Depending on which version of the ontological argument you're endorsing, no, it is not necessarily valid.
I wasn't using any ontological argument. I was using classical logic. The argument I made was absolutely valid. And as long as the premise is accepted, it's sound too. Of course, it would be ridiculous to accept the premise, but that was my point. If your argument is valid, all that means (in logic) is that the conclusion follows from the premise(s). That's why the following is yet
another valid argument:
1) Computers run on gasoline | P
2) If computers run on gasoline, then there is no god |A
Conclusion: there is no god | MP by 1 & 2
That is absolutely valid. It is not
sound, because computers don't run on gasoline. However, my point was (again) to illustrate one of the many problems with the proof given.
In any case, it is either invalid or it is question-begging, regardless of whatever version you use- and none of them are sound.
There are absolutely arguments for god that are sound. However, they always (IMO) require one to accept at least one premise that need not be accepted.
This is all moot. It looks like you're trying to endorse some version of the Modal Ontological argument
Then you should look more carefully. First, I'm agnostic. Second, I have not here or anywhere endorsed any proof of god. Third, I've been actively arguing against a particularly poorly constructed attempt at the ontological argument.
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which has several highly questionable premises, as well as requiring a dubious modal principle for the crucial inference; without this "B-principle" the Modal Ontological Argument is invalid, but if it is granted, it leads to an arbitrary proliferation of entities and ultimately, an apparent contradiction.
You refer to "the" modal ontological argument. Which one? Even when dealing with the same logician, we aren't necessarily dealing with the same argument. Also, I just realized something else. You mention "B-principle". Brouwer's system was at best as "powerful" as S5, but you include only one principle, and I'm assuming it's the so-called "Brouwerian axiom", it's weaker than S5 and different enough from S4 (not just because neither one contains the other) that it is akin to both M and T (and in fact is just the axiom added to T). The only problem I have with it is how it is incorporated into a possible worlds logic.