Since only a narrow range of the allowed values for, say, the fine structure constant will permit observers to exist in the Universe, we must find ourselves in the narrow range of possibilities which permit them, no matter how improbable they are. We must ask for the conditional probability of observing constants to take particular ranges, given that other features of the Universe, like its age, satisfy necessary conditions for life.
John D. Barrow, The Constants of Nature: The Numbers That Encode the Deepest Secrets of the Universe
astrophysics, constants-of-nature, fine-structure-constant, life, science, universe