Monday, 30 April 2007

Copernicus and The Good

An extremely interesting excerpt from Popper's Conjectures and Refutations, where he argues that Copernicus conceived of the earth revolving around the sun under the influence of Platonic notions:
Copernicus studied in Bologna under the Platonist Novara; and Copernicus' idea of placing the sun rather than the earth in centre of the universe was not the result of new observations but of a new interpretation of old well-known facts in the light of semi-religious Platonic and Neo-Platonic ideas. The crucial idea can be traced back to the sixth book of Plato's Republic, where we can read that the sun plays the same role in the realm of visible things as does the idea of the good in the realm of ideas. Now the idea of the good is the highest in the hierarchy of Platonic ideas. Accordingly the sun, which endows visible things with their visibility, vitality, growth and progress, is the highest in the hierarchy of the visible things in nature.

Now if the sun was to be given pride of place, if the sun merited a divine status in the hierarchy of visible things, then it was hardly possible for it to revolve about the earth. The only fitting place for so exalted a star was the centre of the universe. So the earth was bound to revolve about the sun.

This Platonic idea, then, forms the historical background of the Copernican revolution. It does not start with observations, but with a religious or mythological idea. Such beautiful but wild ideas have often been put forward by great thinkers, and just as often by cranks. But Copernicus, for one, was not a crank. He was highly critical of his own mystical intuitions, which he rigorously examined in the light of astronomical observations reinterpreted with the aid of the new idea. He rightly considered these observations to be extremely important. Yet looked at from a historical or genetical point of view, observations were not the source of his idea. The idea came first, and it was indispensable for the interpretation of the observations: they had to interpreted in its light.

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