Gemara

Question: Why did our Tana say 'a woman is acquired', as opposed to 'a man acquires a woman'?

2b - Answer: 'A man acquires' would imply even against her will. Therefore, it says 'she is acquired', which connotes willingly.

Bava Basra 48b (Ameimar): If Levi hung Leah until Leah agreed to accept Kidushin from him, the Kidushin is valid.

(Mar bar Rav Ashi): Mid'Oraisa, she is Mekudeshes. Mid'Rabanan she is not. Since Levi acted improperly, Chachamim fined him and uprooted the Kidushin.

Question (Ravina): Granted, Chachamim can uproot Kidushei Kesef and say that the money was only a gift. But if he was Mekadesh through Biah, how can Chachamim uproot it? (If they do, it was Bi'as Zenus (extramarital relations)!)

Answer (Rav Ashi): Yes, Chachamim transform his Kidushin into Bi'as Zenus!

Rishonim

Rif and Rosh (1:1): The Mishnah says 'she is acquired', which connotes willingly, not against her will.

Rif and Rosh (Bava Basra 26b and 3:51): Ameimar says that if all Levi hung Leah until she agreed to be Mekudeshes to him, the Kidushin is valid. Rav Ashi says that it is invalid. Since he acted improperly, Chachamim did improperly to him (and uprooted the Kidushin). This is the Halachah.

Nimukei Yosef (DH Afke'inhu): Chachamim can uproot the Kidushin, for everyone is Mekadesh 'according to the law of Moshe and Yisrael.' (This includes mid'Rabanan laws.)

Rambam (Hilchos Ishus 4:1): A woman becomes Mekudeshes only willingly. If a man was Mekadesh a woman against her will, she is not Mekudeshes. However, if a man was forced to Mekadesh, she is Mekudeshes.

Magid Mishnah: The Rambam holds that Chachamim uprooted Kidushin when she was forced, for she cannot choose to leave the marriage. They did not uproot Kidushin when he was forced, for he can divorce her if he wants. Ba'al ha'Itur holds that in both cases, Chachamim uprooted it.

Ra'avad: If he was forced, it is valid only if he said that he wants.

Rebuttal (Magid Mishnah): It is valid even if he did not say that he wants, just like a sale. The Ra'avad did not make this condition regarding a sale.

Defense (Lechem Mishneh Hilchos Mechirah 10:1): The Ra'avad made this condition in Hilchos Gezelah (1:9). A coerced sale is valid only if the seller said 'I want' (Bava Kama 62a). If not, the buyer is a Chamsan (extortionist). Why did the Rambam omit this? The Maharik says that for a sale, perhaps it suffices if he received the money in silence. We rely on this until we find a better answer for the Rambam.

Migdal Oz: Giving Kidushin to her is the ultimate way of saying 'I want'! Also, Ameimar said that if a man was forced to be Mekadesh, she is Mekudeshes. Rav Ashi disagreed, but Ravina challenged him. We do not rely on the poor answer given. Also, Ameimar taught his law amidst clear-cut Halachah. If a man was Mekadesh a woman against her will, she is not Mekudeshes (Kidushin 2b). This is like Ameimar. BaHaG and Rav Acha Gaon do not bring the Gemara in Bava Basra. This connotes that they hold like Kidushin 2b.

Poskim

Shulchan Aruch (EH 42:1): A woman becomes Mekudeshes only willingly. If a man was Mekadesh a woman against her will, she is not Mekudeshes.

Semag (brought in Beis Yosef DH u'Mah she'Chosav): "V'Holchah v'Haysah l'Ish Acher" connotes willingly. If she was forced, she is not Mekudeshes. If a man was forced to be Mekadesh, she is Mekudeshes according to Ameimar, but not according to Rav Ashi.

Question (Beis Yosef, ibid.): This is difficult, for the Gemara discusses when he forced her! (It says 'since he acted improperly...')

Answer (Gra 1): Tosfos (Bava Basra 48b DH Kadish) asked why Kidushin works mid'Oraisa through Bi'ah or Shtar, for she gets nothing. This question forced the Semag to say that we discuss when she forced him. The text says 'since she acted improperly...' Those who argue say that Chachamim would not uproot such a Kidushin, for he can divorce her against her will.

Note: If he wanted to marry her relative, divorcing her does not help.

Chasam Sofer (Bava Basra 47b DH uv'Reish Perek 4): The Semag expounds that Kidushin requires her consent. Even if she was coerced, if she agrees in the end this is proper consent.

Shulchan Aruch (ibid.): However, if a man was forced to Mekadesh she is Mekudeshes. Some say that she is not. Therefore, it is a Safek.

Beis Shmu'el (1): The Magid Mishnah says that Chachamim did not uproot Kidushin when he was forced, for he can divorce her if he wants. Nowadays, after R. Gershom's enactment that a man cannot divorce a woman against her will, the law should be the same in both cases. Perhaps R. Gershom's enactment does not apply when he was forced to be Mekadesh.

Chelkas Mechokek (1): The Beis Yosef (CM 205 DH Kosav Ba'al, citing Bedek ha'Itur) and Rema (205:12) disqualify a forced purchase. This is difficult. The Magid Mishnah equates a man forced to be Mekadesh with a woman forced to accept. Just like a forced sale is valid, also a forced purchase is valid. The Rambam holds that Chachamim uprooted the Kidushin only when she was forced. Some say that they uprooted it even when he was forced.

Question (Avnei Milu'im 1): We force a Me'anes (rapist) to marry her, if she and her father want. The Ba'al ha'Itur disqualifies a forced Kidushin! If Beis Din forced a man to divorce, since it is a Mitzvah to obey Chachamim, when he says ' I want', he is sincere. However, the Poskim say that this was a mere Dichuy to say why we cannot learn from there that a forced sale is valid.

Avnei Milu'im (1): The Rashba holds like the Rambam, unlike Ba'al ha'Itur. If amidst coercion a person has Gemiras Da'as to sell, all the more so coercion gives Gemiras Da'as to buy. However, Kidushin is different. He does not monetarily acquire her; he just forbids her to everyone else. Letter of the law, it is valid whether he or she was forced. They argue about whether Chachamim uprooted it when he was forced.

Chasam Sofer (Bava Basra 47b DH v'Lavo): The Rambam and Ra'avad explain that Bava Basra (48b) discusses when he or she was forced. Rav Ashi says 'regarding a woman (who was forced), since he did improperly...

Gra (1): A man who is Mekadesh is like a buyer. If one was forced to sell, it is valid. We did not say so about one who was forced to buy. The former opinion, the Ra'avad, holds that all the more so, this is valid! One should be quick to buy land (but not to sell - Yevamos 63a). The Ra'avad requires that he say 'I want.' One who did an action need not say 'I want.' The Rema holds that if one was forced to give a gift, it is invalid, for he received nothing. If one was forced and received, even if he lost something worth more, it is valid.