Bava Kamma Chapter 4, Mishnah 9 - the final Mishnah in the chapter - returns to the topic of the obligations regarding guarding and paying for animal damage. The first part of the Mishnah deals with transferring responsibility for the animal to another person, known as a guardian. The Torah lists four types of guardians, and the Mishnah establishes that they are all equally liable in place of the owner: if a mishap occurs and the animal causes damage, the guardian responsible for it is the one who pays, and not the owner.
The language of the Mishnah: "Mesaro leshomer chinam, velashoel, lenosei sachar, velashocher" - if he handed it over to an unpaid guardian, to a borrower, to a paid guardian, or to a renter.
The four guardians are:
Unpaid guardian - receives no payment, and the guarding is entirely a favor he does for the owner.
Borrower - borrows the animal for his own needs, so the benefit is entirely his and the owner receives nothing.
Paid guardian - a paid watchman with whom an agreement was reached: a specific payment in exchange for guarding and protecting the animal.
Renter - takes the animal as a rental, in a commercial transaction where he pays for its use.
In all of these cases, the guardian steps in for the owner - literally into his shoes - and is the one who bears the responsibility if damage occurs. The meaning of this regarding payment is: for a forewarned animal (Muad) he pays full damages, whether for Tooth and Foot or for a Horn that has an established history of goring, while for an innocuous animal (Tam) he pays half damages. If the animal is a Tam, the guardian will pay only half damages.
Two levels of guarding:
Halachah recognizes two levels of guarding, meaning two degrees of ensuring that the animal will not get out and cause damage:
Superior guarding - guarding at the highest level, which guarantees protection: a metal chain to secure the animal, or locking it behind a fence that will not open even in strong storm winds. This is the level required in most cases, and when it is done, the animal is considered guarded. If it escaped under normal circumstances, the person can say: I did what was required of me and did not act irresponsibly - and therefore he is exempt.
Lesser guarding - only a basic level of guarding: tying it with a leather strap or rope (and not a chain), or locking it behind a fence that is not supposed to open under normal conditions, but in a particularly strong wind will indeed open.
The standard that applies to an unpaid guardian is lower, and lesser guarding is sufficient for him. Since he is only doing a favor, if he provided basic guarding and the animal got out and caused damage - he is exempt, and the owner is the one who will bear the payment. It emerges that even though the Mishnah establishes that the guardian steps in for the owner and assumes his responsibility, for an unpaid guardian who provided lesser guarding, the responsibility reverts to the owner.
What level of guarding is required to be exempt?
From here, the Mishnah moves to another discussion: when a person is obligated to pay for damage - let us say for Horn, whether a Tam or a Muad - what level of guarding is required of him? The starting point is that superior guarding is required, a high-quality protection such as a metal chain or a fence that will not open under any normal condition, and not even in storm winds. One who did not meet this responsibility - is obligated to pay.
However, the verse speaks of a case of a Muad, and gives a reason for the owner's liability: "Velo yishmerennu be'alav" - the owner did not guard his animal. From here, there is a dispute in the Mishnah whether any level of guarding is sufficient to exempt him from the Muad portion of the payment. For in every case of Horn damage, the owner is definitely liable for fifty percent of the damage, meaning half damages, and the question is whether he is also liable for the remaining fifty percent: for a Tam - no, but for a Muad - yes.
The standard for liability for a tam is when one provided less than a superior level of guarding. However, there is room to say that since the verse states, "and its owner will not guard it," even a lesser level of guarding, a basic protection, is sufficient to exempt him from the second half of the damages for the keren of a mu'ad. This is the dispute before us.
The Three Opinions in the Mishnah:
The Mishnah says: "Kashro be'alav bemoserah vena'al befanav kara'uy, veyatza vehizik - echad tam ve'echad mu'ad chayav, divrei Rabbi Meir" - if its owner tied it with a halter and locked the gate before it properly, and it went out and caused damage, whether it is a tam or a mu'ad he is liable, these are the words of Rabbi Meir. The owner secured the animal by tying it with a leather strap or a rope, or locked a gate in front of it of the type that does not open under normal wind conditions - meaning he provided a lesser level of guarding, a basic guarding - and nevertheless it went out and caused damage. According to Rabbi Meir he is liable for both, a tam and a mu'ad, and we do not differentiate between them: superior guarding is required, and without it he is liable.
Rabbi Yehudah says: "Tam chayav vemu'ad patur, shene'emar 'velo yishmerennu be'alav' - veshamur hu zeh" - a tam is liable and a mu'ad is exempt, as it is stated, "and its owner will not guard it," and this one is guarded. He agrees that for a tam, regarding the fifty percent of half damages, the liability always stands unless he provided superior guarding, and lesser guarding is not sufficient. But for the second half, which is paid because it is a mu'ad, he is exempt if he provided even a lesser level of guarding. This is because the verse makes the liability dependent on the owner not having guarded it, whereas here he guarded it adequately - with a regular fence or a regular strap - and "this one is guarded," which is enough to exempt him from the second half.
Rabbi Eliezer disagrees and says: "Ein lo shemirah ela sakin" - it has no guarding other than a knife. Once the animal becomes a mu'ad, there is no concept of guarding at all, and even a superior guarding is not sufficient. The only way to become exempt is with a knife - to slaughter the animal, since then it can no longer cause damage. As long as it is alive, a mu'ad is always prone to cause damage, and if it causes damage he is liable, even if he guarded it with superior guarding.
In summary: The three opinions agree that for a tam, meaning for the first fifty percent, he is liable to pay unless he provided superior guarding. Regarding the second half, they disagree:
Rabbi Meir: With superior guarding he is exempt, but with lesser guarding he is liable for full damages for the keren of a mu'ad.
Rabbi Yehudah: With lesser guarding he is liable for the first fifty percent, but he is exempt from the second fifty percent, by virtue of the verse, "and its owner will not guard it."
Rabbi Eliezer: Once it becomes a mu'ad, even superior guarding is ineffective, and he is liable for full damages in any situation. There is nothing in his power to exempt himself other than slaughtering the animal, since then it can no longer cause damage.
The halachah follows Rabbi Yehudah, and in a somewhat counterintuitive manner: lesser guarding is sufficient to exempt him from paying full damages, but it does not have the power to exempt him from the first half of the damages, for which he is liable in any case.