The Gemoro on 5a brings a Machloikes to do with paying a Halvo'oh before time or not and brings a Machloikes in Shittos between Raish Lokish (Yochid) and Rovo and Abaye(Rabbim). On 5b it brings proofs either way from our Mishnah here in Bovo Basra then tells us about a furher 2 Amoroim who Paskened like Rovo and Abaye and one Amora who Paskened like Raish Lokish. Then it turns out that the Gemoro Paskens Hilchosoh K'Raish Lokish.
I have found no Rishon Or Acharon or any Nosei Keilim on the Tur,Shulchan Oruch or Rambam who ask my question: How can we Pasken K'Yochid? Not even one Amora does like that Daas Yochid and not like the Rabbim of Abaye and Rovo! Besides, 2 other Amoroim Paskened like the Rabbim as well.
Why does no one seemed to be bothered by this
Boruch Kahan London, London,England
1. The answer is based on an important principle about the way the Gemara rules: "Halachah k'Basrai" -- the Halachah follows the later opinion. See, for example, the Rosh in Bava Metzia (1:49) who writes, "We rule that from Abaye and Rava onwards the Halachah follows the later Amora'im, even when they disagree with their teachers. The Rif wrote this in several places."
2. Printed in the beginning of the first volume of Yoreh De'ah of the Shulchan Aruch, is a page entitled, "Guidelines for Ruling on Matters of Forbidden and Permitted Objects," by the Pri Megadim. In #8, the Pri Megadim writes in the name of the Keneses ha'Gedolah that even when it is a Yachid (individual) against the Rabim (majority), the principle of "Halachah k'Basrai" applies. The Pri Megadim writes that the reason for this is that since the later Amora'im saw what the earlier Amora'im did not see and still disagreed with them based on their arguments, presumably the earlier Amora'im would have agreed with the later ones. This applies even in the case of a Yachid against the Rabim.
3. In the Gemara here, it is Mar bar Rav Ashi who agreed with Reish Lakish. Mar bar Rav Ashi was a very late Amora, as he was the son of the redactor of the Gemara. Therefore, according to the principle of "Halachah k'Basrai," there is a strong basis to rule like Mar bar Rav Ashi even against the majority of Amora'im.
4. The reasoning behind the principle of "Halachah k'Basrai" may be derived from the words of Rashi in Nidah (7b, DH Ha Ka Mashma Lan). Rashi explains that the later Amora'im were particular to understand the reasons of the Tana'im and they established the Halachah clearly. In contrast, the earlier Amora'im were not so particular in their colleagues' words; rather, each Chacham taught his Talmidim what he had heard from his Rebbi the way he had heard it.
5. Therefore, the later Amora'im saw it as their purpose to be meticulous in deciding whom the Halachah follows, as they represented the later generations of the Gemara who had to decide the Halachah, since, once the Gemara would be sealed, it would be no longer possible to decide the Halachah, as the Gemara in Bava Metzia (86a) states, "Rav Ashi and Ravina are the end of Hora'ah."
1) If I can add a He'oroh in support of your Terutz that the Gemoro on the Omud Beys only says Hilchesoh KeRaish Lokish AFTER it says that Mar bar rav Ashi did like him and the other Amoraim did like Abaye.
"Kloimar" only after Mar Bar Rav Ashi,who was the Basro'oh did like Raish Lokish can we say Hilchosoh KeRaish Lokish because the Gemoro could have said it before it relates what these 3 Amoroim did ie after it could not be Poishet the Shaaleh from our Mishnah.
2) Also, can I reply to this Nekuda now further to the previous discussion as I have just learnt a Tosfos Noygea to this topic
Ayin Daf Bovo Basra 21b Tosfos D.H.Peshita who brings the Inyan of Basrooh and ends off VeKymoh Lon Legabby RAV HUNA (BREI DERAV YEHOSHUAH Muchach from the Sugya there that is who we are talking about) DEBASROOH HU. Not like we have said in our Sugya that Mar Bar Rav Ashi was Basrooh.
1. Reb Boruch, a Groiser Yeyasher Kochacha! Now I have a Tana d'Mesaye'a Li!
2. Tosfos in Bava Basra (21b, DH Peshita) means to say that relative to Rav Huna (who was a very early Amora, as he was a Talmid of Rav), Rav Huna brei d'Rav Yehoshua (who is often mentioned in the Gemara as a friend and Bar Plugta of Rav Papa, a late Amora, as a Talmid of Rava) was considered a "Basra." The rule is that the Halachah follows the "Basra" from Abaye and Rava onwards, which automatically includes Rav Huna brei d'Rav Yehoshua. The rule that the Halachah follows the "Basra" applies in every Machlokes, regardless of who the disputants are. In the case in Bava Basra on 21b the Halachah follows Rav Huna brei d'Rav Yehoshua because he is the "Basra" in comparison to Rav Huna, and in the case on 5b the Halachah follows Mar brei d'Rav Ashi, because since he was the son of Rav Ashi (who redacted the majority of the Gemara) he was at the very end of the Amora'im, so he is a "Basra" compared to Abaye, Rava, and Rav Huna brei d'Rav Yehoshua.