The Ontological Argument - valid or debunked?

[Edwardo Piet]

And here's the thing, when speaking of "existence in a possible world" that notion is ambiguous. It can refer to both actual existence in a possible world and possible existence in a possible world. Our world is an example of a world with both possible and actual existence.

When speaking of "existence in possible world" it's important to not use the ambiguity of that notion to equivocate possible existence in a possible world with actual existence in a possible world. If that equivocation is made then it can be fallaciously concluded that other existences in possible worlds are just as actual as our world.

[SteveII]

This is the syllogism in Craig's words verbatim from this video:

Premise 1: It's possible that a 'maximally great being' exists. 
Premise 2: If it's possible that a maximally great being exists, then a maximally great being exists in some possible world.
Premise 3: If a maximally great being exists in some possible world, then it exists in every possible world. 
Premise 4: If a maximally great being exists in every possible world, then it exists in the actual world. 
Premise 5: Therefore a maximally great being exists in the actual world.
Premise 6: Therefore a maximally great being exists
Conclusion: Therefore God exists. 

@SteveII:
The argument assumes that a maximally great being would possess the property of necessarily existing.  If the greatness of a property is subjective, then it's not objectively true that a maximally great being would have the property of existing necessarily.  Premise 3 actually states that a maximally great being would exist necessarily.  Since it's not objectively true that maximal greatness includes necessarily existing, this premise is false, and the proof is unsound.  The only way around this objection is to show that necessarily existing is objectively great, and this you cannot do, for as explained the notion of objective greatness is incoherent.

I still have a problem with the claim that maximal greatness is subjective. We are not talking about the greatest being we can imagine. We are talking about the greatest being possible. Even if a complete picture of what that might mean is unclear, it does not matter.

I mentioned this back a few pages: The difference is between epistemic possibility and metaphysical possibility. Epistemic possibility is simply "for all we know something is possible". On the other hand, to illustrate metaphysical possibility take a math equation 24673244/8=3005567. While we might say "for all we know" this might be true, but if it is true, than it is necessarily true if it is false than it is necessarily false. If a maximally great being exists, it exists necessarily in a metaphysical sense. Therefore, God’s existence is either possible or impossible.

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One can show the absurdity of the argument by proposing an equally valid reductio in which one postulates a maximally evil being who is omnipotent, omniscient, and wholly evil as done in the following video.

Premise 1: It's possible that a 'maximally evil being' exists.
Premise 2: If it's possible that a maximally evil being exists, then a maximally evil being exists in some possible world.
Premise 3: If a maximally evil being exists in some possible world, then it exists in every possible world.
Premise 4: If a maximally evil being exists in every possible world, then it exists in the actual world.
Premise 5: Therefore a maximally evil being exists in the actual world.
Premise 6: Therefore a maximally evil being exists.
Conclusion: Therefore a maximally evil being exists.

https://www.youtube.com/watch?v=YbRSGYRQqic

All that we are doing is arbitrarily picking a set of attributes and attaching the necessarily existing tag to them.  This is no proof that a necessary being exists, whether possibly or actually.

I don't think it is even broadly logical possible that a maximal evil being exists. With omnipotence alone, that being would be required to prevent all good in all possible worlds. Since that is not the case in this possible world, I think the parody fails.

[Alex K]

Speaking as a mathematician, if greatness is not defined on a compact space, there may not be a greatest even in principle.

Also speaking as a mathematician, Craig is an ignorant bullshitting cretin swapping in bogus sophistry for substance.

Also that.

[chimp3]

Premise 1 : It is possible that a maximally great Cheshire Cat exists.
Premise 2 : If it is possible that a maximally great Cheshire Cat exists, then it exists in some possible world.
Premise 3 : If a maximally great Cheshire Cat exists in some possible world then it exists in every possible world.
Premise 4 : If a maximally great Cheshire Cat exists in every possible world then it exists in the actual world.
Premise 5 : Therefore a maximally great Cheshire Cat exists in the actual world.
Premise 6 : Therefore a maximally great Cheshire Cat exists.
Conclusion : Therefore .... : )

[Veritas_Vincit]

'Maximal greatness' is subjective because 'greatness' is subjective. What do you mean by greatness? Size, shape, everything? How do you measure greatness? How could you know if it exists? How could you confirm it? What evidence is there? What if your definition of greatness differs from other people? This is just a total non-starter.

[SteveII]

'Maximal greatness' is subjective because 'greatness' is subjective. What do you mean by greatness? Size, shape, everything? How do you measure greatness? How could you know if it exists? How could you confirm it? What evidence is there? What if your definition of greatness differs from other people? This is just a total non-starter.

Omnipotence, omniscience, morally perfect for starters. Opinions about greatness are beliefs. We are not talking about beliefs. You miss the point that even if we do no know every detail, that does not mean that maximal greatness does not exist.

[madog]

'Maximal greatness' is subjective because 'greatness' is subjective. What do you mean by greatness? Size, shape, everything? How do you measure greatness? How could you know if it exists? How could you confirm it? What evidence is there? What if your definition of greatness differs from other people? This is just a total non-starter.

Omnipotence, omniscience, morally perfect for starters. Opinions about greatness are beliefs. We are not talking about beliefs. You miss the point that even if we do no know every detail, that does not mean that maximal greatness does not exist.

No you miss the point ... even if we know every detail does not mean it does not exist 

[LostLocke]

I don't think it is even broadly logical possible that a maximal evil being exists. With omnipotence alone, that being would be required to prevent all good in all possible worlds. Since that is not the case in this possible world, I think the parody fails.

By that token.... with omnipotence alone, a maximally good being would be required to prevent all evil in all possible worlds. Since that is not the case in this possible world, that would mean a maximally good being does not exist.

[Edwardo Piet]

Our world is obviously a possible world.

Craig doesn't make it clear whether he is talking about actual possible worlds or merely logically possible worlds.

Technically any world that isn't self contradictory is a logically possible world.

And he jumps from that to talking about possible worlds like they're actual alternative worlds.

A maximally great being is logically possible in all worlds but there is no reason to believe it is actual in any possible world.

He goes from "Possibly exists in all worlds therefore actually exists in all possible worlds."

He acts as if those are interchangeable statements when they are two very different things.

If something possibly exists it doesn't mean it necessarily exists at all, not even in a possible on. After all our world is a possible world so if something "exists in all possible worlds" that would mean it exists in ours. But that something possibly exists in a world just means "it might exist, it might not exist."

Logically possible doesn't even mean actually possible it just means not proven to be logically impossible. It just means possibly possible.

Logical possibility is the only demonstrably coherent kind of possibility though. So to jump from that grounding of pretty much fucking anything including the FSM and a maximally great being being logically possible in all worlds to equivocating that with the notion of it being actual in all possible worlds and our world is clearly a possible world therefore it exists in our world is to commit the equivocation fallacy because "logically possible in all worlds" is being incorrectly taken to mean "actually residing in all possible worlds."

It's not made clear whether "possible worlds" is referring to merely possible worlds or all possible worlds including both possible worlds that may or may not be actual and worlds like ours which is both possible and actual.

What happens when something is ambiguous and not made clear and defined properly? It's easy to switch or equivocate between the two to suit one's fallacious argument.

[Veritas_Vincit]

God isn't morally perfect, he is morally evil - he instructed people to enslave each other, to commit genocide (the Amalicites etc) to sacrifice their children (Abraham and Isaac, Jeptha and his daughter) and he himself wiped out most of the world's population. Not only that, he administers infinite punishment for finite crime which is by definition infinitely immoral. He is a monster!

The God of the Bible puts the Nazi party to shame, and the only reason most religious people don't see this is because it's a global paradigm that everyone believes, like when everyone believed the world was flat, when people thought the sun went round the earth, everyone believed it and it was considered heretical for people to break from the conventional viewpoint because it would mean standing up and saying that everyone else is wrong about what they think, and people don't like that. But there is a global awakening taking place because now we are at a stage in the development of our society and culture when people are far more able to think for themselves and break free from what the party line they've been inculcated with and indoctrinated with by their parents and their communities who themselves were wrong in what they believed to be true. Now we are at a point where religious oppression has been driven back in the western world we can step back and say "Hang on, I've been told that this God is true but how do I know?" without being burned at the stake. We can ask "How do the people who told me know? Is it true? Is there actually any good reason and evidence to believe it? What if it doesn't actually add up? What if the world is round, what if the Earth goes round the sun? And we can think for ourselves and discover the truth for ourselves by thinking for ourselves rather than just believing the lies that society has told us to keep us in line.