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This is the weekly Q & A blog post by our Research Professor in Philosophy, Dr. William Lane Craig.

Question

Hi Dr. Craig,

I'm an agnostic undergraduate philosophy student, and I find the idea of divine necessity particularly interesting for whatever reason. I wonder if you might respond to the following question / argument.

When I think about the concept of God --a maximally great being-- it seems clear that God, if he exists, exists necessarily. So if God exists in the actual world, then there is by definition no possible world in which God does not exist. But the problem is this: there seem to be a nearly infinite number of possible worlds in which God does not exist. Here I'm thinking of a world that consists of nothing but a single mereological simple, perhaps standing still or floating through a finite space. Such a world is eminently conceivable and breaks no metaphysical principle that I'm aware of. One might construct a simple argument along these lines:

1. If God exists in the actual world, there is no possible world in which God does not exist (this is merely a statement of God's necessity).
2. But there is a possible world in which God does not exist.
3. God does not exist in the actual world.

Now, this argument of mine (though I'm surely not the first to think of it) seems like a rough inverse of Modal Ontological Arguments, which purport to show that if God's existence is even metaphysically possible, then God must exist. The idea there, of course, is that if there is a possible world in which God exists, and God is a necessary being, then God exists in all possible worlds, including the actual world.

To accept the Modal Ontological Argument, you have to accept that:

1. God's existence is possible.
2. There is NOT even one single possible world, out of the vast, vast array of possible worlds, in which God does not exist.

To accept my argument, you have to accept that:

1. There IS at least one single possible world, out of the vast, vast array of possible worlds, in which God does not exist (And this of course implies that God's existence is impossible, but one need not accept that as a premise of the argument).

Intuitively, my argument seems to be on firmer ground. I find it easier to accept that there is a single possible world without God than that God is possible and therefore exists in every single possible world. This, especially, when I consider what kind of a being God is. The Modal Ontological Argument for theism requires that this immaterial personal being with all of these extreme powers exist in every single possible world. All I need for my argument to get off the ground is for there to be a metaphysically possible world without this immaterial personal being of immense power. Again, intuitively, my argument seems to be on firmer ground.

Please let me know what you think, and if I have gone wrong somewhere. Thanks Dr. Craig.

Robert

United States

Dr. William Lane Craig’s Response

It’s admittedly very difficult for the theist to provide any proof of the key premiss in the ontological argument, to wit

For that reason, Plantinga thought initially, at least, that the argument, though sound, is not “a successful piece of natural theology.” Nevertheless, Plantinga rightly insisted that the argument does show that belief in God’s existence is perfectly rational. For the person who accepts (1) is being entirely reasonable in his modal judgments. I think that counts as success in justifying a “reasonable faith.” For that reason I usually simply leave it to my audience to answer the question, “Do you think that it’s possible that God exists?” The concept of maximal greatness or of a maximally great being (a being that is omnipotent, omniscient, and omnibenevolent in every possible world) seems perfectly coherent and therefore possible.

Now many people have tried to offer reverse ontological arguments (what we might call “Bizarro” arguments after Superman’s �ٴDZ������ä�Բ����) in order to undercut one’s intuitive justification for believing (1). You can appeal to any sort of world in which God does not exist, whether it be a world with nothing in it, or a single particle, such as you suggest, or a world with lots of particles, stars, planets, and a menagerie of things. So long as someone stipulates that ONLY such things exist, one rules out God and, hence, maximal greatness.

I think the problem with all such Bizarro ontological arguments is that your second premiss

begs the question by assuming that the concept of maximal greatness is incoherent. Just because we can imagine a world in which a single particle (or whatever) exists gives no reason for thinking that such a world is metaphysically possible. These scenarios are, as it were, merely pictures with a title underneath “World in which Only a Single Particle Exists.” The fact that I can imagine and label such pictures gives no reason at all to declare them metaphysically possible. To do that, you have to know first that maximal greatness is impossible.

Now you might think, “But isn’t the theist in the same boat? For him to know that it is possible that a maximally great being exists, he must presuppose or know first that it is impossible that only a single particle exists.” Not at all! The theist’s confidence in (1) is based upon the intuitive coherence of maximal greatness, considered in and of itself. He then infers that a world with only a single particle or whatever is impossible. It is a conclusion from, not a presupposition of, the ontological argument. By contrast, the bizarro objection is based, not on the admittedly intuitive possibility of a particle (say, a quark or a boson), considered in and of itself, but rather on the speculation of a world’s consisting wholly of such a particle. The possibility of that speculation is not given to you by the possibility of the particle itself but requires the incoherence of maximal greatness.

It seems to me, Robert, that you mistakenly think that the metaphysical possibility of worlds has to do with probability considerations: isn’t there “at least one single possible world, out of the vast, vast array of possible worlds, in which God does not exist?” You seem to think of metaphysical possibility as rather like a lottery: out of all those possibilities, surely in one of them only a single particle would exist! This is wrong-headed. I could with equal justice say that out of the vast array of possible worlds, surely a maximally great being would exist in one of them. But then He exists in all! The point is that you can’t assess the metaphysical possibility of maximal greatness based on chance distributions.

Again, you seem to think of metaphysical possibility as a matter of simplicity or ontological economy. You think your objection to be on firmer ground because “All I need for my argument to get off the ground is for there to be a metaphysically possible world without this immaterial personal being of immense power.” That’s no reason at all to think that your envisioned world is possible and maximal greatness is incoherent. We want from the objector some reason to think that it is impossible that an “immaterial personal being with all of these extreme powers exist in every single possible world.” Otherwise, we have no reason to think that the objector’s speculative world is really possible.

And don’t forget about the other theistic arguments, which give us grounds for thinking that such a speculation is impossible. For example, Leibniz’s cosmological argument would imply that a world consisting of a single particle is metaphysically impossible, since there is, then, no explanation of why the particle exists rather than nothing. Similarly, the moral argument gives us a personal, metaphysically necessary being as the ground of necessary moral truths, which implies that such a morally neutral world as your single particle world is impossible. Such arguments go to reinforce our modal intuitions about the metaphysical possibility of a maximally great being. The ontological argument is thus best viewed as but one link in a coat of chainmail which constitutes the cumulative case for theism.