Probabilities and the Fine‐Tuning Argument: a Sceptical View

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.