QUESTION: Ilfa states that if an animal in Reshus ha'Rabim stretches its neck and eats food from a bundle on top of another animal, the owner is obligated for payment of "Shen" because it is like his animal did damage in the Reshus of the Nizak. The Gemara attempts to prove this from the Beraisa which states that if an animal stretched its neck and ate from a basket suspended from a person's shoulder in Reshus ha'Rabim, the owner of the animal is liable. The Gemara refutes the proof by suggesting that the only reason the animal is liable in such a case is that it jumped (Kofetzes). The Gemara cites a statement of Rava who explains a ruling of Rebbi Oshiya in this manner as well. Rebbi Oshiya rules that if an animal walks and eats the food of someone else in Reshus ha'Rabim the owner is exempt, but if it stands and eats the owner is liable. Rava explains that there should be no difference between eating while walking and eating while standing, since both acts involve damage done in the course of the normal way an animal behaves. Rather, explains Rava, when Rebbi Oshiya says that the owner is liable when the animal stands and eats, he must mean that the owner is liable when the animal jumps and eats.
If an animal jumps (Kofetzes) and eats in Reshus ha'Rabim, is the owner obligated to pay Nezek Shalem (like Shen) or Chatzi Nezek (like Keren)?
The Gemara implies that for any act done in Reshus ha'Rabim that is a normal way of eating, one is exempt altogether, since it falls in the category of Shen. This implies that the reason why the owner is liable when the animal jumps is that it is not a normal act, and thus it is in the category of Keren and the owner must pay Chatzi Nezek.
The Gemara's implication is consistent with the Tosefta (1:4) which describes an animal that eats from a bundle hanging over a person's shoulder as a case of a Shinuy, or Keren. However, the Gemara earlier teaches that if a goat climbs up to the top of a barrel and eats the turnip that is there, the goat's owner must pay Nezek Shalem for damage done to the barrel in addition to the payment for the turnip, since it is considered the normal manner for an animal to ruin a barrel in order to get to the food that rests on top of it. Accordingly, it also should be considered normal for an animal to jump in order to get to the food that is on top of another animal's back. The Tosefta indeed concludes that when the animal eats from a basket hanging over a person's shoulder, the owner of the animal pays for "what it damaged" ("Mah she'Hizikah"), a term usually reserved to describe the damages of Shen and Regel in Reshus ha'Nizak (for which one pays Nezek Shalem, as the Mishnah says on 19b). If "Kofetzes" is in the category of Shen, why should one be liable in Reshus ha'Rabim altogether, if we do not accept Ilfa's teaching that eating off of the back of another animal is considered eating in Reshus ha'Nizak? Also, why does the Tosefta refer to it as a Shinuy?
(a) RASHI (DH b'Kofetzes) and TOSFOS (21b, DH d'Ilfa) explain that the case of Kofetzes indeed is a Shinuy, an unusual way of causing damage, and the owner of the animal pays only Chatzi Nezek. According to Rashi, the Tosefta which says that the owner is obligated to pay "Mah she'Hizikah" means that the owner pays not the amount that was damaged (i.e. the amount of benefit that the animal received), but according to the amount that was damaged. This means that if the animal which jumped was a Tam, the owner pays half of the amount of the damage, and if it was a Mu'ad he pays the full amount. (Rashi on 19b explains the words "Mah she'Hizikah" in the Mishnah in a similar manner.)
Tosfos (21a, DH uv'Mechazeres) disagrees with Rashi and maintains that "Mah she'Hizikah" means Nezek Shalem. Perhaps Tosfos learns that the Tosefta refers to an animal that was a Mu'ad, or that it rules like Rebbi Tarfon and refers to an animal that damaged in the Chatzer of the Nizak. (See MITZPEH SHMUEL on the Tosefta, #80.)
Why is the case of Kofetzes different from the case of the goat that climbed up the barrel? It is different either because an animal will climb in order to reach food but it will not normally jump to reach food (TORAS CHAIM), or because only a goat does such acrobatics in order to obtain food, but not other animals (PNEI YEHOSHUA). (Tosfos' words there are more consistent with the approach of the Toras Chaim.)
(b) The RAMBAN (in Milchamos) and the RASHBA prove from the Tosefta, which obligates the owner to pay "Mah she'Hizikah," and from the Gemara's case of the goat that climbed the barrel, that Kofetzes is a case of Shen and the owner must pay Nezek Shalem. The Rashba explains that the reason why one is liable for Kofetzes even though one is exempt in a case of an animal that stretches out its neck and eats from the back of another animal is that Kofetzes refers to when the animal jumps onto the back of the other animal (or a person) and eats from there; since the animal is entirely supported by the animal or person carrying the food, it certainly is considered to be in the Reshus of the Nizak. (The Ramban in Milchamos implies that even if the animal that is eating does not land on the other animal's back, but it eats while in flight, it is still considered to be damaging in Reshus ha'Nizak since its feet are not resting in Reshus ha'Rabim.)
(c) The ROSH (2:4) explains that the Halachah of Ilfa revolves around the question of whether or not one is permitted to keep his food in a sack on the shoulders of an animal or person in Reshus ha'Rabim, or whether he is supposed to keep his food away from such places. Perhaps since it is known that animals walking in Reshus ha'Rabim have access to those places, people absolve each other from any responsibility for damages caused to food in such places. (See Rosh 1:1, and Insights to 14:1.)
Even if the Halachah does not follow Ilfa's ruling and it exempts a person for damages when his animal eats the food on top of another animal, the owner still will be obligated when his animal jumps and eats food which is resting on a high ledge. Although jumping in this manner is not considered a Shinuy and it remains an act of Shen (and is not an act of Keren) as the Rashba says, nevertheless people do not forgive each other the damages caused to food resting on a high ledge (or on the top of a tall animal) since it is not expected for animals in Reshus ha'Rabim to get to food in such places. This also seems to be the interpretation of RABEINU CHANANEL.
(According to the Rosh, even if the high ledge is in Reshus ha'Rabim and is not private property, the owner of the animal is still liable for damages of Shen as if the ledge were part of the Reshus ha'Nizak. The reason for this is that when one person uses a particular part of Reshus ha'Rabim, no other person has permission to use that part of Reshus ha'Rabim at that moment, as the Rashba here explains. See also Insights to 14:1.)


QUESTIONS: In order to prove whether or not one must pay for the benefits he gains in a case of "Zeh Neheneh v'Zeh Lo Chaser," the Gemara quotes a Mishnah (Bava Basra 4b) in which Rebbi Yosi and the Chachamim argue with regard to a landowner (Reuven) who owns the fields surrounding the property of another landowner (Shimon) and who builds a fence around his fields. The Chachamim rule that if Reuven builds a fence around three sides of his property where his property borders with Shimon's property in the center, and he ends up enclosing three sides of Shimon's property, Shimon does not have to pay Reuven for any part of the cost of the fences. This implies that if Reuven builds fences around his property so that it entirely encloses Shimon's property (such as when Shimon's property is totally surrounded by Reuven's), Shimon should have to pay Reuven even though Reuven does not lose anything because of Shimon (since Reuven would have had to build the fence around his property in any case). Rebbi Yosi argues and says only when Shimon builds the fence on the fourth side (thus completing the enclosure around his property) must he pay Reuven for part of the cost of all the other fences that Reuven built on the other sides. If Reuven built all four fences, Shimon does not have to pay him anything.
The Gemara proves from the Chachamim's ruling that one is Chayav in a case of "Zeh Neheneh v'Zeh Lo Chaser" (that is, the beneficiary must pay for the benefit he receives when the benefactor loses nothing). The Gemara then rejects the proof by saying that in this case Reuven indeed loses something (and it is a case of "Zeh Neheneh v'Zeh Chaser"), since he can claim that Shimon caused him to build a larger fence than he would have needed to build had Shimon not been there.
The Gemara then proves from Rebbi Yosi's ruling that one is exempt in a case of "Zeh Neheneh v'Zeh Lo Chaser." The Gemara rejects the proof by saying that the reason why Rebbi Yosi exempts Shimon from sharing the costs of the fence is that Shimon may claim that a strong wall provides him with nothing more than he could have gained with a very inexpensive fence made of thorns.
RASHI (DH Ha Revi'is, and DH Ha Makif) explains that the Chachamim's ruling was stated in a case in which Reuven builds a fence around three sides of Shimon's field, and Reuven owns land around only those three sides. When the Gemara infers that if Reuven builds four walls around Shimon, Shimon must pay Reuven for part of the cost, the Gemara refers to a case in which Reuven bought the property along the fourth side of Shimon's field and then built a fence there, completely enclosing Shimon's field. In such a case, Shimon is obligated to pay part of the cost of the enclosure.
Why does Rashi not explain even in the case in which Reuven builds three fences around Shimon's field that Reuven owns the field on the fourth side but chose not to enclose it with a fence? Perhaps Rashi bases his explanation on an inference from the wording of the Mishnah in Bava Basra which says "ha'Makif Chaveiro mi'Shalosh Ruchosav," implying that Reuven owns land around Shimon's field only on three sides and not on the fourth. However, now the question may be asked on the Mishnah there: Why does the Mishnah explain that Reuven's fields surrounded Shimon's only on three sides and not on the fourth?
(b) Rashi (DH mi'Shalosh Ruchosav, and DH Ha Revi'is) explains that the fences on the three or four sides were built on the inner side of Reuven's fields where they border on Shimon's property. Besides these fences, there was another set of external walls around Reuven's fields which separated Reuven's property from the neighbors' property on the side opposite from Shimon.
If Reuven already has external walls around all of his fields that surround Shimon's property, what does Shimon gain by the internal fence? He is already protected from all sides from Reuven's external wall! Moreover, why did Reuven build those internal fences in the first place if he is already protected from outside infiltrators? If he built the fence in order to separate between his fields and Shimon's field, it is obvious that Shimon should share the cost of the fences if he benefits from them; since Reuven clearly built the extra fences only because of the presence of Shimon's field, Shimon's presence clearly did cause Reuven a loss (as the Gemara concludes, Reuven may claim that Shimon's presence caused him to build a longer fence). Why, then, does the Gemara initially suggest that this is a case of "Zeh Neheneh v'Zeh Lo Chaser," if Reuven does lose as a result of Shimon? (TOSFOS DH At Garamt; see NACHALAS DAVID to Bava Basra 4a.)
Tosfos and other Rishonim indeed disagree with Rashi and explain that the Gemara is discussing only the external fences of Reuven's fields (and there are no internal fences).
(c) If Rashi chooses to explain that the fences under discussion separate between Reuven's fields and Shimon's field, why does he mention at all that there is a separate set of external fences which separate between Reuven's fields and his other neighbors? Perhaps there is only one set of fences -- the set about which Rebbi Yosi and the Chachamim argue!
(a) The reason why the Mishnah in Bava Basra explains that Reuven does not own the field on the fourth side of Shimon's land in the case where he builds three walls is that if Reuven owns the fourth side as well, then even he does not benefit from the fences he builds around Shimon's field, since there is still a breach on the fourth side. Accordingly, it is obvious that Shimon would not have to share in Reuven's expenses, since Reuven's fence-building was purposeless. The only situation in which Shimon might be obligated to share the expenses is where Reuven benefits from the fences by his fields being completely enclosed -- which is the case when Reuven owns only the property bordering three sides of Shimon's field and not the property on the fourth side. (The diagram printed in the Vilna Shas is incorrect. The two edges of Reuven's field in the south should also be enclosed by the fence and not left open.) The Mishnah teaches that Shimon nevertheless does not have to contribute to the costs of the fence since Shimon himself is not fully enclosed by it.
(b) Rashi maintains that as long as the person who derives benefit does no action to take something from the person who is Chaser but merely indirectly causes an expense to the other person, it is not called a case of "Zeh Neheneh v'Zeh Chaser." For example, in the case of the person who occupies someone else's vacant house without the owner's consent, where the owner otherwise would have rented out his house for money, the occupant is causing the owner a loss through his action of moving into and living in the house. In the case of the outer fields surrounding the inner field, although Reuven builds a fence between his fields and Shimon's field only to prevent Shimon from entering his field or to mark the borders of his fields, the Gemara initially assumes that this is not considered a loss to Reuven since Shimon is not doing any action. (Indeed, he even might have owned his field before Reuven purchased the surrounding fields. Even if Shimon purchased his field afterwards, his purchase or presence does not constitute an act of causing a loss to Reuven.)
Moreover, Shimon can claim that Reuven did not build the fence because of a fear that he would steal from Reuven, but because Reuven wanted to make the border of his field clear to any potential purchasers. Hence, Shimon is not involved in causing any expense to Reuven.
This explains how Reuven and Shimon both can benefit from the inner fence while, nevertheless, it is considered "Zeh Neheneh v'Zeh Lo Chaser."
The Gemara concludes that it is considered "Zeh Neheneh v'Zeh Chaser" since Reuven built the fence only because of Shimon's presence, even though Shimon did not do any action to cause Reuven's loss, and even though Reuven built the fence only to delineate the boundary of his field (and not out of fear that Shimon would trespass).
(c) Rashi may have inferred that there were external fences around Reuven's property from the wording of the Gemara which refers to the inner fences as "extra fences." These words imply that there already exists some fence that Reuven had to build without Shimon, and the inner fences were built in addition to that fence. (See Tosfos, DH At Garamt.)
The question now, however, is why does the Gemara assume that Reuven built external fences besides the inner ones? The answer might be that if Reuven had built only inner fences, it would be obvious that Shimon cannot exempt himself from sharing the expenses because of "Zeh Neheneh v'Zeh Lo Chaser." Reuven would certainly be considered to be losing something due to Shimon, since Reuven's actions showed that he found it necessary to build the fence there only because of Shimon's presence, but on all other sides of his fields he did not find it necessary to build a fence (as pointed out above in the answer to the second question). Therefore, the Gemara -- which tries to prove from the Chachamim's ruling that one is Chayav in a case of "Zeh Neheneh v'Zeh Lo Chaser" -- must have understood that Reuven built fences around the external boundaries of his property as well as along the border with Shimon's property.