I had a big shock yesterday.
Readers will hopefully be familiar with the basic story described in my monograph The Sun's Path At Night. Many of Chazal subscribed to the ancient Babylonian cosmology in which the universe is a dome, and when the sun sets at night, it does not continue to orbit the far side of the earth; rather, it changes direction, passes through the firmament, and circles up and behind the sky. This model was challenged by the Greek Ptolemaic model, in which the earth is a sphere, and the sun orbits the earth in a circular path. R. Yehudah HaNasi acknowledged that the Greek model appeared correct.
Virtually all the Rishonim accepted R. Yehudah HaNasi's acceptance. The sole exception that I knew of was Rabbeinu Tam, who states that R. Yehudah HaNasi only conceded that the gentiles had better arguments, but insisted that the truth lay with Chazal and the sun really does travel up behind the sky at night. It was remarkable that Rabbeinu Tam, living in the twelfth century, had still not accepted the Ptolemaic model, but it is well-known that the Tosafists of Ashkenaz had virtually no exposure to the Greco-Muslim science that was widespread elsewhere.
But yesterday I discovered another Rishon who sides with Rabbeinu Tam. And it was just about the last Rishon that I would have expected to take such a view. Ramban! In Toras Ha-Adam, he argues for the correctness of Rabbeinu Tam's view that the sun travels through the firmament and then up behind it.
Ramban?! This was most unexpected. Despite his being a prominent mystic, Ramban had a clear rationalist bent; he was no Arizal or Leshem. Ramban was a physician. He was very familiar with philosophy. He argues that the Greeks proved rainbows to be a natural phenomenon, and hence we must reject the (traditional) interpretation of the Torah that rainbows were created after the deluge. He presents Greek understandings of physiology as an alternate way to explaining Isha Ki Tazria from that of Chazal. So Ramban would presumably not have been unwilling to accept R. Yehudah HaNasi's acknowledgment that Chazal having had an incorrect belief; could he really have been unaware that the belief in the sun passing behind the sky at night had long been firmly discredited?
Apparently so. I found an article by Y. Tzvi Langermann in which he notes that Ramban's formative education was under the Tosafists, and he had no training in the sciences. It seems that while he later picked up some scattered knowledge of Greek science, he was not thoroughly schooled in it. And apparently he was insufficiently aware, or insufficiently convinced, of the very basics of Greco-Muslim astronomy.
Just when you think that you know somebody! Next week (amidst some posts that will be very different from the norm) I plan to describe how I came across another source from someone who I might have expected to insist that Scriptural and Talmudic statements about astronomy are correct, but who turned out to be surprisingly rationalistic in this area. Historical context is sometimes more complicated than it first appears.