Recent years have seen a great deal of discussion about the fine-tuning of the universe. It is a well-established fact that the number of values for the physical constants and quantities need to fall into very specific regions in order to have a life-supporting universe. The probabilities, in fact, are infinitesimal.
Though some try to deny this, it isn’t controversial among cosmologists. Fine-tuning is a reality, the only argument is over how to explain it. Other than references to a creator, there have basically been two answers to this: the anthropic principle and the multiverse.
These aren’t mutually exclusive. In fact, they are typically used together. We wouldn’t be observing a universe unless it was fine-tuned in order to support life (so says the anthropic principle), and there are lots of “dead” universes out there (so say multiverse believers). By chance alone, at least one of the astronomical number of universes out there would be suitable for life.
This seems rather plausible at first blush, but the only reason to believe either of the claims above is true is a prior commitment to the non-existence of a creator.
That is to say, in the case of the multiverse, that there isn’t actually any evidence for universes other than this one. This is simply a conjecture in order to explain the fine-tuning.
With regard to the anthropic principle, things are much worse. It is demonstrably false that all, or even most, observers would be found in finely tuned universes. Most of them, given materialism, would be Boltzman Brains: brains that fluctuate randomly out of the quantum vacuum (often complete with false memories), before disappearing again. It is simply false to assert “no one would be here if the universe wasn’t finely tuned”.
So, anyone who is insistent on evidence (as nearly all atheists I encounter are), should reject both the multiverse and the anthropic principle. But this doesn’t leave them with any kind of explanation for the fine tuning of the universe.
Rather, the explanation I typically hear is simply a shrug and a “who knows?”.
But to simply halt inquiry when the evidence starts leading to places one doesn’t like is something much less commendable than intellectual humility. This is doubly true coming from anyone who’s insisted upon evidence, or that we should follow the evidence where it leads.
Certainly, it runs directly counter to the oft-heard claim that there is no evidence for a creator of the universe.