 As McGrew, McGrew, and Vestrup argue (2001), there is a problem here in that, strictly speaking, mathematical probabilities do not apply in these circumstances. When a probability distribution is defined over a space of possible outcomes, it must add up to exactly 1. But for any uniform distribution over an infinitely large space, the sum of the probabilities will grow arbitrarily large as each unit interval is added up. Since the range of C is infinite, McGrew et al. conclude that there is no sense in which life-friendly universes are improbable; the probabilities are mathematically undefined. 