Proponents of the Fine-Tuning Argument frequently assume that the narrowness of the life-friendly range of fundamental physical constants implies a low probability for the origin of the universe ‘by chance’. We cast this argument in a more rigorous form than is customary and conclude that the narrow intervals do not yield a probability at all because the resulting measure function is non-normalizable. We then consider various attempts to circumvent this problem and argue that they fail.

Inflationary cosmology won a large following on the basis of the claim that it solves various problems that beset the standard big bang model. We argue that these problems concern not the empirical adequacy of the standard model but rather the nature of the explanations it offers. Furthermore, inflationary cosmology has not been able to deliver on its proposed solutions without offering models which are increasingly complicated and contrived, which depart more and more from the standard model it was supposed (...) to improve upon, and which sever the connection between cosmology and particle physics that initially made the inflationary paradigm so attractive. Nevertheless, inflationary cosmology remains a promising research program, not least because it offers an explanation of the origin of the density perturbations that seeded the formation of galaxies and other cosmic structures. Tests of this explanation are underway and may settle the issue of whether inflation played an important role in the early universe. (shrink)

It is shown that, for certain classes of cosmological model which either postulate or give rise to infinitely many universes, only a measure zero subset of the set of possible universes above a given size can in fact be physically realized. It follows that claims to explain the fine tuning of our universe on the basis of such models by appeal to the existence of all possible universes fail.