1) THE YIBUM OF A "CHERESH"
QUESTION: The Gemara quotes the Mishnah earlier (104b) which states that a Cheresh and Chareshes cannot perform Chalitzah. The Gemara (here and on 104b) explains that since Chalitzah requires that one say the words in the Parshah of Chalitzah (Devarim 25:7-8), one who is unable to speak cannot perform Chalitzah. However, a Cheresh and Chareshes may perform Yibum, as the Mishnah here states.
TOSFOS (44a, DH Kol she'Eino) asks a basic question on the Gemara. If a Cheresh and Chareshes cannot do Chalitzah, they should also not be able to do Yibum. Just as Chalitzah may not be done in a situation in which Yibum cannot be done (44a), Yibum may not be done in a situation in which Chalitzah cannot be done (see TOSFOS to 44a, DH u'Neyabem). Why may a Cheresh do Yibum if he is unable to do Chalitzah?
ANSWER: TOSFOS answers that the only reason why a Cheresh cannot do Chalitzah is that he cannot recite the words that are part of the Chalitzah procedure. It is not because a Cheresh is inherently unfit to do Chalitzah; rather, he is fit to do Chalitzah but something impedes his performance of the procedure. He is like a person who cannot talk because his mouth is in pain (as the Gemara mentions on 104b). Since a Cheresh is considered fit for Chalitzah, he may do Yibum.
Tosfos apparently follows his reasoning as expressed elsewhere. Tosfos (104b, DH v'Ha Amri) writes that even a person who has no Da'as is able to do Chalitzah, as the Gemara (105b) teaches that a Ketanah may do Chalitzah even though she has no Da'as.
This assertion itself, however, is difficult to understand. Why may a Ketanah and a Chareshes -- who have no Da'as -- perform Chalitzah? Chalitzah requires proper mental intent (106a), and a Ketanah and Cheresh are incapable of having proper mental intent.
Tosfos answers that since Chalitzah is done in the presence of the elders of Beis Din who instruct the Ketanah or Chareshes to have the appropriate intent, her intent is considered sufficient enough for the Chalitzah to take effect (as the Gemara describes in Gitin 22b with regard to a Katan who writes a Get Lishmah). (Although the Tosefta (11) states that a woman who is a Shotah cannot perform Chalitzah because she lacks Da'as, a Shotah is different from a Ketanah and Chareshes in that she has so little Da'as that even when the Beis Din tells her exactly what intent to have in mind, she is unable to do the act with intent that it is for the sake of Chalitzah.)
Other Rishonim disagree with Tosfos and give other reasons for why the Chalitzah of a Cheresh is invalid. The RAMBAN, RASHBA, and RITVA (104b) explain that a Cheresh indeed lacks Da'as, and for that reason he cannot perform Chalitzah, and not simply because he cannot articulate the words. (A Ketanah, however, is able to do Chalitzah because she is able to articulate the words and she has enough Da'as to have proper intent for Chalitzah; see RASHBA to Chulin 12b.) According to these Rishonim, why does the Gemara say that a Cheresh cannot perform Chalitzah because "he cannot speak"?
The Ramban and Ritva answer that the Gemara refers to a Cheresh who is able to speak but cannot hear. When the Gemara says that he cannot do Chalitzah because he cannot speak, it means that he is unable to hear what the other party says. The Rashba (104b) writes that although a Cheresh is actually unfit for Chalitzah because he has no Da'as, the Gemara gives the reason that he is unable to speak in order to teach that even an Ilem, one who can hear but cannot speak, may not do Chalitzah.
According to these Rishonim, what is the Halachah in the case of a Cheresh who can neither speak nor hear? May he do Yibum? If such a Cheresh is considered to have no Da'as, he is completely unfit for Chalitzah and thus he should not be able to do Yibum.
These Rishonim make no mention of the logic of Tosfos. They apparently disagree with Tosfos (44a) and maintain that the rule that Yibum depends on Chalitzah is not reciprocative: one who is unfit to do Yibum may not do Chalitzah, but one who is unfit to do Chalitzah may do Yibum.

110b----------------------------------------110b

2) THE REASON WHY A KETANAH AND A CHARESHES DO NOT EXEMPT EACH OTHER FROM YIBUM
QUESTION: The Mishnah (110a) states that when two Tzaros, a Ketanah and a Chareshes, fall to Yibum together, the Yibum or Chalitzah of one does not exempt the other. The Gemara explains that it is assumed that the deceased brother preferred either the Ketanah or the Chareshes, and whichever woman he preferred as his wife is considered his main wife whose Yibum or Chalitzah exempts the other. Since there is a doubt about which wife the brother preferred, neither one exempts the other. Rashi quotes this reason in the Mishnah.
However, the Gemara soon afterwards gives a completely different reason for why the Yibum or Chalitzah of a Ketanah or Chareshes does not exempt the other. The Gemara says that the Kinyan of a Chareshes is a "half-Kinyan," while the Kinyan of a Ketanah is a "Safek Kinyan" -- it might be a fully valid Kinyan, but it also might not be a Kinyan at all. It is because of that doubt that neither woman exempts the other. This reason is entirely different from the reason the Gemara gives earlier. How are the two Sugyos to be reconciled?
ANSWERS:
(a) When the Gemara says that there is a doubt which wife the deceased brother preferred, the Ketanah or the Chareshes, Rav Ada bar Ahavah suggests that if the dead brother himself was a Cheresh, he obviously must have preferred the Chareshes over the Ketanah. Rav Nachman rejects this suggestion and states that even if the brother was a Cheresh, a doubt still remains about which wife he preferred, the Ketanah or the Chareshes.
It is possible that Rav Nachman argues with Rav Ada bar Ahavah because he understands the doubt in an entirely different way. Rav Nachman maintains that which wife exempts the other from Yibum does not depend on whether the deceased husband was more fond of one than the other. Rather, he maintains that it depends on whether the Kinyan of a Ketanah is stronger or weaker than the Kinyan of a Chareshes. The Gemara which follows is in accordance with the opinion of Rav Nachman and discusses only the question of the strength of the Kinyan of the Ketanah relative to the Kinyan of the Chareshes.
(b) However, the RASHBA (Teshuvos 1:1196) has a slightly different Girsa in the Gemara. According to his Girsa, it is clear that even Rav Nachman maintains that the doubt is which wife did the Cheresh prefer. Rav Nachman maintains that although the brother was a Cheresh, he might have preferred the Ketanah over the Chareshes.
The Rashba explains that the Sugyos actually argue with each other, and the Gemara indeed alters its explanation of the Mishnah at this stage.

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