I couldn't help but notice this interesting paper. I'm guessing some lively discussion will be emergent on the blogs. http://arxiv.org/abs/astro-ph/0610330 What's the trouble with anthropic reasoning? Authors: Roberto Trotta (Oxford University), Glenn D. Starkman (Oxford University & Case Western Reserve University) Comments: 8 pages, no figures. Contribution to the proceedings of the conference "The Dark Side of the Universe", Madrid, June 2006 Selection effects in cosmology are often invoked to "explain" why some of the fundamental constant of Nature, and in particular the cosmological constant, take on the value they do in our Universe. We briefly review this probabilistic "anthropic reasoning" and we argue that different (equally plausible) ways of assigning probabilities to candidate universes lead to totally different anthropic predictions, presenting an explicit example based on the total number of possible observations observers can carry out. We conclude that in absence of a fundamental motivation for selecting one weighting scheme over another the anthropic principle cannot be used to explain the value of Lambda. .