Templeton prizewinner Alvin Plantinga

Alvin Plantinga, professor of philosophy at Notre Dame, has been awarded the Templeton Prize this year (2017), William Lane Craig says that Plantinga is the greatest Christian philosopher alive today. Plantinga has developed a proof for the existence of God, which is somewhat of a spinoff of the ontological argument: Here is a version of it (from Wikipedia)
A being has maximal excellence in a given possible world W if and only if it is omnipotent, omniscient and wholly good in W; and
A being has maximal greatness if it has maximal excellence in every possible world.
It is possible that there is a being that has maximal greatness. (Premise)
Therefore, possibly, it is necessarily true that an omniscient, omnipotent, and perfectly good being exists.
Therefore, (by axiom S5) it is necessarily true that an omniscient, omnipotent and perfectly good being exists.
Therefore, an omniscient, omnipotent and perfectly good being exists.
Craig has a slightly different version of the proof:
It is possible that a maximally great being exists.
If it is possible that a maximally great being exists, then a maximally great being exists in some possible world.
If a maximally great being exists in some possible world, then it exists in every possible world.
If a maximally great being exists in every possible world, then it exists in the actual world.
If a maximally great being exists in the actual world, then a maximally great being exists.
Therefore, a maximally great being exists.

The argument seems to rely on the assumption that if X is possibly necessary, it is necessary in at least one possible world, which I don’t see as being obvious.

In the semantics of necessary/possible modal logic, something being necessary in one possible world is the definition of something being possibly necessary.

If I were to write a paper against the argument, I’d attack the idea of maximal excellence presented. And that even if this being existed in a possible world, it doesn’t mean it exists in all possible worlds - which is what it means to be logically necessary.

The only way a MGB could be maximally great in ANY world is if that MGB actually existed in that world. It wouldn’t make any sense at all to say the MGB was actually the MGB in that world if it didn’t exist in that world. It is a conceptual contradiction to claim it.

Ergo, in order to be the MGB in any world the MGB would necessarily have to exist in that world.

The concept of “possibly necessary” is incoherent. It is like “square-circle.”

A thing is either impossible, possible or necessary. These are mutually exclusive qualities.

If a thing could be necessary in some possible world, what precisely would make it necessary in that world that wouldn’t by the same token make it necessary in every possible world? If it isn’t necessary in every possible world, why would it be necessary in only one or other possible world?

Plantinga’s point is that either the idea of necessary being is a logical contradiction or the MGB is necessary in all possible worlds. There is no middle ground.

He has made the point in a recent interview that the modal form of the ontological argument is sound and valid but is not convincing to many precisely because it is conceptually grounded. Human beings can readily deny concepts they don’t want to be convinced by.

This is incorrect. In formal modal logic, possible necessity of A is simply the formula ◇◻A. And even in very informal modal logic, these three being mutually exclusive would imply that necessary “things” are not possible.

modal status of any proposition:

  • truth: true in the actual world
  • falsity: false in the actual world
  • possibility: true in at least one possible world
  • impossibility: true in no possible world
  • necessity: true in all possible worlds
  • contingency: true in some possible worlds and false in others

I think that the concept of “possibly necessary” is coherent but entirely different from being necessary in one possible world.
Take for example, the Riemann hypothesis, that the Riemann zeta function has its zeros only at the negative even integers and complex numbers with real part 0.5 . Now it is possible that this hypothesis is true. So it is possibly true. Also, if it is true, then it is necessarily true because of mathematical reasoning. So it is possibly necessarily true. But that does not mean that it is necessary in one possible world. You cannot conclude that it is necessarily true at this time. So I see two entirely different things.

Something like its necessity being indeterminate, therefore its necessity, itself, is only a possibility.

Is that what you mean?

Yes it is possible that the Riemann hypothesis is necessarily true. But that does not imply that it is necessary or necessarily true in one possible world. It might be false in all possible worlds so that it would not be necessarily true in one possible world.
So there is not an equivalence between being possibly necessary and being necessary in a possible world.

Yes, but here you are defining what applies as a formal requirement of necessity in modal logic, before the semantic content is spelled out.

Plantinga spells out the content of MGB, so either the MGB exists in all possible worlds or is not possible in any. The only reason the latter would be true is if the Idea of a MGB is self-contradictory and not possible in any possible world.

Again, this is formally true but does not apply to Plantinga’s argument because the MGB is necessary in one possible world. The only way that wouldn’t be the case is if MGB is not possible. So the burden is on skeptics to prove the MGB is self-contradictory because if it isn’t, the MGB is necessary in all possible worlds including the actual one.

Definitions:

Possible world: A state of affairs which is different from the existing world. (The only prerequisite is that it cannot contain a logical contradiction, like a “married bachelor”.)
Possible existence: A being that exists in some, but not all possible worlds.
Necessary existence: The being exists in all the possible worlds.

In no world can a logically contradictory state of affairs exist.

To show that there is a “necessarily existing being” one must examine all the (infinitely many) possible worlds, and find out that this being is present in all of them. That is impossible. On the other hand it is very simple to prove that there is no “necessarily existing” being. All we need is to find is two possible worlds without intersection, and this proves that there can be NO necessarily existing being. Go, and find two such worlds. It is easy! :wink:

The concept of “maximal greatness” is incoherent. The author picked a few “good sounding” (but pretty much nonsensical) attributes, and declared that these attributes are necessary and sufficient for a being to become “maximally great”. It is impossible to find a maximally great “dinner”, or a maximally great “vacation”.

The concept of “possibly necessarily” is even worse. If something is “necessary”, then it is also “possible”. But from the “possible” there is NO way to “necessary”, S5 modal logic or otherwise.

Actually, no it isn’t. It only requires Being whose essence is existence itself, then you couldn’t have any possible world without the possibility of actualizing it – the argument from contingency would therefore require the Uncaused Cause or The Pure Act of Being Itself in order to have something rather than nothing in all possible worlds.

The ontological argument would then be the inverse of the cosmological argument, thus proving BOTH that Necessary Being is not self-contradictory because contingent existents logically require an Uncaused Cause and that, ontologically speaking, the idea of MGB requires it exist necessarily.

It is always a cutesy “trick” to define something into existence. Too bad it does not work. :wink: On the other hand it is quite simple to find two possible worlds which have no intersection, and then the whole “necessary being”, or “essence is existence” is blown out of the water. Not to mention that existence is a prerequisite to “essence”, whatever that might be. You cannot even define what the “essence” of a chair might be, or the “essence” of a cow.

By the way, the phrases of “uncaused cause” or “pure act” or “being itself” do not need to be capitalized. And who (or what) would do the “actualizing” of that “necessary being”? The “necessary being” would actualize itself?

There is another serious error here. You try to play fast and loose with the words of “necessary” and “contingent”. Necessary does not mean that it is logically “necessary”. Contingent does not mean that there is a logical dependence involved. It only means that the “thing” only appears in some (but not all) possible worlds. And what is that “MGB”? You cannot even define what an MGD “maximally great dinner” would be.

But I challenge you to try to think outside the “box” and see if you can imagine two possible worlds without any intersection. Go for it, bro. :slight_smile:

There’s so much to comment on…

I’d like to know how excellence is markedly different from goodness. If they aren’t, then the definition is recursive and not helpful. If they are, then what sort of work does it do in the argument? I’d also ask for an argument for wholly good being required for being maximally excellent. Because in this definition it seems that ‘maximally excellent’ is a naturalistic fact - A+B+C=Excellence. But goodness is normative, which means philosophers are going to fight about it. An ad hoc definition of goodness might be fine for a philosopher with a drum to beat, but it doesn’t work if someone is trying to think critically and leave their preconceptions at the door.

Professor Plantinga can say his argument is sound all he wants. From his first premise I see points I would fight over. I’m sure Professor Plantinga is a better philosopher than I am but premise one isn’t self-evident as true. I also would fight over 10. I don’t see how that is obviously true.

And it seems to me that the argument fails at least in the same way all ontological arguments do - you can replace the maximally great being with a maximally great dog, or table, or TV show, or dinner (as another poster mentioned). The argument seems to work just as well with those maximally great things. Which is absurd.

I think you sell yourself short. :slight_smile: The phrase “possibly necessary” is just a meaningless word salad. If something would be “necessary” (existing in all possible worlds), then it would also be “possible” (exists in some possible world). From the proposition that something exists in a possible world it does not follow that it must exist in all possible worlds.

Let’s not forget that there are infinitely many possible worlds, and it is impossible to examine ALL of them. So a direct verification of a “necessary being” is impossible. On the other hand the refutation is very simple. It is easy to present two possible worlds without intersection, which would get rid of this nonsensical “necessary being” once and for all. :slight_smile: Just for the fun of it, here is one example: “World A contains one ‘up’ quark - nothing else”, and “world B contains one ‘down’ quark - nothing else”. None of these two worlds contain anything else, so they are possible worlds, AND have no intersection. So this is a mathematical / logical proof that there is no “necessary” being. Good bye, God.

Actually, it doesn’t work as you suggest it does. A “maximally great dog” does not need to exist by virtue of what it is. There is nothing in the nature of a dog that logically implies that it MUST exist. Part of being the MGB is that inherent to its nature is necessity of existence because maximal greatness would require the contingency of all other existents upon the necessity of the existence of the MGB. That would be the great making quality sine qua non.

On the other hand, it is self-evidently true that a dog that has actual existence would be greater, ontologically speaking than one that didn’t happen to exist. Given that dogs are contingent existents that only happen to exist if the causal antecedents are in their favour. It is in the nature of what dogs are that they are dependent upon other causes to exist. Hence, necessity is not a property inherent to the concept of dog. It would be true, however, to say that for a dog to be maximally great in whatever possible world you are speaking of, the conditional requirement would be that the dog would have to happen to exist in that world. An imagined or possible dog would not be, if it happened NOT to exist, the maximally greatest dog. Whatever dog that did exist in that world, provided it had more great dog-making qualities than all other dogs, would be the MGD in that world. However, necessity of existence is not a quality of dogs, per se. There is nothing about dogs that make them have to exist by some necessity of their nature.

You are clutching at straws here by giving the same lame canned response, as if merely repeating it, incantation-like, is sufficient to make it true.

Speaking of word salad…

What you are forgetting is that to be a “possible world” at all would require appropriate metaphysical conditions. Merely imagining some world does not, by itself, make that world “possible” in any meaningful sense. The critical question, that you keep evading, is: What necessary and sufficient conditions would be required to make any world at all a real possibility?

There is no need to survey the infinitely many possible worlds, it is merely necessary to comprehend the conditions which would make any of them actually possible and not fanciful, but empty, imaginings. To truly be possible, the conditions for the possible existence of any of those “infinitely many” worlds would need to be properly understood, otherwise, your “infinitely many possible worlds” actually suffer from the “meaningless word salad” problem you wrongly ascribe to God.

In other words, you are completely circumventing the argument by not explicating the very condition which makes possible worlds at all possible. That would be the very same necessary condition which makes this world actual (aka something rather than nothing) instead of merely nonsensical fancy. The only grounds we have for claiming anything could be possible in any sense whatsoever is that what we recognize as “possibles” are merely riffs on existents in this real world. Hence, they are real possibilities because they could exist in the real world, given that proper conditions obtain. What conditions would those be, precisely? You don’t know. Good bye, “infinitely many possible worlds.” They’ve just been tossed into your “meaningless word salad.”

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Existence isn’t a property that can be predicated upon a subject. Existence is a quantifier. I would be happy to read a potential refutation of that, but it’s pretty commonly accepted.

Your argument is still just trying to define something into existence. The MGE exists by virtue of what it is - then why do we need to argue anything. You’ve introduced a premise - the definition of the MGE - that you think defeats critique. Is it possible it exists? Sure. If we grant that it’s possible that anything can exist. But then the argument hand waves moving from possible to necessity because of your definition of the entity. A dog might not exist by virtue of what it is. But the MAXIMALLY GREAT DOG sure does. This MGD is different from a dog, you see. And that Maximally Great Dog possibly exists, which means it must necessarily exist. QED using the same logic and tricks you’ve used. It’s just as valid and sound as the first argument. (Which I admit, I don’t believe is sound) By the same way we can prove the existence of the Maximally Great Widget, Maximally Great Thingy, Maximally Great Whatsit, etc. until our ontology is so full of possible necessary things that it beats out all the concrete things in the world.

And it isn’t self-evident that something that exists is ‘greater’ than something that doesn’t. You’re again making value judgements without any sort of support for it, except by your fiat. You’re treating a normative claim as naturalistic. You think I’m grasping at straws, but you’re plugging your ears going “la-la-la-la-la-la”. You’re getting similar responses because it appears that you don’t understand or acknowledge serious problems in the argument being presented. Your preconceptions are showing. And they are always gauche in philosophical debate.

This is nonsensical. And the only reason you are claiming it is to cling to your failed argument.

I have 10 carat diamond in my hand (an actual one) and I am picturing a 50 carat diamond in my imagination. You can have one or the other. Which will you choose?

If the actual one is NOT “self-evidently greater” than the figment of my imagination, then it wouldn’t matter which you would choose. In fact, you may as well go for the bigger one – it’s worth five times more if there is no difference in “greatness” between existing things and imaginary things.

I’ve heard this claim every time the argument is brought up and it still is irrelevant.

You can call existence whatever your little heart desires you call it. Whether it’s a quantifier or a property makes no difference. Things that exist are ontologically distinct from things which do not. That is the only distinction that needs to be made.

Yes. The Maximally great dog possibly necessarily exists so it does necessarily exist in some possible world. That is the line of one of the Plantinga axioms which I am not buying. Generally, I don’t buy the ontological argument, or the reasoning of Plantinga, because you can reverse it and come up with something unsound and completely untenable and unreasonable.
For example, let’s reverse the argument this way:
The creation of the universe was a great achievement by a Supreme Being.
Now suppose there did exist a Being with one disability making him slightly inferior to the Supreme Being and that this Being created the universe. Then this would be an even greater achievement. He created the universe as it is and yet he did all that even though he had one disability.
Now suppose that there did exist a Being with two disabilities and he created the universe, then that would be even a greater achievement than the preceding two. Now suppose that there was a Being with an infinite number of disabilities and he created the universe, well that would be an even greater achievement. But the greatest possible achievement would be for a non-existent character to have created the universe. This would be the greatest possible achievement, since the character would not exist and yet the universe was created by this non-existent character. Now I have in my mind a clear and distinct real idea of the greatest possible achievement in the creation of the universe. Since that thought really exists clearly and distinctly in my mind and therefore possibly necessarily exists and since the greatest possible achievement would be the case where the Creator does not exist, I must necessarily conclude that the Creator does not exist in some possible world. But if the Creator does not exist in some possible world, then necessarily the Creator does not exist — Because if the Creator existed, He would have to exist in all possible worlds.

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