Rabba answered: Since you require ḥalitza and you do not exempt her completely, all will know that this is merely a stringency and that the Sages did not decide with certitude that the first betrothal was fully valid. Consequently, they would not come to disregard the other betrothal. Abaye raised a challenge: If so, let the mishna teach the case where it is uncertain whether the item is closer to him or closer to her with regard to divorce, and stipulate that she requires ḥalitza. And they would know that this is merely a stringency and not make a mistake.

He answered him: A mistake could in fact be made here, as, if you say that she must perform ḥalitza then she may also enter into levirate marriage. People might mistakenly think that if she is suitable for ḥalitza then she is also suitable for levirate marriage, and as a result the woman might enter into levirate marriage, despite the fact that it is forbidden for her to do so. Abaye objected: Here too, in the case of uncertain betrothal, the concern exists that if you say that she performs ḥalitza then she might also enter into levirate marriage. Rabba answered: So let her enter into levirate marriage, and there is no problem with that. In this instance she remains with her presumptive status as permitted because she was originally assumed to be permitted and was rendered forbidden only due to our concern. However, there would be no actual transgression involved even if she were to enter into levirate marriage.

Abaye raised an objection to Rabba by citing a case where even in places of doubt, the woman requires ḥalitza. As we learned in a mishna (67b): A house fell on him, on a certain man, and on his brother’s daughter to whom this man was married, and he was childless, and it is unknown which of them died first. If the deceased wife had a rival wife, then her rival wife must perform ḥalitza but may not enter into levirate marriage. If the man had died first, then at the time of his death the rival wife was forbidden to the yavam as the rival wife of his daughter and exempt from levirate marriage. If, however, the daughter had died first, then at the time of the husband’s death the second wife was not the rival wife of a forbidden relative, and requires levirate marriage. It is due to this doubt that she must perform ḥalitza and may not enter into levirate marriage.

And according to Rabba’s opinion, why is that so? Here too, let us say: This woman, the rival wife, has the presumptive status of being permitted to marry a man from the general public. This is because she was exempt from levirate marriage for the entire period of her marriage as the rival wife of a forbidden relative. And due to the uncertainty whether her rival wife was the first to die you come to render her forbidden and require that she perform ḥalitza. Do not render her forbidden due to an uncertainty.

And if you would say: Here too, we rule more stringently due to the uncertainty. Nevertheless, this would be a stringency that brings about a leniency, for if you say that she must perform ḥalitza, she may also enter into levirate marriage. However, it is forbidden for her to enter into levirate marriage, because she is possibly forbidden to the yavam as the rival wife of his daughter and therefore forbidden just like the daughter herself. Rabba replied: In cases of divorce, which are common, the Sages issued a rabbinic decree preventing her from performing ḥalitza due to a concern that if she were required to perform ḥalitza then she may enter into levirate marriage as well. In cases of collapse, which are not common, the Sages did not issue a rabbinic decree, because they did not introduce decrees with regard to uncommon matters.

Alternatively, there is another reason to differentiate between the cases. In the case of divorce where there is a forbidden relative who indicates that the rival wife is forbidden due to her status as the rival wife of a forbidden relative, and you require that her rival wife perform ḥalitza, people will say: The Sages determined that this bill of divorce is a full-fledged bill of divorce. Consequently, they required her rival wife to perform ḥalitza, and people may come to consummate the levirate marriage with the rival wife based on this mistaken assumption. In cases of collapse, however, could the Sages have determined who died first in the collapse? As it is known to all that there was a doubt that could not be clarified, it is clear that the Sages required the rival wife to perform ḥalitza only due to this uncertainty. Therefore, there is no concern that she would come to enter into levirate marriage because of this ḥalitza.

The Gemara asks: But did we not learn in a mishna about the case where it is uncertain whether the bill of divorce is closer to him or closer to her with regard to situations of divorce whose status is uncertain? And didn’t we learn in a mishna: In a case where his wife was standing in the public domain and he threw her the bill of divorce, if the bill landed closer to her, she is divorced. If it was closer to him, she is not divorced. If it was half and half, i.e., if the bill of divorce landed midway between the man and the woman, there is uncertainty whether she is divorced or whether she is not divorced.

And we say: With regard to what halakha was the ruling said that she is both divorced and not divorced? The Gemara explains that this affects two areas of halakha. The first is that if the man divorcing his wife is a priest, then his wife is forbidden to him due to the uncertainty that she may in fact be divorced through that bill of divorce. Consequently, he would then be unable to remarry her. The second ramification is that if the woman being divorced was a forbidden relative to her husband’s brother, and her husband died childless, then her rival wife would require ḥalitza. The mishna indicates that in this type of divorce whose status is uncertain as well, the Sages require the rival wife to perform ḥalitza, and we do not say that if you say that she must perform ḥalitza, she may enter into levirate marriage. Here there is no such concern.

The Gemara responds: But wasn’t it stated with regard to that mishna that this is referring to a very specific set of circumstances? It is Rabba and Rav Yosef who both say: The doubt here does not result from the facts of the case themselves, but from conflicting testimonies and an inability to decide between them. Here, we are dealing with two sets of witnesses, one of which says that the bill fell closer to her, and one of which says that it fell closer to him. This, then, is an uncertainty in matters of Torah law, for in this case there are two testimonies, each one complete by itself, yet they contradict one another. Such instances are deemed to have the status of an uncertainty with regard to Torah law, and therefore the ruling is stringent. But the mishna here is referring to one set of witnesses who were divided in their testimony or who could not clarify exactly what had occurred. This is considered to be an uncertainty in matters of rabbinic law alone, as there is only a single uncorroborated testimony, and in cases of uncertainty in matters of rabbinic law the ruling is lenient.

The Gemara asks: And from where is it known that the mishna here is referring to a case of uncertainty with one set of witnesses? The Gemara responds: It is similar to that of betrothal. Just as with regard to betrothal it is referring to a case of uncertainty with one set of witnesses, so too, with regard to divorce it is referring to a case of one set of witnesses. The Gemara wonders: And with regard to betrothal itself, from where is it known that the mishna is referring to a case of uncertainty that involves one set of witnesses? Perhaps it is referring to a case of two sets of witnesses? The Gemara answers: If the mishna is referring to a case of two sets of witnesses who contradict one another, then let her enter into levirate marriage, and there is no problem with that, as there are two witnesses testifying that there was never a betrothal. Therefore, both the cases of betrothal and divorce must be referring to a situation where there is one set of witnesses.

The Gemara challenges: How can one say that? After all, there are witnesses who are standing before us and saying that the object of betrothal fell closer to her. Accordingly, she was betrothed and her rival wife is the rival wife of a forbidden relative. And yet you say to let her enter into levirate marriage and there is no problem with that? And furthermore, with regard to the fundamental difference between two pairs of witnesses and a single pair, the case of two pairs of witnesses is also considered an uncertainty in matters of rabbinic law. This is not considered to be uncertainty with regard to the reality of what actually happened, which would be a case of uncertainty in matters of Torah law, but rather a contradiction between two opposing testimonies. In these cases we say: Place two witnesses against two witnesses, and let the two testimonies cancel each other out. Therefore, the halakha would be to let the woman remain in her original presumptive status. Accordingly, this type of uncertainty stems only from rabbinic law and not from Torah law.

The Gemara cites a proof for this: This is just as it is in the case concerning the property of a man named Bar Shatya, who was referred to by this name because he would occasionally go insane. The case is as follows: Bar Shatya sold property. Two witnesses came forward and said that he sold it when he was healthy and therefore the sale was valid. And two others came forward and said that he sold it when he was insane, and so the sale was void. Rav Ashi said with regard to this matter: Place two witnesses against two witnesses and let the testimonies cancel each other out. As there is no valid testimony to rely on,