There's something about religion that renders its adherents utterly unable to see logical flaws in matters that relate to their deeply held beliefs. We're talking about people who may be, by all accounts, quite intelligent. People who, when shown a logical argument that would support some other religion's God for example, will astutely tear that argument apart, attacking every flaw and weakness. But when shown a similar argument for their own God, they can't see or won't accept those very same flaws and weaknesses.
Such is the case with a modern formulation of the Ontological Argument for the existence of God. In a recent discussion, I stated that the Ontological Argument employs circular reasoning, and I was challenged to show that, given this particular formulation:
1. It is possible that a maximally great being exists.This is the form that has been defended by WL Craig. It is a repackaged version of Plantinga's Ontological Argument using modal logic involving the necessity of God's existence, although this version doesn't explicitly assert the necessity of God, as Plantinga does. Here is Plantinga's formulation:
2. If it is possible that a maximally great being exists, then a maximally great being exists in some possible world.
3. If a maximally great being exists in some possible world, then it exists in every possible world.
4. If a maximally great being exists in every possible world, then it exists in the actual world.
5. If a maximally great being exists in the actual world, then a maximally great being exists.
6. Therefore, a maximally great being exists
1. A being has maximal excellence in a given possible world W if and only if it is omnipotent, omniscient and wholly good in W; andAt first glance, these arguments don't appear to be the same, but Craig rolls up the first three statements from Plantinga's argument into the first statement of his own version. We can be certain that Craig assumes the necessity of God, because that allows him to make his third statement. Only something that is necessary exists in every possible world.
2. A being has maximal greatness if it has maximal excellence in every possible world.
3. It is possible that there is a being that has maximal greatness. (Premise)
4. Therefore, possibly, it is necessarily true that an omniscient, omnipotent, and perfectly good being exists.
5. Therefore, (by axiom S5) it is necessarily true that an omniscient, omnipotent and perfectly good being exists.
6. Therefore, an omniscient, omnipotent and perfectly good being exists
The other qualities associated with maximal greatness are not stated by Craig, but they are irrelevant to the argument. Whatever those qualities are, the only thing that is essential to the argument is the quality of necessary existence. This is made clear by Plantinga's formulation. Those qualities of "maximal excellence" are identified as omniscience, omnipotence, and omnibenevolence by Plantinga, but they could just as well be any other quality you choose without changing the logic of the argument. To see this, let's assume that maximal excellence is defined as "pure redness". Then, Plantinga's statement 2 would become "A being has maximal greatness if it has pure redness in every possible world." And the rest of the argument proceed exactly as stated, up to the final statement, which would read "Therefore, a purely red being exists."
The point of this is that this argument is predicated on the quality of necessary existence, not on the other qualities that constitute maximal excellence. And therefore, it is possible to prove the existence of anything at all, as long as you assert that it exists necessarily. Maximal excellence could be defined as having all the qualities of a unicorn, and then a maximally great being would be defined as a unicorn that exists in every possible world.
This should be a red flag to any Christian that there is something wrong with this argument. The fact is that assuming necessary existence in the definition of God simply begs the question. Of course, something must exist if it exists necessarily. The conclusion of the argument is contained right in the up-front assumption of necessary existence. So this is a clear-cut case of circular reasoning. Nevertheless, many Christians accept the validity of this argument, even though they would reject it if it applied to unicorns, or anything other than their own God. This clearly reveals the Christian blind spot.
Craig attempts to hide the assumption of necessary existence by not stating it explicitly. This is characteristic of many of his theistic arguments. He has a tendency to gloss over points that may be seen as a weakness or a flaw in his logic. However, it seems surprising that the great philosopher Alvin Plantinga would make such an obvious logical error. Well, it turns out that Plantinga has acknowledged that this argument actually proves nothing.
Our verdict on these reformulated versions of St. Anselm's argument must be as follows. They cannot, perhaps, be said to prove or establish their conclusion. But since it is rational to accept their central premise, they do show that it is rational to accept that conclusion - Alvin Plantinga, The Nature of Necessity (1974), pg 221So at least Plantinga is honest about the logic of this argument. But he still maintains that the conclusion is reasonable, based on the assumption that the "central premise" is "rational". What Plantinga is saying is that Christians should just accept the bald assertion that God is maximally excellent and exists necessarily. No logical argument in support of that assertion is needed for the Christian, because it is "rational". And that just goes to show that even Plantinga has a huge blind spot when it comes to beliefs about his God.
The whole purpose of the argument is to assure believers that it is reasonable to believe that their God exists. Without some kind of logical proof, the existence of God is nothing more than an assertion. Christians have a choice here. They can accept the assertion of God's existence, and remain blind to the fact that it has not been demonstrated. They can accept the validity of the Ontological Argument, and remain blind to the fact that it is logically flawed. They can reject this argument and trust that some other argument proves the existence of God, while remaining blind to the fact that there is no such argument. Or they can open their eyes and realize that God exists only in the mind of the believer.