The Ontological Argument for the Existence of God

[Jackalope]

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[God of Mr. Hanky]

Begging the question

Richard M. Gale, a metaphysician from the University of Pittsburgh, claims that the possibility premise begs the question. Basically, one is not justified in an epistemic sense to accept the possibility premise unless one also understands the nested modal operators in system S5. Within the modal system S5, “possibly necessary” means the same as “necessarily”. Since the concept of a being with “maximal excellence” entails this being’s necessary existence in a possible world, the possibility premise (3) contains nested modal operator “possibly necessary”. Since “possibly necessary” is equivalent to “necessarily” (within the system S5 that Plantinga needs for his argument to even get off the ground), the argument begs the question in the possibility premise (3), since the premise contains the conclusion within itself.

Metaphysical vs epistemic possibility

The modal ontological argument, in some presentations, relies on an equivocation between metaphysical and epistemic possibility. It may very well be that the existence of a maximally great being is epistemically possible (i.e. we don't know that it's false) but not metaphysically possible (i.e. non-contradictory). If the concept of a maximally great being is not self-consistent, then it is not metaphysically possible for such a being to exist. Compare: we don't know whether the twin prime conjecture is true or not. Suppose it is false but we don't yet know it; it follows that it is (metaphysically) necessarily false. We might nevertheless agree that it might be true because we don't know its truth value.

The issue with the metaphysical possibility as it relates to the first three premises can be clearly shown with a competing version of the argument:

1. It is possible that a maximally great being (God) does not exist.
   
2. If it is possible that a maximally great being does not exist, then there is some possible world where a maximally great being does not exist.
   
3. If a maximally great being exists in some possible world, then it exists in every possible world.
   
4. A maximally great being does not exist in every possible world (from 2).
   
5. Therefore, a maximally great being (God) does not exist.
   

This further highlights that the argument has two likely sources of error: with the construction of the argument in general (in which case the argument is not useful for proving anything) or a problem specific to the first premise (in which case the possibility of the existence or non-existence of the character God must be defended with further arguments). Of course it is also entirely possibly the problem lies in both areas, and it is neither possible to prove an actuality from a mere possibility or accept a possibility without supporting empirical evidence.

RationalWiki | Ontological argument

I'm not schooled in modal systems, I just google S5 and it isn't playing well with the eggnogg I just had.   But I am curious to know what would it say (not my being a little tipsy at the moment) of non-metaphysical possibilities? For example, I don't think it can be ruled out that on another planet somewhere there could have evolved some type of non-metaphysical pink unicorn (pink horse with a narwal-like horn). If it's possible, and the idea isn't metaphysical, then is it necessarily true?

EDIT: Keeping in mind the universe is finite!

[Angrboda]

I'm not schooled in modal systems, I just google S5 and it isn't playing well with the eggnogg I just had.   But I am curious to know what would it say (not my being a little tipsy at the moment) of non-metaphysical possibilities? For example, I don't think it can be ruled out that on another planet somewhere there could have evolved some type of non-metaphysical pink unicorn (pink horse with a narwal-like horn). If it's possible, and the idea isn't metaphysical, then is it necessarily true?

EDIT: Keeping in mind the universe is finite!

The universe being finite is an important question in relation to the ontology of possible worlds and modal logic. As intimated, I'm not a modal realist, so the question of the limits of this universe are relevant. Plantinga however isn't dealing from the same deck. Chad seems to think that a unicorn can't be a necessary unicorn, metaphysically speaking. I think that drags a whole host of questions about the nature of defining God as necessary along behind it, and those questions suggest that a maximally excellent being may not be necessary in similar veins. So I think it's a toss up; if God can be analytically defined as necessary, then there's nothing standing in the way of the same move in the case of a unicorn.

[Silver]

if God can be analytically defined as necessary, then there's nothing standing in the way of the same move in the case of a unicorn.

I have to agree.

A necessity has to decree some form of observable influence that is absolutely from god rather than from life flowing merely as it does due to the process of time.

[GrandizerII]

I have never seen this argument before, so I'm interested in some discussion of it. A philosopher by the name of Alvin Plantinga states it this way:

The Ontological Argument

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 is 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.
   

Thoughts?

1. It is possible that a maximally great being does not exist. 
2. If it is possible that a maximally great being does not exist, then a maximally great being does not exist in some possible world. 
3. If a maximally great being does not exist in some possible world, then it does not exist in any possible world.
4. If a maximally great being does not exist in any possible world, then it does not exist in the actual world. 
5. If a maximally great being does not exist in the actual world, then a maximally great being does not exist.
6. Therefore, a maximally great being does not exist.

So, using Plantinga's logic, it is as easy to prove that god doesn't exist as that he does.  Any argument that proves both X and not-X is worthless.  It weighs zero in the scales of persuasion. 

An argument so easily slam-dunk refuted shouldn't have any standing or fame.  But this is a famous argument because the Christians have no better arguments.  Since they have no good arguments, they have to field trash like this.

Nice counterargument. Once again, the argument rests on whether Premise 1 is true or not.

Really, the whole ontological argument thingy is pointless if they can't even establish the possibility of such  being existing.

[Brian37]

And again, this elaborate tripe still would not point to one god claim over another in any case.

[Angrboda]

And again, this elaborate tripe still would not point to one god claim over another in any case.

I don't believe this is accurate. As stated, it identifies exclusively those gods that are omnipotent and modally necessary.

[Pat Mustard]

I have never seen this argument before, so I'm interested in some discussion of it. A philosopher by the name of Alvin Plantinga states it this way:

The Ontological Argument

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 is 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.
   

Thoughts?

You've never heard of Thomas Aquinas? Oh, and Plantinga's title is not philosopher, but professional village idiot.

[GrandizerII]

Why are we to believe a personal(anthropomorphic) god is identical to a maximally great being? You got anything beyond semantic tricks?

Because in order for a being to be maximally great, being personal is one of the characteristics is must have by definition.

Personal means that the being has rationality, self-consciousness and volition (will).

A non-personal being which lacks one or more of these things is less great than a personal being.

Let's say this is so. Maximally great, according to Plantinga, also implies omnipotence, omniscience, and perfect goodness. But is omnipotence logically coherent? Is omniscience logically coherent? Is perfect goodness logically coherent?

What is omnipotence? Unlimited power? If so, can an omnipotent being create someone more powerful than itself? If it can, it's not the most powerful, and if it can't, it's still not omnipotent. So omnipotence doesn't seem logically coherent.

What about omniscience? Can an omniscient being know how to think like someone not omniscient? Can an omniscient being know how to cease existing?

Perfectly good? What does that even mean?

Perhaps the best there can be is a really powerful being, not a maximally great being as defined by Plantinga. But then, a super powerful being is just a super powerful being with relatively limited powers and, therefore, doesn't have to be a necessary entity.

[GrandizerII]

A really good counterargument to the Modal Ontological Argument: