1) WHEN A MINORITY OF THE PEOPLE SINNED, AND THEN BECAME A MAJORITY
OPINIONS: The Mishnah later (10a) discusses a dispute between Rebbi Shimon and the Rabanan. If the Kohen Gadol or Nasi commits a sin before his appointment to his position, he brings an ordinary Korban Chatas for his sin. Rebbi Shimon says that if he sinned before his appointment but became aware of his sin only after his appointment, he brings no Korban at all. Rebbi Shimon maintains that one brings a Korban only when his accidental sin and the discovery of his sin occur both before, or both after, he is appointed as Kohen Gadol or Nasi.
The Gemara compares this case to a case in which a majority of the Jewish people sinned by following a mistaken ruling of Beis Din, but they later became the minority of the Jewish people, as some of them died. The Gemara says that Rabanan and Rebbi Shimon will apply their respective opinions to this case as well. However, the Gemara asks about a case in which the people sinned when they were a minority, and later they became the majority, as some of the people who did not sin died. In that case, are they exempt from the obligation to bring a Korban, since their obligation is determined according to their status when they sinned (at which time they were a minority and exempt from a Korban), or are they obligated to bring a Korban since now they are a majority?
(a) RASHI (DH Peshita) explains the Gemara as follows. According to the Rabanan, when the people sinned when they were a majority, Beis Din is obligated to bring a Par He'elem Davar. Just as the Kohen or Nasi was originally obligated to bring a Korban and nothing changes that obligation, when a majority of the people sinned and Beis Din became obligated to bring a Korban, that obligation remains. According to Rebbi Shimon, on the other hand, if the people found out about their sin only after some of them had died and they were no longer the majority, Beis Din would not bring a Par He'elem Davar, since the discovery of their sin occurred at a time when there is no obligation to bring a Par He'elem Davar. The Gemara's question involves only the case in which the minority sinned, and they discovered their sin only after they became a majority, since some of the people who did not sin died. Rashi points out that the Gemara's question in this case is based on the fact that this case is not comparable to the case in the Mishnah later. In the case of the Mishnah, the Kohen Gadol or Nasi is always obligated to bring a Korban; the only question is which Korban must they bring (and what happens if they find out at a later time, when their status has changed). However, in this case, the minority was not originally obligated to bring a Korban at all, since their sin was due to Beis Din's ruling. The Gemara therefore asks whether Rebbi Shimon always considers the sin to have been completed when the person finds out about it. If he does, then when the people find out about their sin only after they become a majority, they are obligated to bring a Korban. On the other hand, perhaps Rebbi Shimon maintains that knowledge of the sin is significant only when the sin occurred at a time at which there was an obligation of a Korban, which was not the case when the minority sinned and then became the majority. The Gemara apparently concludes that the second approach is correct.
TOSFOS (DH Mu'atin) has difficulty with Rashi's assessment of the first case of the Gemara. Rashi says that the first case (in which the sinners were the majority and then they became the minority) is parallel to the case of the Kohen Gadol or Nasi. Tosfos asserts that the cases are not the same. According to the Rabanan, the Kohen Gadol or Nasi would have been obligated to bring a Korban regardless of whether he sinned before he was appointed or after; there never was any point in time at which he would not have been obligated to bring a Korban. In contrast, when the majority sinned and then became the minority, perhaps the Par He'elem Davar is brought by Beis Din only when the people who sinned are a majority at the time they bring the Korban. Perhaps the Rabanan in this case do not maintain that a Par He'elem Davar should still be brought.
(b) Tosfos explains that the Gemara merely seeks to understand the position of Rebbi Shimon. The KEREN ORAH explains Tosfos' understanding of the Gemara. The Gemara infers from the Mishnah later (10a) that Rebbi Shimon maintains that one can be exempt from a Korban if he finds out about his sin at a stage other than the stage during which he sinned. The Gemara is unsure about whether Rebbi Shimon maintains that one also becomes obligated to bring a Korban based on his awareness of the sin at a later date. The Gemara therefore concentrates on the case of "Mu'atin v'Nisrabu" -- "they were a minority and became a majority," and not "Merubin v'Nisma'atu" -- "they were a majority and became a minority," since only the former case can shed light on this issue. (Y. MONTROSE)
2) ONE HUNDRED JUDGES WHO CONVENED
QUESTION: The Gemara teaches that if one hundred Dayanim convened to rule on a matter of Halachah, a mistaken ruling on their part can obligate them to bring a Par He'elem Davar only if they all agree with the ruling. The Gemara derives this from the verse, "v'Im Kol Adas Yisrael Yishgu" -- "And if the whole congregation of Yisrael sins through an error" (Vayikra 4:13), which implies that they are obligated only when all of them make a mistake.
The BE'ER SHEVA has difficulty with this Gemara. There is no court of one hundred Dayanim in Jewish law. The maximum number of Dayanim on a Beis Din is seventy-one, as the Rabanan in Sanhedrin (3a) derive from the verse, "Gather for Me seventy men from the elders of Yisrael" (Bamidbar 11:16). These seventy, plus Moshe Rabeinu, make a total of seventy-one judges. Rebbi Yehudah disagrees with the Rabanan and maintains that Moshe Rabeinu is included in the number seventy. They clearly disagree about the maximum number of judges allowed on a Beis Din. The Be'er Sheva asserts that adding judges is not a possibility, since the source for this Halachah is a verse. Moreover, Rebbi Yosi states in Sanhedrin (42a) that just as judges cannot be added to a Beis Din of seventy-one, judges cannot be added to a Beis Din of twenty-three. Although the Halachah does not follow Rebbi Yosi in the case of a Beis Din of twenty-three, it seems clear that judges cannot be added to a Beis Din of seventy-one. The Be'er Sheva concludes with no explanation for the words of the Gemara.
ANSWER: Perhaps the Gemara may be understood based on the explanation of the Mishnah in Eduyos (1:5). The Mishnah there states that a Beis Din cannot annul the enactment of a different Beis Din unless it is greater than that first Beis Din in "Chochmah v'Minyan" -- "wisdom and number." Many explanations are given for the meaning of these words (see Insights to Avodah Zarah 36:1 for the various opinions.) The definition of the word "Minyan" seems particularly elusive. How can it be that one Beis Din is greater "in number" than another Beis Din? The Sanhedri ha'Gedolah is always comprised of seventy-one judges!
Based on the words of certain Rishonim, the MARGOLIYOS HA'YAM in Sanhedrin (86b) explains that if a certain number of judges agreed with a Halachic decision, a later Beis Din would need more judges who disagree in order to overturn the words of the previous Beis Din. This number could reach more than seventy-one, as implied by the Gemara in Zevachim (12b), where Shimon ben Azai relates that he had a tradition "from seventy-two elders" about a certain Halachah. Why did he mention the specific number of elders? He mentioned the specific number so that the Chachamim would know that in order to overturn that Halachah, they would need seventy-three Talmidei Chachamim who disagreed. (See RAMBAM in Hilchos Mamrim (2:2) who has a similar approach to understanding the word "Minyan.") The Margoliyos ha'Yam quotes additional sources which relate that more judges were assembled who agreed with certain Halachos.
Accordingly, perhaps the Gemara here refers to a case in which many learned Talmidei Chachamim assembled together with the Beis Din in order to understand a certain Halachah. They are counted as sitting together with the Beis Din, as their number is significant with regard to how many Talmidei Chachamim would be needed in the future in order to overturn this Beis Din's ruling. (Y. MONTROSE)