Stenger tackles some of the God-of-the-gaps questions that are genuinely difficult for laymen to answer, and for that I cannot help but feel some gratitude. Additionally, precisely because the theists who seek gaps for their god to hide in tend to seek out tricky and interesting corners of science, any book that shines the light of genuine intelligence on them tends to present interesting science.
Perhaps the most illuminating part of the book was the observation that many of the physical constants whose “fine-tuned” precision people marvel at are really mere artifacts of man-made definitions. To say that (as Stenger quotes theologian John Jefferson Davies) “if the mass of neutrinos were 5×10−34 instead of 5×10−35 kg” then the universe would be utterly different does not really speak to very “fine” tuning—it’s made to sound like a variation of ‘one part in 10−35’, but really refers to a factor of ten. Thus choice of units—man-made and thus arbitrary units not at all fundamental to the universe—obscures the fact that a lot of these purportedly fine-tuned values are in fact very coarsely tuned indeed.
The one argument I felt was missing from this section was the point I once chanced across somewhere on the Internet, where a commenter remarked that to suggest that a value is finely tuned is to imply that its value is chosen within a minute portion of its range of possible values. Since we don’t know how to make universes, it’s not at all clear what those ranges are, and just because we can imagine and mathematically model various ranges this does not imply their physical possibility. Until theologians can scientifically demonstrate that there was a range of possible values that the constants might have taken, and that the (non-arbitrary-unit) constants are finely tuned within their possible ranges, it’s not clear that the claim of fine tuning is even logically coherent. (Stephen Hawking famously quipped, in A Brief History of Time, that God may have had no choice at all in the matter.)
Well, I suppose Stenger wanted to avoid any tack that seemed like brushing the question aside, instead preferring to tackle every assertion head-on and demolish it; and it seems to me he was fairly successful.