1) THE KIDUSHIN D'RABANAN OF A "YESOMAH B'CHAYEI HA'AV"
QUESTION: The Gemara discusses the case of a Ketanah whose father died. The Rabanan instituted that her mother or brother may marry her off with Kidushin d'Rabanan, for which she has the option of doing Mi'un. According to Beis Shamai, from the moment she enters the Chupah (Nisu'in), and even from the moment "that her father passes her over to the husband's entourage," she may no longer do Mi'un.
RASHI (DH Masar ha'Av) explains that when the Gemara mentions "that her father passes her over to the husband's entourage," it cannot refer literally to the father, because a Ketanah whose father is alive may not do Mi'un. When her father marries her off, the Kidushin is mid'Oraisa, for which Mi'un may not be done. Kidushin d'Rabanan exists only when she has no father and her mother or brother marries her off.
Why does Rashi insist that the Gemara does not refer to the father himself, and that in order for the Kidushin to be mid'Rabanan the father must not be alive? There exists a situation in which the father is alive and yet the Kidushin nevertheless is mid'Rabanan and the Ketanah may do Yibum: the situation of "Yesomah b'Chayei ha'Av" -- "an orphan during the life of her father." If the father married her off, and then she was divorced, the father may not marry her off again to a second husband even though she is still a Ketanah; she has the status of a "Yesomah b'Chayei ha'Av." If she then marries someone else while she is a Ketanah, the Kidushin is mid'Rabanan and she has the option to do Mi'un. (Rashi himself discusses this situation on 109a, DH Ketanah, and earlier on 2b and 12a.) Hence, "the father passes her over" indeed can refer literally to the father. Why does Rashi insist that the Gemara does not refer to the father? (RAV YAKOV EMDEN, ARUCH LA'NER; see also Insights to Yevamos 89:1.)
ANSWER: The RITVA addresses this question. He infers from Rashi's words that when the Ketanah is a "Yesomah b'Chayei ha'Av," her father no longer has control over whom she marries at all, and he may not marry her off even with Kidushin d'Rabanan. The Rabanan empowered only his wife and sons with the right to marry off the Ketanah in the event that her father is no longer living; they did not give that right to her father after she was married and divorced from her first husband. The Ritva cites Rashi later (109a, DH v'Hechzirah) as additional proof that this is Rashi's opinion.
The Rishonim discuss what type of Kidushin constitutes the Kidushin d'Rabanan of a "Yesomah b'Chayei ha'Av."
(a) According to the simple reading of the Ritva, he maintains that according to Rashi a "Yesomah b'Chayei ha'Av" cannot become married even with Kidushin d'Rabanan. Since her father is alive, she does not have control over her Kidushin. On the other hand, since she was married once and divorced, her father also has no control over her Kidushin. She thus must remain unmarried until she reaches adulthood.
However, this inference from the words of the Ritva is incorrect. The Gemara in numerous places states that she may remarry while she is a Ketanah. The Gemara earlier (12a) discusses a case of one's daughter who falls to her father for Yibum and does Mi'un to her deceased husband. The marriage in that case clearly was a Kidushin d'Rabanan (for otherwise Mi'un may not be done), and yet the father is still alive. Similarly, the Mishnah later (109a) states that a "Yesomah b'Chayei ha'Av" may get married but not with a "Kidushin Gemurin," implying that the Kidushin d'Rabanan does take effect. Rashi himself, in many places, makes this point explicitly (see Rashi to 2b and 12a). (YASHRESH YAKOV and other Acharonim; see footnote #43 of Rav Aharon Yaffen to the Ritva.)
Apparently, Rashi means that the father cannot marry off his daughter when she is a "Yesomah b'Chayei ha'Av," but she may accept Kidushin herself, in which case the Kidushin is mid'Rabanan. (The Gemara on 108a refers to a Mema'enes who accepts her own Kidushin.) Just as her father does not have the power to marry her off, he also cannot "pass her over for Chupah." This explains why Rashi writes that the Gemara does not mean that the father himself passed her over to the husband. Rashi maintains that the father does not have the authority to do so when she is a "Yesomah b'Chayei ha'Av." The TZAFNAS PANE'ACH (Hilchos Ishus 4:7) reaches the same conclusion, and he points out that Rashi himself writes this explicitly in Gitin (65a, DH u'Chenegdan) and in Kidushin (44b, DH Ma'aseh Yesomah).
Accordingly, it seems clear that when the father cannot marry her off, certainly the other relatives also cannot marry her off. The Rabanan did not empower the relatives with the authority to marry her off in the case of a "Yesomah b'Chayei ha'Av," because in such a case they were not concerned for her well-being (lest she take to the streets), for she has a father who will take care of her.
(The Aruch la'Ner assumes that according to the Ritva's understanding of Rashi, it is only the father who cannot accept Kidushin for the Ketanah, but her mother and brothers may accept Kidushin for her. This assertion, however, is difficult to justify logically.)
(b) The Ritva quotes others ("Yesh Mefarshim") who explain that the Rabanan did institute that the father may marry off the daughter with Kidushin d'Rabanan (and she has the option for Mi'un) even when she is a "Yesomah b'Chayei ha'Av."
The Ritva does not mention whether or not the other relatives may marry her off according to this opinion. It is possible that when the father is alive and can marry her off (mid'Rabanan), the other relatives cannot marry her off.
(c) The BEIS SHMUEL (EH 155:1) writes that not only can the father marry her off, but even the mother and brother can marry off the "Yesomah b'Chayei ha'Av" with Kidushin d'Rabanan, just as they may marry off an ordinary Yesomah.
2) HALACHAH: HOW MANY WITNESSES ARE NEEDED FOR MI'UN
OPINIONS: The Gemara records an argument with regard to how many witnesses must be present when a Ketanah performs Mi'un. The Beraisa first says that according to Beis Hillel, three witnesses must be present. The Beraisa concludes that other Tana'im maintain that two witnesses suffice and that the Halachah follows that view. The Rishonim disagree about what the Beraisa means.
(a) TOSFOS (DH Machshirin) writes that Mi'un may be done even in front of one witness. The reason why the Gemara says that it must be done in front of two is that without two witnesses there is no way to prove that she did Mi'un. The Mi'un itself, however, is valid even when two witnesses are not present and there is no way to prove in Beis Din that it was done. Accordingly, if Mi'un is performed in front of a single person and there are two witnesses hiding nearby who witness the Mi'un, the Mi'un is valid and can be proven in Beis Din. This also seems to be the view of RASHI (108a, DH Chenvani) and the RASHBA.
The RITVA adds that even when two witnesses do not watch the Mi'un from a nearby hiding place, the girl is believed when she admits that she performed Mi'un in front of one witness. However, she is believed only insofar as it is relevant from now on (and not retroactively from the time at which she says she did Mi'un), because it is in her hands to do Mi'un now if she chooses to do so.
The OR ZARU'A (1:673) cites RABEINU SIMCHAH who mentions another case of Mi'un performed in front of one witness, for which proof will not be necessary. Mi'un performed only in front of the husband is valid, and when both she and her former husband later admit in court that she did Mi'un, no further proof for the Mi'un is necessary.
(b) The RAMBAM rules (Perush ha'Mishnayos Yevamos 13:2, Hilchos Gerushin 11:8, and Hilchos Ishus 4:9) that Mi'un must be done in front of two witnesses. This is also the view of RABEINU CHANANEL (cited by Tosfos DH Halachah), the Rashba, and other Rishonim. Rabeinu Chananel adds that l'Chatchilah, Mi'un must be done in front of three witnesses; two witnesses are sufficient only b'Di'eved.
According to the Rambam, two witnesses are required not merely to prove that the Mi'un occurred, but actually to effect the Mi'un. If two witnesses are not present at the Mi'un, the Mi'un is not valid (in contrast to the view of Tosfos). Apparently, the Rambam maintains that Mi'un has the status of a "Davar sheb'Ervah," like Kidushin and Gerushin, and therefore it takes effect only when done in front of two witnesses, and without two witnesses it does not take effect at all. (The witnesses are not "Edei Ra'ayah," witnesses who serve to prove that the event occurred, but they are "Edei Kiyum," witnesses who play an integral role in causing the act to take effect. See Kidushin 65b.)
The CHAZON ISH (111:8) adds that according to the Rambam, even when two witnesses are present when Mi'un is done but they are hidden from view, the Mi'un is not valid. Witnesses who are in hiding at the time they see the act are not valid for Kidushin, or for any other act that requires "Edei Kiyum."
HALACHAH: The SHULCHAN ARUCH (EH 155:4) writes that Mi'un must be done in front of two witnesses, "and there are those who say" that l'Chatchilah it should be done in front of three.