Alvin Plantinga’s Modal Ontological Argument

[Randy_Carson]

Alvin Plantinga’s Modal Ontological Argument

1. It’s possible that a Maximally Great Being (MGB) exists.
2. If it is possible that a MGB being exists, then a MGB exists in some possible world.
3. If a MGB exists in some possible world, then it exists in all possible worlds.
4. If a MGB exists in every possible world, then it exists in the actual world.
5. If a MGB exists in the actual world, then a MGB exists.
6. Therefore, a MGB exists.

Definitions:

Possible World – a hypothetical situation used by philosophers to test an idea to see if it’s logical by asking whether it could exist in a world like our own

Maximally Great Being – a being that possesses all qualities that are better to have (love, wisdom, omnipotence, omniscience) but no negative properties (imperfection, corruption). Specifically, a MGB must have the property of necessity since being necessary is better than the alternatives.

Impossible Being – an entity that exists in no possible worlds (a square circle, a married bachelor)
Contingent Being – an entity that exists in some possible worlds and depends on something else for its existence (children exist because their parents existed)
Necessary Being – an entity that cannot be false or incoherent or fail to exist in any possible world (numbers, shape definitions)

God is not a contingent being; He is a Maximally Great Being whose existence is necessary in all possible worlds including the actual world in which we live.

 

[1Lord1Faith]

He starts out using the word possible, and through a series of assumptions and logic leaps, looses the word by the time he’s done.

 

[Randy_Carson]

He starts out using the word possible, and through a series of assumptions and logic leaps, looses the word by the time he’s done.

:nope:

There are no assumptions and leaps of logic. The argument is valid and sound, and even atheist philosophers concede that premises 2-5 are airtight.

The only matter for debate is the first premise.

 

[1Lord1Faith]

:nope:

There are no assumptions and leaps of logic. The argument is valid and sound, and even atheist philosophers concede that premises 2-5 are airtight.

The only matter for debate is the first premise.

I guess, but going from ‘it’s possible’ to, ‘therefore it is’; that’s just silly to me. That’s not proof.

 

[Bradski]

There are no assumptions and leaps of logic. The argument is valid and sound, and even atheist philosophers concede that premises 2-5 are airtight. The only matter for debate is the first premise.

You might note that in 1, we are introduced to an MGB as a possible entity. Let’s call it a Possible MGB or PMGB. The all of a sudden in 2, it becomes an Actual MGB. How’d that happen? The list should read:

1. It’s possible that a maximally great being exists. We therefore have a Possible Maximally Great Being (PMGB).
   Nothing to argue with so far.
2. A PMGB exists in some possible world.
   About as vague as you can get and it’s actually a tautology. It simply repeats item 1 for no reason. In fact, we can replace Chocolate Bunny for PMGB in both points so far and we are still logically correct. We don’t require item 2.
3. If a PMGB exists in some possible world, then a PMGB exists in all worlds.
   Having skipped item 2, we now say that IF there is the possibility of an MGB, then it (possibly) exists in all worlds. The bracketed (possibility) is required. We haven’t decided anything definite yet. Don’t keep forgetting the IF. We are still talking about a PMGB, not an MGB in actuality. An actual MGB is what we are trying to ascertain so we can’t use it in the lead up to the conclusion.
4. IF a PMGB exists in all possible worlds, it exists in an actual world.
   We are still saying that IF it is possible that an MGB exists, then it would exist in the actual world. Item 5 is exactly the same as item 6, so let’s look at how we get from 4 to 6:

IF it is possible that an MGB exists, it would exist in the actual world (note the ‘IF’ and the ‘would’ – we are still using conditional statements about something that is only possible).

Therefore an MBG exists.

Those last two lines are not logical.

 

[Charlemagne_III]

The defect is in Premise 2.

I don’t see how Premise 2 escapes Aquinas’s criticism of Anselm’s argument.

A Maximally Great Being isn’t proven to exist just because we can imagine it.

 

[Rhubarb]

My problem comes in two parts. The first part is that premises 2-6 reduces to “if God exists, then God exists.” Which is a tautology. The second part is that premise 1 is something people can fight about. The ‘greatness’ of qualities is a lofty idea that needs discussing - what makes a quality great or not great, what constitutes a quality being maximally great, etc. And then, the idea that necessity trumps contingency needs discussing.

 

[Bradski]

The defect is in Premise 2.

I don’t see how Premise 2 escapes Aquinas’s criticism of Anselm’s argument.

A Maximally Great Being isn’t proven to exist just because we can imagine it.

Agreed. He whole shebang is a smoke and mirror trick, moving from something possible to something actual without any logical connection.

It’s worded to appeal to those who already accept it’s premise. To anyone else it’s word salad.

 

[inocente]

Alvin Plantinga’s Modal Ontological Argument

Apparently Plantinga himself agrees that the reverse argument works just as well:

1. There is no entity which possesses maximal greatness.
2. Hence there is no possible world in which there is an entity which possesses maximal greatness.

Parodies of ontological arguments include:

1. The MGB could overcome the greatest handicap.
2. The greatest handicap is not existing.
3. Hence the MGB does not exist.
4. By definition, the MGB is a non-existent being who has every other perfection.
5. Hence the MGB does not exist.
6. It is possible that the MGB does not exist.
7. The MGB is not a contingent being, i.e., either it is not possible that the MGB exists, or it is necessary that the MGB exists.
8. Hence it is not possible that the MGB exists.
9. Hence the MGB does not exist.

plato.stanford.edu/entries/ontological-arguments/

 

[Cheiron]

I think the problem is in premise 3. Why should a Maximally Great Being exist in every hypothetical world if it can exist in some hypothetical worlds? Surely we can also think of a possible world in which the MGB doesn’t exist?

 

[Bradski]

I think the problem is in premise 3. Why should a Maximally Great Being exist in every hypothetical world if it can exist in some hypothetical worlds? Surely we can also think of a possible world in which the MGB doesn’t exist?

Herein lies another problem which arises before we even get to the definitions.

If the MGB doesn’t live in all possible worlds, then it cannot be a MAXIMALLY great being.

So why does it have to be maximally great?

Well, then…um…it wouldn’t be God.

Whoops, gave the game away there.

Incidentally, I used to have an MGB. British racing green, soft top, wire wheels. Gee, I miss that car.

 

[Cheiron]

Herein lies another problem which arises before we even get to the definitions.

If the MGB doesn’t live in all possible worlds, then it cannot be a MAXIMALLY great being.

So why does it have to be maximally great?

Well, then…um…it wouldn’t be God.

Whoops, gave the game away there.

Incidentally, I used to have an MGB. British racing green, soft top, wire wheels. Gee, I miss that car.

The MGB was in Australia?! Who’d have thought?

 

[Peter_Plato]

:nope:

There are no assumptions and leaps of logic. The argument is valid and sound, and even atheist philosophers concede that premises 2-5 are airtight.

The only matter for debate is the first premise.

I think that is correct.

The point to be made is that speaking of an absolutely necessary being (which MGB logically entails) as MERELY possible is as much a logical contradiction as proposing a squared circle – it is a logical contradiction.

Put very simply, a merely possible necessary being is, in principle, a self-contradiction.

Either the MGB is logically impossible or, if not impossible, then necessary, which are the only two alternatives which Plantinga proposes can logically exist.

That leaves it up to his interlocutors to demonstrate that MGB is impossible, which would be the only way to refute a positive claim that the MGB exists.

I suspect that may be why Plantinga concedes the reverse of the argument also holds, but only holds in the sense that to show the MGB does not exist, it would have to be demonstrated that the MGB is logically impossible.

So the probative burden is back on the skeptic.

It isn’t enough to merely claim the existence of the MGB hasn’t been shown, it is necessary for the skeptic to show the MGB is a conceptually impossible. Until then, Plantinga’s argument – along with a positive claim that the MGB exists – remains on the table.

 

[Peter_Plato]

Herein lies another problem which arises before we even get to the definitions.

If the MGB doesn’t live in all possible worlds, then it cannot be a MAXIMALLY great being.

So why does it have to be maximally great?

Well, then…um…it wouldn’t be God.

Whoops, gave the game away there.

Incidentally, I used to have an MGB. British racing green, soft top, wire wheels. Gee, I miss that car.

Gave the game away? This objection hasn’t even seen its way out of the dressing room.

In fact, it doesn’t seem to have an awareness of which game it is that is being played.

 

[Randy_Carson]

“Even among critics, there’s still no consensus as to exactly where the flaw lies in Anselm’s reasoning….the ontological argument, though many regard it as a mere philosophical gimmick, seems the most difficult to refute.” (Yujin Nagasawa, The Existence of God.)

yujinnagasawa.co.uk/

 

[Peter_Plato]

Apparently Plantinga himself agrees that the reverse argument works just as well:

1. There is no entity which possesses maximal greatness.
2. Hence there is no possible world in which there is an entity which possesses maximal greatness.

Premise 1 would have to be demonstrated. It hasn’t.

Parodies of ontological arguments include:

1. The MGB could overcome the greatest handicap.
2. The greatest handicap is not existing.
3. Hence the MGB does not exist.

Not sure how the above is a “parody.” 3 doesn’t follow. If the “greatest handicap” is “not existing” and the MGB “could” overcome that handicap, then it WOULD exist. How does “Hence the MGB does not exist,” follow from the other premises?

By definition, it isn’t that the MGB merely “could” overcome non-existence, but would overcome it necessarily. In addition, overcoming the “greatest handicap” wouldn’t be merely overcoming “non-existence” but overcoming NECESSARY non-existence and that would seem to imply NECESSARY existence.

1. By definition, the MGB is a non-existent being who has every other perfection.
2. Hence the MGB does not exist.

What does that argument even mean? It is semantically empty to define a non-existent being as “HAVING” any perfection whatsoever.

1. It is possible that the MGB does not exist.
2. The MGB is not a contingent being, i.e., either it is not possible that the MGB exists, or it is necessary that the MGB exists.
3. Hence it is not possible that the MGB exists.
4. Hence the MGB does not exist.

Finally, a reasonable reply – kind of, sort of.

It isn’t clear how this serves as a “counter” argument, although premise 2 does highlight the problem for the atheist skeptic, To wit: proving that the MGB is “not possible.”

The form of the argument is just bad though because premise 2 contradicts completely premise 1 by showing that it cannot be merely “possible” for the MGB to exist or not, but rather 2 points out that the real alternatives are:

1. It is NOT possible for the MGB to exist because the very idea of the MBG contains an inherent logical impossibility. Or…
2. It is necessary, by definition, that the MGB exist.

Ergo, you need to show 1) or else 2) stands.

So, where is your proof for 1)?

 

[Peter_Plato]

My problem comes in two parts. The first part is that premises 2-6 reduces to “if God exists, then God exists.” Which is a tautology.

Well, no, it isn’t a tautology so much as pointing out the definitional or conceptual consistency in the claim that “If God (necessary being) exists then God MUST exist necessarily,” otherwise you aren’t properly talking about the manner in which God exists at all.

The second part is that premise 1 is something people can fight about. The ‘greatness’ of qualities is a lofty idea that needs discussing - what makes a quality great or not great, what constitutes a quality being maximally great, etc. And then, the idea that necessity trumps contingency needs discussing.

Bingo.

 

[Rhubarb]

Well, no, it isn’t a tautology so much as pointing out the definitional or conceptual consistency in the claim that “If God (necessary being) exists then God MUST exist necessarily,”

Look at the antecedent of premise 2. And then premise 6. The argument quite literally reduces to A->A. Which is definitely a tautology. The rest are logical links in the chain to get from the implication to the ergo. And then premise 1 is tacked onto avoid the tautology problem. Which you already gave the bingo for.

 

[inocente]

“Even among critics, there’s still no consensus as to exactly where the flaw lies in Anselm’s reasoning….the ontological argument, though many regard it as a mere philosophical gimmick, seems the most difficult to refute.” (Yujin Nagasawa, The Existence of God.)

After making a long list of the flaws in ontological arguments, Graham Oppy concludes the main problem is they’re just not convincing:

“Those who are disposed to think that theism is irrational need find nothing in ontological arguments to make them change their minds (and those who are disposed to think that theism is true should take no comfort from them either)”. - plato.stanford.edu/entries/ontological-arguments/#ObjOntArg

 

[inocente]

Ergo, you need to show 1) or else 2) stands.

So, where is your proof for 1)?

They’re not my arguments, they’re from the article I linked.