This is the weekly Q & A blog post by our Research Professor in Philosophy, Dr. William Lane Craig.
I work at an aerospace firm, and I always assumed that if I were to be convinced of God's existence, it would probably be by something like the teleological argument. The appearance of design in the universe itself and so many things therein is truly intriguing, but has never been enough to persuade me. I understand why theists find it compelling, but I currently still find the counter case sufficiently compelling to remain unpersuaded. It might surprise you then, as it certainly does me, that what I am finding myself struggling to resist is the persuasive force of the Ontological argument, which my inability to actually refute has nagged at me for decades. It started in college when I first read Anselm in an into to Philosophy class. At first I scoffed at the argument along with everyone else, but when I actually heard the rebuttals laid out, I realized they all fell into category errors or otherwise missed the point. I found myself, as a skeptic, defending Anselm in class! I was certain the argument was wrong, but none of the reasons offered against it were good and valid reasons WHY the argument was wrong. I could not find the argument persuasive, but I was really bothered at my inability to explain WHY I didn't. It bothered me so much all semester that I wrote my paper on Anselm's argument. If this argument is so unpersuasive, why on earth can I not explain WHY it is wrong? A few years later, a Christian friend talked me into reading a collection of Descartes' work, and here again I found myself beating my head against this argument. I honestly feel that many modern thinkers don't give Descartes the credit he deserves in the case he makes for this argument, but be that as it may, I was finding myself in quite a jam at my inability to explain why the argument was wrong and yet why it did not persuade me. I read Alvin Plantinga's advancements in the argument and your defense of his articulation of it. I read Bertrand Russel's own wrestling with exactly how one was to show the argument to be invalid. Like me, he didn't believe it, but found it curious that he could give no reason why! Logic aside entirely, I stood at the summit of the lower falls of the Yellowstone River and looked out at the breathtaking grandeur of the basin below, and found myself confronted with what I call the existential evidence for the Greatest Conceivable Being (GCB). The whole world seemed to be telling me the argument was true, but somehow I found myself still unable to believe it. The argument became, as Morpheus says in the movie The Matrix, "a splinter in my mind, driving me mad."
So my question is comes down to this. At long last I find only one reason to question the Ontological argument. If it is true that the GCB is logically necessary, then it must be true that the assertion of a universe that lacks the GCB must be logically absurd and self refuting. I don't need to prove to someone that truth exists because truth is logically necessary, and so they have to affirm it even in the act of denying it. But is the claim that there is no GCB really like that? Is it a logically absurd and self refuting claim? It seems if the Ontological argument is really true, then it must be, but I can't see the purely logical absurdity inherent in the concept of an atheistic universe. Could you show me how the assertion of atheism (or the denial of the GCB) is logically absurd and self refuting? Or else, could you show me how the GCB could be logically necessary but yet denying His existence could somehow NOT be logically absurd?
Thank you for your help, and for being and intellectually engaging theist that honest skeptics can bounce these things off in the search for truth.
Dr. William Lane Craig’s Response
I just love it, Luke, when people honestly wrestle long and hard with a theistic argument, rather than blow it off with superficial comments, such as one routinely sees, for example, on Facebook. These are profound questions which deserve to be pondered.
Like you, I was for years sceptical of the ontological argument. At most it served for me as a model for God, the concept of a greatest conceivable being, which entailed that being’s metaphysical necessity. It wasn’t until I read Alvin Plantinga’s defense of the argument in his The Nature of Necessity (Oxford: Clarendon Press, 1974) and the reactions to it that I, quite to my surprise, became convinced that this is actually a good argument for God’s existence.
For those who are unfamiliar with the argument, let me explain that Plantinga conceives of God as a being which is “maximally excellent” in every possible world. Plantinga takes maximal excellence to include such properties as omniscience, omnipotence, and moral perfection. A being which has maximal excellence in every possible world would have what Plantinga calls “maximal greatness.” It would be what you, Luke, call the Greatest Conceivable Being (GCB). Now Plantinga argues:
1. It is possible that a maximally great being exists.
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.
Now your question is, “Could you show me how the assertion of atheism (or the denial of the GCB) is logically absurd and self refuting? Or else, could you show me how the GCB could be logically necessary but yet denying His existence could somehow NOT be logically absurd?”
I think the answer is that the denial of the GCB is logically absurd but not self-refuting. The assumption of your first question is that “If it is true that the GCB is logically necessary, then it must be true that the assertion of a universe that lacks the GCB must be logically absurd and self refuting.” That assumption is, I think, a mistake.
For the argument is not framed in terms of what Plantinga calls strict or narrow logical necessity but in terms of broad logical necessity. Broad logical necessity is often called metaphysical necessity. It has to do with what is actualizable or realizable. Some state of affairs may be metaphysically impossible, even though it does not involve a logical contradiction and so is not strictly logically impossible. My favorite example from Plantinga is the Prime Minister’s being a prime number. Anyone can see that this is metaphysically impossible, even though it involves no logical self-contradiction. Thus, the assertion that the Prime Minister is a prime number, while (broadly) logically absurd is not self-refuting.
Similarly, the non-existence of the GCB is logically absurd (that is to say, broadly logically impossible) but not self-refuting to assert. One of the shop-worn objections to the ontological argument is that the assertion “God does not exist” is not a contradiction and therefore God’s existence is not logically necessary, as the ontological argument implies. That objection has now been overtaken by the understanding that the modality involved in possible worlds semantics is not strict, but broad, logical possibility and necessity. So you should not reject the argument, Luke, just because it is not self-refuting to assert “The GCB does not exist.”
Now that still leaves the question, “Could you show me how the assertion of atheism (or the denial of the GCB) is logically absurd, [if not] self refuting?”, and the answer to that question just is the ontological argument! It shows that if the concept of a GCB is broadly logically possible, then the GCB must exist. So it all comes back again to whether you think the first premiss is true.
This post and other resources are available on Dr. William Lane Craig's website: www.reasonablefaith.org