Q&A: Deriving an A Fortiori Inference Nowadays
Deriving an A Fortiori Inference Nowadays
Question
Hello Rabbi,
I started learning Bava Kamma and came across the hermeneutic rule of “bameh matzinu” (“from a precedent”). I’m trying to understand whether there is compelling logic to it, or whether we derive by it simply because “that’s how it is” — meaning, just because it is one of the hermeneutic rules?
I’m trying to understand where the necessity comes from to say that there must be some other common denominator in order to derive a law. Why shouldn’t we really say that in cases x and y, the law is indeed due to something unique in each case? Why specifically hang the law on a common denominator? It doesn’t sound necessary to me at all.
Thank you
Answer
I didn’t understand the question. Which Talmudic passage are you referring to? If you want to discuss it, define the question. How are you defining “mah matzinu,” and what is difficult for you about it?
Discussion on Answer
That is not “mah matzinu” but “the common side” (or “what is common between them”).
I have written about this more than once and explained it in detail. See, for example, Column 346 (and also 347).
The question is about the rule itself.
They want to derive an a fortiori inference from case x, and then object that perhaps this stems from something unique to that case, so an a fortiori inference cannot be made. Then they point to case y, which has the same law but not that same uniqueness, and want to say that the law does not stem from that uniqueness. But then they come and show that there is some other uniqueness there, and maybe that is the reason, and so on. Then they bring a common denominator between x and y and derive from it for case z. That’s how I understand “mah matzinu.”
My question is whether there is any necessity to say that the law stems דווקא from the common denominator (and I simply don’t understand it), or whether logically one can indeed say that the laws are the same in both places, except that in each place this stems from that case’s own unique feature. Do we choose to infer the common denominator because there is no other option, or because this is a hermeneutic rule and we are bound by it?