1) HALACHAH: DOES THE LAW OF "ONA'AH" INVALIDATE A SALE OF LAND?
OPINIONS: The Mishnah (end of 56a) teaches that the laws of Ona'ah do not apply to land. The Gemara attempts to clarify the Mishnah and asks whether this means that there is no prohibition against Ona'ah but a sale does become annulled if one party was cheated, or whether the Mishnah means that the laws of Ona'ah do not apply to land whatsoever. Rav Nachman quotes Rav Chasa who says that although there is no prohibition against Ona'ah, the sale does become annulled.
TOSFOS (DH Amar Rav Nachman) asks that Rav Nachman seems to contradict himself. The Gemara later (108a) discusses a case in which one pays 200 for property worth 100. Rav Nachman says that the sale is valid since Ona'ah does not apply to land. Here, however, Rav Nachman says that the sale is not valid when one is overcharged for land.
(a) RABEINU TAM (cited by Tosfos) explains that both statements of Rav Nachman are true. Rav Nachman maintains that Ona'ah invalidates a sale of land only when the amount overcharged is more than double the actual value (in contrast to the standard rate of Ona'ah, which is one sixth more than the actual value). Since the Ona'ah in the case of the Gemara later is exactly (and not more than) double, Rav Nachman rules that the sale is valid. In the Gemara here, when Rav Nachman says that Ona'ah in the case of land can invalidate the sale, he refers to a case in which the overcharge was more than double the value of the land.
This is also the position of RABEINU CHANANEL, the ROSH, and REMA (CM 227:29).
According to Rabeinu Tam, what is the basis for this measure of Ona'ah for land? RAV ELYASHIV shlit'a (as cited in HE'OROS B'MASECHES KIDUSHIN) explains that just as the Torah gave to the Chachamim the authority to determine the amount that constitutes Ona'ah for regular merchandise (one sixth), it gave them the authority to determine the amount that constitutes Ona'ah for land. The Chachamim reasoned that although a given piece of land cannot be ascribed an exact value, an overcharge of more than double its approximate value constitutes Ona'ah.
(b) The RIF, RAMBAM, and most Rishonim disagree with Rabeinu Tam. They rule that there is no Ona'ah for land at all. The Rif explains that although the Gemara here implies that there is Ona'ah with regard to invalidating the sale, the Halachah follows the view of Rav Nachman (who is a later Amora and whom the Halachah generally follows in monetary matters) who says later (108a) that there is no Ona'ah whatsoever for land. When Rav Nachman here says that there is Ona'ah for land with regard to invalidating the sale, he is merely quoting Rav Chasa. Rav Nachman himself rules otherwise.
This is the ruling of the SHULCHAN ARUCH (CM 227:29). The S'MA points out that even according to the Shulchan Aruch, one is not permitted to overcharge for land (or to intentionally not alert a seller when one buys land). The fact that the Torah does not apply the laws of Ona'as Mamon to land does not mean that it permits one to cheat others by selling useless plots of land. A person who knowingly cheats someone in such a manner transgresses the Isurim of Ona'as Devarim and Geneivas Da'as. (Y. MONTROSE)
2) THE SOURCE THAT A SHOMER IS NOT LIABLE FOR FAILURE TO GUARD A "SHTAR"
QUESTION: The Gemara derives through a Klal u'Frat u'Chlal that a Shomer is liable only for movable objects which have intrinsic value. This excludes land which is not movable, slaves (which have the same Halachic status as land due to a Hekesh), and Shtaros (legal documents) which have no intrinsic value.
The KETZOS HA'CHOSHEN (CM 291:5) asks that the teaching with regard to Shtaros seems unnecessary. RASHI in Bava Kama (79a, DH Tiknu) writes that a Shomer's obligation to guard an object takes effect only when he does an act of Meshichah to that item. Shtaros, however, are acquired only through Kesivah u'Mesirah (writing and handing over). For example, the Gemara in Bava Kama says that a person who wants to sell a Shtar (to someone who will collect the debt in his place) writes in a document that "you, the buyer, acquire this legal document and all of its obligations." Only when this paper is handed over does the transaction become valid. Since a Shomer is obligated to guard an item only when he has done Meshichah to it, and Meshichah is not applicable to Shtaros, why would one think that a Shomer has any obligation to guard a Shtar?
(a) The KETZOS HA'CHOSHEN answers that his question may be based on a faulty assumption. Although Rashi in Bava Kama, whom he quotes, indeed writes that Shtaros are acquired only through Kesivah u'Mesirah, the MAHARAM MI'LUBLIN (Teshuvos #22) asserts that Rashi writes this only in reference to one who sells a Shtar. Since the buyer wants the full ownership of the rights in the Shtar, the Chachamim required that the seller explicitly write that the buyer acquires all of the rights in the Shtar. In contrast, if a lender decides to declare a Shtar as Hefker, he loses his claim to the debt written in the Shtar despite the fact that he never put this in writing. Similarly, a Shomer does not have to acquire the actual Shtar which he accepts to guard, and thus there is no requirement that he acquire the Shtar through Kesivah u'Mesirah. Accordingly, the Klal u'Frat u'Chlal is necessary to teach that a Shomer is not liable for Shtaros.
(b) The NESIVOS HA'MISHPAT (CM 291:12) answers based on the words of TOSFOS in Kesuvos (85b, DH ha'Mocher) that there are times when a Shtar indeed is acquired through Meshichah, such as when it is bought for the purpose of selling it to the borrower (see Tosfos at length who says that this becomes an ordinary Mechirah). If a Shomer would receive a Shtar in order to facilitate such a Mechirah (for example, the Shomer himself tries to initiate such a sale), it is logical that he should be held responsible for the Shtar once he has done Meshichah. This is why the Klal u'Frat u'Chlal is needed to exclude the Shomer from liability. (See also CHOCHMAS SHLOMO ibid.) (Y. MONTROSE)