There is a Gemara in Kesuvos (2b3a) where it says that if someone divorced someone on condition and then didn't fulfill the condition, the woman doesn't become divorced, she becomes un-married retroactively.

There were many discussions how to solve mamzeirim problems. Why not have the man give his wife a divorce al tnai and then not fulfill the condition BeOnes (like tell his wife on 1 Adar that she will be divorced if he doesn't come back by the 1st of Nissan and then be so far out of town then that he won't make it back on time).

From the fact that this idea was never proposed, I suspect that it isn't a valid trick.

Why not?

  • 1
    Shmuel Brin, If the Divorcer's intent is not to return, how is that an oneis? Why would we need to apply afkinhu there?
    – YDK
    Aug 1, 2012 at 17:35
  • @YDK, what if he doesn't intend to return, so he puts himself out of range of his wife on purpose. Then when he can't make it back, he is an anus. Though I like your example more for this reason Aug 1, 2012 at 23:26
  • Related: judaism.stackexchange.com/q/28114
    – msh210
    Apr 22, 2013 at 17:19
  • @ShmuelBrin How far back does the retroactive unmarriage go? Till the beginning of the marriage...?
    – SAH
    Aug 1, 2018 at 21:45

2 Answers 2


Fist of all, making women un-married retroactively is possible due to gzeira (decree) of Hazal (the rabbis), and gzeira has strength because "כל דמקדש אדעתא דרבנן מקדש" ("anyone effecting kidushin (marriage) does so intending it to be effective only to the extent instituted by Hazal") and the like.

Tosafot in Gittin 33a ד"ה ואפקעינהו proposes this, and says that in such a case the women doesn't become un-married retroactively becuase Hazal didn't make the gzera in such a case where women would willingly sin with intention of retroactively annulling the get as this would cause moral depravation.

Citation from Tosafot:

ומה שהקשה אם כן יחפה על בת אחותו ויכולין ממזרין ליטהר אי ידעינן שלכך מתכוין לא מפקעינן קדושין מיניה דלתקנה עשו חכמים ולא לתקלה שמתוך כך יהיו בנות ישראל פרוצות בעריות

  • @msh210 I'm not sure that "by the grace of" is correct translation of "אדעתא" (thanks for translation and fixes)
    – jutky
    Aug 1, 2012 at 6:53
  • "intending it be effective only to the extent instituted by"?
    – msh210
    Aug 1, 2012 at 6:59
  • Just looking at your quote, it appear that Tosafot is addressing a different case than the question. Tosafot is talking about Lechatchila marrying with the intention of removing the Kiddushin through a divorce condition that is not fulfilled. The question is asking why not use this method to rectify a situation that already happened. Wouldn't this fall under "לתקנה עשו חכמים"?
    – Menachem
    Aug 1, 2012 at 7:11
  • @Menachem I think you are wrong. Tosafot proposes to solve problem of mamzerim by giving a divorce and then nullifying the divorce with out witnesses. In such case the wife becomes unmarried due to gzeira. When marring, the couple had no intention to remove the kiddushin. Where do you see that Tosafot is talking about lechathila?
    – jutky
    Aug 1, 2012 at 8:10
  • 1
    @YDK I understood it to mean that since she knows it's possible she will be less careful about arayot.
    – Double AA
    Aug 1, 2012 at 16:56

I don't know about the above case, but my Rav was commissioned by the gedolim in eretz Yisrael to cleanse a mamzer in the U.S using a similar tactic:

The mishna says that a man threw a get to his wife in a public domain: If it lands "close to her", she's divorced. "Close to him", she isn't divorced. ""1/2 by 1/2", "she's divorced and not divorced.

The Rosh says on this doubt that the rabbis revoke their (original) marriage.

My rav explained to me that "close" means control. The case of doubt is where one party did not have control over the document more than the other party. I don't know every detail, but he set up the case where the get was thrown over a car in such a way where none of the parties had control over the get more than the other. The son was then permitted to a bas yisrael.

(Btw, my rav said he never would have done this on his own without told to do so by the gedolim.)

  • Why did he use this instance of afki'inhu instead of the shliach case? This seems much more convoluted, and plus does anyone argue on the Rosh?
    – Double AA
    Aug 1, 2012 at 17:33
  • @DoubleAA, see my comment on to the OP. The Rosh seems to be the only one to spell this out, but no one seems to say differently.
    – YDK
    Aug 1, 2012 at 17:39
  • I was asking about the shiach case from gittin 33 not the oneis case from ketuvot 2/3. It seems to be the easiest to arrange and AFAIK it is indisputable.
    – Double AA
    Aug 1, 2012 at 17:43
  • 1
    @DoubleAA, sorry, you did say shaliach. In G 33a he will be transgressing a takana by being mevatel lechatechila.
    – YDK
    Aug 1, 2012 at 17:50
  • 2
    @ShmuelBrin That is the question in Tosfos from jutkey answer. You should see the whole thing inside if you can.
    – Double AA
    Aug 1, 2012 at 18:47

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