“The Reverse Ontological Argument” James Henry Collin, Analysis 2022
This is an interesting little paper which claims to break the symmetry of the modal ontological argument, or MOA. (I prefer to call it "meta-modal", they’re all modal one way or another, but the acronym’s the same.)
The Argument
The MOA is a clever little device made famous by Alvin Plantinga. It uses the existence of reasonable disagreement about the existence of God, as the basis for an argument that God must exist.
Let’s agree, it starts off innocently, that both theism and atheism are coherent. Neither side is flat-out contradicting itself, and even though they disagree they can at least understand each others’ positions. (If you think either atheism or theism is literally incoherent, this argument is not for you.)
So the atheist should agree that it might have been true that God exists, even though in fact it isn't. In possible-worlds talk, there is at least one world in which God exists.
Given that concession, the MOA pounces. God, it points out, is defined as a being that exists necessarily. Of course, you can’t infer directly from the definition that he exists; things can’t be defined into existence. But if there is any world where he exists, then by definition he exists necessarily in that possible world. And that means, given plausible assumptions about modal logic, that he exists in every world. Which means he exists in this world, the actual one.
Tah-dah: the possible existence of God, conceded by the atheist, entails his actual existence. Checkmate, athiests.
But! The MOA is symmetric. Just as the atheist has to concede that there’s a world in which God exists, so the theist has to concede that, since atheism is coherent, there is a world in which God does not exist, and atheism is true. But (as we just saw), if God exists in any world, he exists in every world. So if there’s one world in which he doesn’t exist, he doesn’t exist in any world. Checkmate back!
Breaking the Symmetry
Collins claims to have found a way to break the symmetry: to block the reverse argument while allowing the original MOA to proceed. He starts by pointing out that “God exists” and “God does not exist” are both a posteriori necessities, in Kripke’s sense. (If they were a priori necessities, there would be no need for the MOA, which proceeds from the possibility of coherent disagreement.)
And once a posteriori necssities are in the picture, the inference from coherence (or conceivability) to possibility is complicated. If you think water is essentially H2O, for example, then although it’s conceivable that it could have had some other composition (XYZ), it’s not possible. Since both H2O and XYZ are conceivably water, the only way to work out which of them is possibly water is to find out, empirically, which of them is in fact water.
So far, so still symmetrical. But Collin now appeals to an idea about the relation between God and physical objects. According to at least some theistic views, physical objects necessarily depend ontologically on God. The claim that physical objects depend on God is, like theism itself, an a posteriori necessity. It is coherent, and so is its denial. But what isn’t coherent is that both (a) physical objects depend on the existence of God and (b) there is a world in which physical objects exist but God doesn’t. So the atheist claim that there is a world without God implies that physical objects don’t necessarily depend on God. But there is no empirical warrant for that claim! Nothing we’ve learned about physics tells us that physical objects aren’t ontolgoically dependent on God. So the atheist can’t help themselves to it, and so isn’t entitled to assert the possibility of a world without God.
But isn’t this also symmetrical? No, says Collins. The theist, by contrast, can accept that physical objects are not necessarily dependent on God. So that, even if God exists, physical objects could be ontologically independent of him, even essentially so. So the theist claim that God exists in a world does not entail either physical dependence or its converse. So the theist remains entitled to their possibility claim, while the atheist is not.
This is ingenious, if odd. God is supposed to be the creator of all things! But perhaps being a creator isn’t part of his essential nature the way that existing is. Or perhaps divine creation is a strictly causal relation after all. Anyway, Collin’s argument here raises a striking issue:
"If the actual physical things turn out to be, for instance, essentially non-dependent, such that their existence cannot depend on anything else, this also does not exclude the possibility of a perfect Being. Maximal greatness does not require being able to create that which is impossible to create, so the existence of a perfect Being would not require the dependence of physical things on that Being in worlds where those physical things exist.”
This is an interesting limitation on divine omnipotence! God, it seems, is limited by a posteriori necessity as well as by logical. That means, in particular, that God is not in charge of essences. Where, then, does water get its essential nature? Where, in the example Collin works with, do we humans get our essences of origin?
Responses
This is an intriguing argument. But unsurprisingly to me, I find myself unpersuaded. Here are some thoughts on why:
[1] Collin is rather helping himself to an a posteriori necessity here. “Physical objects depend essentially on God” isn’t something that has some independent plausbility. You might come to believe it as a consequence of theism, but it’s odd to go the other way. Now Collin is careful not to assert that dependence, of course, but implausible a posteriori necessities are cheap, and offer the possibility of revenge.
I suggest: physical objects depend essentially on the absence of God. That is, suppose they are a posteriori necessarily inconsistent with the existence of God. That seems just as coherent as Collin’s principle. But it creates a mirror situation. The theist has to deny it: the existence of any world with a God entails the principle is false. And the atheist can remain agnostic: maybe physical objects co-exist with his absence but don’t depend on it.
[2] The symmetry-breaking a posteriori necessities here are essence claims. People essentially originate in a particular sperm/egg combo; physical objects essentially depend on (or are essentially independent of) God. They are not like “Cicero is Tully”, where the necessity comes from the less controversial necessity of identity. An atheist who doesn’t believe in a posteriori essences (such as myself, some days) needn’t be worried by them. (I take it “God exists necessarily, if he exists at all” involves a definitional, a priori essence. What’s a posteriori is the antecedent, that he exists at all.)
[3] Don’t we have empirical evidence in favour of physical objects not ontologically depending on God? Arguably, all of physics is such evidence. We’ve managed to do a tantalisingly almost-complete job of describing and predicting the phenomena, without appeal to God. That’s pretty good evidence that they don’t depend on God, for the same reason we’re justified in thinking they don’t depend on monads. Collin’s argument seems to depend on a radical separation of metaphysics and science, such that science always leaves metaphysical claims open. (Fine-tuning? Not a fan, personally, but at any rate that tells in favour of a designing/causing creator, rather than an ontologically sustaining one.)
The Original Argument
Of course, the symmetry objection is just a placeholder for an actual refutation of the MOA. If the symmetry objection is right, the MOA can’t work; but how exactly does it go wrong? A real diagnosis has the advantage that it can still work even if, as Collin claims, the reverse argument fails for some reason. (We can pull up the symmetric ladder behind us.)
The answer to my mind is simply that the meta-modal move is improper. Since God exists necssarily, if at all, there is no such thing as a world in which he exists. His existence cannot be witnessed by a single world, because no single world has the resources to represent his necessity. To say God exists at all is to say something about the space of all possible worlds, not just one. The atheist should simply deny, therefore, that there is a possible world in which God exists. (Likewise, the theist should deny that there is a possible world where God does not exist.) Not on the basis that theism is incoherent—we can still accept that there is reasonable disagreement to be had. But its coherence can’t be represented by the formula "∃w: Theism is true at w”. Its coherence comes instead from the intelligibility of the claim that "God exists" is an a posteriori necessity. We’re arguing about a necessary being; that argument has to be had in terms of necessity.