Proper noun
Copernican principle
(cosmology) A principle which states that the location of humanity has no special significance (in constrast to traditional views that the Earth or Sun are located in the center of the Universe).
Peacock (1999), chapter 3 That space is undergoing metric expansion is shown by direct observational evidence of the Cosmological principle and the Copernican principle, which together with Hubble's law have no other explanation. Source: Internet
The Copernican principle represents the irreducible philosophical assumption needed to justify this, when combined with the observations. Source: Internet