 More often than as an inference to the best explanation the argument from fine-tuning for the multiverse is formulated using probabilities, in analogy to the argument from fine-tuning for design (see  Section 3.1).  In a simple version of the argument, reasonable probability assignments are compared for a single-universe hypothesis \(U\) (where the universe has uniform laws and constants) and a rival multiverse hypothesis \(M\) according to which there are many universes with conditions that differ between universes. (For the purposes of the discussion about fine-tuning for life, hypotheses according to which there is only a single universe with constants that vary across space-time qualify as versions of the multiverse hypothesis. They seem to be disfavoured by the available evidence, however, see Uzan 2003 for a review.)