[Avodah] "Mi-di..." is a Kal VaChomar formula

[hlampel at koshernet.com]

"Mi-di [kach...kach]" is a Kal VaChomar formula

I have learned something new in Bava Metsia 23b. We
see the rishonim (Tosefos, Rashba, others)
take it for granted that the talmudic formula
“mi-d’-that--[therefore] this” is not a simple
equation, but a kal va’chomer!

Gemara BM 23b regarding how a person can prove a lost
item is his:

>From the fact that [identifying] the weight of an
object serves as identification [to prove ownership],
[one must conclude that identifying] dimensions or
quantities is also valid identifying proof.

Tosefos: This implies that identifying dimensions is
stronger [than identifying weight].

Rashba: How did the Gemara use a kal va’chomer to
answer...?

(Incidentally, Rashba does not have the girsa
"nammi," "also.")


Zvi Lampel