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What's REALLY Wrong with the Ontological Argument

Brad Pitt, of Course!

A fun (and effective) way to win an argument is whopping an opponent with a reductio ad absurdum — Latin for "bring back to absurdity." Basically, an argument is a reductio ad absurdum when, in order to make its point, it assumes the very opposite of its intended conclusion, then shows that something false, or incoherent, or irrational, or stupid, or just plain intellectually suspect follows from this assumption.

Well that was clear as mud, wasn't it?

Let me give you an example. Suppose I want to argue that Brad Pitt's not particularly intelligent, and suppose I want to argue this via a reductio ad absurdum. To do so, I would assume the opposite of what I want to argue — that is, I'd assume that Brad Pitt is intelligent — then I would show that something intellectually unacceptable follows from this assumption.

Here's how my argument might go:

The main character in the 1999 movie Fight Club is a fellow named Tyler Durden.¹ Tyler Durden is memorable for, among other things, his scathing critiques of contemporary American culture. In the course of these critiques, Durden expresses low regard for Americans who live a particular sort of lifestyle — what we might call "The Comfortable American Lifestyle."

In the movie, Durden is played by none other than Brad Pitt. In real life, Brad Pitt lives The Comfortable American Lifestyle. (In spite of his often unkempt looks, we all know he's not exactly roughing it.) Watching the movie and reflecting on the words coming out of Durden's (i.e. Pitt's) mouth, one is therefore given the privilege of savoring something deliciously ironic: Brad Pitt reciting lines that belittle Brad Pitt.

Now, let's make an observation and, for the sake of our reductio ad absurdum, an assumption.

• Observation: An intelligent man would never belittle himself — at least not in a high-budget movie that's guaranteed to be seen by millions and millions of viewers.
• Assumption: Brad Pitt is an intelligent man.

From this observation and assumption, it follows that Brad Pitt would never belittle himself in a high-budget movie made for the viewing pleasure of millions. This, however, is clearly false, for Brad Pitt has belittled himself in a high-budget movie made for the viewing pleasure of millions; he did so in the movie Fight Club when, as Tyler Durden, he railed against people who live just the kind of lifestyle he, in fact, lives.

We can therefore conclude that, contrary to the above assumption, Brad Pitt is not particularly intelligent.

Okay. This isn't the best argument — there's probably a good explanation for Brad's willingness to play Tyler Durden — but hopefully it gives you an idea of how the reductio ad absurdum works. By assuming the opposite of what I wanted to prove — that is, by assuming that Brad Pitt is intelligent — I was able to deduce something false: that Brad Pitt would never have played the part of Tyler Durden, who expresses low regard for the likes of Brad Pitt. But since something false seemed to follow from the idea that Brad Pitt is intelligent, I had good reason to reject that idea and, therefore, good reason to embrace its opposite: the idea that Brad Pitt isn't intelligent.

Now, believe it or not, Gaunilo's objection to Anselm's argument is also a reductio ad absurdum — though, I must say, a much better one.

That Island than Which None Could be Less Possible

In my last article, we saw Gaunilo's "greatest possible island" objection to Anselm's ontological argument. The logic of Gaunilo's objection goes more or less as follows:

If the ontological argument is valid, then so is my "greatest possible island" argument; if, however, my greatest-possible-island argument is valid, then, just by thinking about the idea of an island than which none greater can be conceived, we can prove the existence of an island than which none greater can be conceived; but obviously we can't prove the existence of an island than which none greater can be conceived, at least not just by thinking about it; therefore, my greatest possible island argument isn't valid; thus, neither is Anselm's ontological argument.

Gaunilo assumes the opposite of what he wants to prove: that the ontological argument is valid. He then argues that, from this assumption, it follows that he can prove the existence of the greatest possible island just by thinking about the idea of a greatest possible island. This, however, is obviously false — he can't prove the existence of a greatest possible island just by thinking about it, and neither can anybody else. Thus, for the same reasons, the ontological argument can't prove the existence of God.

Now Plantinga (whom I introduced in my last article) thinks Gaunilo's objection fails. Why? Because he thinks that, whereas God is possible, a greatest possible island isn't. As Plantinga puts it:

No matter how great an island is, no matter how many Nubian maidens and dancing girls adorn it, there could always be a greater — one with twice as many, for instance. The qualities that make for greatness in islands — number of palm trees, amount and quality of coconuts, for example — most of these qualities have no intrinsic maximum. That is, there is no degree of productivity or number of palm trees (or of dancing girls) such that it is impossible that an island display more of that quality. So the idea of the greatest possible island is an inconsistent or incoherent idea; it's not possible that there be such a thing.²

Plantinga's point is that there's a fundamental disanalogy between Anselm's ontological argument and Gaunilo's greatest possible island argument. Thus, the success of the ontological argument doesn't guarantee the success of Gaunilo's greatest possible island argument. Gaunilo's objection to the ontological argument therefore fails.

Beware of Proof

But Gaunilo's objection does raise interesting questions for Anselm, right? At the very least, doesn't it hint at the possibility of a better reductio ad absurdum? Well, maybe you don't think so, but I do. At any rate, unlike Gaunilo's argument, I can't see a relevant difference between Anselm's proof and the following line of reasoning.

As Anselm says, God is that than which nothing greater can be conceived. What, then, is that than which nothing worse can be conceived? If God is the greatest thing conceivable — and he surely is — then what is the worst thing conceivable?

Well, is Satan the worst thing conceivable? I don't think so. I'm not aware of a passage in Scripture where we're told what Satan's ultimate goal is, but let's assume that it involves the removal of all good from the universe.

In this case, a successful Satan — one very different from the one that actually exists — might be the worst thing conceivable, for it's hard to imagine anything worse than a universe without anything good. Or, perhaps, a universe completely devoid of good might itself be the worst thing conceivable.

In any case — and here's the important point — since God is good, wouldn't the worst thing conceivable involve, among other things, God's nonexistence? Put another way, since God is the greatest thing conceivable, mustn't our description of the worst thing conceivable include the idea that God doesn't exist?³

If the answer to these questions is yes, then Anselm and his ontological argument are in a pretty tough spot. For if the ontological argument proves the existence of God, then, by taking it and substituting "that-than-which-nothing-worse-can-be-conceived" for "that-than-which-nothing-greater-can-be-conceived," atheists can prove the nonexistence of God as follows:

We understand that-than-which-nothing-worse-can-be-conceived,⁴ and what is understood exists in the mind. Thus, since we understand that-than-which-nothing-worse-can-be-conceived, it exists in the mind. If that-than-which-nothing-worse-can-be-conceived exists only in the mind, however, then it can be thought to exist in reality also, which is clearly worse.⁵

Therefore, if that-than-which-a-worse-cannot-be-conceived exists only in the mind, then that-than-which-a-worse-cannot-be-conceived is that-than-which-a-worse-can-be-conceived. But this is obviously impossible. Therefore, that-than-which-a-worse-cannot-be-conceived exists both in the mind and in reality.

As we saw above, however, the existence of that-than-which-a-worse-cannot-be-conceived is incompatible with the existence of God; if that-than-which-a-worse-cannot-be-conceived exists, then God doesn't. Therefore, since that-than-which-a-worse-cannot-be-conceived does exist, God doesn't. (See Figure 1, below.)

But surely there's something wrong with a line of reasoning that can prove both the existence of God and the nonexistence of God?

So far as I can tell, at least one problem with Anselm's ontological argument is this: It employs a line of reasoning that can be used to prove perfectly contradictory things. It can be used to prove the nonexistence of God just as effectively as it can be used to prove the existence of God. If we theists can use Anselm's argument to prove that atheism is false, I see no reason why atheists can't use the above argument (or something like it) to prove that theism is false. Thus, I can't help but conclude that the ontological argument doesn't work.

Then Why am I Even a Christian?

Most of the Christians and theists reading this won't be bothered by my claim that Anselm's argument fails. Some, however, will be inclined to take this failure to be yet another instance of the intellectual indefensibility of Christian and theistic faith. For those of you thus inclined, let me conclude this series with two tidbits of advice.

First, if you're seriously interested in the ontological argument and really want to know if my critique defeats it, I suggest you run this article by your philosophy professors. I only have a B.A. in philosophy, and this means I don't know half as much about this stuff as they do. Don't be surprised if even your non-Christian and atheistic professors point out things I've overlooked.

Second, assuming that there are problems with the ontological argument — not just Anselm's version but every version so far⁶ — don't fall into the intellectual error of letting these problems undermine your confidence as a Christian. Anselm himself did his philosophizing under the banner Fides Quaerens Intellectum — "Faith Seeking Understanding" — and this is significant in this context for a number of reasons.

Historically, philosophers have worked under two assumptions. First, they've assumed that faith and understanding are somehow at odds with one another. If something like the ontological argument brings you to understand God's existence, then it leaves you no room for faith in his existence. Conversely, if you have faith in God's existence, this is only because you don't yet understand his existence — perhaps, as atheists would argue, that his existence is "only in the mind."

This brings us to assumption number two: that faith is somehow inferior to understanding. Historically, philosophers have assumed that faith should be replaced by understanding. Combined, these two assumptions result in the idea that, when one has faith in something like God's existence, he should do whatever it takes to turn his faith into understanding; however one cannot start with faith in order to reach understanding, since the two are at odds; thus, in order to gain understanding, he must exchange his faith for doubt. Faith should therefore always be exchanged for doubt.

Under the banner Fides Quaerens Intellectum, Anselm rejects these two assumptions and the ideas that result from them. According to Anselm — the author of the 927-year-old argument we've been critiquing and one of the greatest philosopher of all time — faith and understanding are not at odds with one another, and this allows him to maintain that faith is an appropriate starting point in the quest for understanding. (Recall that Anselm presents the ontological argument as part of a prayer.)

Moreover, according to Anselm, faith is not inferior to understanding. Anselm does not think that faith should seek understanding because the latter is better than the former. Rather, marching under the banner Fides Quaerens Intellectum, Anselm defends the claim that faith and understanding make great companions — the former making the latter possible, the latter giving the former depth — and I think he's right

So, if you're bothered by my claim that Anselm's argument doesn't prove the existence of God, my advice to you is this: Rather than thinking that the ontological argument's inability to prove God's existence counts against Christian (or theistic) faith, take the argument for what it's worth — a brilliant and strangely beautiful example of faith seeking understanding.