1) THE SOURCE FOR THE RULE OF "GUD O AGUD"
OPINIONS: Rav Yehudah and Rav Nachman argue about whether there is a law of "Gud O Agud." Rav Yehudah maintains that there is such a law, and the Halachah follows his view. Therefore, when two partners own an object that cannot be divided, one partner may force the other either to sell his own portion or to buy his partner's portion.
What is the source of this law of "Gud O Agud," and what is its logical basis?
There are two approaches in the Rishonim.
(a) The ROSH (Teshuvos 98:3) maintains that "Gud O Agud" is a Takanas Chachamim, based on the reasoning of "Zeh Neheneh v'Zeh Lo Chaser, Kofin Al Midas Sedom," which means that whenever one litigant would gain from a ruling in his favor and the other litigant would not lose anything, Beis Din forces the second litigant to allow the first to benefit. In this case, since the jointly-owned area or object is not fit to be used by both partners, and thus neither of them can benefit from it while it is shared, the Chachamim decreed that one partner may force a division and the other is obligated either to sell his own share or to buy the other partner's share. This also seems to be the view of the RASHBA (Teshuvos #906), and RABEINU YONAH (cited by the Shitah Mekubetzes on 13b).
(b) The MABIT in KIRYAS SEFER (beginning of Hilchos Shechenim) maintains that the law of "Gud O Agud" is mid'Oraisa. Just as the other laws relating to partnerships -- such as the right of one partner to force the other to divide the property when it is of sufficient size -- are mid'Oraisa, the law of "Gud O Agud" is also mid'Oraisa. Likewise, when "Gud O Agud" does not apply, mid'Oraisa one partner can force the other to rent the property out to others and to share the profits.
What is the source of this Din d'Oraisa? Where in the Torah is a law written regarding the division of jointly-owned property?
The CHAZON ISH (Bava Basra 8:1), in his explanation of the law of "Gud O Agud," suggests that the Torah commands the Chachamim to establish laws based on the "Chochmas ha'Torah" with which the Chachamim are endowed. This is based on the verse, "v'Asisa ha'Yashar veha'Tov" (Devarim 6:18). Hence, the law of "Gud O Agud" was established by the Chachamim who, in their wisdom, discerned that this is the most ideal way to divide property that two partners inherit or receive as a gift. Once the Chachamim have established the law of "Gud O Agud," it has the force of a Din Torah.
The BI'URIM V'HE'OROS adds that the concept that the Torah gives the Chachamim the power to establish monetary law (which then has the force of Torah law) is learned from the words of the RAMBAN on the verse, "v'Asisa ha'Yashar veha'Tov." The Ramban writes that this verse "is a Mitzvah to act beyond what the law requires, and, likewise, to make enactments for the welfare of the city and the country." Although the first requirement he mentions, "to act beyond what the law requires," is incumbent on individuals, the requirement to "make enactments" is addressed to Beis Din and the Chachamim. Thus, this verse indicates that the Torah commands the Chachamim -- and gives them the power -- to enact monetary laws for the sake of the welfare of society.
(The Bi'urim v'He'oros adds that according to the Chazon Ish's explanation, it could be that the words of the Rosh do not contradict the Mabit. When the Rosh says that "Gud O Agud" is a Takanas Chachamim, he agrees that the Torah gave the Chachamim the authority to enact such laws. When the Mabit says that it is a Din d'Oraisa, he agrees that it was the Chachamim who enacted the law, but that it has the force of a Din d'Oraisa, as explained above.)

13b----------------------------------------13b

2) HALACHAH: ACCEPTING A GIFT
QUESTION: The Beraisa quotes a dispute between the Rabanan and Raban Shimon ben Gamliel regarding a jointly-owned area or object that is not large enough to be divided between the two partners, such as a Chatzer with an area of less than eight Amos. If one partner offers to let the other have the minimum amount that is necessary to divide a Chatzer (four Amos), while he himself will take the remainder, even though it is less than the minimum amount of a Chatzer, the Rabanan maintain that the other partner must accept those terms (for they are beneficial to him) and let the Chatzer be divided. Raban Shimon ben Gamliel argues and says that the other partner may refuse to accept the terms of the division. The Gemara explains that the partner may refuse to divide the Chatzer even though he apparently would benefit from it, because he can claim that he does not want to receive a gift, as the verse says, "One who despises gifts will live" (Mishlei 15:27).
If the verse supports Raban Shimon ben Gamliel's opinion, then why do the Rabanan argue? Why do they not accept the other partner's claim that he does not want to accept the gift because "one who despises gifts will live"?
ANSWER: The RASHBA and RABEINU YONAH (as cited by the Shitah Mekubetzes) answer that when the first partner offers to give a larger part of the Chatzer to the second partner and accept a smaller part for himself, his intention is not to give a gift to his partner. Rather, his intention is for his own benefit, for he would prefer to have a smaller Chatzer rather than remain in partnership with his neighbor. When the giver of a gift also benefits, the verse, "One who despises gifts will live," does not apply to the recipient. (This is also the answer of the S'MA (CM 171:24) as cited by the CHASAM SOFER here.)
HALACHAH: The Rishonim argue about whether the Halachah follows the view of the Rabanan or that of Raban Shimon ben Gamliel.
(a) The RIF and the RAMBAM (Hilchos Shechenim 1:5) rule in accordance with Raban Shimon ben Gamliel's position. The Rif writes that Raban Shimon ben Gamliel's "reasoning is [more] logical."
(b) RABEINU CHANANEL (citing one opinion) rules in accordance with the Rabanan's view, as do RABEINU YONAH, the RASHBA, and the ROSH. Rabeinu Yonah counters the Rif's assertion that Raban Shimon ben Gamliel's reasoning is more logical. He explains, as above, that the principle of "one who despises gifts will live" applies only when the giver himself does not benefit from the gift. In this case, the giver benefits, so there is nothing wrong with accepting a gift, and therefore Beis Din may force the second partner to accept the terms of the division.
3) A POSSIBLE EXCUSE NOT TO GIVE TZEDAKAH
QUESTION: The Beraisa quotes a dispute between the Rabanan and Raban Shimon ben Gamliel regarding a jointly-owned area or object that is not large enough to be divided between the two partners, such as a Chatzer with an area of less than eight Amos (see previous Insight). If one partner offers to let the other have the minimum amount that is necessary to divide a Chatzer (four Amos), while he himself will take the remainder, even though it is less than the minimum amount of a Chatzer, the Rabanan maintain that the other partner must accept those terms (for they are beneficial to him) and let the Chatzer be divided. Raban Shimon ben Gamliel argues and says that the other partner may refuse to accept the terms of the division. The Gemara explains that the partner may refuse to divide the Chatzer even though he apparently would benefit from it, because he can claim that he does not want to receive a gift, as the verse says, "One who despises gifts will live" (Mishlei 15:27).
The principle that "one who despises gifts will live" seems to contradict the general Mitzvah of Tzedakah. According to this verse, whenever a person gives Tzedakah to a poor person, he actually harms the poor person and shortens his life by causing him to accept a gift! How, then, can there be a Mitzvah to give Tzedakah? Similarly, how can one be permitted to give money to support Talmidei Chachamim? Seemingly, the Talmidei Chachamim should not accept the money because "one who despises gifts will live."
ANSWERS:
(a) The CHIDA (in Teshuvos Chaim Sha'al 1:74:42) answers based on the view of the Rishonim mentioned above (see previous Insight) that when the giver intends to benefit personally from giving the gift, his gift is not considered a gift. A person who gives Tzedakah to the poor or supports Talmidei Chachamim receives tremendous reward for his Mitzvah, and thus it is not considered a gift since the giver also benefits from it.
RAV CHANOCH HENOCH KARELENSTEIN zt'l (in SEFER MAR'EI MEKOMOS) answers based on the words of the OR HA'CHAIM HA'KADOSH in Parshas Mishpatim. The verse there says, "When you lend money to any of My people, to the poor person among you, do not act to him as one who demands repayment of a loan, and do not set interest upon him" (Shemos 22:24). The Or ha'Chaim explains that the verse may be read in the following way: "If you see that you have more money than you need for your own needs and thus you lend it to My people, you should know that that money is not part of your allotted portion, but rather it belongs to others -- to the poor person among you." (The TUR (YD 247) writes that the money of a wealthy man is a Pikadon, a deposit, from Hash-m, Who expects the wealthy man to do the appropriate things with that money. This is one source for the concept that the money a person gives to the poor never actually belonged to the giver in the first place; he was merely a conduit for the money to reach its rightful owners.)
Accordingly, when one gives money to a poor person, it is not considered a gift, because that money rightfully belonged to the recipient all along. (I. Alsheich)

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