Plantinga's Modal Ontological Argument

From Reasonable Faith.org

"Plantinga takes maximal excellence to include such properties as omniscience, omnipotence, and moral perfection. A being which has maximal excellence in every possible world would have what Plantinga calls “maximal greatness.” So Plantinga argues:

  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 in 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."

How do you feel about this argument. While it doesn’t feel right, I don’t see any contradictions, or falsehoods in the argument. Thoughts?

Junk argument.

  1. The concept of “maximal excellence” is a subjective hodgepodge.
  2. The “omnimax” attributes are undefined. They are simply “bombastic sounding” words, without substance behind them.
  3. Point #2 is tautology.
  4. Point #3 is a non-sequitur. It is the biggest logical error in the argument.
    Etc…

I suggest you substitite a “maximally great dish” for “maximal excellence” and see where it leads.

A maximally great dish is the one which cannot be surpassed in smell, taste, looks, nutrition and price. Now let’s do the substitution:

  1. It is possible that a “maximally great dish” exist. (says who?)
  2. If it is possible that a “maximally great dish” exists, then a “maximally great dish” exists in some possible world. (tautology)
  3. If a “maximally great dish” exists in some possible world, then it exists in every possible world. (non-sequitur)
  4. If a “maximally great dish” exists in every possible world, then it exists in the actual world. (another tautology)
  5. If a “maximally great dish” exists in the actual world, then a “maximally great dish” exists. (wow! how deep)
  6. Therefore, a “maximally great dish” exists." (No ****, Sherlock!)

Now let’s recall a great and funny wall-poster. It depicted a beautifully prepared table, with superb china, silverware and crystal glasses. On the plate was a steaming pile of excrement. The caption said: “100 billion flies can’t ALL be wrong! Why don’t you taste it, too?”

This about sums up the “value” of Plantinga’s “non-argument”. Just forget it. :wink:

Hard to tell without knowing the complete argument but I’l give you some off the cuff thoughts. 1) looks like some form of the degrees of perfection argument. But that argument leads to the necessary existence of a perfect being not just it’s possibility. Perhaps he has other reasons for concluding that such a being is possible. Do you know what they are? 2) How do we know such a possible world exists? Is there some argument that all possible worlds exist? It is possible that a world exists exactly like our own but I don’t exist in it. How do we know such a world exists? 3) Here he makes the jump from possibility to necessity. Why? Is it some form of ontological argument?. 4) 5) and 6) seem to follow if the preceding are true.

Generally speaking purely conceptual arguments for the existence of God fail. Following St. Thomas you cannot deduce the existence of God from our idea of God. He rejects St. Anselm’s proofs for example. His arguments start with what we know about this world experienced through our senses.

I do not actually see this as an improvement on Anselm. However, this view may better articulate how Aselm might go from conceiving God to “God exists.” Also, Plantinga tries to show God as a necessary being as one that must exist.o

I think one problem is that we do not know how excellent is maximal excellet. There may be some excellences that cannot be maximalized in conjunction. Every possible world may have a possible, or actual, being of maximal excellence, but what if to be maximally excellente in one potential world is different than another.

I think there are some insights to glean from it, but it would certainly not be a go to argument for me.

St. Anselm came up with the ontological argument for God. I like it. :smiley:

God is the greatest conceivable thing.
God is something that we think about, but something is greater if it is in reality than if it is merely in the human intellect.
Therefore, since the greatest conceivable thing would have to be in reality since being in reality would be greater than being just in the intellect, God must be in reality since he is the greatest conceivable thing.

Smells of Thomistic thought over Augustinian thought? I think yes. :wink:

Ccmnxc:

I think the problem is with Prop #3. why must a maximally great being exist in every possible world? Problem: the one and the many - they are not equivalent.

So, you see, I said that without resorting to a rather disrespectful diatribe about how moronic Catholics are! :slight_smile:

God bless,
jd

Nothing there J.D. You can’t go from " possibilities " to actuallities. :thumbsup:

Linus:

Yep. I know modal logic has rules, and that #3 may be the result of one of those rules. But, it should not, at the same time, completely ignore reasonableness

God bless,
jd

#3 is not just “the result of one of the rules of modal logic”, JD, #3 is completely and undeniably true.
A being that exists in every possible world is greater than a being that only exists in some.

The only problem with Plantinga’s argument (and all other Ontological arguments for that matter) is that #1 actually means “It is possible that a being a great as possible exists”, in which case it is tautological and the argument does not get anywhere.

Absolutely true. The Ontological argument, however, is not saying that. It is not simply saying a possibility constitutes an actuality. A being of “maximal excellence” would be a necessary being, not a contingent one. All necessary beings must exist in all possible worlds. Thats why the “maximally excellent dish” critique or the “perfect island” critique are missing the foundation by which the argument comes to its conclusion. The existence of a dish or an island, even the greatest possible dish or island, is contingent. Numbers exists in all possible worlds, not because it is conceivably possible for them to exist in all possible worlds,but because it is impossible for them to not exist. The supposition is that there must be a being of maximal excellence because it is not possible for any possible world to exist without a maximal excellence/necessary being. Maximal excellence in any possible world would have to be necessary. Because it is possible for there to be a being of maximal excellence in any/every possible world, that being must exist because for it not to exist would mean it would be impossible for it to be maximally excellent, which is a contradiction. The existence of God, or the maximally excellent being, is necessarily true as much as 2+2=4 is necessarily true. God’s existence can be concluded a priori. To deny the existence of necessary beings is to deny reality and any possibility for existence, because contingent beings are dependent up non-contingent beings for their existence.

In short, you can’t go from possibilities to actualities, but that which is necessary can only ever be actuality. Plantinga’s use of the word possibility only serves to help us understand why a being of maximal excellence exists.

I have some problem with Point 2, specifically ‘possible worlds’. There is no basis for believing that there is any ‘possible world’, apart from the one we inhabit.

This is linked to Point 1. Are we sure it is ‘possible’ a maximally great being exists? Does the fact we can imagine something, in fact, mean that it is possible? I can image a two headed horse, but does that mean it is ‘possible’.

I question the whole idea of ‘possible worlds’. The only grounds we have for calling something possible is if it IS. Why should I think there are other ‘possible worlds’ at all?

Otherwise it is like the story:
Q- “What might your name be, young man?”
A- “It MIGHT be Cederic, but it ain’t”

PS. I am a Theist by the way. I just don’t think this argument is valid…

I have some problem with Point 2, specifically ‘possible worlds’. There is no basis for believing that there is any ‘possible world’, apart from the one we inhabit.

This is linked to Point 1. Are we sure it is ‘possible’ a maximally great being exists? Does the fact we can imagine something, in fact, mean that it is possible? I can image a two headed horse, but does that mean it is ‘possible’.

Possibility isn’t contingent upon likelihood or even the things existence. Possibility depends upon it’s logical coherency and whether or not the proposed possible entity contradicts itself or not.

I must also thank ApologiaSophia for clarifying a maximally excellent being is necessary.

I think one problem is that we do not know how excellent is maximal excellet. There may be some excellences that cannot be maximalized in conjunction. Every possible world may have a possible, or actual, being of maximal excellence, but what if to be maximally excellente in one potential world is different than another.

It seems to me that if there is any one premise to be attacked, it is the first one.

The problem with this critique is that you cannot just substitute maximally great dish for maximally great being because a dish is a contingent entity. You could, perhaps, have a maximally tasty dish, but a maximally great dish has no defined properties that would make it maximally great.

A maximally great being, besides having omniscience, omnipotence and omnibenevolence would also have necessary existence. Any contingent being could not be maximally great because it would depend for its existence upon some other “greater” being.

The only being that would qualify as being maximally great would be a being that depended upon nothing else for its existence and for which all else would depend. That is a maximally great being.

Whether or not the rest of Plantinga’s argument is valid remains an interesting question of modal logic. Most scholars have no problem with the argument as properly stated by Plantinga. What it hinges upon is whether “maximally great being” is a logically coherent or incoherent concept. If the concept is not self-contradictory, the argument holds. If the concept is self-contradictory the argument fails in the first premise.

A simplified version is simply to insist that a necessary being exists. If “necessary being” is logically coherent, then one must, by definition, exist. How could a necessary being not exist if it is indeed necessary?

The dish of tripe handed out in the above post was nothing more than a dish of tripe, a maximally great dish of tripe, but still a dish of tripe.

Yes, but it is necessary to distinguish between ‘apparent possibility’ and ‘actual possibility’. For example, one might say: “It was possible that it rained today, but it didn’t”. In fact, this is wrong- it would be accurate to say: “It seemed possible that it would have rained today, but it didn’t.” Since it didn’t actually rain, it wasn’t possible at all, it just seemed possible.

Similarly, if we say: “A different universe is possible”, this is actually untrue. It is likely saying “It is possible you won the lottery, but you didn’t”. Since we have this universe, no other universe is possible. The universe, by definition includes ‘everything’. ‘Another universe’ is a contradiction in terms.

In modal logic, the word possible simply means conceivable. It is a conceptual or hypothetical possibility, not one that depends on “actual factuals.” A universe with every planet populated by yellow unicorns is a possible universe in modal logic. A necessary being would have to exist in that universe, too, if it were a logically coherent concept. It could not not exist in any universe.

By the way, if the cosmological argument is true and valid, then it would also work in the yellow unicorn universe, if it existed, because that universe could not really exist without a sufficient explanation.

Most people who dismiss Plantinga’s argument don’t really understand it. They dismiss it without good reason, mostly because it doesn’t sound compelling.

Modal logic is not really my field, but I understand ‘possible’ to mean not merely ‘conceivable’, but ‘logically coherent’. Now, it would seem impossible to predicate the logical coherence of any alternative universe- given the infinite completity of details.

With your example, of the yellow unicorns, one could say, obviously different planets have different distances from the sun, and therefore different temperatures. Therefore, it is not logically coherent that the same species (yellow unicorns) live on each. The point is, it is not possible to propose any alternative universe as being ‘logically coherent’- simply imagining something does not make it ‘possible.’

That’s not what logically possible means. Logically possible means that there is no internal inconsistency that prevents the idea from being conceivable. A square circle is a logical impossibility. We cannot even conceive the idea because it means bringing together two logically inconsistent ideas and trying to merge them when they can’t be merged. There is nothing in logic that prevents a universe of yellow unicorns from obtaining. Laws of physics are not laws of logic.

Another way of understanding this is by asking whether you could imagine it. If you can imagine or think it, it is logically possible. Try to imagine a square circle! Can you imagine a universe where every planet is populated by yellow unicorns. You bet! We could even imagine that if the Big Bang happened in a slightly altered form, there might just have been a universe of yellow unicorns, if God had willed it to be that way.

I could conceive of a universe with millions of identical solar systems where each solar system had ten earth-like planets revolving around a central sun in perfectly configured orbits and on each planet roamed millions of yellow unicorns that thrived on the expansive fields of grass.

For any “something that does not make it possible” I could conceive of something else that would make it possible in some other way. Again, logically possible is a whole different bird compared to possible according to current laws of physics. Those could be conceived to be quite different, as well.

Even with defining universe as such, it could have been the case that the universe did not exist. It could have been the case IS what is being discussed here because anything that could be or could have been diffrent is contingent. The fine-tuned argument contends that the Universe is so specific in its detail that, if it were even slightly different, human life could not exist. Howevr, regardless of the conditions and accidents of the Universe, necessary beings are always in existence. The real critique, however, is if a being can coherrently possess all excellencies and would those excellencies be different in any possible world otger than our own. This does not disprove Plantinga’s argument per se, but it simply say another argument must be made to lay the foundation for this argument.

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