1) A WOMAN'S TESTIMONY ABOUT HER HUSBAND AND CHILD ABROAD
QUESTION: If a woman's husband and Tzarah travel together abroad and the woman finds out that her husband died, she may not do Yibum even though her husband had no children when he left. She must take into account the possibility that her Tzarah bore children to her husband while abroad. On the other hand, she is not permitted to remarry because perhaps her Tzarah did not bear any children to her husband, in which case she is obligated to do Yibum.
The Gemara asks that she should be permitted to remarry because "most married women become pregnant and have children." Beis Din should permit the woman to remarry based on the assumption of the "Rov" that the Tzarah had a child.
The Gemara answers that the Mishnah follows the opinion of Rebbi Meir who maintains that Beis Din must be stringent and take into account the less likely possibility ("Chosheshim l'Mi'ut"). In this case, Beis Din must be stringent and take into account the possibility that the Tzarah did not have a child. (The Chazakah that she did not have a child until now supports that Mi'ut.)
The Mishnah in the end of the previous chapter (118b) discusses the case of a man (who had no children) and his wife who traveled together abroad. The Mishnah states that if the woman returns and says that she gave birth to a child abroad but the child died before her husband died, she is believed (and must do Yibum) because of the Chazakah that until now she was obligated to do Yibum since she had no children. Although she admits that she gave birth to a child and cannot prove that the child died before her husband died, she is believed to say that the child died before her husband died because of a "Migu": she could have said nothing about the child, and she would have been obligated to do Yibum because of the Chazakah (RASHI DH Meis Ba'ali, RITVA). If she says that the child died after her husband died (and she should be exempt from Yibum), she is not believed because she contradicts the Chazakah that she is obligated to do Yibum.
Why should the Chazakah that she did not have children before she departed be the decisive factor in proving that she is obligated to do Yibum? The Rov contradicts the Chazakah and states that she probably became pregnant and had a child (and is not obligated to do Yibum).
According to the Rabanan (who do not take into account the Mi'ut), when the woman says nothing about the child she should be allowed to marry anyone (without doing Yibum) because of the Rov. According to Rebbi Meir, she should be required to do Chalitzah and not Yibum ("Choletzes v'Lo Misyabemes"), because Rebbi Meir takes into account the Mi'ut, the less likely possibility that she did not have children. Hence, even if she says that she had a child abroad and the child died before her husband died, the same Halachah should apply because of the "Migu" -- she should be required to do Chalitzah and not Yibum, "Choletzes v'Lo Misyabemes." (TOSFOS REBBI AKIVA EIGER, Yevamos 15:125)
ANSWER: The RAMBAN and RASHBA address this question. They explain that in the case of a man and his wife who went abroad without a child and the wife returned without a child, all Tana'im agree that the Rov does not overpower the Chazakah. This is because two factors indicate that she is obligated to do Yibum -- the Chazakah that she had no children before she left, and the fact that she returns without a child (with no evidence that there ever was a child). That is, there are two Chazakos -- one Chazakah that she had no children before she departed, and another Chazakah that she had no children when she returned. These two Chazakos overpower the Rov which says that she gave birth to a child abroad. Accordingly, Beis Din assumes that she does not have a child and requires that she do Yibum or Chalitzah. If she says that she had a child and the child died before her husband died, she is believed with a "Migu" that she could have said nothing about a child, in which case she would have been obligated to do Yibum.
The Gemara here, however, discusses the case of the woman's Tzarah who went abroad (and not the woman herself). Since she never returned, there obviously is no Chazakah that states that upon her return she had no children. Therefore, the Rov overrides the single remaining Chazakah (that she had no children when she departed) and states that she probably gave birth to a child abroad.
However, the Mishnah earlier (118b) teaches that if the woman who returns from abroad testifies that the child died after her husband died (and she should be exempt from Yibum), she is not believed because she contradicts the Chazakah that until now she had no children. Why, though, is she not believed? She should be believed because of the Rov that says that she probably did have a child while abroad. Although she says that the child died, she has a "Migu" that she could have said that she had a child and the child is still alive. (She certainly would have been believed had she made such a claim, because her testimony is supported by the Rov.)
The simple answer would be that the Mishnah there follows the opinion of Rebbi Meir (as the Mishnah here does) and maintains that the Rov does not override the Chazakah because of the concern for the Mi'ut. Therefore, the woman must do Chalitzah and not Yibum, "Choletzes v'Lo Misyabemes."
TOSFOS (DH Amai) challenges this answer. If the Mishnah earlier (118b) follows the opinion of Rebbi Meir, why does the Gemara wait until now to prove that the Mishnah follows the opinion of Rebbi Meir? The Gemara should have discussed the matter earlier!
1. TOSFOS answers that the previous Mishnah does not follow the opinion of Rebbi Meir. Rather, it refers to a case in which witnesses testify about the death of the woman's child but do not know whether her child or her husband died first. Their testimony eliminates her "Migu": Once they testify that she had a child, she no longer is believed to say that the child died after her husband, based on a "Migu" that she could have said that her child is still alive. She is not permitted to remarry without first doing Yibum, even according to the Rabanan who normally follow a Rov, since she has no "Migu" to say that the child is still alive.
The MAHARSHA is perplexed by this answer. If the Mishnah there refers to a case in which witnesses testify that she had a child and the child died, she has a Chazakah that she is exempt from Yibum because she had a child! Therefore, if she says that her child died before her husband died, she should not be believed and permitted to do Yibum. On the contrary, there is a Chazakah that she is prohibited to the Yavam. (See ARUCH LA'NER, KARNEI RE'EM.)
The KEREN ORAH answers that Tosfos' intent is to apply the logic of the Ramban and the Rashba even when witnesses come and testify that there was a child but the child died. Since she left without a child, and upon her return the witnesses who testify that she had a child also testify that she no longer has a child, the original Chazakah -- that she is obligated to do Yibum -- is in force. Although there was a point in time at which she had a child (as the witnesses testify), since the birth of that child becomes known only at the same time that the death of the child becomes known, the Chazakah that she had no child and is obligated to do Yibum remains. Just as the existence of the Rov does not preclude the application of the Chazakah, the testimony of the witnesses that she had a child is not reason to reject the Chazakah since she presently has no child. When she says that the child died after her husband died, she is not believed with a "Migu" that she could have said that the child is still alive, because witnesses testified that the child died.
Why does she not have a "Migu" that she could have said that she had twins and the second child is still alive? Perhaps she does not have such a "Migu" because she had no way of knowing that witnesses would testify that her child died, and thus she did not consider making such a claim. Alternatively, a "Migu" alone is insufficient grounds to counteract the Chazakah that she is obligated to do Yibum. (Only the type of "Migu" of "Peh she'Asar Hu ha'Peh she'Hitir," or a "Migu d'Iy Ba'i Shasik," a Migu that she could have said nothing if she indeed is lying, is strong enough to counteract the Chazakah. The logic of the "Migu" validates her claim only when she could have omitted something from her testimony (and thereby made her testimony more plausible) but she said it anyway. It does not validate her claim when she merely could have said a stronger claim than the one she actually said.)
2. Other Rishonim disagree with the answer of Tosfos. The RAMBAN explains that the woman who went abroad with her husband has a Chazakah that she is obligated to do Yibum not only because she left and returned without children, but also "because we never heard that she had children." According to the Ramban, if witnesses testify that she had a child while abroad, even though they also say that the child died the woman no longer has a Chazakah that she is obligated to do Yibum. (It is interesting to note that the Rashba omits these words when he quotes the Ramban here.)
However, if she has no Chazakah that she must do Yibum, the question returns: Why is she not believed when she returns from abroad and testifies, "I bore a son abroad, and my husband died before my son died"? She should be believed because of a "Migu" that she could have said that she bore a son and her son is still alive (a claim which would be believed because of the Rov)!
Apparently, the answer is that the Ramban indeed understands that the Mishnah earlier (118b) follows the opinion of Rebbi Meir who says that Beis Din does not rely on the Rov that the woman bore a child abroad. Therefore, even if the woman says that she bore a child abroad, she is not believed because the Rov which supports her claim is unable to counter the Chazakah that she is obligated to do Yibum.
Why does the Gemara there not mention that the Mishnah there follows the opinion of Rebbi Meir? Perhaps the Gemara does not mention it because it is obvious that the Mishnah there follows his opinion. In contrast, it is not so obvious that the Mishnah here follows his opinion because, as the Gemara points out, if the Mishnah follows Rebbi Meir, the end of the Mishnah contradicts the beginning of the Mishnah.

119b----------------------------------------119b

2) LETTING A WOMAN REMARRY BY PROHIBITING HER TO A KOHEN
QUESTION: The Gemara concludes that if a woman's husband and Tzarah traveled abroad and she does not know whether the Tzarah bore a child to her husband before he died, she is prohibited to remarry (without first doing Yibum) until she verifies that the Tzarah had a child.
The Gemara asks that she should be allowed to do Chalitzah and then remarry. Chalitzah will solve her problem regardless of whether or not her Tzarah had a child: If her Tzarah had a child, she does not need Chalitzah (and she commits no wrong by doing Chalitzah when it is not required), and if her Tzarah did not have a child, the Chalitzah permits her to remarry. The Gemara answers that she is not allowed to do Chalitzah because if it is discovered later that the Tzarah did have a child, Beis Din will have to announce that the woman's Chalitzah was not valid (since there was no obligation to do Chalitzah) and that she is permitted to marry a Kohen. However, such a public announcement that the Chalitzah was not valid is not an efficient way of spreading the word that she is permitted to marry a Kohen. Someone might not hear the announcement, and when he sees the woman marry a Kohen he will mistakenly assume that a Kohen is allowed to marry a Chalutzah. Therefore, the woman is not permitted to do Chalitzah out of doubt in the first place.
The Gemara's reasoning is difficult to understand. Why do the Rabanan prohibit her from doing Chalitzah now due to the fear that later she might marry a Kohen when it is discovered that her Chalitzah was not necessary (and someone might not know that her Chalitzah was not necessary)? The Rabanan should permit her to do Chalitzah now and prohibit her from marrying a Kohen if later it is discovered that she did not need Chalitzah!
ANSWERS:
(a) The PERISHAH (EH 156:29) and the HAGAHOS TOSFOS YOM TOV (ibid.) answer that if the Rabanan permit the woman to do Chalitzah and to marry anyone except a Kohen, when the woman later discovers that her Tzarah gave birth and she did not need Chalitzah she will think that she is permitted to marry a Kohen despite what she was told at the time she did Chalitzah. Although Beis Din tells her that she is prohibited from marrying a Kohen forever once she performs this act of Chalitzah, she will reason that they told her this only because of the possibility that the Chalitzah was valid. She will not understand why she should be prohibited to a Kohen when it becomes known that her Chalitzah was completely unnecessary.
Therefore, the only suitable course of action is to not allow her to do Chalitzah and remarry until she finds out whether her Tzarah had a child. Such a ruling will seem logical to her, as it makes sense that she cannot do Chalitzah as long as she does not know whether or not her husband had children.
(b) An additional answer may be suggested based on the approach of the Perishah. If the Rabanan permit her to do Chalitzah and then prohibit her to a Kohen when it becomes known that her Tzarah had a child and the Chalitzah was meaningless, people will wonder why the Chalitzah was valid enough to prohibit her to a Kohen in the first place. They will incorrectly conclude that the Chalitzah must have been done while the Tzarah was pregnant, before the child was born, and that is why it was valid.
This, in turn, will lead people to conclude that when a man dies with no children but his wife is pregnant, her act of Chalitzah or Yibum is valid even if the child is born healthy and lives, since he was not born before the death of his father. In truth, however, the Halachah in such a case is that the Chalitzah is not valid, and Yibum is prohibited with an Isur Kares (35b). It was because of this concern that the Chachamim did not permit her to do Chalitzah now and prohibit her to a Kohen when her Tzarah returns with a child. (M. KORNFELD)

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