An Explanation of the Ontological Argument

Kenneth Keathley says of the following video:

Does the Modal Ontological Argument prove the existence of God? It at least demonstrates that God’s existence, if possible, would be necessary. So the only way God couldn’t exist is if his existence was impossible. This means there is no 50-50 chance of God existing, no 10% or 90% either. Either God cannot exist or he must exist. The probability of God’s existence is 0% or 100%.

The existence of a necessary being is not contingent on anything else. Therefore, there can’t be one set of circumstances that would cause Him to exist in one kind of reality but another set of circumstances that wouldn’t, such that He would exist in some possible worlds but not in others. A necessary being can’t have a “somewhat probable” chance of existing in a particular world, because He exists by necessity; and the different possible circumstances one could imagine existing around Him have no effect on whether or not He exists, because He’s not contingent on any of them.

For this reason, if a necessary being is possible in any conceivable world, then He would exist in every conceivable world, including this one. 

I still have much thinking to do before this is settled in my own mind, but after watching this video and mulling it over for a few hours, this is the closest I’ve come to understanding (and finding meaningful) the ontological argument for the existence of God. Keathley's point is key: “Either God cannot exist or he must exist.”

Give the ontological argument another chance. Take some time to think about it, and see how far you get. I’m interested in reading your comments as I’m working through this, but don’t comment if you haven’t watched the video.

(HT: @biolapologetics)

Comments

[Anthony Adamski]

Raise this with pascals wager and it pushes you just over the 50/50 edge - belief in God then becomes much more reasonable than the alternative.

[WisdomLover]

Of course, the strict either/or nature of the argument was apparent to Leibniz, but I'm glad people are taking the argument seriously.

As is pointed out in the video, the question of the possibility of God becomes important.

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There is this much to be said, even without a proof of the possibility of God. If God is impossible (in the sense relevant to the argument), that means that the concept of God is contradictory. So see now what the conversation with the Atheist becomes:

Atheist: I don't believe that God exists.

Theist: Why not?

Atheist: Silly theist, it is up to the one who asserts the existence of a thing to prove the existence of that thing.

Theist: Well, it seems that either it is a necessary truth that God exists, or it is a necessary falsehood (i.e. it is contradictory) that He exists.

Atheist: OK, I still don't believe that God exists.

Theist: If God doesn't exist, then isn't there a contradiction in very idea of God?

Atheist: OK, I still don't believe that God exists.

Theist: Well I don't believe that the contradiction exists.

Atheist: Why not?

Theist: Now who's being silly?

This conversation, of course, proves nothing except that the principle that it's up to the one who asserts existence to prove existence is little more than a sophomoric bromide.

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When you move past the bromides and get to actual proof, there is this.

One would like, really, to know what is meant by greatness and why necessity would either be a great-making-property (hereafter, a GMP), or why the possession of all the GMPs would imply necessity.

The video creator simply asserted that necessity is a GMP.

That assertion is the basis of Premise 3, not Premise 1. That is, the premise that if God exists in some possible world, then God exists in all possible worlds. Premise 3 is actually not entirely uncontroversial...it's a very special fact about God that if He is possible, then He is necessary.

So it seems, at least, that to prove the possibility of God, you are going to have to know what the GMPs are and prove that there is no contradiction among them. That would establish Premise 1.

But once you've done that, you'll also want to be sure either that necessity is one of the GMPs or that, taken together, the possession of all the GMPs implies necessity. That would establish Premise 3.

[Phillip A]

The "modal" variation on the classical St. Anselm ontological argument is nothing more than a convolution intended to disguise its flaws. At the core, all ontological arguments work by imagining a "maximally great being", and then asserting that one of the properties of "maximal greatness" is existence (or, in this variation, "necessity") So, a maximally great being exists (or is necessary) The five steps in the video are just fluff, this is really just a one-premise argument, previously bolded. Also known as an "argument by assertion."

The fun, pedestrian way to debunk the ontological argument is to use the exact same logic to prove the existence of a "maximally smelly sock". After all, a sock that exists is definitely smellier than one that doesn't exist. And a sock whose existence is necessary in all possible worlds comes closer to exhibiting maximum smelliness.

[WisdomLover]

So you don't really get what necessity is, Phillip, and why that's important.

Most things like unicorns, human beings, planets (and smells and socks) and so on cannot be consistently described as necessary. Smells, for example, would not exist in a world with no noses. So they cannot be necessary.

(As for your graphic, the answer is "no", not any more than a being who could find a flaw in Modus Ponens or the Law of Contradiction would be greater. Whatever "greater" means, "less rational" is not part of that meaning.)

[scbrownlhrm]

Some basic summaries which may be helpful as modal logic seems lost within Dawkin’s straw man version of the ontological argument proving that pigs can fly. And, a bit more on the logic of the necessary and the possible surfaces once again. Feser looks into the *no-maximality* premise that is the rival to Plantinga’s argument and also into the uncanny fact that one cannot get more existence-like than existence *itself*. Indeed.

[scbrownlhrm]

Hmmm.... Make that Dawkins' straw man......

[scbrownlhrm]

The Non-Theist's definition of LOGIC:

Blindly reverberating particle/energy cascades ceaselessly recocheting/recoiling amid timeless burstings of phosphoresing blisters.

A "hard-stop" appears, and then the inevitable conflation wrapped up inside of equivocation arrives as a post-script:

PS: Outside the skull it's doomed, but, inside the skull a special kind of magic "emerges".

Now, we will hear the complaint from the Non-Theist that such is a straw man, only, that is all we ever here - the mere assertion that such is a staw man. They never do *argue* that such is a straw man.

Whereas, that pigs can fly is shown to be a straw man by the Christian's *arguments* exposing such to be the case.

[WisdomLover]

BTW, there are two classical St. Anselm arguments, and the second one is actually the modal argument.

Anselm argues that God is a being so great that He cannot be conceived not to exist. That is, His non-existence is inconceivable. Anselm is a bit loose with this notion of conceivability. Sometimes, he seems to mean "possibility". At other times, he seems to mean "what one can understand...at least to the degree that the fool understands".

If you take "conceivability" to mean "possibility", then saying that God is so great that it is inconceivable (impossible) that He does not exist is just to say that God's greatness includes impossible non-existence. Impossible non-existence is a convoluted way of saying necessary existence.

So Anselm's second argument is based on the idea that God's greatness includes necessary existence. That is, it is the modal argument.

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Where Anselm fails is that he assumes that the fool's ability to understand what "God" means when he says "There is no God" proves the conceivability of God. Well, if "conceivability" means "possibility", then no, it does not. I understand what is meant by "round square" when I say "There is no round square".

In short, Anselm's argument fails precisely where the video says Modal Ontological arguments can fail...in premise 1.

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Phillip's attack is basically Guanilon's beautiful island attack. Ditto for the attack dealt with in the video with the three dumb atheists (where one of the three concludes that she is green with spots because she can conceive of that).

The three dumb atheists didn't even do the Guanilon attack too well. Since Anselm's claim does not boil down to "If I think it's true, then it is". Phillip did about as well as Guanilon.

The attack focuses on the first, rather than the second of Anselm's arguments. The first argument does turn on the notion of existence being part of the concept of God. Any thing of kind-K exists if it is maximally-K because existence would be part of the concept of maximal-K-ity. Whether it's a maximally beautiful island or a maximally smelly sock. There's certainly never a contradiction in adding existence to those concepts (as there is if you try to add necessity to them).

It's worth noting that really, the attack doesn't get anywhere if you don't finally get around to challenging the notion of existence being part of the concept of a thing. What if one simply said. OK, all those maximal things with maximal K-ity exist. Fine.

What have you done but provide a proof for the existence of Plato's Forms?

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Kant's attack also gets at the first argument of Anselm...at the idea that existence is part of the concept of God.

Unsurprisingly, Kant's attack is much better than Gunilon's (or just about anyone else's).

He notes that existence is part of the concept of not just maximally-K things, but of everything...even things that do not exist. To conceive of a thing is to conceive of it as existing. Because of this, existence is not a real property that can be predicated of things. It's a property things have whenever they have any real property. The first of the three dumb atheists almost got there...no doubt he was trying to reconstruct Kant's celebrated defeat of the Ontological argument util they somehow swerved off into Guanilon's pseudo-reductio.

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Neither Guanilon's nor Kant's attack goes for necessity. Necessity is not part of the concept of everything. There are some things, lots of things, that not only do not, but cannot have necessary existence. To conceive of a unicorn, a rose, or a smelly sock, is to conceive of it as existing. To conceive of those things is not to conceive of them as necessary...indeed, to conceive of them is to conceive of them as contingent. They cannot exist at all unless they exist contingently.

This does not seem to be the case with God. In God's case, He cannot exist at all unless He exists necessarily.

There are other entities like that, e.g. the number 2.

Plantinga, of course, spells all this out in glorious detail in his exposition of Anselm's classic.

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FWIW, I do not think that the fact that the number 2 is necessary implies, as the video asserts, that it is uncreated. All that it implies is that if it is created, it is created in every possible world. And anything created in every possible world has necessary existence.

I think that the number 2, and all those other necessary beings mentioned in the video, have their necessary existence only because they are ideas in the mind of God. Ideas that He, of necessity, thinks.

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What about God Himself? Why should we think He has this strange quality, that if He exists at all, then He exists necessarily.

And if he does have that quality, why think it is even possible for Him to exist?

It comes down to what greatness is.

I take greatness to be independence from contingency. It seems to me clear that there are two qualities which, if possessed, make a being maximally independent from contingency:

1. Omnipotence
   This quality guarantees that no contingency will prevent or undo God's existence, provided God Himself chooses to exist.
   
   
2. Necessary Self-Actualization
   (Sorry, I don't have a better term. Suffice it to say that "Self-actualization" is not used here in the way Maslow used it...which applies to human beings)
   
   God's Omnipotence of necessity is always ensuring God's existence. In short, this quality guarantees that God chooses to exist

I contend that if such a being is possible, it is necessary. Thus, premise 3 from the argument in the video is true.

It also seems to me that the two properties just listed are consistent with each other, provided they are individually coherent.

What is more, the properties seem individually coherent barring the traditional puzzles of omnipotence.

Finally, it seems to me that none of the puzzles of omnipotence actually do work.

The last three paragraphs, taken together, tend to imply that Premise 1 of the argument from the video is true.

[Remington]

Good video. I haven't given much thought to the ontological argument, so this is new to me.

The video states that "God" in this argument can be reduced to "Maximally Great Being" (MGB). As some have pointed out, we might debate whether necessary existence is a great-making property. Maybe we can avoid this by reducing MGB even further to "a necessary being"?

In other words, the argument is:

1. It is possible that a necessary being exists.
2. If it is possible that a necessary being exists, then a necessary being exists in some possible worlds.
3. If a necessary being exists in some possible worlds then a necessary being exists in all possible worlds.
4. If a necessary being exists in all possible worlds then a necessary being exists in the actual world.
5. If a necessary being exists in the actual world then a necessary being exists.

The question would be (1) is such a reduction necessary to the argument and (2) is it specific enough to be a supplement to the other theistic arguments?

The advantage with the reduction might be this: to someone like Phillip A we could just point out that we accept the "maximally smelly sock" argument insofar as it indicates that a necessary being exists. But why should we think the necessary being has smelly sock properties? While we await the atheist's answer we could point out that we do have reasons for thinking the necessary being is a person outside of space-time that is the foundation for morality (cf. the other theistic arguments). The more difficult part might be explaining why we should think the "necessary being" and the "personal outside of space-time being" are the same being. And so maybe it's easier just to stick to the MGB formulation?

[Phillip A]

Remington's reduction actually does quite well in exposing the flaw in this particular argument. The argument plays into ambiguities in the words "possible" and "necessary". With premise 1, It is possible that a necessary being exists, it is tempting to say "Yeah, it's possible, I guess." But you don't realize that "possible" is going to mean, not logical possibility, but probability, which is not the same thing. Of course a "necessary" thing can't have a less than 1, nonzero probability, but it can be "possible" in the colloquial sense without actually existing. You're essentially tricked into admitting the conclusion in the first premise.

Also, the use of the word "being" is as unjustified as if I were to replace "being" with "sock". A "being" has certain characteristics that a generic "thing" does not.

[Remington]

Phillip,

You still haven't understood the argument. Did you watch the video? Possible doesn't mean "probable" in the argument.

And one doesn't need to justify the use of the word "being" unless you think it's impossible that a necessary being exists.

[WisdomLover]

The problem with your reduction Remington, is that there are many necessary beings (as noted in the video). The number 3 is a necessary being...that is, "3 exists" is true in every possible world.

But the number 3 is not God.

The MGB bit was there in order to guarantee that the being that the argument proves the existence of is, in fact, God.

[WisdomLover]

The argument plays into ambiguities in the words "possible" and "necessary". With premise 1, It is possible that a necessary being exists, it is tempting to say "Yeah, it's possible, I guess."

This is not an ambiguity in the argument. It might be an ambiguity in the thinking of the person who says "Yeah, it's possible."

In the argument and in the surrounding discussion the terms "necessary", "possible", "impossible" and "contingent" are used univocally.

For any proposition, P,

1. "P is possible" means "P is true in some possible world"
2. "P is impossible" means "P is true in no possible world"
3. "P is necessary" means "P is true in every possible world.
4. "P is contingent" means "P is true in some, but not all, possible worlds"

The concepts of possibility, impossibility, necessity and contingency are extended to the existence of things univocally. A putative thing, X, is possible, impossible, necessary or contingent precisely when the proposition "X exists" is possible, impossible, necessary or contingent.

And just to complete the picture, a possible world is the condition that would prevail if a maximal consistent set of propositions were true. A set of propositions is maximal if, for any proposition P, P is in the set, or the denial of P (not-P) is in the set. A set of propositions is consistent if no contradiction follows from its members.

So the possibility, impossibility, necessity and contingency being talked about most definitely is logical possibility, logical impossibility, logical necessity and logical contingency...not probability.

[Remington]

WisdomLover,

I think you're right in your assessment of my reformulation of the argument. That's the difficulty I had in mind when talking about trying to plug it into the cumulative case. But it's probably an unnecessary reduction of the argument the more I think about it. I said to Phillip in my last comment that it wasn't necessary to justify "being" unless you thought that was impossible... but I guess that is also true of "maximally great". But maybe my formulation can be helpful in another way.

If we can present this reduced ontological argument (ROA) to the unbeliever and they find it convincing and admit "Okay, so the argument demonstrates that there is something that exists necessarily." then this has helped them see the force of the argument. And then we can present the MGB form of the argument. In the same way that the unbeliever was willing to grant the first premise of the ROA and follow the logic through they should be willing to grant the first premise of the MGB OA.

[Phillip A]

@WisdomLover, now we come to exactly what I was saying in my very first comment. If one of the properties of "maximum greatness" is being necessary, i.e. "true in every possible world", then you have essentially defined God as existing, just like in the more well known version of the ontological argument.* And so, this argument could equally prove the existence of an omnipotent, omniscient God, or it could prove the existence of the All-Sock, by whose smelliness all things are sustained.

*Can someone tell me what, exactly is the function of Premise 1? Even if we deny Premise 1, the rest of the argument just contradicts that denial, since a "maximally great being" is defined as existing "in every possible world". Admitting that such a being is "possible" seems to me to just be icing on the cake.

[WisdomLover]

No, Phillip, your comments remain off the mark.

Socks and smells, by their definitions, depend on the existence of other contingent things (for example, noses and feet). It is logically impossible for their to be a smelly sock with necessary existence.

In contrast, it is logically impossible for there to be a maximally great being with contingent existence.

What that means is not that God exists. What it means is that the second of the following three possibilities (which are exclusive and exhaustive) is ruled out:

1. God is necessary.
2. God is contingent.
3. God is impossible.

We are most decidedly not assuming that God exists, or that He exists necessarily. We are saying His existence is possible ONLY IF His existence is necessary. That there is no middle ground of contingent existence.

Now, Phillip, if you are sure what the purpose of premise 1 is, you might want to consider moderating your certainty that you know what is wrong with the argument.

But to answer your question, the form of the argument is:

1. A
2. If A, then B
3. If B, then C
4. If C, then D
5. If D, then E
6. E

This is a classic argument by chained Modus Ponens inferences. You clearly can't get to the conclusion, E, without premise 1, A.

[Phillip A]

What that means is not that God exists. What it means is that the second of the following three possibilities (which are exclusive and exhaustive) is ruled out:

1. God is necessary.


2. God is contingent.


3. God is impossible.

But why wouldn't No. 3 be ruled out as well? A God whose existence is impossible isn't "maximally great" any more than a God whose existence is contingent is "maximally great". To be "maximally great" in the (rather arbitrary) way that classical apologists defined the term, God must exist, he must exist in every possible world, and his existence must not be contingent on anything else. An argument by assertion any way you slice and/or dice it.

[Remington]

Phillip,

Of course the argument assumes that 3 is not true. That's why the first premise is "It is possible that..." But that doesn't make it an argument by assertion.

An argument by assertion would be to simply say "It is true that a MGB exists."

The OA doesn't start with the assertion that a MGB exists. It starts with a MGB being possible. And it turns out that once you accept that and a few other logical premises you're also committed the the existence of a MGB. That doesn't mean you've been tricked any more than accepting the premises in the argument for Socrates mortality has tricked you. It just means you don't like conclusion.

Notice that when I gave the ROA you didn't object to it on the grounds that was argument by assertion. Instead you just mistakenly thought that we were talking about probability. The form of the argument is clearly not one by assertion.

[WisdomLover]

Phillip, Remington-

Just to make it clear, though, the definition of "God" cannot rule out the impossibility of God. The mere fact of the definition leaves item #3 as a live option. That's why the possibility of God is taken as a premise in the argument. It's that premise, not the definition of "God", that rules out item #3.

The definition of "God" can rule out the contingency of God. No contingent being can be God, because no contingent being can satisfy the definition of "God". That is, item #2 in my 3-item list is ruled out.

The reason that the definition of "God", by itself, cannot rule out the impossibility of God is that the definition might be unsatisfiable. If it is, then, no matter what it says about Maximal Greatness, God is impossible.

That means either that there is some necessary being that satisfies the definition of "God", or the definition of "God" is unsatisfiable.

Premise 1 of the argument, the claim that God is possible, is the denial of the claim that the definition of "God" is unsatisfiable.

[Brad B]

Since this post came up I've been doing some other information gathering and came across this post that I found helpful. It added to this video and discussions following...I've seen this video from Inspiring Philosophy multiple times but didn't really dig in. It helped to get secondary looks.

Also, that linked page includes links to capable others' treatment and discussions [Wartick, Pruss]. Alexander Pruss' work, I suspect will be like candy for WL.[a bit more technical/detailed on fine tuning language to avoid difficulties on some particular points]

[WisdomLover]

D'oh!

Now, Phillip, if you are sure what the purpose of premise 1 is, you might want to consider moderating your certainty that you know what is wrong with the argument.

Proofreading Rule: Make sure you haven't any words out.

Sorry, the section above should have read:

Now, Phillip, if you are not sure what the purpose of premise 1 is, you might want to consider moderating your certainty that you know what is wrong with the argument.

[WisdomLover]

Thanks for the links Brad.

It's always good to remember that Kurt Gödel, the man who proved the incompleteness of arithmetic to every mathematician's satisfaction also thought that the ontological argument was sound, and had his own variation in which he also took aim at proving Premise 1...that a maximally great being is possible.

When you see folks like the three dumb atheists in the video clumsily botching the argument that convinced a towering intellect like Gödel, you can't help but be a little irritated.

I'm not sure Gödel's possibility proof actually works. Some do.

Gödel uses the phrase "positive property" to refer to a great-making-property (GMP). Anselm used the term "perfection" to similar effect. I'll stick with GMP.

I think it's comes down to this proposition taken as axiomatic in the proof: If P is a GMP, then not-P is not an GMP..

But if God is impossible, then it seems that two of His properties, two GMPs, are going to conflict in just the way that Gödel's argument rules out by axiom.

In short, it seems necessary to prove that for any property P, P and not-P cannot both be GMPs. Or, more generally, that no two properties that are in logical conflict may both be GMPs. If that can be proven, then the rest of Gödel's argument will probably sail through.

[Phillip A]

If anyone is interested in a more formal and rigorous presentation of the point that I am trying to make, you could do worse than Richard M. Gale, On The Nature and Existence of God 224-37 (1993). Essentially, you are taking advantage of a layman's understanding of concepts like "necessity" and "possibility", and then slamming them with formal modal logic, in which "possibly necessary" is equivalent to "necessary."

[Phillip A]

So it's an argument by assertion disguised, sure, but an argument by assertion nonetheless.

[Phillip A]

When you see folks like the three dumb atheists in the video clumsily botching the argument that convinced a towering intellect like Gödel, you can't help but be a little irritated.

Yeah, and Sir Isaac Newton, without a doubt one of the greatest intellects in human history, thought that he could discover the keys to the universe in the dimensions of Solomon's temple. Blaise Pascal thought he could blackmail people into believing in God. Henry Ford believed in a global Jewish conspiracy, and don't get me started on Tesla. And so on, and so on.

[Remington]

Phillip A,

So far the only argument by assertion here is your own assertion that this is an argument by assertion.

[Brad B]

Let me know what you think if you go through Pruss' work thoroughly WL, I had a bit of quiet time last night where I was able focus on it and was following along somewhat...got about half way through then scanned to the end. He refers to previous work and I dont have time to chase that down but I can see that the terms in the argument are looked at in every possible way to try to derail it.

Not saying anything is wrong with that, but this again is an example of heightened scrutiny aimed at pro-theism thinking when you get no or minimal scrutiny in all things regarding anti-theism activity.

It takes a certain kind of person[fool] to be satisfied with that kind of blind faith but it takes a self deceiver and an active suppressing of truth to apply one standard on the contrary worldview and a wholly different one on your own worldview.

[Brad B]

Dont know anything about Gale, but I checked quickly with Google and saw that he and Plantiga had a debate so I think I might finish my Sunday night on it...looks to be about 1 1/2 hours.

One thing is for certain, Plantinga, Pruss, etc...and the like are not dealing with this argument on laymans terms...not even close. They are in no way lightwieghts.

[WisdomLover]

Essentially, you are taking advantage of a layman's understanding of concepts like "necessity" and "possibility", and then slamming them with formal modal logic, in which "possibly necessary" is equivalent to "necessary."

No.

The concepts of "necessity", "possibility", etc. are precisely what was given above and do not change. That is, they are the concepts of logical necessity, logical possibility etc. The definitions given are those that would be given in standard S5 modal logic.

As for the principle that "possibly necessary" implies "necessary", I'm not sure that it's at play in the argument given above. But it is a standard principle of S5 modal logic either way.

Here's a way that you can see that the principle is quite true.

The notions of logical necessity and logical possibility are inter-definable. "P is logically necessary" means the same as "not-P is logically impossible".

To put it in terms of possible worlds, "P is true in every logically possible world" means the same as "not-P is true in no logically possible world".

So to say that P is possibly necessary, that it is logically possible that P is logically necessary, is the same as saying that it is logically possible that not-P is logically impossible.

That is, there is some possible world in which not-P is logically impossible.

But logical impossibility does not vary from world to world. Contradictions remain contradictions no matter which possible world they are contradictions in. If a thing is logically impossible in some world, it's logically impossible in every world, including the actual world. As such it is logically impossible.

Now, since it is not-P that we've established to be logically impossible, P itself is logically necessary.

So we started from the assumption that it is logically possible that P is logically necessary, and we got to the conclusion that P is logically necessary. That is, "possibly necessary" implies "necessary".

[Phillip A]

As for the principle that "possibly necessary" implies "necessary", I'm not sure that it's at play in the argument given above.

Well, that theorem and "if a necessary entity possibly exists, then it must actually exist" are pretty easy correlaries of each other.

And that's the ambiguity I keep talking about. If Obama says "In light of the recent mass shootings, new gun control legislation might possibly be necessary", he's obviously not referring to the formal S5 definition of either term. But if someone familiar with S5 modal logic were to look at Plantiga's argument, she would be very hesitant in admitting Premise 1, and would also think twice before admitting logical necessity as a component of "maximum greatness." Certainly no serious philosopher would admit both as self-evident.

But of course, to a layman, you can quote Bible verses about God sustaining all things, and he will call that "necessary", and you can ask an agnostic whether it's "possible" that there is a God, and she will say "yes", and then you can blind them with S5, and it's smooth sailing from there.

[Remington]

Phillip,

Well, that theorem and "if a necessary entity possibly exists, then it must actually exist" are pretty easy correlaries of each other. And that's the ambiguity I keep talking about.

I may not be properly following along at this point. As I said before this argument is relatively new to me, so please clarify if I've misunderstood. But it seems like your complaint is basically that cashing out premise 1 leads to the conclusion you don't want to accept. But can't this sort of complaint be leveled against any logical argument? For instance, take the following argument:

1. Socrates is a man.
2. All men are mortal.
3. Socrates is mortal.

Couldn't we complain that upon examination of premise 1 (what we mean by "man") that being a man and being a mortal are pretty easy corollaries?

If Obama says "In light of the recent mass shootings, new gun control legislation might possibly be necessary", he's obviously not referring to the formal S5 definition of either term.

Are you are trying to find fault in the argument at this point by saying suggesting that the argument hoodwinks people into thinking "possibly necessary" means "probably"? But since the argument doesn't say "probable" or "probably" but instead talks about "possible" what is it *about the argument* that you think is falsely leading people to that understanding? In other words, how is it that the argument promotes a misunderstanding?

But if someone familiar with S5 modal logic were to look at Plantiga's argument, she would be very hesitant in admitting Premise 1, and would also think twice before admitting logical necessity as a component of "maximum greatness."

This is just a self-serving assertion. Why would they be so hesitant about p1 and that a being that exists necessarily is greater than one that exists contingently?

[Phillip A]

This is just a self-serving assertion. Why would they be so hesitant about p1 and that a being that exists necessarily is greater than one that exists contingently?

Because the way these claims will be used in the argument makes them extremely non-trivial, and yet the argument relies on people admitting them as self-evident/common sense.

[WisdomLover]

Phillip-

The argument does not trade on anything but logical possibility, necessity and so on.

What Obama might say or not, how laymen react to Bible verses and so on, are perfectly irrelevant.

Neither Plantinga, nor the video creator, nor Amy, nor me, nor Remington has been trying to trade on a shift in the meaning of "possible", "necessary" and the rest.

No matter how many times you repeat this concern, it has never been part of the argument, nor has it ever been in the interest of the arguers to trade on such a shift in meaning.

The argument is an unquestionably valid Modus Ponens chain only if the meaning of all those terms are treated univocally.

What's more, logical possibility is just about the weakest form of possibility. So Premise 1 is at just about it's most plausible when the possibility involved is logical possibility. Again, it's not in the interest of the arguers for a different notion of possibility to be involved here.

Premise 3, which trades on the notion that contingent existence is ruled out by the definition of God, is also just about the most plausible when the contingency involved is logical contingency.

So all the modal notions involved in the argument are of the logical variety (and as such adhere to S5 modal logic).

There's not even a shadow of a doubt about any of the other premises.

Whether Premises 1 and 3 are self-evident I don't know.

I would settle for them being provably true.

We could also move the entire debate to premise 1 (where the video suggests it already belongs) by saying something like this:

I haven't settled exactly on what "Great" means, but I will only accept a definition of "Great" such that "X is a Maximally Great Being" implies "X is a logically necessary being."

Now the whole question boils down whether "X is a Maximally Great Being" implies a logical impossibility or not.

[WisdomLover]

Sir Isaac Newton, without a doubt one of the greatest intellects in human history, thought that he could discover the keys to the universe in the dimensions of Solomon's temple. Blaise Pascal thought he could blackmail people into believing in God. Henry Ford believed in a global Jewish conspiracy, and don't get me started on Tesla. And so on, and so on.

Great minds make mistakes too. My point about Gödel was not to say that Gödel is smart, so he must be right about the Ontological argument. It was to express irritation at the ignorant smugness of people who, honestly, probably don't have the smarts to show why Newton's thoughts about Solomon's temple are mistaken.

I might also point out that Newton was an expert on physics and mathematics, not archaeology. Ford on manufacturing, not geopolitics. In contrast, Kurt Gödel was an expert on proof.

[CB]

I'm still having trouble with the logical jump from if it is possible God exists then it is nessisary. At the moment it feels like there is a step missing or I need a stronger understanding of modal logic.

[Phillip A]

@CB, in modal logic, "possibly necessary" is a bit of a self-contradiction. A statement being "necessary" means it's either unsatisfiable or true, so a "necessary" thing cannot merely be "possible". Now since we have defined God as a "maximally great being", and defined that as "necessary", then we reach the conclusion that the idea of God is either unsatisfiable or true.

Of course, the problem is that God is defined, not demonstrated, as "necessary", when it's dubious at best that a personal being can be coherently described as necessary in the same way that A=A is.

[Remington]

Phillip

<@CB, in modal logic, "possibly necessary" is a bit of a self-contradiction. A statement being "necessary" means it's either unsatisfiable or true, so a "necessary" thing cannot merely be "possible". - See more at: http://str.typepad.com/weblog/2015/10/an-explanation-of-the-ontological-argument.html#comments>

Earlier you attempted to charge the ontological argument with being deceptive. But now it's your own comment that is deceptive. The fact that it turns out that if a necessary thing is possible then a necessary thing is true (or actual) is in no sense "a bit of a self-contradiction." You're actually the one misleading here. And the ontological argument isn't supposed to be a demonstration that a maximally great being is necessary: it's the demonstration that a maximally great being (which would exist necessarily) if possible is actual.

If you think it's dubious that a being exists necessarily you need to explain *why*.

[Remington]

CB,

The argument in the video is not that "If it's possible God exists then it is necessary." It is that if it is possible that a MGB exists then a MGB exists. Since there were five premises in the argument in the video and you don't say what you think is a "jump" it's hard to know which premise you think needs clarification or more work.

[WisdomLover]

Remington-

I think CB is saying that he's having difficulty with premise 3: "If God (the MGB) exists in some possible worlds, then He exists in all possible worlds."

CB-

I think the best way to look at it is to recognize that these alternatives are exclusive of each other and exhaust all the possibilities:

1. God exists in every possible world (i.e. God is necessary)
2. God exists in no possible world (i.e. God is impossible)
3. God exists in some possible worlds, but not every possible world (i.e. God is contingent)

These three alternatives, by the way, apply equally to anything. WL is either necessary, impossible, or contingent also.

Take a moment to convince yourself that this is true.

Now, the key insight of the modal argument is realizing that the definition of "God" does not permit any contingent being to satisfy the definition. It can't 'turn out' that a contingent being is God.

That rules out alternative 3 and leaves us with these two alternatives:

1. God exists in every possible world (i.e. God is necessary)
2. God exists in no possible world (i.e. God is impossible)

If God exists in any possible world, then option 2 is ruled out, then we are left with option 1. That is to say that if God exists in any possible world then God exists in all possible worlds.

To put it another way, if God is possible, then God is necessary.