Thursday, January 05, 2006

Plantinga's ontological argument, part 2

Now I need to give you a couple of definitions. Plantinga uses these two definitions:

Maximal excellence: Having omniscience, omnipotence, and moral perfection.
Maximal greatness: Having maximal excellence in all possible worlds.

I think we can formulate his argument without using "maximal excellence." I'll just plug in the definition in its place, and I think that makes it more clear.

1. There is a possible world in which maximal greatness is instantiated.
2. Maximal greatness consists in having omniscience, omnipotence, and moral perfection in all possible worlds.
3. Therefore, a being with omniscience, omnipotence, and moral perfection exists in all possible worlds.

4. If something exists in all possible worlds, then it also exists in the actual world.
5. A being with omniscience, omnipotence, and moral perfection exists in all possible worlds. (from 3)
6. Therefore, a being with omniscience, omnipotence, and moral perfection exists in the actual world.

Now lemme try to explain the concept. Let's represent all possible worlds with just five possible worlds. Now granted, there's more possible worlds than you can imagine, but let's just say there's five for the sake of illustration. Whether we are atheist or theist, we must grant that it's at least possible in the broadly logical sense for a being to exist who is all powerful, all knowing, and morally perfect. Some people may object that such a being can exist in the actual world because it contradicts the existence of evil or is otherwise incoherent, but surely they'd at least grant that in some possible world, such a being could exist. So there is at least one possible world in which omniscience, omnipotence, and moral perfection are instantiated. Maybe there are two. Who knows? If so, then maximal excellence is instantiated in at least one possible world. That is, it's at least possible that an all knowing, all powerful, and morally perfect being could exists under some possible state of affairs.

A being is maximally great if it has maximal excellence in all possible worlds, and not just one or two. Now imagine those five possible worlds. Let's say that in one of those possible worlds, there is a being who is maximally great. All we're saying is that it's possible under some possible state of affairs that such a being could exist. Now think about this for a second. If there is at least one possible world in which maximal greatness is instantiated, and maximal greatness consists of having maximal excellence in all possible worlds, then maximal excellence must be instantiated in all possible worlds. That means it's impossible for a maximally excellent being not to exist. Some being who is maximally excellent exists necessarily. And since it is maximally excellent in all possible worlds, it is also maximally great in all possible worlds.

Plantinga's argument isn't without its shortcomings, though. The major shortcoming is the whole premise that there is a maximally great being in some possible worlds. One could completely turn Plantinga's argument on its head by beginning with a different premise. Suppose we say there is one possible world in which maximal excellence is not instantiated. That seems at least possible, doesn't it? There's nothing logically incoherent about it that jumps out at us anymore than there's anything logically incoherent about a maximally great being that we can immediately see. But if there is at least one possible world in which maximal exellence is not instantiated, then it's impossible for maximal greatness to be instantiated in any possible world. There may be maximal excellence in some other possible world, but there can't be maximal greatness in any possible world.

This is really the interesting thing about Plantinga's argument to me. On the face of it, there doesn't seem to be anything incoherent about the existence of a maximally great being, but there also doesn't seem to be anything incoherent about the nonexistence of a maximally great being. Yet, a maximally great being is either necessary or it is impossible. There's no middle of the road. If a maximally great being is possible (if it exists in at least one possible world), then it is necessary, because it would exist in all possible worlds. But if it is possible that a maximally excellent being does not exist (if there is at least one possible world in which maximal excellence is not instantiated), then it's impossible for there to be a maximally great being. There may still be a maximally excellent being, but not a maximally great being.

So far, I haven't found one ontological argument that's convincing to me, but Plantinga's is the best I've found so far.

14 Comments:

At 1/05/2006 9:27 AM , Blogger Jeff said...

Sam, I like what you've written here. I wonder why this approach isn't used by those who argue against God from the problem of evil?

They can observe that this world has no being of maximal excellence based on observation of evil,suffering,corruption... then using this logic that would demonstrate the non-existence of God.

Of course we can attack their premise that the observed world demonstrates that this world has no being of maximal excellence.

In regard to your point that the argument shows either a maximally great being, or precludes it...Well, it's an either/or proposition so only one can be the truth.

Can anyone deny that there exists a possible world in which maximal greatness is instantiated?

Perhaps the actual problem is postulating a trait in one possible world that mandates traits in other possible worlds? Is premise #2 really valid? Isn't that like one universe having a causal affect on another universe? (which physics precludes).

Good questions. I still feel a strong intuition that this argument is true, just don't know how to prove it.

 
At 1/05/2006 9:47 AM , Blogger ephphatha said...

They can observe that this world has no being of maximal excellence based on observation of evil,suffering,corruption... then using this logic that would demonstrate the non-existence of God.

Well that basically is the logical problem of evil. Plantinga also demonstrated to the satisfaction of most philosophers, both atheist and theist, that there is no logical contradiction between an all knowing, all powerful, and all good God and the existence of evil.

Can anyone deny that there exists a possible world in which maximal greatness is instantiated?

There doesn't seem to be any reason to deny it. But the problem is that there doesn't seem to be any reason to deny that there's a possible world in which maximal excellence is not instantiated either.

Is premise #2 really valid?

Premise 2 is just a definition. It doesn't imply any causal influence between possible worlds.

I still feel a strong intuition that this argument is true, just don't know how to prove it.

The way I see it, there's one of two ways of showing the argument to be sound. You either have to demonstrate that there is a possible world in which maximal greatness is instantiated, or you have to demonstrate that there is no possible world in which maximal excellence is not instantiated.

 
At 1/05/2006 3:34 PM , Blogger Jeff said...

"Premise 2 is just a definition. It doesn't imply any causal influence between possible worlds."

Well, my thought was that it may be unjustified to posit a characteristic as having universal applicability. 'Maximal greatness' is just an arbitrary definition for a concept that needs to be defended.

I suppose it's the same as saying that premise #1 isn't established. I don't think you can step from saying that there is a possible world in which maximal excellence is instantiated to saying that there is necessarily a possible world in which maximal greatness is instantiated.

 
At 1/08/2006 12:01 AM , Blogger Jeff Travis Henderson said...

The problem I have with the argument is that I see no reason that you can't replace "omnicient, omnipotent and morally perfect" with any other qualities. Imagine, for example, if your just replaced "omnicient, omnipotent, and morally perfect" with "tall, dark, and handsome".

 
At 1/08/2006 9:52 AM , Blogger ephphatha said...

I agree, Jeff H., but I know there's an answer to that objection. I just can't remember what it is. Your objection is similar to the perfect island objection to Anselm's ontological argument.

 
At 1/09/2006 5:36 AM , Blogger Jeff Travis Henderson said...

I think this has made me realized that I need to entirely re-examine my views on metaphysics. I don't actually know whether I'm a realist or a nominalist. I don't know what existence is. Is it a property?

Any suggestion on where to start?

 
At 1/09/2006 7:54 AM , Blogger ephphatha said...

Funny you would ask. I think the major problem with Anselm's ontological argument is that it assumes existence is a property. But I don't think existence is a property. Rather, existence consists of the having of properties. You have to exist before you can have properties. Having any property assumes that you already exist. So to treat existence as a property seems like a categorical mistake to me.

I would recommend an audio lecture by J.P. Moreland called "Issues in Metaphysics," but it seems to have been removed from the internet. Moreland is a realist.

 
At 1/09/2006 9:05 AM , Blogger Jeff said...

Sam, you may be right about existence not being a property, but I'm not sure I'd agree. I suppose this issue hinges around that and that someone advocating the ontological argument would first need to establish that.

As for JH's statement about this argument applying to any other properties, I think the response comes from the fact that we are conceiving of God as the greatest conceivable being. This is key in the argument working. I can't use this argument to prove Sam exists. It must first be said that the being is the greatest conceivable one, then the point is made that existence is greater than non-existence.

I could see this argument easily being misused to show that God is 'tall, dark and handsome' if we thought that these physical properties were greater than not having them. But we'd be making an anthropomorphic mistake of assuming physical existence is 'greater' than spiritual existence.

 
At 1/09/2006 10:07 AM , Blogger ephphatha said...

Jeff, I think you're confusing Anselm's argument with Plantinga's argument. Plantinga doesn't use "existence is better than non-existence" in his argument, but Anselm does. The "tall dark and hansom" objection applies to Plantinga's argument, but not to Anselm's argument.

Now if we assume that "existence" is a property, then couldn't we prove anything exists just by including "existence" among its properties?

 
At 1/09/2006 3:16 PM , Blogger daleliop said...

This comment has been removed by a blog administrator.

 
At 1/09/2006 3:25 PM , Blogger daleliop said...

Moreland is a realist.

For real.

Imagine, for example, if your just replaced "omnicient, omnipotent, and morally perfect" with "tall, dark, and handsome".

Some think of him more as the strong, silent type.

 
At 1/09/2006 3:35 PM , Blogger Jeff said...

Sam, you are right I was thinking in terms of Anselm's argument.

As for existence being a property, then we cannot say that anything exists unless that thing we are talking about existing is the greatest conceivable thing...God alone. Nothing other than God necessarily needs to exist.

Again, this is still in terms of Anselm's argument.

 
At 1/09/2006 5:24 PM , Blogger Jeff Travis Henderson said...

Hey Sam if you wanted to e-mail me that Moreland lecture that would be swell.
;)

 
At 1/10/2006 2:09 AM , Blogger ephphatha said...

I'd love to Jeff Henderson, but since I can't find it on the internet, I don't have it either.

 

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