BAVA METZIA 6 - Dedicated by Dr. Chaim Bitton of Geneva Switzerland in gratitude to his parents, Shmuel and Rina Bitton, who raised him in the path of Torah and Mitzvot. May they be blessed with long life and good health and may they merit to see much Nachat from their children and grandchildren.

OPINIONS: Rebbi Zeira asks what the Halachah is in the case of two people who come to Beis Din arguing about the ownership of a certain item, and one forcibly removes it from the other's hands in front of Beis Din. The Gemara asks, what exactly is Rebbi Zeira's case? If the person from whom the item was taken remained silent, his silence is a clear indication that he admits it is not his. If he protested, his protest clearly shows that he had no other course of action, and the forced removal of the item from his hands should be inconsequential. The Gemara concludes that Rebbi Zeira refers to a case in which he was silent at first and then protested. Is his original silence an indication of admission, or does his eventual protest show that the only reason why he was silent at first was that he did not realize that the removal of the item from his hands would effect the ruling, since the judges of the Beis Din saw that his opponent grabbed the item out of his hands?
Does Rebbi Zeira's question apply only in a case in which the item was seized from one person's hands in front of Beis Din, or does it apply even when the item was seized from his hands outside of Beis Din (in the presence of witnesses)?
(a) The RAMBAN, RITVA, and others write that Rebbi Zeira's question applies specifically in front of Beis Din. If the item would be seized from him only in front witnesses and he would not protest immediately, his initial silence unquestionably would be a show of admission. This is evident from the Gemara's suggestion that the only reason why he was quiet at first was that the judges saw what happened, which implies that if only witnesses saw what happened, he would not have been silent (unless he admits that the item is not his).
(b) The RASHBA takes the opposite approach. Since the person claims ownership in Beis Din, if the item is seized from his hands and he does not protest, he shows that he forfeits his claim. However, when only witnesses saw the object seized from him (outside of Beis Din), not only is his initial silence not a sign of admission, but even if he remains silent the entire time and does not protest at all, his silence is not a sign of admission. He reasons that since he is not in front of Beis Din, there is no point in protesting.
(c) The SHACH (CM 138:6) seems to present a third opinion. After he cites the other opinions, he concludes that when the item is taken in front of witnesses, the Halachah is the same as when the item is taken in front of Beis Din.
The TUMIM (CM 138:5) does not understand how the Shach can cite the Rishonim and then take a third approach. The Tumim himself rules like the Ramban. (Y. MONTROSE)
QUESTIONS: The Gemara proves that one who is "Chashid a'Mamona" (suspected of stealing) is not "Chashid a'Shevu'asa" (suspected of swearing falsely) from the fact that Beis Din makes a person swear a Shevu'as Heses even when he is Kofer ha'Kol and is suspected of lying and trying to steal. The Gemara cites further proof from the ruling of Ben Nanas in the case of "Chenvani Al Pinkaso," in which the storekeeper and the workers both must swear and collect from the employer, and from the Halachah of Shevu'as ha'Shomrim.
(a) How can the Gemara prove from Shevu'as Heses that one who is "Chashid a'Mamona" is not "Chashid a'Shevu'asa"? The Gemara earlier teaches that when a person is Kofer ha'Kol in the case of a Milveh, he remains eligible to serve as a witness (and certainly for making a Shevu'ah) since it is assumed that he merely is stalling for time ("Mishtamet"), and he is not "Chashid a'Mamona." (TOSFOS DH Ela)
(b) Why does the Gemara not prove that "Chashid a'Mamona" is not "Chashid a'Shevu'asa" from the Shevu'ah d'Oraisa of Ed Echad, which a person must make when he is Kofer ha'Kol (and suspected of stealing, similar to a case of Shevu'as Heses)? (MAHARAM SHIF, MEROMEI SADEH)
(c) The Gemara's second proof is from the Shevu'ah that the Rabanan instituted in the case of "Chenvani Al Pinkaso," in which the storekeeper and the workers both collect money on the basis of their Shevu'os. Since the Shevu'os in that case are not merely to retain money but rather to collect money from someone else, the claimants are considered to be "Chashid a'Mamona," since the logic of "Mishtamet" applies only when one is trying to refrain from paying and not when one attempts to take someone else's money.
Why does the Gemara prove that one who is "Chashid a'Mamona" is not "Chashid a'Shevu'asa" from this specific case of Shevu'ah? The Mishnah in Shevuos (44b) provides an entire list of Shevu'os that a person swears in order to collect money from someone else. The Gemara should prove from all of those Shevu'os that a person may make a Shevu'ah even when he is "Chashid a'Mamona"! (TZELACH, TUMIM 91:3)
(a) The Rishonim propose a number of answers to this question.
1. The RASHBA writes that the proof from Shevu'as Heses is not a strong proof, and indeed the Gemara could have refuted it in this manner. However, the Gemara knew that there were better proofs, such as the one from Shevu'as ha'Shomrim, and therefore it did not bother to refute this one.
2. TOSFOS and the RAMBAN explain that the Gemara had a tradition that Rav Nachman requires a Shevu'as Heses even in a case where a person denies owing a Pikadon that is in his hands. (Tosfos points out that this seems to contradict the Gemara in Shevuos 40b).
3. The RAMBAN answers further that even though a person does not become Pasul l'Edus when he denies owing a Milveh, perhaps he should become Pasul for making a Shevu'ah on the money that he denies owing. The reason for this is as follows. When a person is prepared to lie in order to stall for time ("Mishtamet"), he also will be willing to swear falsely or testify falsely regarding the payment of that loan. Even if a person who is Kofer ha'Kol is trying to be "Mishtamet," he cannot be trusted to make a Shevu'ah that he does not owe that money, since he might swear falsely in order to delay the payment. Nevertheless, a person who is Kofer b'Milveh is allowed to testify that somebody else owes money, because he is not suspected of lying in order to cause money to be taken away from its rightful owner. The logic of "Mishtamet" only gives a person a reason to refuse payment of something, but not to cause a person who does not owe money to have to pay money (as mentioned in the third question above).
4. RASHI (DH Neima Migu) does not seem to follow any of these approaches. He writes merely that a person who is Kofer ha'Kol is not being "Mishtamet," and is therefore "Chashid a'Mamona."
How is Rashi's comment to be reconciled with the Halachah that one who is Kofer b'Milveh is a valid witness? The RA'AVAD explains that according to Rashi, when two witnesses testify that a person owes money and he pays the money based on their testimony, he is not considered "Chashid a'Mamona." It is only when a person denies money and there are no witnesses to prove him guilty that he is considered "Chashid a'Mamona" if he is lying. (The RAMBAN also mentions this logic in the name of "Yesh Mefarshim.")
This is consistent with the explanation of the RITVA cited earlier (see Insights to 3b and 4a). The Ritva explains that a person will deny a loan that he borrowed in front of witnesses only if he plans to delay the repayment and eventually to pay when the witnesses come to testify against him. Therefore, if witnesses testify that he owes money, it may be assumed that he was only stalling for time. However, if there are no witnesses who prove that the borrower was only stalling, it is likely that the borrower indeed is a thief, since he was brazen enough to deny the entire loan. Therefore, it can be proven that one who is "Chashid a'Mamona" is not "Chashid a'Shevu'asa" from the Halachah of Rav Nachman who says that one who is Kofer ha'Kol must make a Shevu'as Heses even when no witnesses are present.
(b) The MAHARAM SHIF explains that according to Tosfos, the answer is simple. The case of Shevu'as Heses proves that one who is "Chashid a'Mamona" is not "Chashid a'Shevu'asa" only because the Gemara had a tradition that a Shevu'as Heses is made even when a person denies that an object that is known to be in his possession is a Pikadon. Since the object is known to be in his possession, the person who denies it is not stalling for time ("Mishtamet"), and nevertheless he makes a Shevu'ah. However, with regard to Shevu'as Ed Echad, the Torah never specifies that a person must make such a Shevu'ah even when the witness testifies that an object that is known to be in the possession of the defendant is a Pikadon. Perhaps no Shevu'ah is made in such a case because the defendant is "Chashid a'Mamona," and one makes a Shevu'ah only when the Ed Echad claims that he owes money due to a loan. Since a person can be "Mishtamet" when he owes money of a loan, this case does not serve as proof that one who is "Chashid a'Mamona" is also "Chashid a'Shevu'asa."
However, this answer is valid only according to the first two answers to the previous question. According to the answers of the Ramban and Rashi to the previous question, even a person who denies a loan is "Chashid a'Mamona." Consequently, whether the Ed Echad makes a person swear that he does not owe money, or whether he makes him swear that an object of his is not a Pikadon, the defendant is "Chashid a'Mamona" since he was Kofer ha'Kol. The Gemara should be able to prove from Shevu'as Ed Echad that one who is "Chashid a'Mamona" is nevertheless able to make a Shevu'ah!
The answer to this question seems to be that even according to Rashi, there are times at which a person who is Kofer ha'Kol is not "Chashid a'Mamona." Rashi writes that a person who is Kofer ha'Kol is "Chashid a'Mamona" only because he was brazen enough to deny the entire loan, and therefore he cannot possibly be stalling for time (see Gemara, end of 3a). However, the only reason why denying a charge is considered brazen is that the lender did a favor for the borrower and therefore the borrower should feel guilty denying that he ever borrowed. When a Shomer watches a Pikadon for someone, the owner did no favor for him by giving him the Pikadon, and therefore it does not take brazenness to deny receiving the Pikadon, as Rashi writes in Bava Kama (107a, DH Aval b'Pikadon and DH Me'iz). Therefore, if an Ed Echad testifies that a person received a Pikadon and he does not testify that the Pikadon is presently in the possession of the Shomer, the Shomer is not "Chashid a'Mamona" and might simply be trying to stall for time in order to pay back the Pikadon that was lost through his negligence (Peshi'ah). It is for this reason that one who is Kofer b'Pikadon is not Pasul l'Edus when witnesses do not testify that the Pikadon was in his possession at the time he denied it. Perhaps it is in only this case that the Torah requires a Shevu'ah to counter the Ed Echad, but not in the case of Kofer b'Milveh.
(In practice, even Rashi will agree that a person must make a Shevu'ah to counter a single witness who testifies that he owes money due to a loan, because the Rabanan instituted that a Kofer ha'Kol is not "Chashid a'Mamona"; see following Insight. Perhaps such a Shevu'ah even has the severity of a Shevu'ah d'Oraisa, since it is "k'Ein d'Oraisa." This would answer the question of Tosfos to 3b, DH b'Chulei.)
(c) The MAHARAM SHIF answers that the Gemara prefers to prove that one who is "Chashid a'Mamona" is not "Chashid a'Shevu'asa" from the Shevu'ah of "Chenvani Al Pinkaso," and not from the other cases of Shevu'os ha'Nishba'in v'Notlin, because in this case not only is one party suspected of stealing, but there is certainty that one of the two parties is stealing.
The TORAS CHAIM offers a similar answer and adds that this is the reason why Rashi (DH Neima) points out that in this case one of the defendants is certainly ("Vadai") "Chashid a'Mamona."
QUESTIONS: Rebbi Yochanan (5b) maintains that one who is "Chashid a'Mamona" (suspected of stealing) is not "Chashid a'Shevu'asa" (suspected of swearing falsely). The Gemara here cites support for his view from the law of Shevu'as Heses: Beis Din makes a person swear a Shevu'as Heses even when he is Kofer ha'Kol and there is suspicion that he might be lying and trying to steal.
Abaye disagrees with Rebbi Yochanan and says that even if one who is "Chashid a'Mamona" is "Chashid a'Shevu'asa," the Shevu'ah of the Mishnah is still appropriate since it may be assumed that the person who seized the Talis intends to collect it as payment for an old loan that he thinks the other person owes him ("Safek Milveh Yeshanah"), and he has no intention to steal it (and therefore he will not swear falsely).
(a) Why does the Gemara prove from the law of Shevu'as Heses that one who is "Chashid a'Mamona" is not "Chashid a'Shevu'asa" when it could prove the same thing from the Mishnah itself? The Mishnah states that a person must swear that the Talis belongs to him, which shows that a person suspected of taking a Talis that is not his is trusted to make a Shevu'ah.
One might suggest that the Gemara prefers to prove that he is not "Chashid a'Shevu'asa" from the case of Shevu'as Heses since the Shevu'ah of the Mishnah might be due to the concern of "Safek Milveh Yeshanah" as Abaye suggests, and not because he is "Chashid a'Mamona" and suspected of attempting to steal. However, this answer does not suffice because Abaye's reasoning also explains why Beis Din administers a Shevu'as Heses and does not suspect that the person is trying to steal. The person who denies the claim might have taken the object as payment for an old loan, as TOSFOS (DH Safek) explains. What, then, does the Gemara prove from Shevu'as Heses that it could not prove from the Mishnah?
(b) According to both Rebbi Yochanan and Abaye, it is clear that a person may make a Shevu'ah that he did not take unjustly what is not his. Rebbi Yochanan allows a Shevu'ah because one who is "Chashid a'Mamona" is not "Chashid a'Shevu'asa," and Abaye allows a Shevu'ah because the defendant might be taking the object as payment for a "Safek Milveh Yeshanah" and he is not "Chashid a'Mamona." (Abaye's logic seems to apply to any case in which a person takes money from someone else.)
Why, then, does RASHI write in a number of places (3b, DH v'Hai; Gitin 51b, DH uv'Chulei) that a person cannot make a Shevu'ah to deny a claim that he is taking money unlawfully, since one who is "Chashid a'Mamona" is "Chashid a'Shevu'asa"? Rashi writes this not only as the Havah Amina of the Gemara (see Tosfos to 3b, DH Aval) but even according to the Gemara's conclusion (and the Halachah)! (TOSFOS 3b, DH b'Chulei)
(a) The Mishnah does not provide conclusive proof that one who is "Chashid a'Mamona" is not "Chashid a'Shevu'asa." The Gemara earlier (2b) explains that in both cases of the Mishnah -- the case of Metzi'ah and the case of a sale (Mekach u'Memkar) -- it is possible that the defendant is taking what is not his because he is Moreh Heter. Since he is not committing an outright act of stealing, there is no reason to suspect that he will swear falsely.
Rashi alludes to this when he writes (5b, DH v'Neima) that the Gemara infers that one who is "Chashid a'Mamona" is not "Chashid a'Shevu'asa" from the wording of Rebbi Yochanan and not from the Mishnah. This rule is not evident from the Mishnah itself because, in the case of the Mishnah, the claimants might not be "Chashid a'Mamona." (See SHITAH MEKUBETZES in the name of MAHARI ABUHAV and MORI HA'RAV; see also RAN and RAMBAN to 2b.)
(b) As Tosfos implies there (3b, DH b'Chulei), Rashi maintains that although mid'Oraisa a person is not trusted to swear when he is "Chashid a'Mamona," nevertheless the Chachamim did permit him to make a Shevu'ah d'Rabanan. There are two possible reasons for this. One possibility is that the Chachamim saw that in later days people recognized the severity of swearing falsely more than they recognized the severity of stealing and therefore they may be trusted to swear. Alternatively, according to Abaye, the Chachamim took into account the minute possibility that the suspected thief is not really a thief but is merely attempting to reclaim a "Safek Milveh Yeshanah."
All of the proofs cited by the Gemara to show that a person may swear even when he is "Chashid a'Mamona" are from Shevu'os which the Rabanan instituted and which the Torah does not require: the Shevu'ah of the Mishnah, a Shevu'as Heses, Shevu'os of Nishba'in v'Notlin, and the Shevu'ah of a Shomer who swears that the item is not in his possession.
Tosfos there rejects Rashi's approach for two reasons. He proves from the Gemara in Shevu'os that the Chachamim may apply Halachos which normally apply only to Shevu'os d'Oraisa when an Ed Echad testifies that the object that a person is holding belongs to someone else. (This question on Rashi is addressed earlier in Insights to 5b.)
Tosfos also challenges Rashi's approach from the Shevu'ah of a Shomer who swears that he was not "Shole'ach Yad b'Pikadon," which is a Shevu'ah d'Oraisa. Rashi (here, DH she'Lo Shalachti, and on 5a, DH v'ha'Gazlan) answers this question by pointing out that "she'Lo Shalachti Bo Yad" does not mean that "I did not take the Pikadon for myself" (or that "I did not eat it," as Rabeinu Tam explains in Tosfos DH Shevu'ah). Rather, it means that "I did not use the Pikadon without permission." If the Shomer uses the Pikadon without permission, then even if he returns it to its former place he becomes obligated from that point on to pay for any damage, even if the object becomes damaged by an Ones. Therefore, the only practical difference between when a Shomer is Shole'ach Yad and when he is not exists when the object is destroyed by an Ones. If he was Shole'ach Yad, he must compensate the owner even though he is a Shomer Chinam (or Shomer Sachar). However, if the Shomer denies owing compensation to the owner for an Ones, he might be attempting to stall for time ("Mishtamet"), since the payment that he owes is like a debt and not a specific object, and thus he is considered to be denying a debt and not a specific object.
Why, though, does he not become "Chashid a'Mamona" at the moment at which he used the Pikadon and was Shole'ach Yad? At that moment, he certainly was stealing, and thus he should be "Chashid a'Mamona."
The RAMBAN here answers that a Shomer's misappropriation of a Pikadon does not make him "Chashid a'Mamona" because he is Moreh Heter and says that he will return it to its place as soon as he is finished using it.


QUESTION: The Gemara asks what the Halachah would be when one of two people holding on to a Talis is Makdish the Talis. If the law in a case in which one person grabs the Talis away from the other permits him to keep the Talis (because the silence of his opponent is considered admission that the Talis is not his), what is the Halachah when one of the contestants is Makdish the Talis? Is this considered like grabbing it away (such that the silence of his opponent is considered admission that it is not his) or not?
The Gemara (7a) asks a similar question about a bathhouse over which two people were quarreling, and one of them was Makdish it. Is it Kadosh or not? Rav Hamnuna attempts to prove that it is Kadosh from a Mishnah that states that a Safek Bechor is Kadosh and therefore is Asur b'Gizah v'Avodah, because if a Kohen would seize it he would be permitted to keep it. (The Gemara assumes at this point that the Kedushah of a Bechor stems from the fact that it belongs to the Kohen and is his property.) The Gemara rejects this proof and says that the Kedushah of a Bechor is independent and is not related to the Kohen.
When the Gemara says that when one of the claimants grab the Talis from the other (and the other is silent at first and then later protests), he is allowed to keep it, the Gemara explains that the silence of the opponent at the time the Talis was seized from him is considered an admission to the fact that the Talis is not his. (Some Rishonim understand that his silence is not an admission that the other person owns it, but it is a sign of agreement to give it to him from now on.)
Presumably, when the Gemara says that declaring the Talis as Hekdesh is comparable to physically grabbing the Talis, it is also addressing the question of whether or not the silence of the opponent is considered an admission. The Gemara is discussing a situation in which the opponent was silent at first and then protested. How, then, can the Gemara prove from the case of a Safek Bechor that silence to a declaration of Hekdesh is considered an admission that the Talis does not belong to him? In the case of a Safek Bechor, neither the Kohen nor the Yisrael knows whether the animal is Kadosh or not (see Rashi, DH Echad Bechor Adam)! In such a case, the silence of the Yisrael cannot be an admission that the animal does not belong to him! Moreover, in the case of a Safek Bechor, the animal is Kadosh even if the Kohen never says a word, and even if the Yisrael protests the Kedushah. How, then, can the Yisrael's silence be considered an admission?
(a) TOSFOS (6a, DH Hikdishah) explains that although the case of "Hikdish Talis" involves only a question of whether Hekdesh is like Hoda'ah, admission, the case of the bathhouse which one of the claimants was Makdish involves an additional question. When two people argue over the ownership of a bathhouse, the Halachah is "Kol d'Alim Gavar" (the stronger one prevails), according to Tosfos, since neither one is in physical possession of the disputed bathhouse. Therefore, even if the silence of the opponent is not considered an admission, perhaps the act of making it Hekdesh is considered a way of overpowering the other party. For that reason, just as when one of the claimants takes possession of the bathhouse for himself it is considered fully his and he may be Makdish it, so, too, when he is Makdish it without grabbing it, it is considered fully his and it becomes Kadosh. (The act of grabbing and the Kedushah are considered to occur simultaneously, "Ba'in k'Achas"; see RITVA, end of DH Im Timtzi Lomar.)
It is this question which the Gemara attempts to resolve from the Halachah of Safek Bechor. The Gemara thinks that the Kedushah of the Bechor stems from the ownership of the Kohen, and since if the Kohen overpowers the Yisrael and takes the Bechor it becomes his, therefore even if he does not physically overpower the Yisrael to take the Bechor, the Bechor becomes Kadosh because of the Kohen's rights to ownership.
How is this related to the question of the Gemara in the case of one who is Makdish the Talis? Tosfos explains that the Gemara's proof, that one's silence when his opponent makes the Talis Hekdesh is considered an admission, is from the Gemara's conclusion (7a) in the case of the bathhouse. The Gemara there concludes that the bathhouse does not become Kadosh. From this ruling two things are evident: First, making something Hekdesh is not considered a form of overpowering one's opponent, even where the Halachah is "Kol d'Alim Gavar." Second, the silence of one of the claimants is not considered an admission when the other party is Makdish the object.
(b) The RITVA writes that the Gemara intends simply to prove whether a declaration of Hekdesh has the same power as an act of physically grabbing the item. Although, with regard to the Safek Bechor, Hekdesh cannot prove the ownership of the Kohen in the same way that it can prove the ownership of one of the claimants of the Talis, nevertheless it is clear from the case of Safek Bechor that in a situation where seizure can acquire an object for someone, Hekdesh also can take effect. Similarly, with regard to an object in doubtful ownership such as the Talis, if grabbing the object can determine the ownership of the object, then so, too, Hekdesh can effect. (The proof is not absolute, but rather "Dumya b'Alma Nakat," as the Ritva writes.)
(c) The CHIDUSHEI HA'RAN explains that if an act of grabbing the Talis can determine the ownership of the Talis, this shows that even an act which does not provide clear proof of ownership (since the opponent, although silent at first, eventually protested) can determine the true owner of the Talis. The fact that one's act of grabbing the Talis determines that he is the rightful owner demonstrates that when the two claimants entered Beis Din holding a Talis together, their joint possession of the Talis was not taken as an indication that each of the parties definitely owns half of the Talis (as the Gemara mentions on 3a; see Insights to 2b). Rather, when two people enter Beis Din holding a Talis together, the ownership of the entire Talis is in question in the eyes of the court. Since it is possible that the entire Talis belongs to the one who later grabs it, the questionable proof of silence in the face of seizure suffices to determine that the one who seized it is the true owner.
The Gemara therefore asks what the Halachah will be if one of the claimants holding the Talis is Makdish it. Does the Hekdesh take effect out of doubt (mi'Safek) because the one who was Makdish it is a Safek owner, and once it takes effect mi'Safek it must be removed from the hands of the opponent since it might be Kadosh? Perhaps, on the contrary, since the one who was Makdish it is not a true owner and could not prove in court that the Talis belongs to him, it is considered "Eino b'Reshuso" and the Hekdesh does not take effect at all. (This is consistent with the Girsa in our text of the Gemara at the end of 6a which says that one can be Makdish only something that is "b'Reshuso," in his possession. Many of the Rishonim do not have this Girsa.)
According to this explanation, the proof from Safek Bechor is clear. In that case, the Kohen has a Safek ownership of the animal, and yet the animal can become Kadosh mi'Safek by virtue of his rights of ownership (even though his ownership cannot be proven in court).
This also seems to be the approach of RASHI (see Rashi to 6b, end of DH l'Olam, and DH ha'Motzi me'Chaveiro).
QUESTION: The Gemara discusses a case in which an animal which was already designated as Ma'aser Behemah jumped back into the pen of uncounted animals and became lost among them. In such a case, all of the animals are exempt from Ma'aser Behemah because the Torah requires that the animal of Ma'aser be Ma'aser Vadai, definite Ma'aser. The SHITAH MEKUBETZES explains that one might have thought that the owner may rely on the "Rov" and continue to count the animals and designate every tenth animal as Ma'aser, since all but one of the animals were not counted yet. The Shitah Mekubetzes adds that whenever the Halachah requires that something be definite, one may not rely on the Rov. A Rov does not establish fact; it merely tells one to conduct himself in a case of doubt.
The Gemara in Kidushin (73a) discusses the Torah's prohibition against a Mamzer joining the Jewish people, the "Kahal Hash-m" (Devarim 23:3). The Gemara explains that the Torah prohibits a Mamzer from marrying into a "Kahal Vadai," a "definite congregation" (a reference to a Jew of pure lineage, excluding a Shetuki and others of questionable lineage; see Kidushin there). Since the identity of a person's father is always based only on Rov and is never known for certain, it is apparent that the condition of "Kahal Vadai" means a congregation of people who are from the definite congregation of Hash-m as based on the Rov.
The SHEV SHEMAITSA (2:15) asks that the Gemara in Kidushin contradicts the explanation of the Shitah Mekubetzes here. According to the Shitah Mekubetzes, how can there ever be a "Kahal Vadai" if paternal lineage is established only based on Rov?
(a) The Shev Shemaitsa answers that the statement of the Shitah Mekubetzes was said only with regard to a "Ruba d'Isa Kaman." "Ruba d'Isa Kaman" refers to a situation in which the Rov is physically in our presence. For example, when one piece of Tereifah meat became mixed up with two pieces of kosher meat, the Rov is in front of us. Similarly, when there is a doubt about whether the animal being counted as Ma'aser is from those not yet counted or from those already counted, the Rov cannot determine from which set this animal comes. Both possibilities are equally likely. This is in contrast to a "Ruba d'Leisa Kaman." A "Ruba d'Leisa Kaman" refers to a majority in frequency; something usually occurs in this manner. There is no tangible item in front of us, however, which presents that Rov. For example, there is a Rov that "most animals are not Tereifos." This Rov is not related to any tangible item in front of us; rather, this Rov states a fact in the frequency of the occurrence of mortal blemishes in animals (i.e. that most animals are born healthy). In such a case, the Shitah Mekubetzes would agree that the Rov establishes the reality, and therefore a "Kahal" can be a "Kahal Vadai" based on such a Rov.
The KEHILOS YAKOV (#7) writes that he never understood the logic behind the Shev Shemaitsa's answer. The reality of a "Ruba d'Isa Kaman" is the same as the statistics of a "Ruba d'Leisa Kaman." Both have the same chance of happening. Why should there be a difference between a situation which has a physical representative of the statistical probability ("Isa Kaman") and one that is purely statistical in nature ("Leisa Kaman")?
RAV ELIMELECH KORNFELD shlit'a suggests that the Shev Shemaitsa means that there is a fundamental difference between the two types of Rov. In the case of the animal of Ma'aser Behemah (Ruba d'Isa Kaman), it is known as a fact that an animal that was already counted jumped back into the herd. The fact that most of the animals were not yet counted does not remove the doubt that each animal may be the one that was already counted. However, in the case of "Kahal Vadai" (Ruba d'Leisa Kaman), there is no evidence that the man assumed to be one's father is not really his father. In a case where no doubt presents itself in front of us, the Shitah Mekubetzes would agree that a Rov creates a situation of "Kahal Vadai."
(b) REBBI AKIVA EIGER (Teshuvos, 2:108) answers that the Shitah Mekubetzes agrees that when a Rov has already been used to determine other Halachic matters that do not need a definite status (for example, in the case of the Rov that tells us that a father is the real parent of his son, the Rov also tells us that the father is obligated to perform a Bris Milah for his son, and that the son is obligated to honor his father, etc.), the Rov becomes a certainty. He proves this from the case of Ma'aser Behemah itself. According to the Shitah Mekubetzes, how can one ever perform the Mitzvah of Ma'aser Behemah when it is possible that there is an animal among those counted which is a Tereifah? The answer is that there is a Rov that most animals are not Tereifos. The fact that we rely on this Rov, despite the fact that Ma'aser Behemah needs to be Ma'aser Vadai, shows that even the Shitah Mekubetzes himself agrees that a Rov which establishes itself once turns into a Vadai.
A similar explanation is given by the HAFLA'AH in Kesuvos (15a). Rov is not applied to cases of monetary judgments ("Ein Holchin b'Mamon Achar ha'Rov"; see Bava Kama 27b). However, there are many monetary cases which apparently do follow a Rov. One example is the case of Ones u'Mefateh (rape and seduction), where the guilty man must pay a fine to the father of the girl involved. Since it is known that the girl's father is her real father only because of a Rov, why does the criminal not invoke the principle that Rov does not apply to monetary judgments and say that he does not owe money to the person who claims, based on Rov, to be the girl's father? The Hafla'ah explains that apparently once a Rov is used, it is considered factual. However, the Hafla'ah adds that it appears that the Rishonim do not agree with this approach. (See Hafla'ah at length. See also Kehilos Yakov 7:3 for an additional answer.) (Y. MONTROSE)