1) YIBUM WITH A WOMAN TO WHOM ONE'S BROTHER WAS NEVER REALLY MARRIED
QUESTION: The Mishnah (87b) states that when a woman marries another man under the assumption that her first husband died abroad, and then her first husband returns alive, she is prohibited to both men. The Mishnah adds that if either man dies with no children, the brother of that man must perform Chalitzah with the woman, and he may not perform Yibum.
The Gemara explains that the brother of the first husband must perform Chalitzah because he is the brother of her real husband, and thus the Mitzvah d'Oraisa to perform Chalitzah or Yibum takes effect. He cannot perform Yibum, however, because the Rabanan penalized the woman and gave her the status of a Sotah mid'Rabanan (a Sotah, or woman who is suspected of being unfaithful to her husband, may not do Yibum when her husband dies). The brother of the second husband performs Chalitzah only mid'Rabanan; mid'Oraisa there is no need for Chalitzah since the second husband was never really married to her. The Gemara adds that for the brother of the second husband, Yibum is "not mid'Oraisa [because she was not really married to the second husband], and not mid'Rabanan [because the Rabanan do not allow her to marry the brother of the second husband]."
The Gemara earlier (88b-89a) discusses why the second husband must give a Get to the woman when her first husband returns alive. The Gemara explains that the Rabanan instituted that a Get must be given as a penalty for the woman for not adequately investigating the matter to ensure that her husband was dead. In order that people not mistakenly assume that the first husband divorced the woman and her marriage to the second husband was valid, the Rabanan required that she receive a Get from the second husband.
RASHI (89a, DH Kansuha, as explained by the ROSH 10:1) explains that the Rabanan penalized the woman and required that she receive a Get only when there is logical basis for such a penalty (such as the concern that people will think that she was divorced from the first husband and married to the second). The combination of a logical basis for a Get and grounds to penalize her for wrongdoing is what requires her to receive a Get. (See also the Gemara on 95b.)
If a penalty is not administered unless it has a logical basis, why is the brother of the second husband not allowed to perform Yibum? In the case under discussion, the second husband died before he was able to give her a Get. While the reason to penalize her (for marrying another man without adequately verifying that her first husband was dead) remains, that reason is not enough to prohibit her to the second man's brother without a logical basis. However, the logical basis (that people will think that her first husband divorced her and she was really married to the second man) does not justify prohibiting the brother of the second husband from performing Yibum. If it is true that the first husband divorced her and she was married to the second man, she certainly is allowed to perform Yibum with the brother of the second husband. If, on the other hand, she was not married to the second husband (which is the actual case), she still should be permitted to do Yibum with the second man's brother because she does nothing wrong by marrying the second man's brother -- she was never married to his brother ("Eshes Achiv")! (MAHARSHA, REBBI AKIVA EIGER)
(a) The MAHARSHA suggests that in the case of Yibum, the Rabanan administer a penalty even with no logical basis. This is because Yibum involves an act of Bi'ah which is "Ikar Isura," a primary act of Isur itself.
This answer is problematic, however, because Yibum has the status of "Ikar Isura" only with regard to the brother of the first husband. (If the woman has relations with another man while married to the first husband, she is a Sotah and may not do Yibum when her husband dies.) There is no actual Isur with regard to the brother of the second man, since Yibum may be done with him (because she was never married to the second man, and thus she is not forbidden to his brother as "Eshes Achiv"). (See YASHRESH YAKOV.)
(b) Perhaps in this case the Rabanan indeed instituted a penalty with no logical basis and prohibited the brother from doing Yibum. Although they relied on a logical basis when they required that the second husband give the woman a Get when her first husband returns, they did not rely on any logical basis when they prohibited the brother of the second husband from performing Yibum. The Rabanan have the authority to enact, with no logical basis, a "passive" penalty which requires that a person not do an action (Yibum), while they must have a logical basis when they enact an "active" penalty which requires that a person do some action (write a Get). (M. Kornfeld. The YASHRESH YAKOV offers a similar solution.)
(c) RABEINU AVRAHAM MIN HA'HAR (87b) explains that there is a logical basis for the Rabanan's enactment in the case of Yibum as well. The Rabanan prohibited the brother of the second husband from performing Yibum lest people mistakenly assume that the first husband divorced her, and the second husband married her after he committed adultery with her while she was still married to the first husband. In such a case, the second husband who committed adultery with her is forbidden from marrying her (because a Sotah is forbidden to the man with whom she committed adultery). Just as the brother of a Sotah's husband may not perform Yibum, the brother of a Sotah's adulterer may not perform Yibum (if the adulterer marries the Sotah and then dies with no children). The CHELKAS MECHOKEK (EH 17:150) and the RASHASH here suggest the same answer.
(Whether or not the brother of the adulterer is actually prohibited to perform Yibum is a question discussed at length by the Rishonim and Acharonim. See TOSFOS to 3b, DH l'Fi, and MISHNEH L'MELECH, Hilchos Yibum 6:19.)
(d) The RASHASH suggests that the Mishnah and the Gemara mean something else entirely. When the Gemara says that the brother of the second husband "does not do Yibum mid'Rabanan," it does not mean that he is not permitted to do Yibum, but rather that he has no Mitzvah to do Yibum. When the Gemara says "he may not do Yibum, not mid'Oraisa and not mid'Rabanan," it means that there is no Mitzvah for him to do Yibum, neither mid'Oraisa nor mid'Rabanan.
Accordingly, if the brother of the second husband desires to marry her, he certainly may do so. However, if he marries her through an act of Bi'ah b'Ones or Bi'ah b'Shogeg (acts which are valid for Yibum but not for Kidushin), she does not require a Get from him. (That is, although the concern exists that people will assume she was married to the second man and they will think that the obligation of Yibum applies to her, the Rabanan did not go so far as to require a Get in a case where the brother performs Bi'as Ones or Bi'as Shogeg.)
2) AN "AYLONIS" WHO EXEMPTS HER "TZAROS" FROM YIBUM
QUESTIONS: The Gemara presents two cases in which a woman was obligated to do Yibum but instead married another man under the mistaken assumption that Yibum was not required. In both cases, when it is discovered later that Yibum was required, she is penalized with all of the stringencies mentioned in the Mishnah (87b).
In the first case, a woman's husband died childless, her Tzarah performed Yibum, and she went and married a second husband. Later it was discovered that her Tzarah was an Aylonis, to whom -- RASHI explains (DH v'Halchah) -- the laws of Yibum do not apply at all. Consequently, the obligation of Yibum rests with one of the other Tzaros, all of whom are prohibited to remarry until one of them does Yibum or Chalitzah.
In the second case, a woman's husband died childless, and she went and married a second husband because her Tzarah was an Ervah to the Yavam. The Mishnah in the beginning of Yevamos (2a) teaches that when one of the deceased man's wives is an Ervah to the Yavam, she exempts all of the other Tzaros from Yibum and Chalitzah. Later it was discovered that the Ervah was an Aylonis. RASHI (DH Halchu Tzaros) explains that since the Ervah was an Aylonis, her original Kidushin was done in error (since the man who married her assumed that she was healthy and he did not know that she was an Aylonis), and thus she was never married to the man who died and is not a candidate for Yibum at all.
Rashi implies that if Kidushin with an Aylonis would be valid, the Tzaros in this case indeed would be exempt from Yibum and would be justified in remarrying, since they are exempt from Yibum as Tzaros Ervah. (If this were not so, Rashi should have been consistent with his explanation of the first case and explained that the Tzarah is not exempt even if the Ervah turns out to be an Aylonis who was married properly to the deceased brother.)
Rashi's words are difficult to understand for several reasons.
(a) The Gemara earlier (12a-b) cites two opinions about whether an Aylonis exempts her Tzarah from Yibum. Rav Asi maintains that an Aylonis exempts her Tzarah from Yibum, even when the Aylonis is not an Ervah. Rava maintains that an Aylonis does not exempt her Tzarah from Yibum, even when the Aylonis is an Ervah.
Whose opinion does Rashi follow in his explanation of the Gemara here? In his first comment, Rashi writes that when one of the Tzaros is an Aylonis, only the Aylonis is exempt; the other Tzarah is obligated to do Yibum. Rashi clearly explains the Gemara according to the view of Rava that an Aylonis does not exempt her Tzarah.
Rashi's second comment, however, apparently follows the view of Rav Asi. Rashi implies that an Ervah who is an Aylonis does not exempt the Tzarah only because of the element of Mekach Ta'us involved. Had the husband known that she was an Aylonis at the time he married her, the marriage would have been valid and the Ervah would have exempted the Tzarah from Yibum. (REBBI AKIVA EIGER; see also YASHRESH YAKOV.)
(b) Rashi in Gitin (80a, the source for the Mishnah quoted by the Gemara here) explains in both cases that the reason why the Tzarah is not exempt from Yibum is because the man's marriage to the Aylonis was a Mekach Ta'us. Rashi there seems to rule like Rav Asi, because he implies that if the Kidushin would have taken effect, the Aylonis would have exempted the Tzaros. Rashi repeats this explanation earlier in Yevamos (2b, DH v'Chulan she'Meisu), where the Mishnah states that an Ervah who is an Aylonis does not exempt her Tzarah from Yibum. Rashi explains that it is because her Kidushin was a Mekach Ta'us.
Why does Rashi explain the Gemara according to the opinion of Rav Asi? The Gemara (12b) states clearly that the Halachah follows the view of Rava who says that an Aylonis does not exempt her Tzarah from Yibum! Rashi should explain that even if the marriage to the Aylonis was not considered a Mekach Ta'us, her Tzarah is still obligated to do Yibum because the laws of Yibum do not apply to an Aylonis. (NIMUKEI YOSEF 2b, in the name of the RASHBA)
(REBBI AKIVA EIGER (30b) explains that Rashi on 2b explains the Mishnah according to the Gemara's initial understanding, which is in accordance with Rav Asi's opinion. This is consistent with Rashi's general approach of explaining a Mishnah according to the Gemara's initial understanding of the Mishnah. However, this does not answer why Rashi explains the Gemara according to Rav Asi in the other places.)
(a) RAV SIMCHAH M'DESVI (in his Hagahos printed in the back of the Vilna edition of the Gemara) answers that perhaps Rashi understands that there is a third opinion in the Gemara (12b) with regard to whether or not an Aylonis exempts the other wives from Yibum. After the Gemara there rules like Rava that a Tzarah of an Aylonis is obligated to do Yibum even if the Aylonis is an Ervah, the Gemara mentions the view of Ravin who maintains that a Tzarah of an Aylonis is obligated to do Yibum. The Gemara makes no mention of whether she must do Yibum even if the Aylonis is an Ervah. Perhaps Ravin maintains that the Tzarah of an Aylonis must do Yibum only when the Aylonis is not an Ervah, but when the Aylonis is an Ervah the Tzarah is exempt from Yibum and Rashi follows the opinion of Ravin.
This answer is somewhat forced because the Gemara does not imply that Rava and Ravin argue. Also, this answer does not address the second question.
(b) Perhaps both questions may be resolved with the following approach.
Although the Gemara (12b) rules like Rava even in a case in which the Aylonis is an Ervah, the Gemara has a strong question on Rava's opinion. The Gemara asks that the wording of the Mishnah does not support the view of Rava. The Mishnah states that an Aylonis who is an Ervah does not exempt the Tzarah when she was "found to be an Aylonis," which implies that if the husband knew from the start that she was an Aylonis, she does exempt her Tzarah from Yibum. The Gemara answers that according to Rava the wording of the Mishnah must be emended to read "was an Aylonis" instead of "found to be an Aylonis."
The Gemara's question, and its forced answer, imply that the Halachah does not follow Rava with regard to the Tzarah of an Aylonis who is an Ervah, since Rava's view in this matter is contradicted by the straightforward reading of the Mishnah. An Ervah exempts her Tzarah, even when the Ervah is an Aylonis. Support for this ruling is found in a Beraisa earlier in Yevamos (15a), in the words of the Tana Kama.
(When the Gemara (12b) says that "even if the Aylonis was an Ervah her Tzarah is obligated to do Yibum," it might not be referring to the Halachic ruling that immediately precedes this statement. Rather, the Gemara there is asking a question: "Is this the Halachah even in the case of a Tzarah of an Aylonis who is an Ervah?" Although the Gemara does not say that the Halachah is not like Rava in the case of an Aylonis who is an Ervah, Rashi chooses not to rule like Rava because of the question from the Mishnah which the Gemara there asks.)
According to this understanding, Rashi here does not contradict himself. An Aylonis does not exempt her Tzarah even if the man knew she was an Aylonis at the time of the Kidushin. However, if the Aylonis is an Ervah, she does exempt her Tzarah from Yibum. Therefore, Rashi must write that the reason she does not exempt her Tzarah from Yibum is because her marriage was a Mekach Ta'us. This also explains the words of Rashi on the Mishnah (2b) and in Gitin (80a), where the Mishnayos discuss an Aylonis who is an Ervah.
How, though, does this approach explain the second comment of Rashi in Gitin, where he writes that the Yibum of an Aylonis who is not an Ervah does not exempt the other Tzaros because the marriage to the Aylonis was a Mekach Ta'us? Even without the reason of Mekach Ta'us, the Aylonis cannot perform Yibum, and her Tzarah remains obligated to do Yibum.
Perhaps Rashi there gives the reason of Mekach Ta'us only for practical considerations. In Gitin, the case of the Aylonis who was an Ervah is mentioned before the case of the Aylonis who was not an Ervah. Since Rashi already explains the reason of Mekach Ta'us in the first case of the Mishnah, he repeats this reason in the second case. In the Gemara here, however, where the cases are cited in the opposite order, Rashi explains in the first case (where the Aylonis is not an Ervah) that the Tzarah is obligated because the Halachah is that an Aylonis does not exempt the Tzarah from Yibum. (M. Kornfeld)