You're not entirely wrong that it's unscientific, I think we're answering metaphysical questions. (It seems like questions of "why" ends up unerringly in either metaphysics or religion at some point.)
That said, I believe the chain of logic (haven't watched the PBS video yet) is simply that were these fine-tuned constants to take any other value, there wouldn't be intelligent life to observe them. If the values were to be anything outside a narrow range, they would remain unobservable by entities within that hypothetical universe, and because we are making an observation we are implicitly sampling from the distribution of observable values. It's a Bayesian metaphysical argument?
That sounds like it presumes a multiverse, but I don't think you need an infinite number of universes or a god for that to be true... that said, it does purport to explain how fine-tuning doesn't violate certain (metaphysical?) principles of science that call for "naturalness" (which a friend once told me boils down to "all unitless constants should be either 1 or 0 otherwise it's inelegant" or something): the fine structure constant is what it is because otherwise nothing would exist to observe that it was 1/139 or 42 or whatever.
I hope this is even slightly more satisfying to read than it was to write.
That said, I believe the chain of logic (haven't watched the PBS video yet) is simply that were these fine-tuned constants to take any other value, there wouldn't be intelligent life to observe them. If the values were to be anything outside a narrow range, they would remain unobservable by entities within that hypothetical universe, and because we are making an observation we are implicitly sampling from the distribution of observable values. It's a Bayesian metaphysical argument?
That sounds like it presumes a multiverse, but I don't think you need an infinite number of universes or a god for that to be true... that said, it does purport to explain how fine-tuning doesn't violate certain (metaphysical?) principles of science that call for "naturalness" (which a friend once told me boils down to "all unitless constants should be either 1 or 0 otherwise it's inelegant" or something): the fine structure constant is what it is because otherwise nothing would exist to observe that it was 1/139 or 42 or whatever.
I hope this is even slightly more satisfying to read than it was to write.