I commend to readers niwrad’s “The oxymoron of the multi-universes,” pausing only to note his comment re the multiverse advocates,
Let’s suppose their answer is these universes are fully isolated. In this case no experimental evidence is possible. This is a big problem, especially for the “multi-cosmologists”, who are supporters of methodological naturalism, and – as such – trust only what can be experimented.
Not quite. Methodological naturalism is treated as an axiom. When it is asserted, it stands in for evidence.
That was the point of the questions I raised earlier:
1) if fertile Earth is just an average planet, why isn’t barren Mars?
2) Why is it science to speculate that ET might be hiding in our junk DNA (or on moonless planets or exoplanets’ moons) but not that Bigfoot might be hiding in the mountains?
3) Why does faith, elsewhere derided, seem to play so great a role in the speculations around life on other planets? Why is doubt, for once, the identified problem, not faith?
It is because the Copernican Principle—that Earth cannot, as a matter of axiom, be unusual—stands in for evidence. Evidence for propositions that would otherwise be dismissed for lack thereof.
And the Principle itself is a direct outcome of methodological naturalism.
So, to address one of the questions above, that is why the space alien is science and Bigfoot is non- or anti-science. The space alien is grandfathered by methodological naturalism and fathered by the Copernican Principle. Bigfoot is not.
And we haven’t even got to the multiverse yet …
Niwrad noted as a symptom of the weakness of the argument for a multiverse that the sheer numbers of such entities varies dramatically from estimate to estimate. But the reason that arbitrary speculations on the many infinities of multiverses are treated as science, not nonsense, has been spelled out quite clearly for us:
But the main reason for believing in an ensemble of universes is that it could explain why the laws governing our Universe appear to be so finely turned for our existence … This fine-tuning has two possible explanations. Either the Universe was designed specifically for us by a creator or there is a multitude of universes — a multiverse.
That is why the multiverse exists. It is grandfathered into existence by methodological naturalism, and is exempt from demands for evidence and from the need to follow any conventions whatever. I will abundantly demonstrate the latter point in my continuing series at Evolution News & Views (linked here).
– O’Leary for News