Earlier today I posted chapter 27 of book 1 of Summa contra gentiles. After reading St Thomas' argument in §7, I wondered if it had any validity in our time, since it seemed inseparable from a defunct Aristotelian cosmology of perfect, perpetual celestial motion. The context of the argument is that of a longer demonstration of the doctrine that God is not the form of any body. In §6 Thomas writes that the doctrine:
...can also be reached in the following way from the eternity of motion. If God is the form of some movable body, since He is the first mover, the composite will be self-moving. But something self-moving can be moved and not-moved. Both possibilities are found in it. But such a being does not of itself have an indefectibility of motion. [Sed movens seipsum potest moveri et non moveri. Utrumque igitur in ipso est. Quod autem est huiusmodi, non habet motus indeficientiam ex seipso.] Above the self-moving being, therefore, we must posit another first mover, which gives to the self-moving being the endlessness of its motion [quod largiatur ei perpetuitatem motus]. Thus, God, Who is the first mover, is not the form of a self-moving body.
As I tried to parse this section, Thomas is saying that moving bodies can move and can cease to move. In Aristotelian terms, and I would say in basically any terms, moving bodies, such as dogs, have their principle of motion within themselves. Dogs run by pivoting and leveraging some parts of their bodies against other parts, but always in connection with something stable and unmoving, such as the ground. However, if God were the form of eternally mobile bodies, they would have a completely immobile form as their principle of being, which means they would lack the principle of self-motion. It would be as if dogs were "all ground": they would have an immobile form to 'ground' their motion but would would be formally immobile entities and would ipso facto lack self-motion. Hence, God qua immobile mover, is not the form of mobile beings, even if they are eternal.
In §7 Thomas continues by saying that, while "this argumentation is suitable for those who posit the eternity of motion... [, those] who do not posit it [i.e. eternal motion] can reach the same conclusion from the regularity of the motion of the heavens [eadem conclusio haberi potest ex regularitate motus caeli]."
For just as a self-mover can be at rest and in motion, so it can be moved more swiftly and less so. The necessity in the uniformity of the motion of the heavens, therefore, depends on some higher and absolutely immobile principle [Necessitas igitur uniformitatis motus caeli dependet ex aliquo principio superiori omnino immobili], which is not a part of a self-moving body as the form of that body.
Earlier I wrote, "This argument seems so closely tied to Aristotelian physics that I wonder if it is worth saving." Later on in the day, though, I was pondering the problem and I came upon a way this argument might indeed find some relevance in contemporary physics and metaphysics. I don't think this is the reaction of a craven Thomist "fanboy" who must salvage all of Aristotelianism. Indeed, not only do I admit that a great deal of Thomistotelian "natural science" is totally and rightly defunct, but I am also very open to calling myself something other than a Thomist, such as if I were to return to the Augustinianism I held in college (Pope Benedict XVI is rather vocal about being an Augustinian rather than a Thomist), or if, for instance, I morph into a Scotist, or perhaps if I go for broke and don the hat of a Jakian-Keefian!
The point is, while I don't feel a desperate need to salvage every jot and tittle of classical metaphysics, I do defer to the ancient wisdom of my predecessors and try to read "the Ents" charitably. I believe the core of scholastic thought can be "transposed" into modern coherence. This is why I found William Wallace's essay, "Is Nature Accessible to the Mathematical Physicist?", so fascinating. Wallace is a leading scholar of the history and philosophy of science, as well as a Dominican priest, so he is qualified to transpose scholastic metaphysics into contemporary physics, if transposed it can be. At various points in the essay, Wallace notes how the "strange" notions of Aristotelian metaphysics actually have correlates in modern physics and show a remarkable resilience as physical concepts per se.
Wolfgang Smith has a similar knack for transposing the wisdom of ancient metaphysics into modern parlance (cf. this brief interview). In his 1970 essay, "Matter, Elements and Substance in Aristotle", Robert Sokolowski performs a similar transposition, and this website on classical Philosophy of Nature has numerous links to articles demonstrating how viable such transposition is. The recent work of scientists and scholars like Anthony Rizzi, Stephen Barr, and Fr Robert J. Spitzer, among others, adds great depth to this transpositionary synthesis. And even though one of my greatest role models in the Church and in the history/philosophy of science, Fr Stanley Jaki, was less than enthused about Aristotelian physics--he reports having once felt "mental vertigo" as a graduate student in physics at a major university vigorously argued that Aristotelian physics must be vindicated at nearly any cost--, yet a great deal of Jaki's work shows how the core principles of classical metaphysics surface again and again in the progress and coherence of exact physical science.
Moreover, there is a principled philosophical reason to "salvage" what we can from earlier scientific discourses. As theories get increasingly broad and robust, they show their strength not only by conforming to empirical data, and not only by predicting new phenomena, but also by accounting for the truths some previous theory (or theories) maintained. Hence, Einsteinian relativity did not so much "nullify" Newtonian physics as transpose the latter's main elements into a system of thought that better accounted for why the latter was held to be true for so long. After all, if Newtonian physics were wholly false, there wouldn't be much "science" or "evidence" upon which Einstein could have drawn for his own breakthroughs. Falsity presupposes truth. Total falsity is as incoherent a notion as utter chaos. The march of scientific 'progress'--Kuhn and the post-Kuhnians notwithstanding--obliges that scientists continually "redeem" earlier theoretical artifacts in order to demonstrate their theories' broader coherence vis-a-vis their predecessors. Hence, as odious as we may find pre-modern science, we can't simply deny it was wholly scientific. Even the theory of empyrean rings was itself a kind of byzantine empirical theory, a way of "saving the phenomena" in terms of higher laws. Indeed, why did the ancients believe there were perfectly spherical and smoothly mobile "stars" rather than believing that stars were tiny dots seen inside the human cornea? As crude as it may seem, the fact of the matter is, the former theory better accounted for "the heavenly signs" than the latter theory. For instance, why would our retinal stars disappear when we closed our eyes? Or why would they still shine at night if no light was shining on the cornea? And so forth.
We can't summarily lambast the ancients for "being so dumb" that they "just couldn't see" how wrong and crazy their ideas were, for if we did that, we would have to lambast generations of the leading minds in 19th-century physics for "just not seeing" that the ether was a fiction. More to the point, we should also have to issue promissory guillotines for our own necks, devices which later generations shall use to defame and decapitate our own folly. As I have noted at least once before, exact physical science is actually strongest as a form of inquiry when it admits it is perhaps weakest as a means to attaining lasting truth. The point is that even contemporary astronomy has not done away with the essential motive of pre-modern cosmology, namely, to make sense of what we see in terms of broader theories, higher laws, and simpler principles. Hence, moving beyond classical cosmology is not to say that cosmology was utterly wrong, but rather to say that it, like any prior theory, was merely not right in the same ways its progeny still seem to be.
Having said all that, let me explain how I think Thomas' argument in §7 deserves more of a hearing than I first recognized. Recall that Thomas says that, even if we deny the eternity of celestial motion, we can know God is not the form of movable bodies "from the regularity of the motion of the heavens [eadem conclusio haberi potest ex regularitate motus caeli]." Recall that he further states, "The necessity in the uniformity of the motion of the heavens, therefore, depends on some higher and absolutely immobile principle [Necessitas igitur uniformitatis motus caeli dependet ex aliquo principio superiori omnino immobili]." We no longer accept the perfectly circular, unperturbed motion of the "empyrean rings," but contemporary physics is still rife with "regularity" and "uniformity" of natural dynamics. The perfect orbits of the highest heavens were for the pre-moderns an abstraction, indeed, a seemingly necessary postulate to account for subluminary imperfection and change. Yet exact physical science has by no means done away with such natural idealizations, as I have discussed before in, e.g., this post, and this post. Indeed, to speak of the "regularity" of physical motion is to speak of physical regulae, or rules. And while scientists may now be more inclined to downplay talk of "physical laws" in favor of "scientific models"--as Nancy Cartwright, i.a., point out, natural laws point to a natural Lawmaker! (cf. "No God, No Laws")--, yet natural regularity and constancy still pervade current science. Consider, for instance, Planck's constant, or the (Einsteinian) constancy of the speed of light in a vacuum, or the (Galilean) constancy of acceleration as a physical reality, or the stable rates of radioactive decay and the unvarying energy levels of electron orbitals in one element versus another. Indeed, what scientists seek as physically true are natural invariances--invariance, mind you, being a synonym for regularity. Hence, Thomas' point in §7 may still be very pungent in so far as we admit that the regularitate of physical variables still points to the need of some unmoved principle which fixes their specific--and therefore contingent--modes of existence, action, and change.