Mistakes about science

Today's daf talks about spontaneously generated lice. There's a dispute among tannai'm whether you can kill a louse on Shabbat (Shabbat 12a, 107b). Rav Yosef explains that the disagreement only applies to insects that "do not reproduce," but killing all other insects is forbidden (107b). The rishonim then discuss which species of insect are generated from sweat, from rot, from dirt, etc., or from eggs. The halakhah concludes that killing lice is permitted.

There are much more dramatic Torah-versus-science issues out there than this one. If you're looking for explosive controversy, you want evolution. If you're looking for out-of-date science in the Talmud, this collection is just a start; Pesahim 94b is a big one in particular. If you're looking for a legal and moral mess, look into organ donation.

But, even if relatively undramatic, the issue of spontaneous generation is centrally important to science versus Halakhah. It's unique as a black-and-white case of a canonized halakhah based on rejected science.