Rebbi Eliezer suggests further than the verse is necessary in a case where
the animal intended to kill another animal and ended up killing a person. In
such a case the animal is not Chayav Misah and therefore it would be
possible for the owner to pay Chatzi Kofer.
The Gemara cites two Amora'im who argue about the sequence of Rebbi
Eliezer's answers. Both Amora'im agree that the first answer mentioned above
is a weaker answer. Rav Tavyumi says that Rebbi Eliezer first said the
weaker answer, and then when he thought of a better answer, he said the
better answer. Rav Kahana argues and says that Rebbi Eliezer first said the
better answer, and then he added the weaker answer as additional support to
his words.
Why should Amora'im argue about such a seemingly insignificant point? What
difference does the sequence make in which Rebbi Eliezer suggested his two
valid answers? He could say them in any order!
(a) The BA'AL HA'ME'OR explains why Rebbi Eliezer would have ignored the
better answer and suggested the weaker answer first. It must be that he was
simply trying to test Rebbi Akiva to see if he would reject the weaker
answer by himself. This demonstrates that Rebbi Akiva was a pupil of Rebbi
Eliezer and of lesser stature compared to Rebbi Eliezer, such that Rebbi
Eliezer would find it necessary to test him.
Rav Kahana, who says that Rebbi ELiezer presented the better answer first,
maintains that Rebbi Akiva was closer to being a "Talmid Chaver," a
colleague, to Rebbi Eliezer, and therefore Rebbi Eliezer would not have
tested him. Rather, Rebbi Eliezer was adding the second answer as an
additional possibility, albeit a weaker one, to answer his question.
It is still not clear, though, what the practical difference would be
between the opinions of Rav Tavyumi and Rav Kahana. What difference does it
make whether Rebbi Eliezer was greater than Rebbi Akiva or whether they were
of equal stature?
The answer might be that the Gemara in Kesuvos (84b) teaches that although
the Halachah follows the view of Rebbi Akiva when he argues with another
contemporary Tana, the Halachah does *not* follow his view when he argues
with his rebbi, such as Rebbi Tarfon.
Like whom will we rule when he argues with Rebbi Eliezer? This is the
subject of the Machlokes between Rav Tavyumi and Rav Kahana. According to
Rav Tavyumi, the Halachah will follow Rebbi Eliezer, since Rebbi Akiva was
clearly a student of his. According to Rav Kahana, the Halachah might follow
Rebbi Akiva, because he was a Talmid Chaver of Rebbi Eliezer (see Bava
Metzia 59b regarding "Tanuro Shel Achna'i")!
(b) The RAMBAN (in Milchamos) explains that the Gemara implies that
according to Rav Tavyumi, Rebbi Eliezer *changed his mind* about the weaker
answer and rejected it as a possible answer. According to Rav Kahana, on the
other hand, the weaker answer remains a valid answer. The reason Rebbi
Eliezer changed his mind about the weaker answer, according to Rav Tavyumi,
is because even though the Shor is not killed unless two witnesses testify,
since -- even when one witness testifies -- the Shor is worthy of being
killed had two witnesses been there, it is obvious that the owner of the
Shor Tam should be exempt from Kofer (because it is similar to a Shor
ha'Niskal and cannot pay "mi'Gufo," according to the testimony of the single
witness or of the owner). (This is why Rebbi Eliezer changed his mind
according to the Ramban. Alternatively, Rebbi Eliezer changed his mind
because Kofer is Mamon and not Kaparah. Therefore, the owner of a Shor Tam
would be exempt from paying if he would be incriminated only by his own word
or by the word of a single witness, because of Modeh b'Kenas. If so, there
would be a clear practical difference between Rav Tavyumi and Rav Kahana: a
case where a Shor *Mu'ad* kills a person, and we know it only from the
owner's testimony or from the testimony of a single witness.)
(See also PNEI YEHOSHUA, who suggests a different approach.)