"In these last two chapters we have been looking at the ways in which intellectual change has knock-on consequences. The discovery of America killed off the two-spheres theory of the Earth. Copernicanism led to the idea that the planets shine by reflected light, which was confirmed by the discovery of the phases of Venus; and this killed off the Ptolemaic system. There was nothing arbitrary or contingent about these changes; they were as inevitable as the discovery of America once Columbus had set sail. These were intellectual transformations of fundamental importance, yet historians of science barely discuss them. They have become dark stars themselves—effectively invisible."Why? Since Kuhn's Structure history of science has focused on controversy between scientists, the assumption has been that every major new theory is contentious, and that there is nothing inevitable about the process by which one theory supplants another. This approach has been extraordinarily illuminating. But, in shining a light on controversy, it has left in the shadows all those changes which took place almost silently and were inevitable—indeed, could be seen to be inevitable at the time. Nobody (or, rather, only a few confused and ill-informed individuals) sprang to the defence of the two-spheres system after 1511. . . . By 1624, eleven years after he had made public his discovery that Venus had a full set of phases, Galileo could take it for granted that no competent person would defend the Ptolemaic system. . . . The evidence is clear: Ptolemaic astronomy was unaffected by Copernicus; it went into crisis with the new star of 1572, but by the end of the sixteenth century it had fully recovered. The telescope, on the other hand, brought about its immediate and irreversible collapse.
"Sometimes there are real, live, enduring controversies in science. In the seventeenth century such conflicts took place between those who believed in the possibility of a vacuum and those who did not, between those who believed in the possibility of a moving Earth and those (after 1613, supporters of Brahe rather than Ptolemy) who did not. Sometimes the outcome really does teeter and hang in the balance. But, at other times, vast, well-constructed, apparently robust intellectual edifices are swept away with barely a murmur because, to paraphrase Vadianus, experience really can be demonstrative."
David Wootton, The invention of science: a new history of the scientific revolution (New York: HarperCollins Publishers, 2015), 245-247.
