From Peter Fisher Epstein at Philosophy of Science:
Abstract. According to the Fine-Tuning Argument (FTA), the existence of life in our universe confirms the Multiverse Hypothesis (HM). A standard objection to FTA is that it violates the Requirement of Total Evidence (RTE). I argue that RTE should be rejected in favor of the Predesignation Requirement, according to which, in assessing the outcome of a probabilistic process, we should only use evidence characterizable in a manner
available prior to observing the outcome. This produces the right verdicts in some simple cases in which RTE leads us astray; and, when applied to FTA, it shows that our evidence does confirm HM. More.
This is what philosophizing comes to these days. There is no evidence for any universe other than our own—and it is not clear that there ever could be.
And if there were, in the age of naturalism, how would we know? Our brains, they say, are shaped for fitness, not for truth,
Alternatively, if our universe appears fine-tuned, that is probably because it is.
But expect lots of casuistry to come. It’s pretty much what they have got now.
See also: What becomes of science when the evidence does not matter?
and Multiverse cosmology at your fingertips