Isn't the fine tuning argument ad hoc?

[Mister Agenda]

I didn't say that the multiverse hypothesis was originally proposed to explain fine-tuning, but that users here (and elsewhere) do so for that reason.

In other words, people who are aware that multiple universes are a possibility suggested by physics note that if that is the case, even if the speculation that the universal constants could have been almost anything is true, our universe is still not remarkable by virtue of the many opportunities for our universe to occur. It would be unparsimonious to make up the multiple universe hypothesis to explain the fine tuning conjecture, but it is not unparsimonious to co-opt an existing hypothesis derived from multiple cosmological models (infinite space/time, bubble universes, daughter universes, and parallel universes, off the top of my head). The reason the multiverse hypothesis exists does make a difference in whether it's a parsimonious explanation or not.

The actual option here is between an entity that we have some slight scientific evidence for (multiverse) and one we have no scientific evidence for (a creator). I agree the multiverse is weak, but throwing in a creator is weaker...and fine-tuning actually being the case is least-supported part of this equation.

I didn't say that Occam's Razor isn't applicable to God, just that the multiverse hypothesis being proposed for the explicit reason of voiding fine-tuning does so much more.

The multiverse is a far more respectable hypothesis in cosmology than fine-tuning itself is. It makes no more sense to complain about the multiverse being proposed for the explicit reason of voiding fine-tuning than it does to complain about God being proposed for the explicit reason of explaining fine-tuning.

I'd agree, but then it could still be levelled by theists (correctly, I think) that that solution is still susceptible to the razor.

It would be levelled correctly if they could provide a good reason why we should assume there's only one universe.

You lost me here. We don't assume more universes until we've solid evidence for them, we don't assume there are more because we don't have contrary evidence there aren't more.

You're half right. We also don't assume there is only a single universe until we have evidence of that as well. Unless you can explain a scientific or logical principle that requires us to hold that if we find one of something, we must assume it's the only example of its type of thing in existence. With a sample size of one, it's improper to assume it's multiple or singular. It's not improper to point out that it could be multiple or singular. And the odds (given present knowledge) that the universe is multiple are greater than the odds that all the assumptions behind the fine-tuning conjecture are true.

The problem here is that you're invoking possibilities, and I've heard some physicists like Victor Stenger say that there are problems with cyclic models. I don't think invoking possibilities here helps much.

Fine-tuning is nothing but invoking possibilities. Why do you give that side of the equation special treatment?

I don't recall asserting that there were: I'm an atheist.

You've asserted that God is a more parsimonious explanation for fine-tuning than multiple universes are. Given two options, one known to be possible and one not known to be possible, the former is more parsimonious.

My point is that it does seem to be a valid point that proposing the multiverse of an indefinite number of universes is contrary to parsimony. I repeat, that does not make it false, nor does it make God likely, it's just not parsimonious.

Occam's razor recommends that among competing hypotheses, the hypothesis with the fewest assumptions should be selected. In application, we proceed toward simplicity until simpler explanations offer less explanatory power. For God to be more parsimonious than multiple universes, God would have to be a simpler explanation with equal or more explanatory power. I maintain that God does not fit this description in comparison to multiple universes.

Note that although I think there's as much reason to suppose there are multiple universe as to suppose there are not, my preferred explanation for why fine-tuning is not evidence of a fine-tuner is that it's speculative BS: I go with the more parsimonious explanation that universal constants aren't actually like independent roulette wheels with billions of settings spun when a universe forms.

Actually I'm not. Apologists like William Lane Craig and Alvin Plantinga equate God's omni- attributes with "maximality" of those characteristics not an infinity (which Craig ostensibly believes cannot exist in reality), and even make use of them (ex: Plantinga's Ontological argument uses them).

I don't think Craig and Plantinga defining God that way makes it standard. Their definition being the first one most people think of when they want to describe God would make it standard.

I have noted in several posts that regardless of if the multiverse is to contain an infinite amount of universes or just an immensely large number, it's still not a parsimonious answer to fine-tuning.

You've noted and asserted, but you have not shown. The way you show it is to provide a simpler explanation with equal or greater explanatory power.