Q&A: Laws Dependent on Reality
Laws Dependent on Reality
Question
Jewish laws of prohibition and permission (in the format studied for rabbinic ordination) begin with the laws of salting meat.
Already in the very first סעיף, the Beit Yosef brings several possible reasons for rinsing before salting: without rinsing, the blood on the outside will be absorbed into the salt and prevent it from drawing out the blood inside; rinsing softens the meat and makes it easier for the salt to draw out its blood; without rinsing, the blood on the outside will be reabsorbed into the meat after salting and render it forbidden….
The common denominator among them is that these are factual arguments that, seemingly, could be tested in a laboratory, to determine what draws out the blood and what does not.
This is just one example, and there are many others like it, where the halakhic decisors (and sometimes also the Talmud) conduct the discussion on the basis of assumptions about reality: whether blood is absorbed or expelled, whether a second vessel cooks, the laws of an animal mauled by a predator, which are all based on the assumption that animals have venom and that it is released when they wish.
How should this be approached? Should we dismiss everything they say, and let the law be determined by reality? To what extent is engaging with the views of the medieval authorities (and in other cases also the Talmud) on such matters still Torah study of value?
Answer
In principle, you are completely right. The words of the medieval authorities have no special standing on matters like these, certainly where reality becomes clear to you otherwise. And indeed, experiments were done at Bar-Ilan regarding absorption in vessels that cast quite a few halakhic rulings in these areas into doubt.
But in many cases, the experiment cannot decide the issue, because the question is what level is required in order to prohibit or permit, and that cannot be determined scientifically. To what extent does blood absorbed in the salt prevent it from drawing out additional blood? Something like that certainly exists, but what quantity is enough to matter for prohibition and permission? Science has no answer to that.