Q&A: Determining Jewish Law on the Basis of Science
Determining Jewish Law on the Basis of Science
Question
The Talmud in Sabbath 85a explains the laws of planting mixed species on the basis of scientific knowledge (“the rabbis know this”; it is learned from soil experts, as explained there). And Tosafot wrote: “The rabbis know that five in six do not draw sustenance from one another. And Rabbenu Tam says that nevertheless a verse is still needed, for were it not for the verse I would have said that even though they do not draw sustenance, there is still intermingling and it is forbidden. Therefore the verse teaches us that in such a case there is no intermingling. And the verse alone would also not suffice, because we would not know with regard to how much space five are permitted by the verse. But now that the rabbis know that five in six do not draw sustenance, we should establish the verse as referring to six.”
That is, scientific knowledge alone cannot determine Jewish law, because even once the proper distance is maintained between one seed and another, we still need “confirmation” from Scripture that this is what the Torah intended.
Is there not room to prove from here that scientific knowledge is not the be-all and end-all in halakhic ruling?
Answer
First of all, obviously it is not the be-all and end-all. Scientific knowledge does not tell us whether there is drawing of sustenance, but how much drawing of sustenance there is. The line marking from when that drawing of sustenance is significant enough to count is a halakhic line. See my article on Jewish law and expertise (and the Zoom series that just ended on Jewish law and reality).
Beyond that, here it is even stronger. The novelty Tosafot brings is something beyond scientific knowledge, and therefore here it is clear that the verse is also required. Maybe there is intermingling even without drawing of sustenance? Science cannot determine that.
Discussion on Answer
Science*
For example, absorption in utensils. The laws of niddah (what the source of the blood is), and many others.
If absorption in utensils were proven to be incorrect, would there be no place to prohibit meat and milk?
Regarding niddah likewise: if a stain looks like blood, and in a lab it is clarified that it is not blood, would it not be considered a stain?
Every such question requires a detailed answer. But in principle, yes.
By the way, it should be noted that many times the Talmud proves from a verse things that we know with certainty from other sources as well (common sense, minimal life experience, and so on).
Moshe, I’d be happy for examples, because there is also the principle of “Why do I need a verse? It is logical.”
And by the same token there is the principle of “If you wish, say it is from a verse, and if you wish, say it is from logic.” There are lots of principles.
So when does science have significance, then?
If possible, an example too.
Thanks.