GITIN 33 - dedicated to the memory of Hagaon Rav Yisroel Zev (ben Rav Avrohom Tzvi) Gustman, ZT'L, Rosh Yeshiva of Yeshivas Netzach Yisrael-Ramailes (in Vilna, Brooklyn, and then Yerushalayim), author of Kuntresei Shi'urim, and renowned Dayan in pre-war and post-war Vilna, in honor of his Yahrzeit (28 Sivan). Dedicated by Talmidim who merited to study under him in Yerushalayim.

1) THE AUTHORITY OF THE RABANAN TO UPROOT A MARRIAGE
QUESTIONS: The Gemara teaches that the Rabanan have the authority, in certain situations, to end a marriage by uprooting the Kidushin retroactively. The Gemara here discusses the case of a man who sends a Get to his wife and then annuls the Get after the Shali'ach has departed, without informing the Shali'ach of the annulment. Although the Get is not valid when the Shali'ach gives it to the woman, the Rabanan instituted that the Get takes effect. What authority do the Rabanan have to make the Get valid when, mid'Oraisa, it is not valid? The Gemara explains that the Rabanan utilized their authority to uproot the Kidushin (retroactively) -- "Afke'inhu Rabanan l'Kidushei Minei."
(Another case is described in Kesuvos 3a: a man gives a Get to his wife on condition that he does not return from abroad, and then circumstances beyond his control prevent his return. Although mid'Oraisa the Get is not valid (since a fulfillment of a condition against one's will is not considered a fulfillment of the condition), the Rabanan instituted that the Get takes effect (for the reasons the Gemara there describes).)
How does this mechanism of uprooting the Kidushin work? When the Rabanan uproot the Kidushin, is it considered as though the man and woman were never married? If it indeed works this way, it should be possible to remove the status of a Mamzer from a child born to a married woman through rape or an adulterous relationship. By uprooting the Kidushin retroactively (such as by having her husband send her a Get with a Shali'ach and then annul the Get), the child's status as a Mamzer should be able to be removed. In the same manner, a man should be able to save his wife from being punished with Misah when she willfully committed adultery. (TOSFOS DH v'Afke'inhu)
Furthermore, the PNEI YEHOSHUA points out that if the Rabanan uproot the Kidushin retroactively, if the brother of the husband later marries the woman (who is forbidden to him as "Eshes Achiv"), the Kidushin should take effect mid'Oraisa (and she should require a Get if she wants to leave him) since she is not his "Eshes Achiv." Is this indeed the Halachah?
Another question is that if the Rabanan are able to remove Kidushin in such a manner, then why do they not use it in a broader context -- such as to permit Agunos to remarry? For example, in a case in which a husband drowns at sea ("Mayim she'Ein Lahem Sof") and there is no positive testimony that he is dead, the Halachah is that his wife may never remarry. The Rabanan should permit her to remarry by exercising their authority to uproot the Kidushin retroactively! (See also Insights to Kesuvos 3:1.)
ANSWERS:
(a) TOSFOS explains that it is true that where the Rabanan uproot the Kidushin, a child who is a Mamzer due to the presence of the Kidushin becomes legitimate, and the woman becomes exempt from punishment for committing adultery (and, presumably, if she marries the brother of her husband, the Kidushin with him will take effect). However, a person cannot intentionally take advantage of this power of the Rabanan to correct the status of a Mamzer. In such a case -- where a man intentionally sends a Get to his wife with a Shali'ach and then annuls the Get in order to save his wife from punishment or to make his wife's illegitimate children legitimate -- the Rabanan do not uproot the Kidushin. They uproot the Kidushin only when a man annuls the Get innocently, with no ulterior motives.
Why do the Rabanan not exercise their authority to uproot Kidushin in order to permit Agunos to remarry? The RAMBAN and RASHBA explain that the Rabanan exercise this power only where there is some form of Get that was already given. Although the Get itself is not valid, the Rabanan uproot the Kidushin based on the giving of that Get.
This also seems to be the intention of RASHI here who repeatedly writes that the Rabanan uproot the Kidushin "when a Get is given." (Rashi in Shabbos (155b) writes that the reason the Rabanan permitted a woman to remarry based on the testimony of a single witness is because of the principle of "Afke'inhu." Here, Rashi explains why the Rabanan do not apply "Afke'inhu" to permit Agunos in other situations. Rashi is explaining that in the case of a single witness who testifies that the husband died, there is at least some sort of testimony that he died, and thus there is a basis for the Rabanan to uproot the Kidushin. According to Rashi, wherever there is some form of Get or some form of testimony of death, the Rabanan may apply "Afke'inhu.")
(b) The RAMBAN and RE'AH write that although the Rabanan uprooted the Kidushin d'Oraisa, they nevertheless established in its place a Kidushin d'Rabanan. Therefore, the child born to the woman from another man will still be a Mamzer d'Rabanan, and the relatives of the husband will be prohibited to the woman mid'Rabanan. Similarly, she will be prohibited mid'Rabanan to marry a Kohen.
(c) The Rishonim here (RAMBAN, RASHBA) and in Kesuvos (3a) quote the RASHBAM (see also PNEI YEHOSHUA here) who suggests that when a condition of the Get is fulfilled against the husband's will, and when a husband annuls a Get after having sent it with a Shali'ach, the Kidushin is not uprooted retroactively, but rather it is uprooted from now on -- "mi'Kan ul'Haba." (See also SHITAH MEKUBETZES who quotes the words of the Rashbam as found in a marginal note in a manuscript of Rashi's commentary.)
The Rashbam explains that the Gemara means that the Rabanan have the right to uproot the Kidushin retroactively, and if they do so, all of the Be'ilos retroactively become Be'ilos of Z'nus. Since nobody wants his Be'ilos to become Be'ilos Z'nus, when he gives a Get with a condition he has in mind that even if the condition is fulfilled later against his will he still wants the Get to be valid. Similarly, when a man annuls a Get, since he knows that the Rabanan will make his Be'ilos into Be'ilos Z'nus if the Get is annulled, he does not really want to annul the Get.
The Ramban asks that according to this understanding, in a case in which a woman is only betrothed (with Erusin) and her husband gives her a Get on condition or annuls a Get that he sent with a Shali'ach, the Kidushin should be uprooted retroactively since the man has not had relations with his wife and thus has no fear that his Be'ilos will be made into Be'ilos Z'nus. The Ramban answers that even though there was no Be'ilah, the husband has in mind that the Get should take effect even if the condition is fulfilled against his will, because he knows that his intention will not prevent the Get from taking effect (since the Kidushin will still be uprooted against his will). Therefore, he intends for the Get to take effect under any circumstance.
(d) RASHI cites a fourth explanation in the name of "all of my teachers." This explanation is found in PERUSH RABEINU GERSHOM to Bava Basra (48b). He explains that all Kidushin nowadays is only mid'Rabanan in any case, and that is why the Rabanan are able to uproot it from now on. Rabeinu Gershom asserts that Kidushei Kesef (and Kidushei Shtar) are mid'Rabanan, while Kidushei Bi'ah -- which is mid'Oraisa -- cannot make a Kidushin d'Oraisa nowadays since the Rabanan prohibited one from being Mekadesh a woman with Bi'ah (Kidushin 12b). The Rabanan went further and said that since everyone is "Mekadesh Al Da'as d'Rabanan," no act of Kidushei Bi'ah works mid'Oraisa nowadays (it makes only a Kidushin d'Rabanan).
(Once the Rabanan instituted that one may be Mekadesh a woman with Kidushei Kesef, it became an act of effrontery to be Mekadesh a woman with Bi'ah. Therefore, when the Rabanan instituted Kidushei Kesef, they also instituted that a person may not be Mekadesh with Bi'ah and they annulled that form of Kidushin, based on the premise that when a person gets married he does so according to the will of the Rabanan.)
Rashi and the other Rishonim challenge the explanation of Rabeinu Gershom.
1. Rabeinu Gershom's assertion that Kidushei Kesef and Kidushei Shtar are mid'Rabanan contradicts the Gemara (Kidushin 2a) which clearly derives Kidushei Kesef from a Gezeirah Shavah in the Torah.
Apparently, Rabeinu Gershom understands that the Gezeirah Shavah is not an actual Gezeirah Shavah mid'Oraisa, but only an Asmachta. (The same applies to Kidushei Shtar, which is derived through a comparison with Get (Kidushin 9b). Rabeinu Gershom understands that comparison as only an Asmachta.)
2. Rashi asks that a Ne'arah Me'urasah is defined as a woman who was assumed to be a Besulah at the time of the Nisu'in but was found to have had relations with another man while she was an Arusah. The Torah punishes such a woman with Sekilah. How can the Torah consider her to be a Besulah at the time of Nisu'in if, mid'Oraisa, there is no such thing as Kidushei Kesef or Kidushei Shtar? The only way she could have become an Arusah mid'Oraisa is through Kidushei Bi'ah, in which case she would not be a Besulah and thus it is not possible for there to be a case of Ne'arah Me'urasah!
Rabeinu Gershom apparently is not bothered by this question because he understands that the Kidushin mid'Oraisa could be done with an act of Bi'ah she'Lo k'Darkah. Such a Bi'ah serves to make the woman an Arusah, but it does not make her a Be'ulah and she remains a Besulah. (See at length the Gemara in Kidushin 9b. Although the Gemara there rejects this possibility, perhaps Rabeinu Gershom understands that the Sugyos are arguing.)
Rabeinu Gershom apparently was not bothered by this question, because we could say that the Kidushin was done with a Bi'ah she'Lo k'Darkah. Such a Bi'ah serves to make the woman an Arusah, but it does not make her a Be'ulah and she remains a Besulah. (See in full the Gemara in Kidushin 9b. Even though the Gemara there rejects this possibility, perhaps Rabeinu Gershom understands that the Sugyos are arguing.)
3. Rashi in Kesuvos asks that according to Rabeinu Gershom, a woman who gets married with Kidushei Bi'ah should be permitted to leave her husband without a Get. Rabeinu Gershom apparently understands that although the Rabanan removed the Kidushin d'Oraisa, they nevertheless substituted in its place a Kidushin d'Rabanan which requires a Get.
4. Finally, Rashi here asks that if Kidushin through Bi'ah is Kidushin d'Oraisa, how can the Rabanan enact a prohibition (against performing Kidushin through Bi'ah) and prevent the Kidushin from taking effect?
Rabeinu Gershom apparently understands that it is possible for the Rabanan to make a prohibition which prevents a change of status from taking effect mid'Oraisa. TOSFOS in Sukah (3a) mentions such a concept with regard to a person who sits in a Sukah in a manner which the Rabanan prohibited. In the case of one who performs Kidushin with Bi'ah, it is possible that the Rabanan prevented the Kidushin from taking effect in the following way: The reason why the act of Bi'ah accomplishes Kidushin is that it demonstrates Ishus; it is an act through which the man and woman conduct themselves in the manner of husband and wife. By conducting themselves as though they are married, the marriage takes effect. When the Rabanan prohibited Kidushei Bi'ah, the act of Bi'ah became an act of Z'nus and not an act of Ishus. Since it no longer demonstrates the conduct of husband and wife, it cannot effect Kidushin.