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#204 Two Questions on the Ontological Argument

March 14, 2011

Hello Mr. Craig! My name is Jakob and I'm a great fan of yours from Sweden. I'm a 22 year old philosophy student who really have been encouraged by your work. I even started an apologetics blog for swedish teenagers this autumn to spread many of the arguments you present (we have very little of that stuff here).

My question is about the ontological argument. It came up within the first lectures on the philosophy course. The teacher merely mentioned it, but a student asked if it was a solid argument or not. He answered:

"Well, hm... No, of course not. You can't justify existence of something, just out of pure definitions."

He wasn't ridiculing the argument or anything, simply mentioning what he genuinely seemed to think (know) about it. I asked if he knew if anyone would seriously use this argument today, and he very much doubted it. I was surprised because the teacher is very knowledgeable. Since many christian apologists use this argument seriously, I figured he doesn't pay too much attention to religious philosophy (sadly it's not very serious here).

How would a proper response to his statement sound? Is Alvin Plantinga's representation of the argument different from the original presentation of it (maybe the teacher haven't heard the renewed version)?


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Dr. craig’s response


Jakob, I plan to be in Sweden on a university speaking tour next year, so perhaps I’ll see you then. Payton, I’ll be in the U.K. this fall, though not as far north as you are. You are in highly secularized environments, which makes it tough-going as a Christian. I recall that the last time I was in Sweden one of my debate opponents, a prominent Swedish philosopher, informed me that there are no Christian philosophers teaching at any university in Sweden! That can make you feel pretty isolated.

So let me take your questions in order. I think you’re probably correct, Jakob, in surmising that your professor is not familiar with the current literature on the ontological argument. For there obviously are philosophers who defend the argument today. In response to his objection that you can’t infer the existence of something just out of pure definitions, all you need to do is present Plantinga’s version of the ontological argument:

1. It is possible that a maximally great being (God) 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. Therefore, a maximally great being exists in the actual world.

6. Therefore, a maximally great being exists.

7. Therefore, God exists.

Notice that Plantinga’s argument doesn’t do what your professor alleges: infer something’s existence from its definition. Rather it is based upon a crucial modal premiss that it is possible that a maximally great being exists. One doesn’t simply infer the existence of such a being from its definition. One infers its existence from the possibility that such a being exists.

Your professor’s objection may have been relevant to older versions of the argument, but Plantinga’s version appropriates G. W. F. Leibniz’s insight that the ontological argument assumes that the concept of God is a possible one, that is, a coherent one. Criticisms of one version of the argument may be quite inapplicable to another version.

That same point applies to your misgiving, Payton. Some earlier versions may have assumed that existence is a property and so would be subject to Immanuel Kant’s criticism that existence is not a property, as you remind us. (For my own agreement with you on that head see my “Is Presentness a Property?” American Philosophical Quarterly 34 [1997]: 27-40.) But from that it doesn’t follow that existing necessarily is not a property. In any case, Plantinga’s version doesn’t assume that even necessary existence is a property. It assumes merely that a being is greater if it exists necessarily rather than contingently. That strikes me as pretty evidently true. The idea of a being which is omniscient, omnipotent, and morally perfect in every possible world seems perfectly coherent.

By contrast, if you were correct that it’s impossible for anything to exist necessarily, then you’d have an ontological disproof of numbers, sets, propositions, properties, and so on, which is surely as stunning a result as the ontological argument.

- William Lane Craig