Gemara

(R. Aba): (R. Eliezer says that a Get 'Chutz mi'Ploni', i.e. regarding Ploni, she is still married, is valid; Chachamim disagree.) Both equate divorce and Kidushin due to "v'Yotzah v'Haysah". They argue similarly about Kidushei Chutz ('you are Mekudeshes to me, but regarding Ploni, you are still single').

Kidushin 58b (Mishnah): If Reuven told Leah 'you are Mekudeshes to me from now and after 30 days', and Moshe was Mekadesh her during the 30 days, she is Mekudeshes and not Mekudeshes.

59b (Rav): She is forever Mekudeshes and not Mekudeshes.

(Shmuel): She is Mekudeshes and not Mekudeshes until the 30 days end. Then, Moshe's Kidushin vanishes, and Reuven's Kidushin is completed.

Rav is unsure whether 'after 30 days' is a Tenai (that he not retract within 30 days), or a retraction (of 'from now'). Shmuel is sure that it is a Tenai.

(Abaye): According to Rav, if Levi was Mekadesh 'from now and after 30 days', then Moshe was Mekadesh 'from now and after 20', then David was Mekadesh 'from now and after 10', she needs a Get only from Levi and David, but not from Moshe. If it is a Tenai, she is Mekudeshes to Levi. If it is a retraction, she is Mekudeshes to the David. She cannot be Mekudeshes to Moshe.

Objection: This is obvious!

Answer: One might have thought that 'from now and after 30 days' has both connotations, and there is an independent doubt about each man's intent, so she needs a Get from every man. Abaye teaches that it has one fixed meaning.

(Ula citing R. Yochanan): She can be Mekudeshes to any number of men (Moshe was Mekadesh 'from now and after 20, David was Mekadesh 'from now and after 10...')

(Rav Mesharshiya brei d'Rav Ami): R. Yochanan holds that each man was Mekadesh her in a way that leaves room for another man to Mekadesh her.

Question (R. Chanina - Mishnah): If a man divorced 'from today and after my death', it is a Safek Get. If he died childless, she does Chalitzah, not Yibum.

This supports Rav ('after my death' is a Tenai or retraction). Shmuel can say ' the Mishnah is like Chachamim. I hold like Rebbi (surely it is a Tenai).' But R. Yochanan holds that he leaves a remnant. The Get should be totally Batel!

Answer (Abaye): Mid'Oraisa, the Get is Batel; she may do Yibum. Chachamim decreed, lest women do Yibum after a Get 'from today if I die' (which is valid).

Bava Basra 136a - Question: If a man wrote his property to his children 'from today and after I die', why does it help? If one gave a Get 'from today and after I die', she is doubtfully divorced. If he died, she may not do Yibum!

Answer: There, we are unsure if he intended to make a Tenai, or retracted. Here, he surely gave the Guf today, and the Peros after death.

Rishonim

Rif and Rosh (Kidushin 24a and 3:3): The Halachah follows Rav. Moshe's Kidushin goes away only through a Get.

Ran (DH u'Vasar): R. Yochanan holds that each man left room for others. Every Kidushin takes effect on her b'Vadai, even if it finishes after a previous one (e.g. 'from now and after 40 days'). Rav holds that a Kidushin takes effect mi'Safek only if it finishes before all previous ones.

Ran (DH ul'Inyan): The Ra'avad says that R. Yochanan says, unlike R. Aba, that even Chachamim hold that Kidushei Chutz works. If so, surely the Halachah does not follow R. Yochanan. R. Chananel rules like R. Yochanan; perhaps R. Yochanan holds like R. Aba. The Ramban says that the Rif holds like Abaye. He omitted this leniency, lest the Halachah follows R. Yochanan.

Rambam (Hilchos Ishus 7:12): If Reuven told Leah 'you are Mekudeshes to me from now and after 30 days with this Dinar', and Moshe was Mekadesh her 'from now and after 20 days', and David was Mekadesh 'from now and after 10 days', even if 100 men were Mekadesh her like this, every Kidushin takes effect. She needs a Get from each, for she is doubtfully Mekudeshes to all of them.

Question (Ran, ibid.): The Rambam rules like R. Yochanan. Why does he say that each Kidushin is Safek? The Gemara says that it is Vadai. After a Get like this, Yibum should be permitted! Perhaps the Rambam is stringent, for he is unsure if the Halachah follows Rav or R. Yochanan. However, if so, why must each Kidushin be 'like this', i.e. finish before all previous ones?

Magid Mishneh: Normally, we follow R. Yochanan against Rav, but here, the Sugya is like Rav. Also, also Shmuel opposes R. Yochanan. Even though Shmuel also opposes Rav, this is not for R. Yochanan's reason. Also, we are stringent to say that there is Safek Kidushin like Rav. This is why the Rambam did not rely on Abaye's leniency. Amora'im argue about it, so we are stringent. This is why the Rif brought only Rav's opinion.

Rebuttal (Kesef Mishneh): No one argues with Abaye. The Gemara said that his law is obvious! Rather, the Rambam rules like R. Yochanan. However, the Gemara rejected the explanation that each man left room for others. We do not rely on the answer given. R. Chanina (who asked) explains that R. Yochanan has an independent Safek about each Kidushin, if it is a Tenai or a retraction, unlike Abaye. Therefore, each Kidushin must finish before the previous ones. We hold like R. Yochanan against Rav. This resolves all the Gemaros that say that it is a Safek Tenai, Safek retraction. Perhaps the Rif agrees; he did not want to elaborate. Saying 'the Halachah follows R. Yochanan' would connote that each man left room for others.

Question (Chelkas Mechokek EH 40:9): If each Kidushin is an independent Safek, even if it finishes after the previous ones we must be concerned!

Gra (EH 40:6): The Kesef Mishneh's explanation is difficult. It is merely the Rambam's style to adopt the wording of the Gemara ('like this')

Rosh (ibid.): Abaye teaches that Rav holds that if others were Mekadesh her 'from now and after 20' and 'from now and after 10', she needs a Get only from the first (perhaps it is a Tenai) and the last (perhaps it is a retraction). I do not know why the Rif omitted this, and the Rambam requires a Get from all of them. No one argues with Abaye! R. Chananel rules like R. Yochanan, for we rule like him against Rav and Shmuel (Beitzah 4b). The Rif's Pesak is more reasonable, for everywhere it is a Safek Tenai, Safek retraction. Also, we had difficulty finding a widow from two men (Gitin 82b). According to R. Yochanan, we find this!

Ran (ibid.): The Ramban says that we found a widow from two men only mid'Rabanan (through Ma'amar). According to R. Yochanan, the case arises mid'Oraisa! The Rashba answers that in Bava Basra (136a) we answered on behalf of Rav because the question was against only him. We find a widow from two men according to R. Yochanan's opinion only if the men died simultaneously. We hold, unlike R. Yosi ha'Galili, that this cannot be.

Poskim

Shulchan Aruch (EH 40:4): If Reuven told Leah 'you are Mekudeshes to me from now and after 30 days', and Moshe was Mekadesh her 'from now and after 20 days', and David was Mekadesh 'from now and after 10 days', even if 100 men were Mekadesh her like this, every Kidushin takes effect. She needs a Get from each of them, for she is doubtfully Mekudeshes to all of them.