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| Alvin Plantinga, John A. O'Brien Professor of Philosophy at the University of Notre Dame |
Ontological arguments have been around for centuries and began with St. Anselm’s ontological argument. Unlike design arguments and cosmological arguments ontological arguments do not draw upon empirical evidence to prove God’s existence, they use a priori reasoning. One of the more recent and effective versions of the ontological argument is posited by Alvin Plantinga, who is the John A. O'Brien Professor of Philosophy at the University of Notre Dame. His argument can be formulated as follows:
Premise 1--It is possible that a maximally great being exists.
Premise 2--If 1, then there is at least one logically possible world in which a maximally great being exists.
Premise 3--Therefore, there is at least one logically possible world in which a maximally great being exists.
Premise 4--If a maximally great being exists in one logically possible world, it exists in every logically possible world.
Therefore--A maximally great being (that is, God) exists in every logically possible world.
Plantinga defines maximal greatness as a being that is omniscient, omnipotent and all good. Critics of this argument like point out that you could plug anything, like a unicorn, into premise one and have this argument work, but as you think about all possible worlds then this parody doesn’t hold up. For example, a unicorn couldn’t exist in a universe that is hostile to biological life such as a universe that is a million degrees Fahrenheit, or in one where no matter exists. For a being to exist in every possible world it must be a spiritual being with maximal properties.
Not everyone appreciates the non-empirical nature of this argument, but I think that this conceptual argument, when back up by empirically oriented arguments like the cosmological arguments it can be another arrow in the apologist’s quiver.
I've never been a fan of the ontological argument because it looks like logical sleight of hand to me. I don't think that Premise 4 follows from Premise 3. Since the skeptic can easily conceive of a logically possible world in which a maximally great being does not exist, God does not exist in every logically possible world.
ReplyDeleteBut I do appreciate Alvin Plantinga, who teaches at my alma mater, Notre Dame. :)
' For a being to exist in every possible world it must be a spiritual being with maximal properties.'
ReplyDeleteI see.
So Plantinga claims his god exists in every possible world.
Has he spoken to the Plantinga, who had to go through extreme contortions to try to find even *one* possible world where his god and evil can co-exist?
If he did speak to the other Plantinga, he would be told that there are possible worlds where his god and evil can't both exist.
The two of them should really get together and sort out if god and evil can exist in only one possible world or in all possible worlds.
The ontological argument, an a priori argument based on possible world semantics, is not predicated on empirical evidence such as a conversation with God. The conclusion of the argument follows from the definition of God as a necessary being who posses aseity. God exists in every possible world because existence is in his nature and he needs nothing in order to exist. You can see this best when you contrast God with contingent beings like people, who can’t exist in all possible worlds. In order to exist you need parents to cause your existence. You also need a planet to live on. You need oxygen, food and water in order to exist. You also need matter in order to exist. So, in possible worlds without matter or worlds where stars and planets don’t form people can’t possibly exist. God, on the other hand, can exist as he doesn’t even need matter in order to exist.
DeleteIn regards to the logical problem of evil, you should be aware that no credible philosopher still uses this argument as it was sunk years ago. The problem with it is that just the mere possibility that God could have some good reason to permit evil is enough refute this argument.