We have learned that in the event that a shor tam – an ox with no violent history – gores another animal, its owner will pay hatzi nezek mi-gufo – half of the value of the damage that was done, but no more than the value of the shor tam itself. The Mishna on our daf teaches that if the shor tam was worth a maneh (100 dinar) and it killed an ox that was worth 200 dinar, the owner of the dead animal will simply take the shor tam as his own (since its value is half of the damage that it caused).
The Gemara identifies the author of this Mishna as Rabbi Akiva, who believes that in a case where both sides agree to the details of what took place, there is no need to involve the courts in the matter, since the law is clear and the two parties can work it out between them. Rabbi Yishmael disagrees, arguing that only the beit din can decide the value of the two animals and declare how much must be paid. The Gemara explains that while Rabbi Yishmael believes that the accident creates a monetary obligation for the owner of the damaging ox to pay, Rabbi Akiva believes that the accident automatically gives the owner of the ox that was injured a part ownership (or in this case, full ownership) in the shor tam that gored.
In response to the Gemara’s request for a practical difference between these two positions, the case that is raised is a situation where the owner of the dead animal were to state that he was consecrating the shor tam to the Temple. According to Rabbi Yishmael his statement is meaningless, since the animal does not belong to him; according to Rabbi Akiva the hekdesh will take effect.
According to the Rashba, shor tam is a very unique case, since the half damages paid by the owner of a shor tam is considered a kenass – a penalty – and Jewish law frees a person from paying kenass if he steps forward on his own and admits to responsibility. Thus, Rabbi Akiva’s ruling is difficult to understand, since if the owner of the shor tam admits to his guilt, the shor tam will not transfer to the damaged party. Apparently in the case of shor tam, since the payment is actually less than the value of the damage that was done, we do not apply the rule of modeh be-kenass patur – that someone who admits his responsibility is free from his obligation to pay.