2) DAMAGE CAUSED BY ONE'S LION
QUESTION: The Mishnah teaches that a lion, wolf, bear, leopard, and snake are always considered "Mu'adim" to do damage, unlike Shor and other more docile animals.

Why are these wild animals different from other animals? According to the opinion (15a) that maintains that the payment of Chatzi Nezek is a Kenas, it makes sense why the Mishnah singles out these animals. The reason the payment of Chatzi Nezek is a Kenas is that a Shor is "b'Chezkas Shimur," it is assumed not to do damage and thus the owner should not be obligated to pay. These animals, in contrast, are considered Mu'adim from the start because they are not "b'Chezkas Shimur"; one must expect them to do damage.

However, according to the opinion that maintains that Chatzi Nezek is Mamon because a Shor is not "b'Chezkas Shimur" (and thus the owner should have watched his Shor more carefully), what is the difference between these wild animals and an ox? Just as the Torah exempts the owner of an ox from Chatzi Nezek because of a Gezeiras ha'Kasuv, the owner of any of these animals should also be exempt from half of the Nezek because of the same Gezeiras ha'Kasuv!

ANSWERS:
(a) TOSFOS (16a, DH veha'Nachash), the ROSH, and RASHBA explain that indeed these animals are Mu'adim only if they damage in the way they normally damage. If they damage in such a way, the owner must pay Nezek Shalem because it is a Toldah of Shen. If they damage in an unusual way, the owner must pay only Chatzi Nezek, and even if they damage in a normal way in Reshus ha'Rabim, the owner will be exempt, as he is exempt for Shen in Reshus ha'Rabim.

(Tosfos points out that when a Nachash kills an animal or walks on it, it should not be considered a Toldah of Shen, since the Gemara in Ta'anis teaches that a Nachash "does not have Hana'ah from its prey" (since it does not necessarily kill in order to eat). The Gemara earlier (4a) teaches that having Hana'ah from what it damages is one of the defining characteristics of Shen, and therefore any damage that a Nachash does must be a Toldah of Regel. The RASHBA (2b) argues that the damage of the Nachash could also be a Toldah of Shen, since the Nachash does derive Hana'ah from biting and killing what is near it, even though it does not derive Hana'ah by eating it afterwards. According to the Rashba, even a Hana'ah that is not derived from the damage itself, but rather from the act that causes the damage, also puts it into the category of Shen.)

According to this answer, what is the Mishnah teaching? It is obvious that any animal that damages in its normal manner is Shen v'Regel! Moreover, why does the Gemara (16a) ask that the Mishnah should count more than five forms of an animal becoming a Mu'ad, since these animals are also Mu'adim? These animals were already included in the Mishnah when it counted Shen v'Regel as Mu'adim!

The TOSFOS HA'ROSH answers that the Mishnah is teaching that these animals are even Mu'adim to eat animals that are larger than they. Other animals, in contrast, are Mu'adim only to eat animals that are smaller (as the Gemara says earlier).

(b) RASHI on the Mishnah (DH Harei Elu Mu'adim) implies that the owner of these wild animals is liable for Nezek Shalem for any damage they cause, even damage that is unusual. This is also the ruling of the RAMBAM (Hilchos Nizkei Mamon 1:6, cited by the Hagahos ha'Gra to 16a), according to the way the TUR (CM 389) understands his ruling .(The MAGID MISHNEH, however, learns that the Rambam rules like Tosfos.) It seems that they maintain that nothing is considered an unusual type of damage for these animals.

The Gemara (16b) seems to support the explanation of Tosfos. Shmuel teaches that if a lion killed another animal and ate it right away ("Toref"), the owner of the lion is liable when the damage was done in Reshus ha'Rabim. If the lion eats an animal live ("Daras") in Reshus ha'Rabim, the owner is exempt because it is an act of Shen in Reshus ha'Rabim. This clearly implies that there is such a thing as an unusual manner of damage for a lion, which is included in the category of Keren, and the owner should have to pay only Chatzi Nezek for such damage since it is unusual for the animal to do it. (Rashi himself writes on 16b, DH Chayav, that even a lion only obligates its owner to pay Chatzi Nezek if it causes damage in an unusual manner.)

The LECHEM MISHNEH (Hilchos Nizkei Mamon 1:6) and the VILNA GA'ON (Hagahos ha'Gra, CM 389:15, 16, 20) explain that the Rambam does not rule like Shmuel (see Hilchos Nizkei Mamon 3:7) because the Gemara asks a number of questions on Shmuel's ruling, and the RIF also omits Shmuel's ruling. This is why the Rambam rules that no damage is considered unusual for these animals.