1) A CHAZAKAH WITHOUT A CLAIM
QUESTION: The Mishnah states that a Chazakah is a valid proof of ownership of land only when it is accompanied by a claim (such as "I bought the land from you"). If, however, the Machzik says merely that he has occupied the land for three years and no one told him to leave, his Chazakah does not establish his ownership of the field.
The RAMBAM (Hilchos To'en v'Nit'an 14:12) rules that even though a Chazakah without a claim is not a valid Chazakah, the Machzik cannot be evicted from the property unless the claimant brings two witnesses who testify that the field belongs to him.
The VILNA GA'ON (in BI'UR HA'GRA, CM 146:20) challenges the Rambam's ruling on the basis of the Gemara earlier (35b). The Gemara there discusses a case in which two people dispute the ownership of an object and neither one has proof of ownership (such as witnesses or a Chazakah). The Gemara states that in such a case, Beis Din does not get involved. Rather, whichever one of the disputants is able to seize the object for himself is entitled to do so. The Gemara continues and says that if a third party -- who makes no claim of ownership of the object -- comes and seizes the property, the Halachah is that he is considered a thief and he must return the property to the first two claimants.
The Gemara there seems to contradict the ruling of the Rambam. The Rambam rules that a Machzik who has no claim to the property, but who has a Chazakah, is not evicted, but the Gemara there states that the property is removed from the Machzik who seizes it with no claim, even though the two claimants have no proof of prior ownership!
ANSWER: The NESIVOS HA'MISHPAT (146:9) answers that in the case of the Mishnah, even though the Machzik does not have a valid claim on the field, the claimant also has no proof that the field is his (if he does not bring witnesses that he owned the field). Therefore, this case is comparable to the case of a lost object which belongs to the finder until someone else either brings witnesses that the lost object belongs to him, or is able to describe to the finder identifying marks on the object which would require the finder to give it back to him. Similarly, in this case, the field remains in the possession of the Machzik until someone else brings proof of ownership (such as witnesses). In contrast, in the case of the third party who seizes the property from the two claimants, since each of the two claimants argues with certainty that the property is his, they both have a claim of "Bari" (even though they have no proof), while the third party has no claim at all and therefore is considered no better than one who has a claim of "Shema" (an uncertain claim). Therefore, the property is considered the possession of one of the first two claimants, and, consequently, the third party who seized it must return it to them. It is not known with certainty to which of the claimants it belongs, but it is assumed to belong to one of them.
2) DISPUTED TESTIMONY
QUESTION: The Gemara relates that a flood in Rav Kahana's field washed away the fence around his field. Rav Kahana replaced the fence, but it was not clear where the original fence had stood. Rav Kahana's neighbor brought two witnesses before Rav Yehudah. One witness testified that Rav Kahana had taken two rows of land from the neighbor's field and annexed them to his own field. The second witness testified that Rav Kahana had taken three rows from the neighbor's field. Rav Yehudah ruled that Rav Kahana must return two rows of land to his neighbor. The Gemara states that this ruling is in accordance with the view of Beis Hillel, who says that when one witness says that a debtor owes 100 Zuz and another witness says that he owes 200 Zuz, the Halachah is that the debtor must pay 100 Zuz, because the two witnesses are in agreement about the first 100 Zuz.
The SHACH (CM 31:1) cites the "Chochmei Brisk" who discuss the Halachah in a case in which there is conflicting testimony from the witnesses. Are those witnesses believed to give testimony in a different case? Perhaps they may not testify as witnesses in a different case, since each witness has been contradicted by the other, and thus he has the label of a liar. The Shach cites proof from the RAN in Kesuvos (10a of the pages of the Rif, DH Ed) who writes that both witnesses are disqualified from future testimony because each one has been contradicted.
Why does the Shach not cite proof from the Gemara here to the contrary? When one witness testified that Rav Kahana owed his neighbor two rows, and the other testified that Rav Kahana owed three rows, Rav Yehudah ruled that Rav Kahana must return two rows, and the witnesses were not rendered invalid as a result of contradicting each other!
ANSWER: The MINCHAS CHINUCH (end of #37) writes that proof for the Shach's ruling is found in the NIMUKEI YOSEF here (22a of the pages of the Rif). The Nimukei Yosef asks why the witnesses are believed at all if one of them is certainly a liar. The Nimukei Yosef answers that in this case it is possible that neither of the witnesses is lying deliberately. Rather, one of the witnesses is merely making a mistake, because it is easy to err between two rows and three rows of land. Similarly, a person could make a mistake about whether a borrower owes 100 Zuz or 200 Zuz.
The words of the Nimukei Yosef imply that in a case in which it is not possible to justify the conflicting testimony of both of the witnesses, and it is clear that one of them is lying (but it is not known which one), the Halachah is that they are both disqualified from future testimony. Hence, the Gemara is actually a proof for the Shach's ruling that both witnesses are disqualified. (In fact, the Minchas Chinuch writes that he is perplexed that the Shach himself does not cite this proof from the Nimukei Yosef.) (Y. MARCUS)