Rubah Dlesah Lekaman

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    A Rubah Dlesah Lkaman is when we bring statistical proof as to which side is correct, even though the elements of statistics are not in fronr of us (such as 9 stores Kosher and one Traif, which would be a Rubah DEsia LKaman).

    A classic example is the Gemorah in Bava Basra 93a, where the gemorah states that if one has a Camel which is at its time to have children, it is Muchzak to damage other animals, and is more statisticly likely to damage than other animals, and therefore if another camel is damaged by an unknown camel, we assume the camel which is at its time to have children is the damager. This is true even if we do not go after the majority (rov) by monetary cases, statistical proof is better than the simple “majority of cases”.

    Please feel free to add or correct, it has been a while since I went through the topic.


    Yes, but each camel has x probability assigned to it, and this one has the highest probability. We do not add up the various other camels to say they (in sum) had a higher probability.

    This is without getting into the issue of Muad vs. taam for being in a specific “state” and how that plays into assigning blame.


    chas veshalom i didnt mean to argue with a gemara



    thanks for starting this thread! I just looked quickly at that gemara, not be’iyun, so if I’m wrong I’d appreciate someone correcting me.

    There seems to be 2 separate things, a rubah d’leisah kaman and a statistical proof. The latter is called a chazaka or an umdena. The camel case is a chazaka not a ruba d’leisa kaman. Also, to answer squeak’s question, the case was that this particular camel was next to the dead camel so between the fact that it was right there and the fact that camels during that time normally get violent there is an umdena that this camel killed the other one.

    A ruba d’leisa kaman is by definition a statistical majority, i.e. more than 50%, not a statistical certainty.

    The gemara starts out on 92b with a machlokes between rav and shmuel if by financial issues we go by rov to force someone to pay. The case there is a ruba d’leisa kaman – when someone bought a cow which turns out be a gorer and the buyer says its a mekach ta’us and wants his money back. The seller says he doesn’t have to return the money because it is fit for shechita and that’s what he was selling it for (even though he never said so prior to the sale). Rav says the seller has to return the money because there is a rubah dleisah kaman that most people who buy cows are buying it to use it and not for slaughter, so if this cow was only suitable for slaughter the seller should have said so. Shmuel agrees that there is such a rov but says that the seller doesn’t have to return the money anyway because we don’t go by rov in dinei momenos.

    Then on 93a the gemara wants to compare this to the case of the camels where its more than a ruba d’leisa kaman, instead its a statistical certainty.

    The gemara wants to say though that the 2 cases would have the same halacha as each other, but then the gemara says that this is not necessarily the case. One can hold of ruba and still not go by chazaka in the camel case because over there there is also a rov that says not like the chazaka, namely squeak’s rov – that there are many camels in the world that could have done it so why say it was this one. Or you can not hold of rov and still go by chazaka because chazaka is more of a certainty than a rov.



    chazaka (in some cases, like the camels) means a general happening (such as any chazaka of “in general” (the stam) which is a rubah d’leisah kaman.

    You (seem) to be talking about Ruba D’alma, which is similar to a Ruba D’eisa Lkaman as it uses actual probability based on # of items, vs. generalizations based on prior (not current) patterns, such as “camels in general when in this state damage” or “people in general do not pay their loans before they are due”.

    Chazaka can also be the status quo (different idea). That is not the Chazaka meant here.

    Like you, I am also rusty on the topic.

    P.S. I apologize for not being able to respond until I get back to work. It does give me a chance to go over the sugya, though.

    Yasher Koach!



    I am very rusty so shkoyach to you for getting me into it. You’re right I was talking about ruba d’alma. Ouch, it hurts to realize how rusty you are, no? although you seem less rusty than me.


    Disclaimer: I still have not looked up the gemara.

    GAW – what you replied to me strengthens my statement, namely that it appears rubah d’lessa lekaman is not statistically sound. It sounds more like a rule that the assumption (as in the camel example) is acceptable. Statistically, the assumption is invalid. (This does not in any way mean that the gemara cannot say that it is valid; rather, it is valid on a premise that is not statistically accurate. But statistically accurate is generally considered an oxymoron anyway.)

    Just to clarify; let’s assume there are 3 camels. One has a 90% probability and the other two have a 80% probability (each – I give an outlandish example to magnify my point). Given that an incident occurs, the probability that it was caused by the 90% animal is only 36% and the combined probability it was caused by one of the two others is 64%. Statistically, we would say it was caused by an 80% animal. The gemara logic (according to your presentation) would say it was the 90% animal.

    Charlie brown said that the 90% animal was standing right there when we arrived on scene. If so, the premise of the rule is changed from my original understanding.

    Pashuteh Yid

    First of all, Rusty’s full name is Rustowitz, and he prefers to be addressed that way.

    Second, in probability there is a priori and a posteriori probability. Given A, what are the chances that B will occur is a priori, sometimes called conditional probability. Given B, what is the chance that A has occurred is a posteriori. If Bayes rule sounds familiar, you will remember what I mean. I havenb’t had time to look up the sugya in Bava Kamma, but I believe that you need to keep the above in mind.

    Third, on a related topic, I thought of a simple hesber for the din of kol deparish meruba parish, kol kavua kmechtza al mechtza. When a piece of meat is on the ground, and their are ten butcher shops of which 9 are kosher, we have an objective, physical leidas hasafek in front of us. We therefore use the rov. However, when a person forgot which butcher shop he went to, the leidas hasafek is in his own mind. It is not an objective physical reality. If he remembered, then it is kosher, but if he didn’t remember, then we don’t use rov, since remembering and forgetting are only in this person’s head, and the rest of the world doesn’t know what is really going on in his mind. However, I seem to recently have come across a din which doesn’t fit with this hesber. Let me know what you think.


    First I am Gavra_at_work just not at work or home. This is learning, so I thought it worthwhile to post, so I borrowed a computer.

    The Gemorah I described is a Rubah Dlesah Lkaman in the Hava Amina, but in the Maskana, it changes to a chazaka. The Shmytza in Shmaytza Daled (i think perek Zayin) says this case is a chazaka (due to the din of Muad applies to its state), and not a Rov. He is Mashma (I feel) that Tosfos in Sanhedrin daf 3b would argue and say it is still a Rov, but stronger (and therefore usable by Mammon) due to it not being Taloui in daas, rather in nature (similar to what I explained above regarding “in general”).

    A more classic (and less confusing!) case is that Rov women give birth after nine months. This is not Lakaman (we have not counted), but the tevah is that most women give birth after nine months.

    There is also the case there (on that sugyah) of a seed seller, who is assumes to sell it for planting due to the rov (the Rashbam there calls it a Rubah Dlesa Lekaman). That is a much more difficult case, as there you also have Rov Olam (similar to squeaks question) who buys to eat. Over there, it is Taloui in the daas of the buyer and seller, and is a weaker Rov.

    The final Rov is the Rov of 9 stores which I brought earlier.

    I have not gone through the entire sugyah, so there may be more.

    Please feel free to add or refute, Torah He VLilmod Ani Tzarich.

    Yasher Koach to all those who post here.


    thanks for finding that shmaytsa, gavra. (I like your roaming_gavra user name 🙂 )

    I looked up the shmaytsa it starts in perek vov and continues into zayin. He brings down a tosfos like you said in sanhedrin 3b which says that shmuel only says we don’t go basar rov by momoin in the case of ruba l’radia – a majority buy for the purpose of using cows, not shechting them, but by other cases of rov then shmuel will agree to rav that we do use rov even by momoinos. Tosfos doesn’t explain why this is so. The shmaytza brings down 2 sevaros, one from the bach which is similar to squeak’s tayna. I didn’t look inside the bach but I think he quoted him as saying that more cows are bought for shechita but more buyers are buying to use the cows alive. The Ramban and the Ritva say a different sevara which the shmaytsa wants to use to explain tosfos – which is gavra’s sevara above – that a rov which is based on a person’s decision (ruba l’radia) is weaker than a rov which is based on nature (giving birth after 9 months).

    However, I think both are called ruba d’leisa kaman, just there is a halachic difference between them by momoin according to those rishonim. The rashbam clearly calls the ruba l’radia a ruba dleisa kaman.

    The shmaytsa asks on tosfos from your camel case. In that case it is a rov based on nature so according to tosfos shmuel should agree there that one does go basar rov, so why does the gemara say that shmuel could agree there because its gufo muchzak, instead the gemara should say that shmuel agrees by the camel because its a rov based on nature, not based on a decision.

    On the answer that gemara gives, that gufo muchzak, I’m not sure what that means. Does it mean the camel is a muad? The rashbam in the hava ameina clearly says this camel has never done this before and that is itself the chidush of the camel case. Is the maskana changing that assumption or does it mean something else?

    oh, and squeak, the rashbam says clearly that the camel was next to the dead carcass.

    I’ll just add with an agreement to gavra that I have not gone through the entire sugyah, so there may be more.

    Please feel free to add or refute, Torah He VLilmod Ani Tzarich.

    Yasher Koach to all those who post here.


    oops I meant to put those last few lines in quotes to show I was quoting gavra and saying that I second what he said.


    charlie brown:

    The Shmaytza is bringing a Rayah from the gemorah of the camels that Shmuel doesn’t hold of Rov by mammon in any case. We see according to Shmuel in the Maskana that the case is not dealing with a rov, rather with “Gufo Muchzak”, which (seemingly) is a chezkas haguf that this camel is the one that damaged.

    Tosfos in Sanhedrin, which holds Shmuel does hold of rov by mammon in certain cases, would hold our case is also a rov, but a stronger one due to it being in Tevah.

    I specificly do not want to get into the rov vs. karov issue.

    Thank you to all those who post here.

    I am surprised by the lack of other posters on this thread. In a “yeshivish” site, does nobody want to discuss a Gemorah?


    Pashuteh Yid:

    Kavuah in general refers to the subject (stationary, such as the Boel going to the Eisha), not the daas. Could you please point out the location of the gemorah you are refering to that uses this svorah of forgetting and not using Rov?




    I agree with you what the shmaytza’a raya from the camel case is. I was trying to say the same thing but you said it clearer.


    wow real talmidei chachomim



    The others on this thread seem very much to be but I definitely am not unfortunately. And that is really truly not just modesty, it is a fact. But hopefully one day I will be one.


    me to i”yh



    Kedushin 49b!


    thanks gavra. Based on that gemara I can certainly say I am neither a talmid nor a chacham. But thats not the standard I had originally meant, lol.

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