What do you think of this argument for God?

[SuperSentient]

True, God is the postulated to be the greatest possible being in theistic thinking, but this argument fails to demonstrate neccessity and what this being is. {A}

As for the ontological argument you mentioned, the greatest conceivable being is no better since that relies on epistemic possibility rather than metaphysical possibility. {B}  Also, how do you define 'greater'? It suffers from the same problem as the "possibility" argument, that would be, How do you define what is 'conceivable'? I cannot conceive a being that is outside space-time, immaterial, and omnipresent at the same time, therefore the monotheist concept of God doesn't count in this argument, since it is inconceivable. Being conceivable is dependent upon experience and knowledge. {C}

I fail to see any more success in that argument.

The real argument can be formulated as follows:

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.

A. The argument hangs on the concept of necessary (within premise 3) and as such, you need to clearly understand how the word is used. The opposite of necessary is contingent. Since being contingent on something is a defect it would not be considered maximally great to be contingent. A maximally great being would be a necessary being because it could not be contingent on another (then that would be a greater being).  It is important to understand the S5 modal logic that if something is even possibly necessary, it is actually necessary. If God necessarily exists in one possible work, then he exists necessarily in all possible worlds.

B. The key is understanding the difference 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.

C. When Anselm first wrote this argument, he was careful to distinguish between what we could think of as the greatest possible being and God is the greatest being possible, that is to say, it is impossible for there to be any being greater than God. While greatness might be subjective, maximal greatness is not. If a description of God allowed for a greater being, then God would not be God because that being would be God and the definition becomes a logical impossibility. Even a limited grasp of God's properties does not entail that our conception of God is false because it would be impossible to have full knowledge of God.

The main problems with this argument is with 1 and 3. First, "great" is a value statement which is contingent upon the subjective viewer. The question is, what constitutes objective greatness? 1 is simply an assertion with no basis in reality than what anyone would personally think to be true.

3 is false since greatness is logically separable from logical necessity. Value statements have no basis in possibility. Just as you can't derive an ought from an is, you can't derive an is from an ought. 

Elvis Presley is a great being to many people, I can say that he is a necessary being. It would be no less accurate to say that than to say God is a necessary being. The assertion that God is necessary has no justification. Maximal greatness is subjective if you accept that greatness is subjective, since the measurement of greatness would be subjective, it would apply to whatever you would measure to be the "greatest".

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I heard an argument like this:

1. God is the greatest possible being.

True

2. God is a necessary being, which means that God exists in every possible world (If God exists). 

Define all the possible worlds. Why would God have to exist in all of them?

3. If God exists in one possible world, God must logically exist in every possible world. 

Why, this is stating something an omnipotent being must do in reference to the physical?

4. Since God is the greatest possible being, it follows that every aspect of God (being possible) exists in some possible world.

In #3 you said every possible world, now your down to some possible world, why?

5. Therefore, God exists (in all possible worlds, including ours).

You have once again switched from some to all, why? Why is it necessary for God an omnipotent being to exist in any world but this one, why are any other worlds even necessary?

I actually just structured the premises this way myself but is the same idea as an argument I heard before. 

What do you think of it?

As you can see by my questions I have serious doubt.

GC

2- Basically, every possible event, scenario, and existing thing. 
3- If God is necessary, then God exists in all possible worlds.
4- Every possible world includes every one individual possible world.
5- No other worlds are necessary, this argument claims that this being exists in all possible worlds.

This argument is a failure, but you don't seem to quite understand it.