Rabbi Aryeh Leib Feinstein

(1821-1903; Lithuania), Shiltei Hagiborim, Sela Hamachlekot 2:

ר' אריה לייב פיינשטיין, שלטי הגבורים, סלע המחלקות, ב (ווראשא, תר"ס); ז"ל

Hebrew text available at http://www.hebrewbooks.org/31346, pp. 74-76 (HebrewBooks pagination).

To this category [of dispute] belong also Talmudic disputes regarding knowledge of the world and of nature. For it is known that most of the tannaim and amoraim were knowledgeable in all disciplines, as many gentile scholars testified (Me’or Einayim, Imrei Vina), and as the contemporary scholar R. Y.M. Rabinowitz has demonstrated in his book, Mevo Hatalmud. Notwithstanding that most of the knowledge of the world and of nature has already been discovered by scientists, with clear demonstrations and reliable experiments, there are still many things that have not been reliably determined. With regard not merely to specific details, but to general approaches and broad theories as well, the opinions of scholars still diverge, with different scholars adopting differing approaches. Therefore it is not surprising if in the Talmud, too, there are disputes in matters of nature, even regarding matters that have now been clarified through new experiments. There are therefore many disputes regarding tereifot [i.e., which physical injuries are fatal], salting [of animals], mixtures [of permissible and forbidden foods], the laws of niddah, pregnancy and nursing, which all relate to the disciplines of physics, chemistry and medicine. Even now, with our own eyes, we see that there are disputes between prominent physicians about major issues, like bacteria, for example. There is no reason for surprise at the existence of disputes among Chazal, in their days, before the various disciplines, including the sciences, developed. Similarly there are many disputes in matters of seeds and saplings, which are rooted in the knowledge of the abilities and the nature of plants (botany). This is especially true in matters related to astronomy, which, as is known, was not well understood in the times of Chazal, before later generations investigated and established it using telescopes.... Early gentile scholars, as well as Chazal, in their day, believed the earth to be flat, in contradiction to what has now become clear through compelling demonstrations and the testimony of those who have circumnavigated the earth—that the earth is spherical. They also accepted the Ptolemaic view of the sun’s motion, against the Copernican model which has now been proven with compelling demonstrations. Therefore we find that both the sages of Israel and the gentile sages were of two minds regarding whether the sun revolves above or below the earth and regarding the orbit of the constellations, until one time the gentile sages agreed with the Jewish sages, and one time the opposite. The dispute we quoted earlier between Rabban Gamliel and Rabbi Yehoshua regarding the sanctification of the new moon is not surprising, even though they were both great in intellectual reasoning, because the various disciplines had not yet been researched, and they used reasoning and hypotheses founded upon comparison and analogy, without demonstrative experiments. However, in matters founded upon pure intellectual reasoning (pure mathematics), like the reckoning of measurements and triangles, and in inferences proven with physical trials, there is no dispute amongst the sages. If one or many sages made an error in such matters, the rest of the sages quickly determined that it was not so; it did not enter into the study hall as a matter of dispute at all—just as they at once contradicted and immediately rejected the rabbis of Caesarea (at the beginning of tractate Sukkah) who said that [the area of] a circle that is inscribed within a square is [less than the latter by] a half [sic], when it is not so, for we can see that that is not accurate.

[Translation by DES.]