The internet and popular books abound in attempts to refute theistic proofs (say, St. Thomas’s First Way) but few if any of them show any awareness of the thing they are trying to refute. Eliminating such objections is necessary and valuable work, but it has an important limitation: if your objector is shallow, your dialogue with him stays shallow, and the objection he raises has little power to develop your ideas.
So just what are the principled objections to the First Way? Michael Augros raises ten wonderful objections here and responds to them, and there is very little I can add to the list. But there are a few more to include. I’ll give no responses here, since all of my responses are in various degrees of incompletion (I have pretty good refutations of some, others I’m still working on).
1.) The Scotistic Objection to omne quod movetur ab alio movetur. Peter King gives an extensive account of the objection here, but to summarize:
The necessity of something being moved by another comes from the incompatibility of actually possessing X and not actually possessing X.
But an equivocal cause can actually possess X in a more eminent way and not actually possess it in the lower way appropriate to univocal causes.
Therefore an equivocal cause has no need of being moved by another.
2.) The objection against motion being proper to bodies. St. Thomas is clear that the reason why everything in motion is moved by another is because only extended bodies are in motion. But this leaves us having to argue either that there is a luminiferous aether for all EM waves, or that nothing in the EM spectrum moves. Similar objections arise from considering magnetic fields or space, which admit of a bona fide motion and change without being extended bodies in any obvious sense of the term.
To be clear, the objection does not say “because physical thing X is not an extended body, therefore it is a mathematical point.” The objection rests on the claim that extended magnitude and points do not exhaust all possible physical subjects.
This objection is a broader critique of the science in which St. Thomas found the First Way. Such a science held that the formal object of Natural Philosophy was mobile being, and the material object was a physical body. St. Thomas always insisted that the formal object was self-evident but that the material object required proof and so was less certain. Now one can certainly say, as many thomists are tempted to say, that we can disregard the whole science in which St. Thomas located the First Way and yet keep the proof. But this is more of a critique of St. Thomas than a support of his thought; and it is ultimately an attempt to separate the grin from the cat.
3.) The objection from the adequacy of science. This is Milton Munitz’s objection in chapter four of his The Mystery of Existence. Roughly, physical science either can give an adequate account of the causes of motion or it cannot. If it can, then there is no reason to invoke some cause outside of physics, even if it is invoked as a term. But if it cannot, then what is inadequate about the causes it appeals to? Note that we cannot say “oh, natural science gives a perfectly adequate physical account or motion, but the First Way gives a metaphysical account of it.” The whole possibility of metaphysics rests on the inadequacy of the physical as physical to explain change.
4.) The objection that one cannot move from act as a principle to act as a separate act. Hans Kung might be hinting at this sort of objection in his critique of the First Way. Just as we only understand potency as the subject of some form, we only understand form as the act of some subject. But to conclude to a immobile mover requires moving from act as the act of something to act all by itself. But this change is as radical as moving from a tire or wagon wheel to a Euclidean circle.