Then aren't all metaphysical arguments for God's existence pointless, since there is ultimately nothing that can rigorously support them? I mean you can't even get a good probabilistic estimate out of it. Since almost all of Dr. Craig's proofs (except maybe the historicity of Jesus, and the argument for morality...though the latter has many very serious logical errors in my opinion) centrally rely on some "fact" about the this realm outside of our universe, shouldn't they all be discarded?
To explain the simplest case, couldn't it be that an omnipotent God is metaphysically impossible? How do you even begin to discuss (probabilistically, at the very least) whether an omnipotent being can exist? If "intuitive grounds" is the best we have, then it seems like you don't really have anything at all as we have no way to judge whether our intuitive understandings extend reliably (or at all) to the realm outside of our universe.
Hello and welcome to the forum!(a) It's possible to tell that something exist by observing its effects without observing the thing itself. Also, a logical argument that has a valid form and true premises guarantees the truth of the conclusion even if the conclusion has not been empirically verified.(b)You can't use thought to undermine the rules of thought, such as the law of identity and the law of noncontradiction, without cutting off the branch you're sitting on. We can allow for the possibility that we are mistaken about whether something is contradictory, but we can't allow for the possibility that reality doesn't behave logically.(c) Something can't cause itself to exist, but rather it must be caused exist by something outside of itself. In other words, the cause of physical laws can't be physical laws, but must be something that is outside of them and not subject to following them. So if the natural world has a cause, whatever the cause is, it must be supernatural.
With respect to why metaphysics is not sufficient on its own, you refer to a statement "out of nothing, nothing comes" as an example. But this is not really an absolute statement of reality but a limited, logical understanding based on your experiences in one universe. I don't think you should confuse that with the entire range of realities that could ever exist outside of our universe, which is precisely what metaphysical arguments attempt to address.
The simplest argument I can make is that such a larger reality (beyond our universe) may be incomprehensible to you, and that perhaps what you believe to be impossible is not in fact impossible when considered from this wider perspective. As to why random objects don't just pop into existence, I would say again it may simply be incomprehensible to us.
Lastly I am not trying to argue that God is metaphysically impossible. But I do feel that for those who do argue for God's existence, they have to first demonstrate that God is logically possible outside of our universe. But in this respect it is impossible for them to make that argument for reasons (I) and (II) that I outlined above.
I agree with your definition of observational knowledge, and generally speaking it makes sense not to be concerned with the possibility that the ball may not drop to the ground after a thousand tries. But the main difference between the ball and the metaphysics I am discussing is that the ball is well-known to us both in terms of empirical support and the fact that it inhabits the same universe as we do, and to whatever extent we can take our sense of logic (in this universe) and probably centuries of empirical support seriously, we can safely say that Newton's laws will accurately describe the trajectory of the ball. You're right that in theory there could be some higher dimensional thing that comes in and messes with our fundamental sense of logic, but we at least have some empirical support that this doesn't seem to happen, and our sense of logic is indeed stable.
But I think the general point of (a), (b) and (c) was to show that the theories we might propose to explain how the realm beyond our universe behaves have such little backing in terms of empirical or even logical support that whatever theory you come up with is going to be at best speculative, and that it is generally incorrect to ever claim that some aspect of meta-reality is definitively true or even that it is probably true.
Because there are simply too many unknowns. To have a reliable theory you have to have some reason to believe that your basic sense of logic isn't trumped by a massively superior form of metaphysical law which renders practically all of its conclusions to be wrong or so incomplete that they don't qualify as a meaningful description of anything.
So in general I would say we can't make any metaphysical claims with any real degree of certainty, and this would extend both to claims of God's existence, to how causality operates outside of our universe, to String theory. But the difference between how scientists treat string theory and how Dr. Craig treats God is that in the latter case Dr. Craig wants to claim that his arguments are "probably" true or even that they simply *are* true (i.e. with respect to what exists outside of our universe, Dr. Craig seems to believe that it is definitively true that only abstract numbers or God could exist there). Meanwhile scientists would at most say that string theory is one possible theory, and that whatever evidence we collect in CERN might be able to validate it a little more than it is, but certainly not to any level of certainty compared to the laws in our universe. In fact there are quite a lot of scientists who would say that string theory isn't real science because there's no real way to prove it, like what I am discussing here.
Finally you mentioned something about why there is something rather than nothing. I guess my answer is that that is a mystery. Whatever argument Dr. Craig has come up with is going to be speculative and I have no reason to take it seriously because of the aforementioned comments on the application of (a), (b), and (c) to the realm outside of our universe. In general though, I see no reason to believe that the cause has to be conscious rather than non-conscious. One would need a proof to demonstrate that one or the other are impossible, or more likely than the other, but the whole trouble with metaphysics is that I don't think such a claim (either way) can ever be made.
I really believe that at some point we have to accept that we simply don't know the answer, and that while you can hypothesize ideas, they are going to be so far removed from any evidence, or certainty about their logical support, that it is mostly meaningless to discuss such ideas.