Gemara

17b - Question (Rava): If an animal stepped on a Keli, and it rolled to another place and broke there, what is the law? Does it depend on the beginning, and it is like bodily damage (since it stepped on the Keli)? Or, does it depend on when it breaks, and it is like Tzeroros (the animal was not touching it when it broke)?

Question: He should learn from Rabah's law!

(Rabah): If Reuven threw a Keli off the roof, and Shimon broke in it mid-air with a stick, Shimon is exempt, for it was already (destined to be) broken. (This shows that it depends on the beginning!)

Answer: Rava was unsure whether or not Rabah's law is true.

Answer (Beraisa): If chickens pecked at the rope of a bucket, and the rope snapped and the bucket broke, they pay full damage. (This proves that it depends on the beginning.)

Rejection #1: The Beraisa obligates full damage for the rope.

Question: It is abnormal to peck at a rope!

Answer: There was dough on the rope.

Objection: If he pays for the rope, why did the Beraisa mention the bucket?!

Rejection #2: The Beraisa is Sumchus, who obligates full damage for Tzeroros.

Objection (Seifa): If a fragment flew off (the bucket) and broke a Keli, he pays full damage for the first Keli, and half-damage for the second. (Sumchus would obligate full damage for both Kelim!)

Suggestion: Perhaps Sumchus distinguishes between Ko'ach and Ko'ach Kocho (the damager set something in motion, and it set something else in motion that later damaged).

Rejection: Rav Ashi asked whether or not Sumchus considers impetus of impetus like impetus, and never resolved this. If the Beraisa is like Sumchus, this shows that he does not consider it as impetus!

Conclusion: The Beraisa is like Chachamim. Impetus is like bodily damage.

Rejection (Rav Bivi bar Abaye): No. The case is, the chicken was pushing the bucket the entire time, until it broke.

(R. Zeira): If an animal strewed up pebbles in a Reshus ha'Rabim, since it is exempt there, it is exempt even if they damaged in a Reshus ha'Yachid.

Question (R. Yirmeyah - Beraisa): It was walking and strewed up pebbles, whether in a Reshus ha'Rabim or Reshus ha'Yachid, it is obligated.

Answer (R. Zeira): It strewed up in a Reshus ha'Rabim, and damaged in a Reshus ha'Yachid. (He retracted.)

Rishonim

Rif (7a): If a chicken pecked at a rope, and it snapped and the bucket broke, it pays full damage, if the chicken pushed the bucket the entire time, until it broke.

Rif (11b): If Reuven threw a Keli off the roof, and Shimon broke in it mid-air with a stick, Shimon is exempt, for he broke a broken Kli.

Question (Ba'al ha'Ma'or): I am unsure whether this is the Halachah. Rava is Basra, and he was unsure. Therefore, this is like money in doubt, so they divide it. Normally, ha'Motzi mi'Chavero Alav ha'Re'ayah. Here we are concerned for Rabah, and the Rif who ruled like him. Why did the Rif obligate above only if the chicken was pushing the bucket the entire time? This shows that it depends on when it broke, unlike he ruled here!

Answer #1 (Ra'avad, brought in Rosh 2:1): The Rif explains that Rav Bivi explains that there was no dough on the rope, and the chicken was trying to drink from the barrel. Therefore, it is normal.

Milchamos Hash-m: If the Halachah is a Safek, the Rif properly exempted both in Rabah's case, and regarding the bucket (if the chicken did not push it the entire time). The Rif often brings an unresolved Halachah when due to the Safek, the Halachah follows it. However, I say that we always follow one who was sure against another who was unsure, even if the Talmid was sure and the Rebbi unsure, and all the more so if vice-versa! The Rif ruled that Tzeroros pay from the Aliyah, like Rav Papa, even though his Rebbi Rava was unsure. Ha'Nagid R. Shmuel also said so. However, why did the Rif bring Rav Bivi's rejection? It seems that the Rif is stringent in such cases, for the latter opinion did not accept the former. Alternatively, Rabah holds that it depends on the end, for he did not obligate the one who threw the Kli. Since he needed to exempt the latter, this shows that the first is exempt. This is not due to Gerama. Rather, his action did not break the Kli. The latter is exempt, for there is nothing to pay for (the Kli has no value, for it will break).

Rambam (Hilchos Nizkei Mamon 2:14): If chickens were pecking at the rope of a bucket, and the rope snapped and the bucket broke, they pay full damage. This is if the bucket rolled due to them until it broke. If there was food on the rope and they broke it while eating, they pay full damage also for the rope.

Rebuttal (Ra'avad): The Gemara asked about the Beraisa itself that this is unusual (also for the barrel, one pays full damage only if it wanted to eat)!

Magid Mishneh: The Meforshim explain like the Rambam.

Rosh (2:1): Rava asked about an animal that stepped on a Keli, and it rolled to another place and broke there. The Gemara wanted to answer from Rabah's law. The Rif rules like Rabah. Even though Rava was unsure, Rabah's certainty overrides Rava's doubt. Also, Rava was Rabah's Talmid. Therefore, he pays full damage, like Rabah. Rav Bivi bar Abaye showed how we can reject the proof from the Beraisa; he did not say so l'Halachah.

Rosh (2:2): If an animal strewed up pebbles in a Reshus ha'Rabim, and they damaged in a Reshus ha'Yachid, he is liable. Even though if an animal stepped on a Keli, and it rolled to another place and broke there, we follow the beginning and obligate, here it depends on where the damage occurred. The Torah said "it consumed (damaged) in another's field."

Rebuttal (Yam Shel Shlomo 2:4 DH v'Od, brought in Taz and R. Akiva Eiger): The Rosh holds that the law depends on the beginning only when everything happened in the victim's Reshus. If so, where is one liable for Tzeroros? If it depends on the beginning, it is (bodily damage,) not Tzeroros! Rather, it depends on the beginning only when it stepped on a Kli and made it roll, or one threw a Kli off the roof, for the action was done to the Kli that was damaged. Regarding Tzeroros, at the time the pebbles were strewed, the Kli was not destined to be damaged until the pebbles went elsewhere. Therefore, if it stepped on a Kli in Reshus ha'Rabim and strewed it to Reshus ha'Yachid and it broke there, he is exempt, for we follow the beginning (Tzeroros are exempt in Reshus ha'Rabim). The Rosh would obligate.

Poskim

Rema (CM 390:5): If an animal stepped on a Keli, and it did not break, and it rolled to another place and broke there, it pays full damage.

Beis Yosef (DH Darsah): The question was settled.

SMA (14): Since it broke because the animal stepped on it, the law depends on the beginning. Regel itself broke it, not Tzeroros.