Q&A: The Modal Ontological Argument
The Modal Ontological Argument
Question
I recently came across the modal ontological argument. I assume the Rabbi is familiar with it, but I couldn’t find any discussion of it on the site, so I’m asking here.
Very briefly, the argument goes like this:
1. It is possible that a necessary perfect being exists.
1.1 That is, there is a possible world in which a necessary perfect being exists.
2. If there is a possible world in which something exists necessarily, then it exists in every possible world as well; that is, it is necessary (this is an assumption of modal logic).
3. Therefore, a perfect being exists necessarily.
The modal-logic assumption by which one reaches the conclusion is very plausible and intuitive, so it is hard to challenge. On the other hand, agreeing to the first assumption—that there is a possible world in which a necessary perfect being (God) exists—seems almost trivial.
Has analytic philosophy really managed to escape its emptiness and prove the existence of God analytically? This argument was developed by the philosopher Plantinga as an upgrade of the regular (and failed) ontological argument, and it seems that he did a pretty decent job.
I already have a few thoughts about problems with this argument, but since things still aren’t clear to me, and I know the Rabbi deals a lot with the analytic and synthetic, I’d be glad to hear his opinion about this argument.
I’m attaching here a more detailed link about the argument:
https://plato.stanford.edu/entries/ontological-arguments/#PlaOntArg
Answer
I don’t see how this is any better than the regular ontological proof, about which I wrote at length in the notebooks and in The First Existent.
The assumption that a world is possible in which a necessary perfect being exists is not compelled at all. The atheist will disagree with it, and that’s that. The whole idea of an ontological proof is that it is based on conceptual analysis alone, without assumptions. This proof is not ontological at all, since it assumes a premise. In any case, it is exposed to the problem of every non-ontological proof: one can simply refuse to accept its premise.
And we haven’t even gotten to the question of whether that premise is reasonable at all, even in my view. The possibility of a world with a necessary being is a concept that requires analysis, because possibility and necessity are interacting here in a very non-simple way. It may be that this premise is simply nonsense, not merely something one can dispute. But this is not the place to get into that analysis. Maybe I’ll write about it in the future.
Discussion on Answer
First, he can say that too (that in his view it’s impossible, or just nonsense that says nothing).
Beyond that, by the same token you could prove the existence of “necessarily salty sugar.” There may be a world in which there is sugar that necessarily has a sour taste. And from that it follows that in all worlds there is salty sugar (whose saltiness is not necessary in every such world). Which was to be shown. This is Gaunilo’s “existing island” or “perfect island” claim in full force, but here there is no way to reject it (with Anselm I think there is).
But that is only a proof that this argument cannot be correct. I still haven’t pointed out exactly where the flaw in it lies. It seems to me that one can point to the flaw in the following ways:
1. In the modal sense, “exists necessarily” (which is usually interpreted intrinsically/internally, without reference to other worlds) is translated into “exists (not necessarily) in every possible world.” Plantinga’s argument mixes these two senses, and so it is riding on an equivocation. It assumes that in one particular possible world there exists X necessarily. But once you are speaking within the modal sense, you can no longer speak of necessary existence in the accepted meaning (the intrinsic, non-modal one). This explains why that premise is meaningless nonsense. The atheist doesn’t need to reject it; he only needs to ask for an explanation of what exactly you mean.
2. Another formulation: let’s translate everything into the modal sense. You are really saying that in one possible world there exists something that exists in every possible world. Who says that is true? Now you can understand that this is an implausible premise that could prove anything you want. No wonder the atheist rejects it.
3. A third formulation: you are really saying that there necessarily exists a possible world in which a necessary being exists. You smuggled necessity in here, so naturally you get necessity out. When you speak about something possible, you cannot say that there necessarily exists a possible world in which it exists, even though that apparently is exactly the modal sense of possibility. And again, in my opinion the reason is that you are using the term “necessity” in two different senses. And if it is not necessary that such a possible world exists, then the proof collapses.
Thanks again for the reply! The time and resources you invest in the site and in answering questions are really not something to take for granted.
With pleasure.
The column is now up (580): https://mikyab.net/posts/81684
Thanks for the answer! I’d really be glad if you write about it in the future.
Regarding what you wrote, “The assumption that a world is possible in which a necessary perfect being exists is not compelled at all. The atheist will disagree with it, and that’s that” —
doesn’t that basically force the atheist to say that the probability of God’s existence is absolute zero? That’s a much stronger and harder claim for the atheist to justify than saying, “There is a small probability that God exists.” After all, if he claims there is even a small probability, then seemingly the proof could still work on him.