The same way we would settle it if I said X was a triangle and you said it was not: we'd open some sources on logic, and we would find that all of them say the same thing- validity is when the conclusion of an argument follows from its premises.
Only "valid" in a different sense of the word "valid".
It isn't a criteria for truth. Validity and truth are related, but not the same. But if you understand this simple point I'm making- about validity being a necessary but not sufficient condition for a sound deductive argument (and a good deductive argument being one that is sound, or at least probably sound) then so much of what you've said is irrelevant. More likely you just want your cake and to eat it too.
Most of this is not relevant- what you think people say or think about the cosmological argument has no bearing on whether it is valid, sound, or compelling. It is none of these, because of the simple fact that its premises could be true, and the conclusion false.
Any in which deductive inference is involved.
This is called "throwing a whole bunch of ***** at the wall and hoping some will stick". Good gravy, what on earth is going on here? Talk about all over the place and confused... Fortunately, none of this is really relevant at all, so we'll just move along.
"Reasonable" is very vague. The cosmological argument is not valid- that is, even if its premises were true, the conclusion would not follow. It's premises are also neither true nor probably true, but appeal to facts not in evidence/are extremely contentious/are extremely speculative. But since it is not valid to begin with, the truth of the premises is sort of a footnote only, since they could be true and the conclusion would nevertheless not follow.
Of a deductive argument? Validity and true premises (i.e. soundness), and pertinence.
Yeah, its not- or if it is, our common standard for what is reasonable has become a total joke, if it lets invalid arguments somehow count as "reasonable".
Well no, not really- or at least is only "acknowledged as such" by a handful of apologists and theologians. But what people have acknowledged for thousands of years is not relevant to what is the case- that would be an argumentum ad popularum, and we both know you don't give fallacious arguments, so that can't be what you're trying to say, right?
An invalid deductive argument cannot be reasonable, so this objection has no teeth, as we've pointed out several times now.
Actually, not that its relevant, but I seem to recall Plantinga saying that he doesn't think the cosmological argument is sound, which is why he endorses a modal ontological argument for the existence of God and his foundationalist epistemology. Given the latter, Plantinga has no use or need for arguments for the existence of God since for him, belief in God constitutes epistemic bedrock. But this is merely a footnote, and I could be remembering incorrectly.
Yeah, try as you might, validity is a crucial property of ANY good/compelling/reasonable deductive argument. And the cosmological argument is not valid. We could grant the premises, and it would still not follow that God exists/created the universe/was the first cause/etc. This makes it a garbage argument, which is one reason why it is only of scholarly interest in the philosophy of religion- it is a relic of a bygone age, an example of reasoning gone amok that we can learn from. Again, this isn't especially relevant to the question at hand, but it seems to me that Craig is the only contemporary thinker of ANY distinction whatsoever who endorses the cosmological argument, and that's not a good sign since Craig is considered a pariah, in part for that very reason, in most academic circles.
