1) WHY IS ONE BELIEVED TO SAY THAT HE DID NOT EAT "CHELEV"
QUESTIONS: According to the Rabanan who argue with Rebbi Meir in the Mishnah (11b), when two people say to a person, "You ate Chelev," and he denies their words and says, "I did not eat Chelev," he is exempt from bringing a Korban. The Gemara concludes that the reason why he is exempt is that "had he wanted, he could have said that he acted intentionally," in which case he would not have been obligated to bring a Korban. RASHI explains that this means that the person has a "Migu" that enables us to believe him. Had he been lying, he would have said the more effective lie to exempt himself from a Korban, and therefore the claim that he actually makes is presumed to be the truth and he is exempt.
Rashi's words are problematic.
(a) It is clear from the Gemara here the person is believed not because of a Migu, but because he could have "explained his words" and said, "When I said that I did not eat Chelev, I did not mean to say that I ate no Chelev at all. Rather, I meant to say that I did not eat it b'Shogeg, but rather I ate it b'Mezid, and therefore I am exempt from a Korban."
Why, then, does Rashi mention the concept of Migu? A Migu is effective with no need to explain his words at all!
(b) Rashi in Bava Metzia (3b, DH Edim Ein Mechayavin) gives a third explanation for the person's exemption. Rashi says that we learn from the verse, "O Hoda Elav Chataso" (Vayikra 4:28), that one is Chayav to bring a Korban only when he finds out about his inadvertent sin himself, but not when others tell him about it. If, as Rashi here says, he is believed because of a Migu, then why is it necessary to quote a verse as the source for his exemption?
(a) To answer the first question, we first must address a different question that the Rishonim ask on Rashi's explanation. How is it possible that the person is believed with a Migu to say that he ate the Chelev intentionally? He would not be believed to make such a claim, because he would never be so brazen as to claim that he sinned intentionally. Consequently, he has no Migu to support his actual claim! (Rashi himself raises this point later on 12b, DH Modeh Rebbi Meir.)
We may answer that when the person first claims, "I did not eat Chelev," and the testimony of witnesses contradicts his claim, even if he then claims that he ate the Chelev b'Mezid, Beis Din certainly does not believe him that he ate b'Mezid. It is obvious that he made that claim not because it is the truth, but only in response to the witnesses, in order to exempt himself from the obligation to bring a Korban. However, if he explains his words after he has already claimed, "I did not eat Chelev," and he says, "I meant that I did not eat b'Shogeg, but rather I ate b'Mezid," this is not considered an act of brazenness. Therefore, only when he is able to explain his words that he has already uttered is he believed with this Migu.
(b) The second question may be answered as follows. It seems that the reason why a verse is necessary to teach that the person is exempt from a Korban is that without the verse, the Migu would not exempt him. A Migu is not powerful enough to override the testimony of witnesses (see, for example, Bava Kama 81b, and see TOSFOS here, DH O Dilma). The verse is necessary to teach that in this case, a Migu is believed against witnesses. (The Gemara does not explain that the verse is referring to a case in which he does not have even a Migu, because a Limud of a verse is applied to teach only the most limited Chidush, "Tafasta Merubah Lo Tafasta.") (M. KORNFELD)
2) "TUMA'H YESHANAH" WITHOUT A "MIGU"
QUESTION: The Gemara teaches that even when witnesses testify that a person who is Tamei with an "old" Tum'ah (he became Tamei on a previous day) sins by doing an act that he is not permitted to do while Tamei, the person cannot always exempt himself from a Korban with a claim of a Migu that he had already immersed in a Mikvah (before he did what the witnesses claim that he did)). The Gemara explains that the case in which one cannot exempt himself from a Korban with such a claim is when witnesses say that he ate Kodshim while Tamei.
Why is there no Migu in such a case? The person should be believed to say that he did not eat Kodshim while Tamei, since he has a Migu that he could have said that even though he ate Kodshim, he immersed in a Mikvah before he ate the Kodshim!
(a) RASHI (end of 12a, DH uv'Mai Askinan) explains that when the witnesses say that they saw him eat Kodshim while Tamei (as opposed to saying that they saw him enter the Mikdash while Tamei), their testimony relates to both the person (because it obligates him to bring a Korban) and the food that he ate or touched (because it necessitates that the Kodshim, which became Tamei, be burned). Even if the person later tells the court, "I went to the Mikvah before I ate the Kodshim," his words imply that he immersed in a Mikvah only before he ate the Kodshim, but not before he touched them. Since he did not openly contradict the witnesses' testimony about the status of the Kodshim (whether they are Tamei or Tahor), we must assume that he touched them before he immersed.
(Although the accused sinner would have been believed had he said that he immersed before he touched the Kodshim, since a person normally does not think of making such a claim (because the status of the Kodshim does not concern him) he has no Migu that he could have made such a claim. A Migu is effective only when the claim of the Migu is one that the person would have thought of himself.)
Based on this assertion -- that the Kodshim would remain Tamei even if the accused sinner would say that he immersed in the Mikvah -- we may propose that after he proclaims that even the Kodshim he touched are Tahor (by saying that he was always Tahor), he is not believed to say later that he indeed was Tamei when he touched the Kodshim, but that he had immersed in a Mikvah. Such a claim would contradict his original claim with regard to the Kodshim, and thus the person would not be trusted with such a claim even with regard to his obligation to bring a Korban. This appears to be Rashi's reason for why there is no Migu in a case of one who is accused of eating Kodshim while Tamei. (M. KORNFELD)
(b) RABEINU GERSHOM understands the Gemara in an entirely different way. According to his reading, the Gemara is differentiating between various ways in which witnesses might express their testimony.
If two witnesses say to the person, "Why did you eat Kodshim? You were Tamei!" and he reacts, "I was not Tamei," then the person is able to explain later that he meant to say, "I was not Tamei when I ate Kodshim, because I had immersed beforehand in a Mikvah." However, if the witnesses challenge the person by saying, "You know that you were Tamei! Why did you eat Kodshim?" and they mention Kodshim last, then the response we would expect from the accused is, "I did not eat Kodshim," if he really did not eat Kodshim while Tamei, since he immersed. If the person does not say, "I did not eat Kodshim," but rather he says, "I was not Tamei," then his words are not subject to re-interpretation afterwards. They must be understood literally, and they cannot be understood to mean that he immersed in a Mikvah prior to eating the Kodshim.
3) A PERSON IS BELIEVED ABOUT HIMSELF MORE THAN A HUNDRED WITNESSES
QUESTION: The Gemara (12a) discusses a case in which witnesses say that a person was Metamei Taharos, and the person denies it. Rebbi Yehudah says that "a person is believed about himself more than a hundred witnesses." Rav Yosef teaches that Rebbi Yehudah's ruling applies only to matters "Beino l'Vein Atzmo ul'Atzmo" -- only the person himself who asserts that the Taharos are still Tahor may eat them, and only in private, lest others will be lax with regard to Taharos.
The teaching of Rebbi Yehudah -- that a person is believed about himself more than a hundred witnesses -- is derived from the verse, "O Hoda Elav Chataso" (Vayikra 4:28), which is written only with regard to the obligation to bring a Korban. This verse teaches that a person does not bring a Korban when he was informed by others about his sin. How does Rav Yosef derive from this verse that one who says that his Taharos are not Tamei may continue eating the Taharos? Eating Taharos is unrelated to the Chiyuv to bring a Korban! (CHAZON ISH)
ANSWER: The CHAZON ISH answers that the verse of "O Hoda Elav" teaches that a Korban is one's own private matter, and it is not like other matters (such as punishments) that are subject to the jurisdiction of Beis Din. Both Rebbi Yehudah and the Chachamim agree with this. They argue about whether one may act according to his own conviction against what the witnesses say about these private matters. According to Rebbi Yehudah, one may act according to his own conviction, and therefore witnesses cannot obligate him to bring a Korban. According to the Chachamim, one may not act according to his own conviction, and therefore he must act according to the witnesses' words.
According to this understanding of the argument, it is clear how Rav Yosef derives from Rebbi Yehudah's words that one may eat food that he asserts is Tahor. The food that one eats certainly is his own, private matter, like a Korban. Therefore, according to Rebbi Yehudah, he may act according to his own conviction. The Chachamim who argue with Rebbi Yehudah in the case of a Korban will also argue with him in the case of eating food that witnesses attest is Tamei.
The Chazon Ish concludes by ruling that one is permitted to eat food that he is certain is permitted, even when witnesses testify that it is not permitted. However, only he may eat the food, and in private, and he may not feed it to anyone else. (Mordechai Zvi Dicker)