Gemara

Beraisa: "Yakriv" teaches that if Shimon must bring an Olah, Beis Din forces him to bring it.

Suggestion: Perhaps we force him against his will!

Rejection: "Li'Rtzono."

Question: How do we fulfill both verses?

Answer: We force him until he says "I want to bring it."

Bava Basra 48a - Rav Huna: If Reuven hung (or afflicted in another way) Shimon until Shimon agreed to sell his property, the sale is valid.

Question: Why is it valid?

Answer (Beraisa): "Yakriv" teaches that if Levi must bring an Olah, Beis Din forces him to bring it... We force him until he says 'I want' (and we learn from there to sales).

Rejection: Perhaps that is different, because (after coercion) he truly wants to bring it to get atonement!

Conclusion: Rather, it is logical. Amidst the coercion, he has Gemiras Da'as (decides absolutely) to sell.

Kidushin 50a - Rava: (Unspoken) thoughts in the heart have no consequence.

Question: From where does Rava know this?

Answer (Beraisa): "Yakriv" teaches that Beis Din forces one to bring an Olah. We force him until he says that he wants to bring it.

Question: Why is this valid? In his heart he does not want!

Answer: This shows that thoughts in the heart are ignored.

Rejection: Perhaps that case is different. Surely, he wants to bring the Korban to get atonement!

Kesuvos 86a - Beraisa: (Forty lashes) apply to Chayavei Lavin; but regarding a Mitzvas Aseh, e.g. if one refuses to make a Sukah or take a Lulav, we lash him until he dies.

Kidushin 41b (R. Yehoshua ben Korchah): Why does it say "All of Yisrael will slaughter (Korban Pesach)"? Only one person slaughters (each Korban)!

Answer: This teaches that we attribute a Shali'ach's actions to the one who appointed him.

Rishonim

Rambam (Hilchos Ma'aseh ha'Korbanos 14:16): Even though it says "Li'Rtzono", we force one until he says 'I want'. Whether he vowed and did not separate a Korban, or separated but did not offer it, we force him until he offers it.

Rambam (Hilchos Gerushin 2:20): If the Halachah is that Reuven must divorce his wife but he does not want to, Beis Din of Yisrael in every time and place hit him until he says that he wants. Ones invalidates an action only if the person was not obligated to do it mid'Oraisa, e.g. to sell or give a gift. But if one's Yetzer ha'Ra seized him and enticed him to Mevatel a Mitzvah or do an Aveirah, and he was hit until he did like he is required, this is not Ones. He wants to be a Yisrael and do all the Mitzvos. (Until he was hit) he was Ones due to his evil intent!

Question: Why do we need a verse to teach that we force one to bring a Korban? We force people to fulfill (virtually) any Mitzvas Aseh!

Answer (Tosfos 6a DH Yakriv): Because it says "li'Rtzono", one might have thought that we do not force.

Question (Tosfos Bava Basra 48a DH Ela): Since we conclude that we learn from logic (amidst the coercion, he has Gemiras Da'as), why is a verse needed to teach that we force one to bring Korbanos?

Answer (Tosfos): One might have thought that since he agrees only through coercion, this is "Zevach Resha'im To'evah". The verse teaches that the Korban is Kosher.

Question: Why do we need a verse to teach that Shelichus works for Korbanos? A verse teaches that the Kohen Gadol must slaughter his Par Chatas on Yom Kipur. This implies that Shelichus normally works!

Answer (Tosfos Kidushin 41b DH Nafka): Regarding Chatas it says "Oso", to teach that we may offer it b'Al Korcho (against the owner's will). This is a reason why Shelichus should work. One might have thought that Shelichus does not work for other Korbanos.

Maharsha (DH b'Emtza Devarav): The opposite is true! We take security from people to force them to bring Olah and Shelamim, but not for Chatas and Asham (since people themselves are eager to bring them for atonement - Erchin 21a)! Rather, the text of Tosfos should say 'since regarding Chatas it does not say 'Oso' to teach that we may offer it b'Al Korcho, it is reasonable that Shelichus should work. We cannot learn to other Korbanos that can be brought b'Al Korcho.

Rebuttal (Chasam Sofer OC 176 DH v'Al): If so, why can we learn from Pesach? Also regarding Pesach it does not say 'Oso' to teach that we may offer it b'Al Korcho! Also, the Gemara said that we cannot learn Shelichus from Gerushin because Gerushin works against her will. This shows that b'Al Korcho is a reason why there should be Shelichus! Also, we learn from "Yakriv" (which is extra) that Olah may be offered b'Al Korcho, not from "Oso"!

Question: Why does Tosfos say that we may offer (at least some) Korbanos b'Al Korcho? The owner must say 'I want'!

Answer (Igros Moshe Kodshim 9 (OC 1 p.360)): Tosfos holds that Ratzon (consent) through compulsion is not considered full Ratzon. This is why Tosfos (Bava Basra 48a DH Ela) said that one might have thought that it is "Zevach Resha'im". The verse does not teach that he has full Ratzon. It only teaches that the Korban is Kosher. Olah and Shelamim do not require Ratzon; they may be brought after death, even if the owner was a convert without heirs. Perhaps we may offer them after death even if the owner did not agree while alive.

Igros Moshe (DH v'Ayen): If a thief stole Levi's Korban and slaughtered it in the Mikdash l'Shem Levi, is as if he returned the animal (Levi was Yotzei - Bava Kama 76a). We cannot consider this like Levi's action through Shelichus, since he did not know about it. Zachin l'Adam she'Lo b'Fanav does not apply, for this is not Zechus (Levi lost the Mitzvah of Semichah). Rather, we must say that others can slaughter his Korban b'Al Korcho without Shelichus; as long as we did not hear that Levi does not want to get Kaparah. Tosfos (Kidushin), who says that Shelichus is needed, must explain that since Levi will not be able to do Semichah in any case, it is Zechus for him that the Korban be Kosher. Zachin l'Adam applies, so the thief is considered Levi's Shali'ach.

Ra'avad (on Toras Kohanim Emor Parshesa 7:2, DH li'Rtzonchem): The Toras Kohanim learns from "Li'Rtzonchem" (22:19, in Parashas Mumim) that we do not force the Tzibur. I.e. we do not forcibly take Shekalim from them, but we force them until they say 'I want', for they are obligated. Since Korbanos Tzibur are obligatory, not voluntary, one might have thought that we can force them even if they do not say 'I want'. The verse teaches that they must consent, just like for a Korban Yachid.

R. Shimshon (ibid.): Regarding a Korban Yachid it says "li'Rtzono", but it also says "Yakriv", therefore we force. About a Korban Tzibur it says only "Li'Rtzonchem", so we do not force. We take security from people to give Shekalim not to force them, rather, to encourage them to give quickly.

R. Shimshon (on Toras Kohanim Emor Parshesa 10:5): The Toras Kohanim learns from "Li'Rtzonchem" (23:11, regarding the Omer) that we do not force the Tzibur to bring Korbanos Tzibur. This is because it is a disgrace.

Minchas Chinuch (Sof Mitzvah 302 DH u'Midei): It is not clear why the Rambam did not bring this Beraisa. He often brings Beraisos that are not brought in the Gemara! Zayis Ra'anan (on Yalkut Shimoni 643) says that even though we force for Temidim and Musafim, we do not force for the Omer. Since in any case Yisrael are eager to bring it to permit Chodosh, it is like a Chatas Yachid (for which we do not take a security). This is not clear, for in any case Chodosh will be permitted the next day.

Aruch ha'Shulchan ha'Asid (Kodshim 115:13): We force the Tzibur, just like an individual.