1) THE "ESHES ISH" WITHOUT A HUSBAND
QUESTION: The Mishnah states that one who has relations with his daughter-in-law is liable for transgressing both the prohibition of "Kalaso" ("his daughter-in-law") and "Eshes Ish" ("a married woman"). This is true whether he committed the act during his son's lifetime or after his son's death, and whether his son and daughter-in-law were married with Nisu'in or only with Erusin.
The CHIDUSHEI HA'RAN has difficulty with the Mishnah. If the son is dead, the daughter-in-law is no longer married. Why, then, is the father-in-law liable for transgressing the prohibition of "Eshes Ish"? She is a widow and no longer a married woman! The Chidushei ha'Ran does not accept the possibility that the Mishnah means that if the widowed daughter-in-law marries another man, her former father-in-law is liable for "Eshes Ish," because this is obvious and there is no need for the Mishnah to teach this. What is the meaning of the Mishnah?
(a) The CHIDUSHEI HA'RAN answers that the Mishnah is teaching a Halachah about the woman's status as his daughter-in-law. One might think that as long as the woman is widowed, she still is considered forbidden to her father-in-law, but once she remarries it is possible that she loses the status of his "daughter-in-law" since she now is another man's daughter-in-law. The Mishnah therefore teaches that the woman is always called his "daughter-in-law," even if she remarries and is now an "Eshes Ish" and someone else's daughter-in-law.
(b) Alternatively, the Chidushei ha'Ran suggests that the Mishnah is teaching a Halachah about the woman's status as an "Eshes Ish." According to the opinion that "Ein Isur Chal Al Isur" -- one Isur cannot take effect when there is already an Isur in effect (see Pesachim 35b), one might think that if the woman is widowed and is now only "Kalaso" but not an "Eshes Ish," even if she remarries she is not called an "Eshes Ish" to her father-in-law because of the rule of "Ein Isur Chal Al Isur." The Mishnah is teaching that the Isur of "Eshes Ish" does take effect, because it is an "Isur Kolel"; since it forbids all men from being with her, it is an exception to the rule of "Ein Isur Chal Al Isur."
The ARUCH LA'NER asks two obvious questions on this answer of the Chidushei ha'Ran. The previous statement of the Mishnah discusses the prohibition of a stepmother, an almost identical case to the prohibition of a daughter-in-law. The Mishnah says that one who has relations with his stepmother is liable for both the prohibition of "Eshes Aviv" ("the wife of his father") and "Eshes Ish." This is whether his action transpires during his father's lifetime or after his father's death, and whether his father was married with Nisu'in or only with Erusin. Why does the Chidushei ha'Ran not ask his question on that case of the Mishnah? If the Chidushei ha'Ran means that his answers should be applied to both cases of the Mishnah, then why does the Mishnah need two separate cases to teach the same concept?
The Aruch la'Ner answers that the Chidushei ha'Ran is discussing only the latter case in the Mishnah. The first case in the Mishnah comes to argue with Rebbi Yehudah (54a), who says that one who has relations with his stepmother is not liable for "Eshes Ish" but only for "Eshes Aviv." Moreover, it is not clear that the Tana Kama in this case would conclude that a daughter-in-law who remarries is also an "Eshes Ish." This is because everyone maintains that two Isurim which take effect on one object at the same time ("b'Bas Achas") are binding (even according to the opinion that normally applies "Ein Isur Chal Al Isur"). In the case of a daughter-in-law, the prohibition of "Eshes Ish" (when she remarries) takes effect after the prohibition of "Kalaso" was already in effect. This is the additional Chidush of the second case, and this is why the Chidushei ha'Ran does not ask his question on the case of "Eshes Aviv." (Y. MONTROSE)
2) "YIBUM" OR "CHALITZAH" WHERE KIDUSHIN WILL NOT TAKE EFFECT
QUESTION: The Gemara earlier (53a) establishes that Rebbi Yehudah follows the famous opinion of Rebbi Akiva (Yevamos 10b), that an act of Kidushin is not valid when the relationship involves any type of negative prohibition (Lo Ta'aseh). The Gemara asks that this does not seem to be Rebbi Yehudah's opinion in a different Beraisa which discusses a woman whose husband dies childless, but whose Yavam is forbidden to her with an "Isur Mitzvah" or an "Isur Kedushah." The Tana Kama defines an "Isur Mitzvah" as one who is forbidden because of Sheniyos (prohibitions of Arayos d'Rabanan, such as one's maternal grandmother), and an "Isur Kedushah" as a woman who is forbidden to a Kohen Gadol (e.g. a widow) or to a Kohen Hedyot (e.g. a divorcee). In a second Beraisa, Rebbi Yehudah reverses these definitions and explains that an "Isur Mitzvah" refers to a woman forbidden to a Kohen, and an "Isur Kedushah" refers to Sheniyos (see RASHI DH Rebbi Yehudah Machlif for his reason).
The Gemara asks that the words of Rebbi Yehudah imply that he agrees with the conclusion of the Tana Kama that such a woman is permitted in some way to the Yavam, but because of an external prohibition she should do Chalitzah instead of Yibum. This can be true, however, only if Rebbi Yehudah does not follow the view of Rebbi Akiva. According to Rebbi Akiva, just as a woman who is prohibited to the Yavam because of an Isur Kares performs neither Chalitzah nor Yibum (she has no connection to the Yavam since her Kidushin with the Yavam would not be valid at all), a woman who is prohibited to the Yavam because of any Lo Ta'aseh performs neither Chalitzah nor Yibum (since, according to Rebbi Akiva, Kidushin does not take effect with someone to whom she is prohibited with a Lo Ta'aseh). If Rebbi Yehudah follows the view of Rebbi Akiva, he should say that the woman does neither Chalitzah nor Yibum. The Gemara answers that Rebbi Yehudah merely intends to tell the Tana Kama that he incorrectly named the categories, but he does not intend to argue about whether his conclusion regarding Chalitzah and Yibum is accurate.
TOSFOS (DH v'Chayavei) is bothered by the Gemara's question. It is true that according to Rebbi Yehudah and Rebbi Akiva, Kidushin with a person whom one is forbidden to marry -- by an Isur Kares or by any Lo Ta'aseh -- is invalid. Why, though, does the Gemara assume that in both cases, the woman who falls to Yibum does neither Chalitzah nor Yibum? The principle of "Aseh Docheh Lo Ta'aseh" should apply, and the Mitzvas Aseh of Yibum should override the Lo Ta'aseh which forbids the marriage! (See Yevamos 3b.) In contrast, even Rebbi Akiva would agree that a very serious prohibition, one punishable with Kares, is not pushed aside for the fulfillment of a Mitzvas Aseh. (See Yevamos 8a, where the Gemara discusses this logic.) Why is the Gemara so certain of its assumption that because the Kidushin is invalid in both a case of a Chiyuv Kares and the case of a Chiyuv Lav, that the law with regard to Yibum in both cases is the same? (Tosfos here and in Yevamos (9a, DH v'Harei Isur) leaves this question unanswered.)
ANSWER: The ARUCH LA'NER proposes the following answer. The verse regarding Yibum states, "He will take her for a wife and do Yibum with her" (Devarim 25:5). The Gemara in Yevamos (20a) learns from this verse that once Yibum is performed, she is considered his wife. This implies that Yibum is valid only when the man can make the woman into his wife. Even if the first act of marital relations would be permitted because of Tosfos' logic that the Mitzvas Aseh overrides away the Lo Ta'aseh, the man and woman would be prohibited to each other after that. Since the Mitzvah of Yibum was performed already, there no longer is a Mitzvas Aseh to fulfill. Therefore, the Kidushin remains invalid. If the Kidushin is invalid and she cannot be his wife at all (in contrast to an Isur Lav, where the Kidushin is valid and she technically does become his wife), the Torah's requirement that Yibum makes the woman become his wife is not fulfilled. This is why the Gemara assumes that as long as the Kidushin is invalid, the woman has no connection to the Yavam or to the Mitzvah of Yibum, and thus she requires neither Chalitzah nor Yibum.
The CHIDUSHIM U'VI'URIM suggests a similar answer, but he concludes that this answer is not entirely satisfactory. The Gemara in Yevamos (8a) which discusses the concept of whether or not a Mitzvas Aseh overrides a Lo Ta'aseh she'Yesh Bo Kares implies that if it would override such a Lo Ta'aseh, then the Mitzvah of Yibum could be performed. This means that the Gemara apparently disregards the problem that the woman will not really become his wife. (Y. MONTROSE)