The Impertinent Anthropic Principle
Because this premise is less than certain, many of those who espouse the WAP advocate many universes, so that we just happen to be in the one that contains us. Nick Bostrom (2) points out that the Anthropic Principle may be considered presumptive evidence for many universes "in the absence of any plausible alternative." Unfortunately, there is no observational or experimental ("scientific") evidence whatsoever for any universe besides the one we inhabit. And even the idea has serious problems, both physical and philosophical (I would like to say metaphysical, but that's not always a respectable term, even to philosophers).