The Copernican "Principle"
What Would Copernicus Say?
The actual "Copernican principle" of Nicolas Copernicus (in Commentariolus around 1514 and the 1543 De Revolutionibus Orbium Coelestium) is merely that the planets revolve around the Sun, the earth is another planet that rotates, and the stars are far away. That idea was extended by Newtonian physics 200 years later, and Laplace 100 years after that. It was only in 1838 that Friedrich Bessel first measured stellar parallax, proving what was already widely believed, that stars are scattered in three dimensional space.
The Copernican "Principle" is a recent, and temporary, intellectual fad. It is a lazy placeholder for empirical evidence we do not yet have, and in some cases (i.e., "cosmological expansion", possibly the conflation of "double pulse" quark stars (?) in the early universe with recent type 1a supernovae) an excuse to claim violations of accepted physical laws such as conservation of energy.
Copernicus did NOT claim that human beings were not special, merely that mathematical reasoning rooted in careful observation did not physically place them 6400 km above the geometric center of the universe. My guess (I don't read Latin) is that Copernicus placed man spiritually close to God, far more important than physical location.
Copernicus made no claims that the far universe resembles the nearby one - that "principle" was extrapolation by others, centuries later. Copernicus rearranged our conceptions, and helped us gain the perspective that permits the contemplation of a uniform universe. What we are learning today is that the laws of physics are universal and simple, but their observable consequences in an evolving and varied universe are anything but simple. The Kepler space telescope has found thousands of very different planetary systems, none resembling ours. To paraphrase another iconified scientist, God plays dice with the universe at every scale. The universe is not Levittown.
The phrase "Copernican principle" has been appropriated by successive philosophers of science, most recently by Carl Sagan, to support worldviews that the devout Catholic canon Copernicus might have abhored.
Copernicus was a polymath, but his day job was physician. If he could advise us today, I imagine his first prescription would be to eat healthy, exercise, and pray. After that, his "principle" might be to cherish God's creation by studying the sky and helping other people. I am agnostic - I am not a "principled Copernican" - so I have no right to write about "God". However, I object to those who would twist Copernican ideas 180 degrees, assuming his historical views (especially his faith and his many other accomplishments) are irrelevant. It is an intellectual crime to rewrite the past so we can pretend to agree with it, a crime also practiced by many so-called theologians.
It is time to resurrect and restore the actual Copernican Principle as a monument to the actual genius who risked everything to promote it, and assign new names like "Sagan Principle" to more ephemeral ideological speculation. The Catholic Church has been unjustly accused of persecuting Galileo for his science (instead of his obstreperousness). Perhaps it is time for a Vatican astronomer to restore and defend brother Copernicus, a man whose gentler approach to temporal authority Galileo might have profited from.