Monday, February 16, 2009

ruba d'isa kaman / ruba d'leisa kaman

For those getting tired of the emunos v'deyos topics (namely, me), back to the world of gemara. Reuvain sells Shimon an ox. After purchase, Shimon discovers that the ox will not plow his field, so he comes back to Reuvain and demands a refund for his lemon. Most people buy oxen to plow, and this ox is clearly not in the mood to work. Reuvain responds that the ox is certainly usable -- it can be shechted and made into a nice steak dinner. It's not his fault that Shimon (like most people) insists on using his ox only to plow, and he (Reuvain) never agreed to those terms in the contract. Rav holds in this case a refund is owed because we determine the meaning of the contract based on rov and rov people buy oxen to plow. Shmuel, however, disagrees and holds "ain holchin b'mamon achar harov" (B"K 46, B"B 92).

Rashbam (Baba Basra 93a d"h d'hu gufei) writes that Shmuel's principle only holds true when we speak of a ruba d'leisa kaman, a rov based on behavior of the masses.

Tosfos in a number of places implies that Shmuel's principle applies even to a ruba d'isa kaman, a rov based on the statistics before us. For example, the gemara (Kesubos 15) writes that a foundling in a city where the majority of the residents are Jews is treated as a Jewish child even with respect to monetary halachos like returning a lost object to him. Tosfos questions how this gemara fits Shmuels dictum that "ain holchim b'mamon achar harov". In this case we are not dealing with a behavioral phenomenon like why people buy oxen but rather we are dealing with the statsitical liklihood of a child being Jewish based on an accounting of the residents of a specific city (see Ch. R' Akiva Eiger Sanhedrin 3b for another Tosfos along these lines).

According to the Rashbam, there is no question from this gemara on Shmuel. Shmuel rejected only ruba d'leisa kaman as proof, but not ruba d'isa kaman.

My son and I were discussing last night what the point of disagreement between Tosfos and the Rashbam might be. Floor is open for comments before my 2 cents get thrown in.


  1. perhaps the Rashbam limits Shmuel to cases where there is the possibility of birrur (ie. where we can ask the buyer if he wanted the ox for ploughing or for meat) but in a case where we must rely on statistical rov, we revert back to Achrei Rabim Lehatot. Tosfot on the other hand believes that Shmuel has made a statement with respect to mamon and Rov that applies across the board (perhaps they understand that according to Shmuel, Achrei Rabim Lehatot applies only to capital cases but not to civil cases)

  2. Working backwards, I agree with your approach to Tosfos, but why is it that rov does not work for dinei mamonos?

    I'm not sure how you are explaining the Rashbam. The buyer claims he wanted an ox for plowing, which is exactly what most people buy oxen for, yet Shmuel tells us that we ignore the buyer's claim despite it being supported by rov.

  3. Anonymous6:05 PM

    For those getting tired of the emunos v'deyos topics (namely, me)I wouldn't say it but I completely agree

  4. Glad to give you a reason to keep reading.

  5. Mike S.10:58 PM

    Tosphot's position is pretty clear, it seems to me. Namely, that a rov does not meet the burden of proof required to be motzi mammon from a muchzak. Not clear whar RashBa"m position is. In particular, although he writes in the cited text that we do not follow a rubah d'leisa l'kaman, he doesn't say we will follow a ruba d'issa l'kaman; the beginning phrase of the Rashba"m seems to follow a straightforward reading of the text that this isn't a case of rov at all, but of chazaka. That would leave the question of why Rasba"m should mention "d'leisa l'kaman" at all if he did not mean to imply that we will follow a rubah d'issa l'kaman.

  6. Mike S.11:05 PM

    In fact, Tosphot in Sanhedrin (is that the one R. Eiger cites?) points out that Rov is an area where dinei mammonot is more chamur than dinei nefashot (e.g. we will execute someone who has relations with a 4 year old girl whose father has accepted kiddushin for her on the assumption that the will not be an "ailonit.") and therefore we cannot learn that we will follow the majority of the dayanim on the court (rather than require unanimity) from a kal va'chomer with dinei nefashot.

  7. Anonymous6:03 PM

    Ad Mosai No Parsha No Post