The Ontological Argument - valid or debunked?

[Angrboda]

I think it's a form of begging the question.  Once you define something, anything, as necessarily existing, then unless it is logically contradictory, you are declaring that it exists.  Modal logic here is simply dressing up the assertion that an MGB would by definition be necessary.  As noted, because of the problem that great making properties don't exist as such, one cannot assert that a great being would have this or that great making property.  The assignation of properties then becomes merely arbitrary assertion.  As stated, making that particular arbitrary assertion is tantamount to claiming the entity exists and thus begs the question.

I don't think it is question begging. Through inductive reasoning you conclude that a MGB would be necessary. It is not an arbitrary property assigned to trigger the modal logic. 

I don't see how induction would help you there. Can you explain?

I understand if you grow tired of this. No hard feelings if you don't want to continue.

I'm not so much tired of it as I feel it has run its course and I don't know where we would go from here. You feel that greatness could be in principle defined, if not by this then by other arguments, whereas I find the notion incoherent. It seems we are at an impasse. I keep coming back to the same question: what makes necessarily existing a good thing or great thing, "independent of the attitudes and opinions of individual minds?" So far you've demurred from giving an answer.