Edward Feser’s claim that there can be no morality without Aristotelianism is silly. But should we continue to accept Aristotle’s metaphysics in the face of modern science anyway? The answer is no–and understanding why will help us understand modern science.
Aristotle’s theory of change
Aristotle’s metaphysics has two key components: his theory of change, and his theory of causation. I’ll begin, as Feser does, with the theory of change. Feser sets up Aristotle as responding to an argument from Parmenides: For a thing to change, there must be a cause for the change outside the things itself. But there is only one thing in the world. Therefore, change is impossible. Yes, that really is the argument: Parmenides thought that the apparent existence of more than one thing in the world (my Mountain Dew bottle, my Nalgene bottle, my stack of six-ounce coke cans, etc.) is an illusion.
Aristotle, being not as crazy as Parmenides, though this was not an illusion, and therefore rejected the argument. But he and Feser accepted the claim that change must come from outside a thing, and thought this entailed the existence of a God of sorts: everything that causes change must do so of its own power, or as a tool of some other thing. In the second case, though, you will eventually get to something causing change of its own power. And there can only be one such thing, which must be God.
The reasons for this last claim are confusing, and Feser half-admits they depend on the Aristotelian version of the “explain why stuff exists” argument. He also makes this claim: if A changes B, and B changes C, then B isn’t changing C on it’s own, is being used as tool for change by A. This, though, is a fallacy: the Earth causes the Moon to orbit the Earth, and the Sun causes the Earth to orbit the Sun, but the Sun doesn’t use the Earth as a tool to cause the orbit of the Moon.
Aside from this, at first glance it looks like Aristotle was wrong accept Parmenides’ assumption that change must come from outside, since, if current understanding of physics is right, an object in motion (one that’s changing position) will stay in motion (keep changing position) until acted on by an outside force. Feser notices this problem, but counters:
we want to know why things are governed by this principle. To that one might respond that it is just in the nature of things to act in accordance with the principle of inertia… it just leads to the further question of what is the cause of a thing’s existing with the nature it has…
What Feser wants to say here, but does not say, is that motion is caused by a thing’s nature, and a thing’s nature is something outside the thing itself. I assume Feser wants this to be equivalent to what he does say, but I don’t know why this would be. By asking about the explanation for a thing’s existence, we also end up back at the “how do we explain existence” argument rather than the “how do we explain change” argument that Feser is supposed to be defending. But worse, from the point of view of defending Aristotle, is the fact that even if God had to cause the existence of natures, the nature of an object flying through space wouldn’t have to change as the object flies through space, which contradicts the Aristotelian model of how movement happens. Therefore, Feser has failed to square Aristotelianism with modern science.
The “existence” argument for God’s existence
This is the standard “how do you explain why things exist” argument for God’s existence. Skip this section if you’re only interested in Aristotle and science, but for those who care: Feser defend this argument by saying that God, alone, gets away with existing uncaused because God is “pure being.” I’m not entirely sure what this means, unless it means that God exists necessarily–could not possibly have not existed. But in order to get from this to a God as normal people understand it, he needs ever more assumptions:
1) A being that exists necessarily must be unchangable
2) To lack a feature is to potentially have a feature
3) To potentially have a feature is to be changable
4) If (2) and (3), then an unchangable being must have all features
5) A being with all features is God
Feser never gives a reason to think (1) is true. (2)-(4) seems plausible, except that the idea of a being with all features seems incoherent, which would mean there is no unchangeable being. Feser tries to get around this by saying that in cases where two features seem to be incompatible opposites, one is really a lack of a feature. But (2)-(4) seem on their face to be as applicable to lacks of feature as to positive features, so the argument doesn’t work. Thus, even aside from the scientific problems with Feser’s claims, his argument doesn’t amount to much.
Aristotle’s theory of causes
The conflict between Aristotle’s theory of change and modern science is small compared to the conflict with Aristotle’s theory of causes. Aristotle thought of things as having four causes: matter, form, the thing that brought it into being, and its ultimate purpose. Ultimate purpose is important for Feser’s natural law ethics, and it’s also a big point of contention between Aristotle and the scientific world view.
On Feser’s take, the end state that a thing is headed towards is literally it’s cause. If Acorn A is going to become tree A, then Tree A is actually causing Acorn A’s growth. Feser claims both that this is obvious and that this is a puzzle, and says this could only be if Tree A already existed in God’s mind when Acorn A began growing.
Like Aristotle’s theory of change, this seems to be contradicted by modern science on this ground: Acorn A becomes Tree A not because of some mysterious way in which a future tree guides the growth of a present acorn (what Feser would have us believe) but due to the complex historical processes called evolution, though those did involve lots of acorns becoming trees. In a sense, yes, the Aristotelian view looks right, but only because of a confusion between the causal work of the future Tree A and the causal work of a lineage of past trees closely resembling Tree A.
Feser defends Aristotle from Darwin with roughly the following argument: Aristotle was obviously right, and couldn’t possibly have been wrong, so he would have been right even without evolution. Trouble is, Aristotle’s metaphysics is nowhere near so obvious. Consider this quote from pre-Darwin philosopher Samuel Clarke, trying to protect the idea of purpose from the criticisms of Spinoza:
if there be any final cause [i.e. purpose] of anything in the universe, then the supreme cause is not a necessary but a free agent. This consequence Spinoza acknowledges to be unavoidable. And therefore he has no other way left but with a strange confidence to expose all final causes as the fictions of ignorant and superstitious men, and to laugh at those who are so foolish and childish as to fancy that eyes were designed and fitted to see with, teeth to chew with, food to be eaten for nourishment, the sun to give light, etc.
None of this is true in the sense that God obviously designed these things. And even allowing Darwinian purposes to be “final causes,” we know from modern science that food and sunlight are things which life on earth has evolved to exploit, much unlike eyes and teeth, which at least evolved for purposes. Clarke’s view of the world was naive, and not immune to scientific correction.
Science and mumbo-jumbo
In this post, I’ve tried to write around one aspect of Feser’s book: heavy use of (English translations of) Aristotelian jargon like “actuality,” “potentiality,” “final cause,” “form,” and so on. The words aren’t actually that important, if you know what they mean, go ahead and re-read the review making appropriate substitutions. But they do serve one important function in a system like Aristotle’s: they create a feeling of security, a feeling that you know what you’re talking about. If you have no idea how the world really works, they feel like a real explanation. But once you start seriously trying to figure out how the world might work–once you even notice the modern scientific worldview as a possibility–the “obviousness” is gone.