Modal ontological argument

[Jehanne]

So the upshot is that if the maximal being exists in any possible world, it exists in all of them, and if it doesn't exist on one of them, it doesn't exist in any of them. So it's finally been proven: God is either real or not real.

News flash!

[GrandizerII]

On the question of whether the possibility of the existence of a maximally great being (as per P1 of the MOA) is meant to be understood as logical possibility vs. metaphysical possibility, theists like WLC seem to be suggesting they're referring to metaphysical possibility as opposed to logical.

See this quote for example:

As for the atheist’s retort that it’s not self-contradictory to say, “God does not exist,” this is irrelevant because the argument is framed in terms of broadly logical possibility/necessity, not narrowly or strictly logical possibility/necessity. There’s no contradiction in asserting “The Prime Minister is a prime number,” but that hardly shows that such a statement is possibly true in the relevant sense (that there is a possible world in which that statement is true). The atheist has to maintain that the idea of maximal greatness is broadly logically incoherent, like the idea of a married bachelor. But the idea of maximal greatness seems perfectly coherent and therefore possible—which entails that maximal greatness is exemplified!

Here, broadly logical possibility seems to mean the same as metaphysical possibility.

[emjay]

How is one to even get started learning about modal logic when according to the wiki, it seems a veritable pick 'n' mix of different types/uses? And what practical use does it have beyond these sorts of questions, or was it developed strictly for these types of questions? This goes out to anyone.

Yeah, modal logic can be a mess.

The basic problem is how to deal with counter-factual claims. So, for example, "If Caesar did not cross the Rubicon, the Roman Republic would have lasted for another century".

In classical logic, this statement is *true* since Caesar *did* cross the Rubicon and a false implies anything.

But the statement "If Caesar did not cross the Rubicon, then the Roman Republic would have still fallen within the year" would *also* be true for the same reason.

The upshot is that any counterfactual implication is always true.

So the idea is that there are 'possible worlds' that are close to ours, but different. We can then ask in which of those possible worlds Caesar did not cross the Rubicon and ask what then happened.

Now, a bit more formal treatment defines a possible world as a 'maximal logically consistent system'. So, it is *logically* consistent to have a world in which Caesar did not cross the Rubicon, even though in the 'real world' he did. Notice that this is very different than the notion of a multiverse, for example. it is logically possible to have worlds where the laws of physics are very different.

This also then can deal with the notions of 'necessity' and 'possibility'. The definition of 'necessity' in this framework is 'happens in all possible worlds' and 'possibility' means 'happens in some possible world'.

The difficulties happen when you want to say things like 'it is possible that it is necessary that...' or some other situation where there is more than one use of 'possible' or 'necessary'. This inevitably leads to questions about relations between possible worlds. But different possible worlds are mutually contradictory (since they are maximal consistent systems).

Thanks for the run down... I'll definitely give it some thought. The ever-amusing 'British States of America' from the TV series Sliders springs immediately to mind here... ie what would/could have happened in a parallel world if we the British had won the American War of Independence

[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.

The problem is in the assumption that it is possible that there is a necessary being. THAT is problematic. To be 'necessary' means it happens in all possible worlds and to be 'possible' means it happens in *some* possible world.

So what does it even mean to be possible to be necessary?

There's no logical problem whatsoever.  The assertions may be unsound, but that's an evidentiary problem. As Angr pointed out, if a necessary being exists in one possible world it exists.. necessarily, in the set of all worlds. The statement "This being exists" is true of the warehouse if it's true of just one box in the warehouse.

That's possible worlds semantics - take it or leave it.

There is no logical rejection of this argument (though there is evidentiary rejection) outside of rejecting any other thing that possible worlds and modal logic suggests - the vast majority of which you probably wouldn't think was an issue.

[BrianSoddingBoru4]

The problem is in the assumption that it is possible that there is a necessary being. THAT is problematic. To be 'necessary' means it happens in all possible worlds and to be 'possible' means it happens in *some* possible world.

So what does it even mean to be possible to be necessary?

There's no logical problem whatsoever.  The assertions may be unsound, but that's an evidentiary problem.  As Angr pointed out, if a necessary being exists in one possible world it exists.. necessarily, in the set of all worlds.  The statement "This being exists" is true of the warehouse if it's true of just one box in the warehouse.

That's possible worlds semantics - take it or leave it.

There is no logical rejection of this argument (though there is evidentiary rejection) outside of rejecting any other thing that possible worlds and modal logic suggests - the vast majority of which you probably wouldn;t think was an issue.

I’m happy to allow that necessary beings exist.

Boru

[The Grand Nudger]

Then the statement " A Necessary Being Exists" is (possibly) true in this world. That's the long and short of it. Does it help god botherers? Not really - but if they can leave it at that and get a few more people dumping bills on the plate, more power to them.

[R00tKiT]

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

Ontological arguments are too suspicious to be regarded as correct, even if few people really understand why they fail. How can one possibly prove the existence of anything by wordplay without appeal to any premises or fact about reality? 

One is faced with what is called Hume's fork, there is a thick layer between "relations of ideas" (analytic propositions) and matters of fact. Although there is no total refutation of ontological arguments, they are unfortunately vulnerable to all kinds of fallacies and parody arguments.

I think the teleological argument is far better to argue for God's existence (indeed, it was universally regarded as convincing until some people started babbling about Darwin's theory being a "fatal blow")

Suppose that it is possible that there never was anything, that nothing ever existed.  Is this possible?  Of course.  If that's the case then it's trivial to produce a modal ontological disproof of God.

1. There exists a possible world in which nothing exists;
2. If nothing exists in some possible world then a maximally excellent being does not exist in that world;
3. If a maximally excellent being does not exist in some possible world, then it does not exist in all possible worlds;
4. Therefore, a maximally excellent being does not exist in this world.

Your argument is invalid because premise 1 is false. A world that simultaneously exists and doesn't exist is an impossible world. (P and non-P) is never true, 

It's invalid when he's using the same term in more than one way. This would change his X or Y, for example to an X* or Y* on some occasions but not others. So the inferencing would fail. When his terms are being used equivocally then his form is invalid.

But yes, the premises are also unsound the begin with.

So, basically, there isn't really anything charitable to say here besides the fact that he can at least spell words or something (I mean—there are plenty of times when theists can't even do that, even when English is their first language and they're neither dyslexic nor disabled—theists are just, generally, that thick. Sure, so are most atheists and agnostics. But, in general, theists are even dumber. But I digress. Plus, it's perhaps fairer to just say that they're more irrational and emotional. It's one thing to have an intellect and quite another thing to know how to use it and to not let your emotions corrupt it).

It's really not trivial to disprove the ontological arguments, especially given how many variants there are. I don't think you can hand-wave them away with a few accusations of equivocation.

[The Grand Nudger]

Of course we can, because each argument just as readily "proves" there is no god..and can be no gods..if we believe they prove anything at all.

Logic is a double edged sword. A fact that the religious have not yet come to terms with. If you tell me how you can prove your stupid god..you've also given me every tool required to disprove it, by your own self supplied metrics. Go ahead, give it a try. Tell me how you think you've proved your child fucking warlord god?

[R00tKiT]

The gratuitous slur directed to my beliefs proves you have no idea what you're talking about. Feel free to dismiss arguments without understanding them, I know for a fact that philosophers devote entire books to arguments like the ontological to explain why each variant doesn't work and where it fails exactly, meanwhile you're just insulting arguments and people left and right. There are many other variants of the ontological not covered in the thread like Descartes's, Leibniz's, Hegel's, etc, do you have some total refutation of these variants (and any other possible variant) that you care to share with us? Additionally, I doubt many people here seriously studied modal logic to even understand the words used in the arguments.

[Fake Messiah]

There are many other variants of the ontological not covered in the thread like Descartes's, Leibniz's, Hegel's, etc, do you have some total refutation of these variants (and any other possible variant) that you care to share with us? Additionally, I doubt many people here seriously studied modal logic to even understand the words used in the arguments.

I have studied logic more seriously than you who is still using logical fallacies.

The bullshit premise is bullshit no matter who studied it. The logical fallacy that I should read all possible books about it, especially from sound names, is like saying that you should read books on alchemy by Newton, Paracelsius, Jean Baptista Van Helmont, etc.