Ontological proof of God's Existence

Philosophy Forums Religion and Spirituality
41 
 Then what more can I say? Here I am on a philosophy website, and I provide an argument that shows Omnipotence exists. As far as you know, the argument is solid- you've had no luck refuting it, what's more you haven't really tried. Your only retort is to demand philosophy is somehow 'cheating' or 'invalid' and that I have to use science, and then you go on to admit that no matter what I say, you're convinced that no argument for the existence of God can be successful anyway- for no less a reason than logic isn't good enough for you!  So convinced of his are you, that [i]even when you see one you can't refute[/i], you're still convinced they can't exist.  I mean, do you see how desperate this all looks from my side, and do you see how much nonsense it is to ask for a 'scientific explanation of the possibility" of a thing? I mean look:
  1. There is gravity.
    C) Omnipotence is possible.

Seem like an unrelated premise? Well it is, and so would any other I could possible provide, because A) We’re talking about omnipotence, not a natural law, and B) All you need to to to establish possibility is show a lack of conflict- so the argument above is successful to the degree which any argument can be.

Who cares? You said logic doesn't apply to things like this, and that no argument will ever convince you anyway, so my new argument is "Ham Sandwich". 

Oh look at that, and then you go on to cite a bunch of philosophers in reference to God and try to make logical points about it. So atheists get to use logic to prove their points but theists aren't allowed to try by your rules. I'm all done now. You're right, I'm wrong, goodnight.

That's the most successful argument I've seen against this version of the Ontological argument in the past. I'm moving into untested waters now, so I'm anxious to here what you say about this.

Let me begin by saying,

  1. There is a possible world which does not contain an omnipotent Being.
    and
  2. One of the traits of omnipotence is necessity.
  3. Omnipotence can possibly exist.

It seems to me that 1 contradicts 3 on 2. In order for you to claim 1, you have to assume that either 2 or 3 is impossible, for the possibility of both entails

  1. God exists in the actual world.

    I can take 2 as true, or I can take it as possible. Same with 3. If there probabilities taken together are higher than 0, no matter how low, then 4 must be true.
    So it seems to me that your statement requires impossibility of 2 or 3, and mine requires possibility of 2 or 3. It further seems to me that when faced with a choice between the possibility and impossibility of a thing, possibility is the more rational choice in the absense of argument to the contrary, so going ‘my way’ on this has more initial justification. Is that so?

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You’re using necessity in an attempt to levy an advantage for the existence of omnipotence over the non-existance of omnipotence, which is fine, as it was a good argument. However, perhaps in the possible world where omnipotence does not exist, it is necessary that there not be an omnipotent being for the universe to exist. I suppose, one of the properties of this world would be the necessity of no omnipotent beings, because the mere existence of one would cause it to self-destruct.

43

Oh for god’s sake. Please, Ussicore–I recognize this argument; it’s a form of Plantinga’s modal ontological argument. But even Plantinga doesn’t think it shows anything; I don’t understand why you do. Based on what we know of the world, an omnipotent being, a being able to somehow do everything, is impossible. Unless you want to say that this being IS the universe itself.

Now, you probably want to say that this being exists OUTSIDE the known universe (that it’s not contingent on natural laws, etc), but that would assume too much; first, you would have to know that there is an “outside” to this universe, and second, you would have to know that the same laws of logic apply out there as they do in here. Neither of which you can establish. So if you are really trying to prove God’s ACTUAL existence, this is a bad argument. But you seem to take this personally, so I won’t push it any further.

I’ll assume for the sake of argument that this is just a logical puzzle (which, I happen to think, is a perfectly valid project); and on that level, I can accept your premise that an omnipotent being is possible. But even on that level this is a bad argument, and I’ve pointed that out. Your response to my pointing it out was,

Then you have the audacity to tell me,

No, Ussicore. I happen to have shown that the argument does not work on any level because in order to establish a necessary truth you have to derive that truth from other necessary truths. Which you have not done. You’ve just asserted that an omnipotent being’s existence is necessary.

I’m going to re-post my last rebuttal, and, if you can lose the attitude, maybe you can tell me just what was wrong with it.

Freedom to exercise an ability is an ability in itself, so that doesn’t change anything. I’m not sure where this connection between freedom and necessity comes from. How is a necessary being more free than a non-necessary being?

Well “greater” is just a value judgement. I mean Jesus proved that, didn’t he? “The greatest among you will be the servant…” There’s nothing objective to the predicate “great.”

Well here’s the problem. You can’t just attribute necessary existence to anything; you have to establish a necessary truth from other necessary truths. Now, there’s always been a lot of debate among philosophers about whether anything actually exists necessarily. But lets, for the sake of argument, take the idea that something does exist to mean that something exists necessarily; what can you derive from this idea? Well, you sure as hell don’t get a morally perfect, omnipotent personal being. If perfection means simply “necessary existence,” and if God means perfection, then fine: God exists. But among those who make these kinds of arguments, much more is attributed to God along the way that does not follow from the idea of necessary existence. Descartes made this mistake, Leibniz made it, and now you’re making it.

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So logic is fair game again, Logo? Let’s give it a whirl.

First of all, an omnipotent Being wouldn’t have to be able to do everything in a propositional sense- I realize I used the term ‘everything’ a bit ago, but let me explain. In order to be Omnipotent, a Being would only have to be able to do everything possible for any one Being- in other words, there may be classes of things that God can’t do without Being something other than God. I dunno, like experience my memories (and only my memories) perhaps, or disbelieve in God.
That said, on what basis would a God have to be the universe in order to be omnipotent?

I dunno if ‘outside the universe’ is the term I mean- but yes, I think God wouldn’t be subject to say, gravity. I’d say He created those laws, and existed ‘before’ them, as much as it makes sense to say ‘before’ if He created time itself.

I don’t see why- I’m not concieving of it as an actual place.

 As long as humans are 'in here', that's not needed. Logic isn't a rule that governs the cosmos (like nuclear force or something), it's more of a set of grammatical rules we use to make sure our words mean stuff. Besides, even if the laws of logic do exist in places somehow, why is it intuitively uncertain whether or not  'If a or b, and not a, then b" holds in all of them?  Did people theorize whether or not the laws of logic held in the Americas before it was colonized? Does anyone (other than HP Lovecraft, perhaps) speculate about the laws of logic not existing on Saturn?
 It seems to me that we can rest assured that the laws of logic apply everything- and even if we can't be  [i]certain[/i], it seems intuitive enough to base an argument on the assumption. If I had an argument that only failed if the laws of logic didn't apply to a certain place, I'd be totally happy with that argument. 

So, is there an infinite regress of necessary truths, or do they wind up being circular? Neither way makes any sense. Besides, the above can't be [i]always[/i] true, or [i]necessarily[/i] true, can it?
What Plantinga believes about the ontological argument (unless he's recently recanted) is that it worked [i]so long as[/i] the arguer believed that omnipotence as he defined it was possible.  He granted the argument wasn't conclusive because a good number of atheists would, of course, not accept that premise and he had no proof for it.

Because a non-necessary Being would have it’s existence contingent on some prior state of affairs, and it wouldn’t have the ability to exercise it’s omnipotence before that state of affairs.

You don’t get every quality of the Christian God, certainly- I’m sure there will never be a purely philosophical argument that proves the Trinity, or that Moses parted the Red Sea. I said above that that’s why rene’s argument from perfection failed- it doesn’t saying anything beyond ‘a thing exists’. So I guess you’re right, necessary existence needs to be attached to a trait of God’s like omnipotence or omniscience in order to have real value.

I’m trying to wrap my head around this… Are you saying that if O is omnipotence as I defined it, that “Necessarily not-O” is as valid a starting point as “Possibly O”, where O entails necessity? I would agree that neither is incoherent or anything. It seems to me that a probabilistic argument for theism or atheism could be had here- if both of these to arguments are solid, it’s a matter of seeing which starting premise is more likely, right?
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(Thought I’d throw a nice fat red herring in here just to break up the boredom a bit!)

There is somehow something very unwholesome and nauseating about certain kinds of dispute.

This so-called ‘ontological proof of god’s existence’ argument, for instance, what on earth has it to do with philosophy or religion?

Haven’t you boys lost the plot here! It’s OK to conduct such sham-philosophy-cum-theology argumentation in private but why post it on ILP? Are you perhaps weird exhibitionist freaks, or what?

I mean, I read through this stuff, and I am embarrassed by it. It isn’t even entertaining, Jesus, I got more laughs from S. Augustine’s, City of God!

We are in the twenty-first century now in case it had escaped your attention. This pedantic-obsessive disputation about irrelevancies that have been long dead and buried is insane.

My dad can beat your dad. No he can’t, my dad can beat your dad! My dad’s bigger than your dad! My dad’s a wrestler! My dad’s a policeman! nuuh…….!

Whatever happened to dignified debate?

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I don’t think that either can be proven more likely, but I can sense you’re itching to go down this road, so let’s see what your argument is, I’m curious anyhow :slight_smile: . I should also note that I’ll be on vacation for the next ten days, so my repsonse will be a bit tardy- I apologize in advance.

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Well, then you need to define “being” here. It seems to me quite easy to say, simply, “the universe is able to do everything that it is possible for the universe to do.” If universe simply means everything, and omnipotence is the ability to carry out every action that can be done by everything, then I suppose there is such a thing as omnipotence. But a specific being? That’s really very vague. Does it mean just a thing? In that case, omnipotence is also proven, for a thing is able to do everything that it is possible for a thing to do. Is omnipotence just a tautology then?

Perhaps being means something more. Does it mean a living thing? An intelligent thing? A person? What is it for a person to do everything that it is possible for a person to do? Well, the people I know are able to think and eat and sleep, etc…and there are many things they can’t do–like live forever. But if we’re talking about a “person” beyond our set of experiences, we can only speculate about the qualities this person might have. You want to say that it is possible that one of this person’s qualities is that s/he exists necessarily.

In my mind, necessary existence means, if anything exists, “p” exists. In other words, the VERY CONCEPT of existence requires that “p” exists. It is not just that “p” is not contingent on any other state of affairs; it is that it is IMPOSSIBLE for anything to exist without “p” existing. If you want to show the possibility for a being to exist necessarily, you have to derive the idea of that being from the very idea of existence, which no version of the ontological argument has ever done. In the absence of such a derivation, we have to accept the possibility that God does not exist necessarily, which of course means that God does not exist necessarily.

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 Ten days may just give me enough time to think of something!! Off the top of my head, it seems the ontological argument defeats the common attitude of "Even if God is possible, He still may not exist" which is a [i]huge[/i] part of the traditional atheistic argument.  Since anything that grants the possibility of God grants his existence because of this argument, the only non-theistic stance left is hardline "The concept of God is impossible" arguments, which are both quite few and quite weak these days it seems.

Perhaps. It seems, though, that the fine tradition of people telling others what does and doesn’t ‘count’ as philosophy while at the same time offering no intelligible ideas of their own is still alive and well. Pity.

 That's not what I said. I said God can do anything that [i]any[/i] one Being can do. In other words, he can do more than any other Being- but if there are two abilities such that having one contradicts another, he need not have them both. Similarly, if there is an ability such that having it makes God not God, he need not have it.

Yes, all of those things are commonly held by theists to be true of God. I didn’t realize I had to restate them. perhaps there are beings that don’t have one or the above qualities, but God does. You said you are familiar with Plantinga ontological argument, right? Well, in it, he doesn’t say God has just omnipotence, but several of his ‘omni-’ qualities necessarily, more explicitly defining the being in question.

I don’t see how proving or demonstrating that fact has any bearing on the internal logic of the ontological argument as a whole. Again, you haven’t done anything at all to show why God, omnipotence, or necessity is impossible, so without that, maintaining that it’s possible is the only sensible thing.

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But you don’t claim to be proving God’s existence–just the existence of at least one omnipotent being. And my two questions are: what does “being” mean here, and what does “omnipotent” mean? If you are going to show something to be true by definition, part of what you have to do is DEFINE the thing. And define it very clearly. When we talk about “gods” we are not talking about things we keep lying around the house; these are not beings that can be experienced in the same way that physical objects are experienced. And since there are so many different meanings that theologians attach to terms like “god” and “omnipotence”, it is incumbent upon you to show what exactly it is that is you are demonstrating.

What I’ve done is to define necessity, something that always seems to get left out of these sorts of proofs. Establishing the possibility for a necessary truth is not like establishing the possibility for just anything. Otherwise you’d be able to show the possibility for anything to be necessary. In order to establish that “p” MIGHT exist necessarily, you have to have a concept of what it MEANS for a being to exist necessarily. And what it means is that there is no logical possibility for anything to exist without “p” existing. So a proof for the necessity of an omnipotent being would have to sound something like:

(p) it is possible that:

(q) there is no logical possibility such that (t) something exists and an omnipotence does not.

But if you can’t show that an omnipotence is inherent to the very concept of existence, then (q) is false because in that case you MUST allow for the possibility of (t), i.e. that there are logical possibilities beyond the existence of an omnipotent being. So to say it is possible that (q) is true is to say that it is possible for a falsity to be true, which, of course, is impossible. So (p) is false.

The problem with Planginga’s argument (and probably why philosophers of language get so pissed off at him) is that he treats the term “possibly necessary” just like any other possibility. When in reality, the reason why “possibly necessary” = “necessary” is because saying “p is possibly necessary is just another way of saying “I can show how p is necessary.” It’s one of those axioms that logicians use within a logical system (like a=a) that have no particularly interesting application in the real world.

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Well, what qualities of God do I have to establish in order for the ontological proof to be evidence of Him? Certainly not all of them- not all of God's properties are necessary anyway, so it wouldn't apply.  The ontological argument defines an all-powerful, all knowing Being.  I think all omnipotence and omniscience together strongly imply person-ness.

Omnipotence in this case means “Being maximally powerful- capable of doing all possible things”. Omniscience would be “knowing with certainty the truth value of all propositions of which it is possible to know.” These are extended into necessity by the premise that a Being that had these certainly would be ‘greater’ than a Being that had these only possibly, or only conditionally. In fact, it’s said that omnipotence isn’t really omnipotence if it’s posessed only conditionally- so it must be nessecary if it exists at all. If then, a theistic God is granted as a possibility, he must exist.

The argument can't discern between, say, a Christian and Muslim view of God, or even a Christian vs. deistic view of God, and it's not intended to.

The implication of “If P is necessary, then nothing can exist unless P” is that existence somehow relies on or comes from P. Why not drop this useless, unproven aspect and state it simply

“IF P is necessary, then for any possible world containing true states of affairs (all of them?), P will be one of those true states of affairs.”

That seems to sum it up nicely, since any possible world will have at least 1 true state of affairs. This describes necessity without implying any cause and effect that may or may not exist. If we accept the above version of necessity, then even if the universe does rely on God to exist- which may be true- we need not establish or prove that in order to talk sensibly about Him being necessary.

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Absolutely not! Because when you use the term “O exists necessarily” you mean that the concept of O is implied by the concept of something existing. Because if O is not derived from the idea of existence, then there are possible worlds in which something exists and O does not. Period. O may or may not be responsible for all existent things in some physical, cosmological sense, but the idea of existence is logically dependent on O if O is necessary. Just as the idea of truth is logically dependent on 2+2=4. If ever there is a world in which 2+2=5, then the concept of truth no longer has any meaning. That’s what necessary MEANS. You can say something to the effect of, “an omnipotent being’s existence would be logically necessary;” but that’s obviously false because “logically necessary” is not some strange property that an unseen being would possess. Logical necessity literally means that you can show, here, now, how this thing COULD be true in all possible worlds–meaning you would have to EXAMINE all possible worlds and show how it is logically impossible for something to exist without O existing. AND THE ONLY WAY TO DO THAT IS TO SHOW THAT O IS IMPLIED BY THE VERY CONCEPT OF EXISTENCE.

…which you haven’t shown to be true of omnipotence. Hiding behind possible world semantics won’t help you here because the reason why “true in all possible worlds” = “necessarily true” is that something that is true in all possible worlds HAS no other logical possibility. That’s what “possible world” MEANS: logical possibility. And until you can show that there is no logical possibility beyond an omnipotence existing–i.e. that there is no possible world in which something exists and an omnipotence does not–you have no case.

There is no “if necessary” here. A thing is either necessary or it’s not. To say “necessary” means “no logical possibility but…” and until you show “no logical possibility but…” you CANNOT USE THE TERM NECESSARY. You can’t stipulate necessity, and you can’t speculate on the possibility of necessity without showing what that necessity means; in other words, you have to prove it in order to prove it is possible. That’s why it’s not like showing the possibility of anything else.

Oh yes there is. Necessarily P IS impossible until shown to be possble. Because “possibly non-necessary” and “possibly necessary” are mutually exclusive. And you have to refute “possibly non-necessary” before you can say, “possibly necessary.”

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No, not period. You have establish a claim like this. First off, what do you mean by 'the idea of existence'- and if it's not a predicate, how do we 'derive' things from it? Take a commonly held necessary truth like 3+1=4.  Use that to show me how you 'derive it from the idea of existence'. Better yet, you seem to be hinting there are no necessary truths, so show me how a thing like 3+1=4 could be false. 

 No case other than that I argued from premises commonly held to be true to a conclusion inescapable by the combination of those premises. You already agreed that in a broadly logical sense the argument works. Your claim that I have to 'do more' in order to make my case is empty, unless all you mean is that I have to 'do more' to convince [i]you[/i], which is readily apparent.
Besides, showing that no possible world can exist without an instantion of omnipotence is precisely what the argument does, providing we grant that omnipotence is possible. 

  Why would that be true, even if I grant anything else? If they are mutually exclusive, then one is just as good a starting point as the other- assuming the premises behind them are equivalent.  My starting premises are that omnipotence is possible, and that omni-greatness would require necessity- by definition. What are yours?
  As far as I can see, you have two options: "Omnipotence as defined is impossible," which requires an argument where assuming possibility does not.  Or, "Omnipotence is not-necessary" which doesn't require an argument, but on the other hand either assumes your conclusion or else fails to interact with my argument because it takes a different definition for 'omnipotent'. 
 Besides, even if all we take from this is that "Either omnipotence is necessary or else impossible" then the advantage is still for the theist, since necessity flows very easily from the nature of omnipotence (unless it's impossible), and arguing that God is impossible has pretty much been abandoned for favor of showing that belief in God is irrational- which of course is not true if Omnipotence is necessarily instantiated.
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3 apples and 1 pear do not make 4 apples or 4 pears.

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The idea that something exists.

I don’t know what that means. 2 + 2 isn’t a predicate, and yet we derive 4 from it.

Well you can’t; that’s why you have to preface all existence talk with, “if something exists.”

No. Never said that. I’m not sure that the statement, “something exists” is logically necessary because logic deals with the values of truth and falsity; not something/nothing. So if you want to say that something exists necessarily you have to logically construct this by saying, if (A) anything exists, then (B) O exists. This way we can then give truth values to the sentence fragments. What this means is that if there is an example in which A is true and B is false, the sentence is false.

What the argument does is it assumes that an omnipotent being would be logically necessary; but we can test whether or not omnipotence would be logically necessary with the following argument:

(1) The concept of something existing does not require the concept of an omnipotent being; (2) therefore, since something does not require an omnipotence in order to exist, it is concievable that something exists and an omnipotence does not; (3) therefore an omnipotence, were it to exist, would not be logically necessary. Now what I’m doing here is showing that your argument is based on a false premise, i.e. that omnipotence would be logically necessary. And what you’re telling me is that I’m wrong because the argument shows the premise on which it is based to be true. There’s a name for that…begging something…

Ummm…if “illogical” can be included under “broadly logical,” maybe.

No these premises are not held by anyone to be true except those who have already accepted the argument’s conclusion.

Because if it’s not true, you could call anything possibly necessary. This is basic modal logic here: the reason why the axiom, “possibly necessary” = “necessary”, works is because necessity is the one property of a statement where you have to prove it in order to show it to be possible.

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  OK...so then is 3+1 not a necessary truth, or was your request to 'derive a necessary truth from the idea of existence' an impossible request from the get go? I'm still waiting to see how you derive any necessary truth (your pick) from the idea of existence- or, failing that, how you show there are no such things as necessary truths- for example, could "If A is blue then A is colored" have been false?  

It gets kind of pendantic at this point, but the ontological argument relies on the proposition "Omnipotence obtains" to be necessarily true, and not strictly on the necessity of a particular Being- the existence of a Being is the thing proven, it doesn't need appear in the premises.  So existential questions can be about true/false as much as any other.  As to whether or not 'Something exists' is necessary, are you a nominalist?  That is, if you believe propositions are 'something' then it seems that 'something exists' would be quite clearly necessary.

This I agree with. If there is any possible situation A in which O(mnipotence) can’t possible exist, then the conclusion of the ontological argument must be false. That’s a good project for the atheist, though, because it seems to be the current arguments for showing that God is impossible happen to suck.

 The premise isn't that Omnipotence is necessary- that's the conclusion.  The premise is that omnipotence [i]must be[/i] necessary or else impossible if it exists.  This allows room for the impossibility of omnipotence, so the argument isn't circular. All that's remaining is to point out that Omnipotence is [i]possible[/i], an assumption that all theists, agnostics, and many if not most atheists argee to. 
If a person wants to argue that Omnipotence is not possible, then they can- but there needs to be an argument. Saying "prove to me that it's possible" is rubbish. If a person wants to argue that omnipotence can be sensibly thought of without necessity, they can do that too- but then the theist is free to come up with a new term (say, Superomnipotence) which means omni-greatness that obtains in all possible worlds, and the ontological argument proves [i]that[/i] instead- and the atheist is back to trying to prove the impossibility of superomnipotence. 
The only real 'out' is to construe an argument like Matthew E did that mirrors the ontological but comes to an opposite conclusion by using 'O is not necessary' as a starting place. The real challenge lies in trying to figure out if either 'O is possible' and 'O is not nessecary' have any intuitive or probabalistic advantage.

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3+1? No. 3+1=4 is a necessary truth, but 3+1…? 3+1 of what?

No there are truths that must necessarily follow from “something exists.” For instance you can say, “not nothing”, and, “at least one thing.” You’re right that necessary existence is not a very exciting idea, and it certainly doesn’t lead to something like omnipotence. And so I’ll just say it again: it is conceivable that there are possible worlds in which something exists and an omnipotent being does not. Until you disprove this, you can’t say that logical necessity is a property of omnipotence. To say, “the argument disproves it” is obviously circular.

Okay, so a premise of the argument is that logical necessity is a property of omnipotence. Well that’s just false, unless, perhaps you can prove otherwise. And you haven’t come close to doing that. Logical necessity is not something you can just tack on to an attribute because you happen to think that it would be “greater” that way. You prove logical necessity from prior concepts, using axioms and logical laws. Your argument is basically, “property O includes logical necessity because it’s nature is to include logical necessity.” Basically, it does because it does–which is quite ridiculous in itself. But even further, “logical necessity” doesn’t mean anything if it just exists as some imagined property somewhere; necessity is a relation. “Necessary truth” means, “necessary to the idea of truth” (i.e. necessary to the laws and axioms that render truth judgements possible). So “if something then not nothing” works as a necessary truth because to have something and nothing at the same time would violate the law of contradiction and therefore render meaningless the very idea of truth.

Necessity therefore means that the proposition in question (P) is implied by or derived from some prior concept (E). So “if E then P” becomes the form of the derivation; P is necessary to E, in all possible worlds where “E” obtains. Now if you talk about things existing necessarily, you are talking about things inherent to the idea of something existing: things that must exist because something exists. I don’t see how there can be any other definition of necessary existence, and you haven’t given one. I’ll grant that there’s not much we can prove through necessary existence, which is why we rely on experience for the majority of what we say exists.

I don’t know what this means. Do you mean that assertions of things existing can be given true or false values?

Again…how? You use the word necessary far too lightly, and you really haven’t defined it.

The statement “something exists” cannot in itself be logically necessary because it is not contained in any logical axiom, and it cannot be derived from any axiom. Logical necessity deals with relations between propositions and statements. However, the statement, “something exists” is shown true through experience, and is necessary for experience to be possible–particularly, as you said, the experience of a proposition. I hardly see how this is relevant though…

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Then what’s all this nonesense about omnipotence as a property “containing” or “including” logical necessity? THAT’s what needs to be proven. As far as I can tell, you (and Plantinga, from what I understand of what he’s written) haven’t used “necessary” in any meaningful way that would warrent the conclusion that God exists.

You can use whatever term you want. It won’t change the century-long development of modern logic showing necessity to be a relation and not a predicate.

The only thing that “means” necessity is the proof of necessity. And what I mean by that is a proof that omnipotence (or whatever term you want to use) includes necessity.

My problem with this is that it obviously means someone, somewhere along the line, has misconstrued “necessity.” I strongly suspect the mistake lies on your side of the argument. Because if the idea of God’s existence is really necessary you shouldn’t be able to come to two different conclusions.

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It is proven- that's what the argument does.  It supposes a property- Plantinga calls it 'maximal greatness', I'm calling it omnipotence for simplicity- that includes as it's qualities 'obtaining in every possible world', and then the argument goes on to show how this property must be either impossible or else necessary.

Existence probably isn’t a predicate, I see no reason to believe, though that necessary existence is not. There is a difference between a thing that exists and a thing that exists necessarily- the difference is clear when put in possible world semantics. The arguments against existence being a predicate (which I agree with) don’t apply to necessity.

I must be misunderstanding you here, because you can’t prove that a term contains something. Can you prove that the term ‘unicorn’ contains ‘onehornedness’? Of course not, we simply assert that it does and move on with trying to determine if the concept obtains in reality. Plantinga here creates a concept ( a set of qualities), and shows that the concept must obtain in reality.

 There's two usages of 'necessity' going on here, is the problem.  The first is a quality that is asserted as part of omnipotence- "Omnipotence is the quality of having maximal power in every possible world" or something like that.  That says nothing about whether or not this quality actually obtains, all it does is force the concept to be either necessary or impossible- there is no middle of the road with a concept that contains necessity. The second usage of Necessity is saying that the concept (which itself includes the idea of necessity) must be necessarily true as opposed to impossible- this is done through the premise that Omnpotence (so construed) is possible, that is, not logically inconsistant.  Something that's not logically inconsistant cannot be impossible- it can merely be false.  But mere falsehood is not an option here- the concept must be either impossible or necessary.  Barring some argument for logical inconsistancy, then, "Omnipotence (so construed as to include necessity) obtains" must be necessarily true, and hence, true in the real world.

The only other premise needed by the ontological argument is that “Omnipotence (so construed) is possible”. In other words, it’s not logically inconsistant. If it’s not logically inconsistant, then it’s not impossible, which leaves only one result- omnipotence necessarily obtains.

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Yes; in fact this seems to be the crux of our debate. You are attempting to employ a notion of metaphysical necessity–the idea that necessity can be a predicate. This position has been almost unanimously rejected by modern logicians and philosophers of language. Plantinga has tried to revive it by making use of Kripke’s possible world semantics. While I haven’t read The Nature of Necessity I do know that the ideas proposed in it have been rejected by many of Plantinga’s collegues. This, of course, doesn’t make Plantinga wrong, but it does mean you’ll have to convince me that there is such a thing as metaphysical necessity before I’ll even accept the premise of your argument that omnipotence (omni-greatness, whatever) can include necessity. Because it is not generally accepted that necessity can be a predicate.

It would be hard to deny that at least one valid use of “necessary” denotes a relation of analytic symmetry or entailment between statements. This concept is very easy to understand. It means that statements like, (1) “all bachelors are unmarried men” are necessary truths because an unmarried man is exactly the same thing as a bachelor. So (1) becomes simply an instance of the rule that a thing is identical to itself–which is fundamental to a notion of truth. We can say that (1) is logically necessary.

Further, necessity can be a condition or relation of entailment in sentences like, (2) “if A then B.” What this means is that B is necessary to A–and that there can be no instance in which B is true and A is false. However, (2) must be proven; B must be shown fundamentally relevant to A. You could say, “if [A] Joe is a bachelor, then [B] Joe is unmarried.” Here [B] is derived from the concept of [A], and is a necessary condition for the truth of [A]. You can also word this, “[A] only if [B].” If necessity can be construed as a property here, it is the property only of sentence [B] in relation to [A].

If terms like logical necessity and possibility are to be treated as properties, they are only properties applicable to sentences. So to say that the statement “God exists” is true in all possible worlds is to say that it is either a necessary condition for the truth of some prior sentence that is true in all possible worlds, or that it is a tautology that must be true because it is an instance of a logical axiom. It is clear (to me at least) that neither is the case. So God’s existence is not logicallynecessary.

Now, you want to introduce a concept of metaphysical necessity–where it is not simply that the statement “God exists” can be said to be true in all possible worlds (because in that case you most certainly WOULD need to derive that sentence from a prior concept), but it is also that God himself possesses some quality that makes him exist in all possible worlds. I have two responses to this:

First, I see no reason to believe that there is any such quality. It seems to me that the only reason to accept a notion of metaphyisical necessity is if you are set on proving the existence of God to begin with. I’m obviously not trying to do that, so the idea is, in my mind, useless. I don’t need it in order to have a concept of logical necessity or truth; I don’t need it in order to conceive of something existing; and, like Hume, everything I conceive of as existing I can also conceive as not existing.*

Second, possible worlds semantics was invented by Leibniz, so “possible worlds” did not really exist until the 17th century. It seems that any property that a being could have that would somehow make it exist in all possible worlds would be dependent on the existence of possible worlds to begin with; thus, even if God does exist NOW in all possible worlds, he didn’t before the 17th century–which may detract slightly from his alleged omni-greatness.

Your stated project was to prove the existence of an omnipotent being on the merits of logic alone. Well logical necessity pertains to sentences, not beings. It is fundamentally a relation between concepts. If you want to introduce the idea that a being’s existence could be necessary, I have simply to ask, “necessary to what?” To a notion of truth? To a concept of something existing? To experience? What? No, just necessary. Well that doesn’t mean anything to me or to most logicians, and it certainly is not stated in such a way as to render true the sentence “God exists.”

  • even if I accept your nominalism example, where the statement, “nothing exists” is a contradiction because the statement would be something, I would still be using necessity in relation to something else; I would be saying, “it is necessary that something exists in order for me to utter this statement.” It does not mean that the statement “something exists” is necessary in some unlimited or unrelated sense.
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The main reason I see necessity as being a valid predicate where existence is not is that as far as I can tell, the arguments that convinced me that existence was not a predicate don't apply to necessity. 
Let's say we have a computer on which is listed every true proposition in the world.  Somewhere on that list, you would see the proposition "Uccisore has a dog".  Obviously, changing the nature of propositions changes other propositions.  For example, if we change "Uccisore has a dog" to "Uccisore has a cat", then the proposition "Uccisore owns a litter box" probably converts from false to true and so on.  But if we change "Uccisore has a Dog" to "Uccisore has a dog that exists", I don't see how anything changes at all. In fact, "Uccisore has a dog" implies existence- existence being a grounding that is required for properties to obtain, rather than being a property itself and all that. 
But if we change "Uccisore has a dog" to "Uccisore has a dog that exists necessarily", then I think other propositions [i]do[/i] change- "IT could have been that Uccisore didn't have a dog" becomes false, for example.  "Uccisore's dog might cease to exist" could be false, because it implies that the existence of the dog requires some other thing- food, water, life-sustaining temperatures, etc. It seems to me that necessary existence has content where existence doesn't.
Simply, there is no difference between a thing and a thing that exists. There is a difference between a thing that exists, and a thing that exists necessarily, so therefore necessity has content and is a predicate.

I’m not sure about the validity of the distinction here- if the sentence “God exists” was necessarily true, wouldn’t that imply metaphysical necessity as you define it here? In any event, let’s not argue about that because I’m pretty sure the argument works if we only talk about concepts, and not existent things.

  1. The concept of Omni-Greatness includes having omnipotence, omnibenevolence and omniscience in all possible world.

  2. Omni-Greatness is possibly actualized.
    2a) A concept is possible if it is not logically inconsistant.
    2b) If a concept is possible it is true in at least one possible world.

  3. There is one possible world in which the concept of omni-greatness is actualized.

  4. (on 3 and 1) Omnigreatness is actualized in every possible world.

  5. Omnigreatness is actualized in reality.

Now, as I said, this implies that there is some quality about God that makes Him necessary, but that implication is not part of the argument itself.

In response to your claim that Omni-Greatness must be either axiomatic or else based on other necessary truths to be itself necessary, we can say that we don’t see it to be such, but that doesn’t mean it’s not. What I mean is,
(555x987)(-23)=-1250985

Is a necessary truth if it's true at all, but it's not readily apparent without going through a lot of steps. Omni-Greatness may be like that- necessary, but not obvious.  Again, I think it falls on whether or not it can be shown to be inconsistant (impossible).