1) WHY DOES ABAYE NOT GIVE A SIMPLE ANSWER
QUESTION: The Mishnah (28a) states that if one's barrel breaks in the public domain and someone either trips on the barrel or slips on the fluid which spilled from the barrel, the bearer of the barrel must pay for the damages. Rebbi Yehudah says that "with intent" the owner is liable, and "without intent" he is exempt.
Rabah (28b) explains that Rebbi Yehudah means that if the bearer of the barrel slipped while unloading the barrel from his shoulder and the barrel fell, broke, and its content spilled out, he is liable for any damage caused by the barrel and its contents. Slipping is considered an act of negligence.
Abaye asks that Rabah's statement implies that Rebbi Meir (the Tana Kama), who disagrees with Rebbi Yehudah, maintains that the bearer of the barrel is liable even when the barrel breaks due to an unforeseeable cause (for example, it was weak and fell apart). Rabah confirms that this is an accurate inference. Abaye responds that it is not possible that Rebbi Meir would obligate the bearer of the barrel in such a case, because the Torah does not hold one responsible for circumstances beyond one's control.
Therefore, Abaye says that Rebbi Meir and Rebbi Yehudah argue about two separate points. Their first argument involves whether or not one who trips is deemed negligent. Their second argument involves whether or not one is obligated for the damage his objects cause after he makes them ownerless. Rebbi Yehudah maintains that one is obligated for damages caused by his Bor (any potentially harmful object which he placed in Reshus ha'Rabim) only when it belongs to him. According to Rebbi Yehudah, even if he placed the potentially harmful object there deliberately, he is exempt from the damages if he makes them ownerless before they cause damage.
Why does Abaye need to give all of this information in order to answer his own question on Rabah? He should say simply that Rebbi Yehudah means that one is liable only when he deliberately breaks a barrel and not when he trips!
ANSWER: The PNEI YEHOSHUA answers by pointing out that the Mishnah's choice of terminology is unusual. Rebbi Yehudah does not say merely that "he is exempt," the common term used by the Mishnah when two Tana'im argue about a specific case. Rather, he says, "If he has intent he is liable, if he does not have intent he is exempt." This phrase must mean that Rebbi Yehudah's statement is not a direct argument with Rebbi Meir. In what way does Rebbi Yehudah argue?
In order to answer this question, Abaye explains that the statement of Rebbi Meir also implies two rulings in two different cases. Rebbi Yehudah responds to Rebbi Meir accordingly and says that one is never obligated unless he has intent to damage. Moreover, Rebbi Yehudah adds that even in such a case he is liable only if he intends to pick up the pieces or contents of the barrel. This is the meaning of the phrase, "if he has no intent." It means that he has no intent to retain the pieces or contents of the barrel, and therefore he is exempt.
The Pnei Yehoshua says that although this explanation is consistent with the opinion of TOSFOS (DH Pligi b'She'as Nefilah), the RIF apparently understands that Abaye's conclusion is that the primary argument between Rebbi Meir and Rebbi Yehudah involves the ownership of the pieces of the barrel. Accordingly, Abaye cannot say that Rebbi Yehudah refers to a case in which the owner deliberately broke a barrel, because the primary argument involves the ownership of the pieces. This is why, according to the Rif, Abaye does not give a simple answer. (Mordechai Zvi Dicker)

29b----------------------------------------29b

2) HOW HIGH MUST A "KINYAN HAGBAHAH" BE
QUESTION: The Gemara quotes Rebbi Elazar in the name of Rebbi Yishmael who says that there are two things that are not actually in a person's possession but the Torah considers them to be in his possession. One of these things is a Bor in the public domain.
The Gemara asks that Rebbi Elazar apparently contradicts himself. The Mishnah states that one who turns over a block of fertilizer in the public domain and it subsequently causes damage to someone, the one who turned it over is liable for the damages. Rebbi Elazar explains that he is liable only if he intended to acquire the fertilizer. If he did not intend to acquire the fertilizer, he is not liable. Rebbi Elazar implies that when one makes his things ownerless, he is not obligated for the damage they cause!
Rav Ashi answers that the Mishnah refers to a case in which he turns over the fertilizer by picking it up less than three Tefachim from the ground. RASHI (DH k'she'Hafchah) explains that since he did not pick up the fertilizer three Tefachim high, the fertilizer is considered like an open Bor both before and after he touched it. Nothing changed when he picked it up since he did not pick it up high above the ground. However, if he has intention to acquire it, it becomes his property that damaged and therefore he is liable to pay.
The Gemara here seems to contradict the view of Rashi's in Kidushin (26a, DH b'Chavilei Zemoros). Rashi writes that a person must lift an object three Tefachim high in order to perform a Kinyah Hagbahah, an acquisition through lifting. Rav Ashi here, however, implies that Rebbi Elazar rules that if one has intent to acquire the fertilizer, he acquires it even if he lifts it less than three Tefachim. The RASHBA quotes RABEINU TAM who cites proof from the Gemara here against the opinion of Rashi in Kidushin (see also ME'IRI). How does Rashi there understand the Gemara?
ANSWERS:
(a) TOSFOS (DH Ela) answers that for an ownerless object, merely moving it is a mode of acquisition. Therefore, it makes sense that one acquires it when he lifts it less than three Tefachim high. Rashi himself here gives this reason for why lifting the fertilizer less than three Tefachim high is a valid form of acquisition of the ownerless fertilizer.
(b) In his second answer, Tosfos explains that the person turns over the fertilizer with his vessel, and his vessel acquires the fertilizer for him (not through a Kinyan Hagbahah, but through a Kinyan Chatzer).
(c) In his third answer, Tosfos explains that one's hand has the ability to acquire something through lifting it, even if he lifts it less than three Tefachim from the ground (see Kesuvos 31a). (Mordechai Zvi Dicker)