All cosmological models are constructed by augmenting the results of observations by a philosophical principle. Two examples from modern scientiœc cosmology are the principle of mediocrity and the so-called anthropic, or biophilic, principle. The principle of mediocrity, sometimes known as the Copernican principle, states that the portion of the Universe we observe is not special or privileged, but is representative of the whole. Ever since Copernicus demonstrated that the Earth does not lie at the center of the Universe, the principle of mediocrity has been the default assumption; indeed, it is normally referred to as simply “the cosmological principle.” This principle underpins the standard Friedman-Robertson-Walker cosmological models.