Modal ontological argument

[Fake Messiah]

I recently came upon William Lane Craig's addition to the ontological argument which is called "Modal ontological argument" that "proves" God's existence.

According to Wikipedia, it goes:

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.

Umm, hello. Notice the claim in 3 & 4 "in some possible world", I mean WTF are these "other worlds" he is talking about?

Is it like a multiverse? Because Craig usually mocks the idea of a multiverse.
Like in the video below (after 2 minutes mark), he says he is highly skeptical we are living in a multiverse, that if we were living in a multiverse everything should look different (like rabbits would be wearing pink hats and perpetual motion machines would work), but the real reason he hates multiverse is because he feels it robs him of a "prime mover" and therefore his profession as a theologian is redundant.

https://youtu.be/bkpEzOM2gIc

So could it be that WLC is just another dishonest theist who changes his worldviews according to the argument he is trying to push, or is he just high on bullshit and spewing phrases like "other worlds" because his followers don't really listen to what he says but just nod their heads?

[HappySkeptic]

Statement 2 is multiplying an infinitesimal times infinity and getting a non-zero. Well, duh.
Statement 5 is a tautology.

The rest are bullshit. Statement 1 is a premise, and I would argue that it is false. A maximal being has zero possibility of existing, because it is self-contradictory.

[Mister Agenda]

What is 'maximally great'? Does a sufficently advanced alien count? It's entirely possible that 'maximally great' falls far short of omnipotent, and it says nothing about this maximally great being creating any universe...and I thought God was supposed to transcend the universe anyway, you're not going to find that God based on what's possible in a universe.

[Deesse23]

He has to prove that there is an actual "possibility" of some world to exist. The claim alone is meaningless. Otherwise everyone could go and claim  4: "if some BS-i-just-made-up is true for every world i just made up then its true for the actual world."

[brewer]

My god, if only he were talking about porno.

[Nay_Sayer]

1
It is possible that FSM exists.

2
If it is possible that FSM exists, then FSM exists in some possible world.

3
If FSM in some possible world, then it exists in every possible world.

4
If FSM exists in every possible world, then it exists in the actual world.

5
If FSM exists in the actual world, then FSM exists.

6
Therefore, FSM exists.

[The Grand Nudger]

That argument that william lane craig uses/butchers is platingas modal ontological argument. Possible worlds analysis is a type of semantics used to explore propositional and first order modal logic. The quantifiers all, some, necessarily, and possibly are added to the usual and, or, not...and if-then.

Nothing to do with a multiverse.

@Mister Agenda

Platingas formulation makes it explicit.

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.

[polymath257]

That argument that william lane craig uses/butchers is platingas modal ontological argument.  Possible worlds analysis is a type of semantics used to explore propositional and first order modal logic.  The quantifiers all, some, necessarily, and possibly are added to the usual and, or, not...and if-then.  

Nothing to do with a multiverse.

@Mister Agenda

Platingas formulation makes it explicit.

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.

Platinga makes a basic mistake in modal logic when he assumes it is possible for a being with maximal greatness to exist. That is an assumption, not in a single world, but in ALL worlds.

What he *should* have assumed is that it is possible that a being of maximal excellence exists (which means it exists in at least one possible world). But that does not lead to a valid argument for the rest of his steps.

The trick is saying it is possible that a necessary being exists. That is a double quantification over possible worlds in a way that is invalid.

[HappySkeptic]

From Quora:

De Dicto (of the proposition): The scope of the modal operator ranges over the entire statement, [Necessarily, there is some X such that it is A].

De Re (of the thing): The scope of the modal operator ranges over a particular element/variable, [There is some X such that it is necessarily A].

Thus, De Dicto statements have an existential quantifier within the scope of a modal operator, while De Re statements have a modal operator within the scope of an existential quantifier.

Existential fallacy: a formal fallacy where a class is presupposed to have members, but the argument did not state or assume that it does in fact have members.

When either are using the word "possibly", they are trying to make either a De Dicto or De Re statement.  The word "possibly" in modal logic does not mean "hypothetically", it is a statement of actual necessity.

Therefore, these arguments contain the conclusion in the premise, but the premise is completely false.  The English language is what lets us down.  The same arguments can be used to "prove" that a God does not exist, or that Santa Claus exists or does not exist.

[The Grand Nudger]

Platinga doesn't make any basic mistakes in his argument. The form is valid. Hence it's somewhat misleading designation as a successful argument. From it being possible that it's necessary that p, a person can infer that it's necessary that p.