept of body (279). She offers no argument for this claim. Presumably she worries that if material and immaterial entities can co-occupy places simultaneously one might not merely mistakenly attribute some properties to bodies when one should, perhaps, attribute these to immaterial entities, but once this possibility is raised, one might leave body without any (stable set of) properties.17
Kochiras’ worry gains strength from the observation that despite toying with the idea in the Principia Newton never explicitly defines body.18 Of course, one might read a line in the Third Rule of Reasoning as an explanation why such a definition is not forthcoming: “the qualities of bodies can be known only through experiments; and therefore qualities that square with experiments universally are to be regarded as universal qualities.” This is presumably an example of what Kochiras calls “the very broad reach of Newton’s empiricism” (267). Some philosophers have lauded Newton for allowing an open-ended conception of body (see Harper, in press). I think Katherine Brading is surely correct to see in the three Newtonian laws of motion (all three refer to bodies) a kind of law-constitutive conception of body (Brading, in press). These laws provide the revisable, conception of body that is required for Newton’s rational mechanics.
Now it’s true that no experiment on bodies can, in principle, rule out that the revealed properties are not really properties of immaterial entities. This presumably helps explain why Newton is so cautious in attributing any essential (i.e., intrinsic) qualities to bodies. So, Kochiras’ claims might be thought un-refuted. Yet, the fourth rule of reasoning (added to the third addition of the Principia) offers a convincing methodological stance: until one has very compelling empirical evidence, that is, one has established a “phenomenon” one should not worry about competing hypotheses.19 So, if experiments on bodies reveal certain properties, one should stick to interpreting these in terms of bodies (and forces). It is Newton’s great insight that while one should certainly be open to speculation on the causes of gravity, one can continue with rational mechanics without knowing such a cause. The subsequent history of science has amply vindicated this hope (Smith, unpublished manuscript).
Section snippets
Passive Matter
Kochiras claims that Newton is committed to two “rationalist” features: i) that all matter is “passive” (275) and ii) “that matter cannot act where it is not” (268) or, what she also calls, the principle of local causation (277). These two features combined are crucial for Kochiras’ claim that Newton rules out material action at a distance. Kochiras’ evidence for both features is thin.
In fact, in support of the first principle Kochiras only cites a single unpublished manuscript sentence,
Is Newton an extreme empiricist?
Against Kochiras I argued that Newton does not endorse the principle of local action or passivity of matter. But to state this is not to endorse unqualifiedly the Stein/Di Salle reading in which Newton is a kind of extreme empiricist. Rather, I claim that Newton’s empiricism is itself a hard-won achievement. In particular, prior to the second edition of the Principia, Newton has at least three non trivial speculative principles.
First, the original hypothesis 3 reads: “Every body can be
Acknowledgements
I thank John Henry, Ori Belkind and Zvi Biener for detailed comments on an earlier version. The author is also grateful to Bijzonder Onderzoek Fonds, Universiteit Gent, for a grant that made possible this research.
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2013, Studies in History and Philosophy of Science Part ACitation Excerpt :Newton attempts to do so by harnessing the widely accepted view—it is certainly accepted by all Cartesian and Leibnizian philosophers—that God’s power or action is omnipresent. As Eric Schliesser rightly notes, the idea that God’s action or power is omnipresent—the idea that God is omnipresent per virtutem—would not ordinarily mean that God is omnipresent, and it certainly would not mean that for a Cartesian or Leibnizian (Schliesser, 2011, 164). But the further idea that God is omnipresent not merely per virtutem, but also per substantiam, would mean that God is actually located everywhere.