Observation: The difficulty in Rashi's explanation (of this concept) in Kidushin (11a) regarding Rebbi Yanai's daughters, who were stringent to only accept three Kav of Dinarim as their Kidushin, is explained in (Tosfos DH "she'Kein Ishah" in) Kidushin (ibid.).

Explanation: The fact that it is effective to cause acquisition is without reason. (Note: In other words, it does not rely on any known mechanics of Kinyan.) However, there is definitely reason why Chazal instituted Ma'amad Shelashtan, as they did so in order that people should not have to bother to make many Kinyanim (i.e taking from B and giving to C, in order that this can be done in one easy Kinyan where B now owes C).

(Note: Tosfos now discusses the two other laws described as "laws without a reason.") Regarding someone who signs his possessions over to his wife (that the law is that she is only considered a caretaker, not the owner, of his possessions), the reason that this is the law is because a person does not leave his son (without inheritance) and give to others. It is not normal to give her all of one's possessions, but rather to honor her by appointing her the caretaker (of his estate).

Regarding the law that someone who marries off his son (is presumed to give him the house in which they are getting married as a present), when a father removes all of his possessions from the house, the son relies on the fact that his father is giving him the house (due to his profound happiness). This is as explained in Bava Basra (144a, see also Rambam in Hilchos Zechiyah u'Matanah 6:15).

Question: We already know that Rav said in Bava Metzia (49a) that there is no prohibition against retracting words committing to making a deal (there is an argument among the Rishonim regarding the exact case when Rav says there is no prohibition). The Gemara there compares a small present to a sale where money was not given yet given along with the verbal commitment. (Note: Accordingly, we already know that Rav holds that committing to giving a present is not a strong commitment. Why, then, would we think that a small present would not have to be given in a usual manner of Ma'amad Shelashtan (without the third party being present)?)

Answer: Here, where he says to the guardian or creditor that he should give the deposit/monies as a present to a third party, we would think that it is more likely that the acquisition is valid than in a case where one person commits to give another person a present.

Explanation: The Rach and Rabeinu Tam explain that the case is where the people involved agreed, or it was known through clear testimony, that in fact nothing was left by him.

The implication of their words is that on his own he would not be believed to say that he made a mistake when he admitted. This is despite the fact that he would have a Migu that he could have said that he already paid what he owed.

Proof: This is also implied by the Mishnah in Shevuos (38b). The Mishnah discusses someone who claims that his friend owes him a Manah and his friend agrees that this is so. After asking to be paid the next day, if his friend says that he already paid him, he is indeed exempt from paying. If he denies that he ever borrowed the money (contrary to his statement the day before), he is obligated to pay. The Gemara in Bava Basra (6a) explains that the reason for this law is that when someone says that he did not borrow, it is equivalent to his saying that he didn't pay.

Why isn't this borrower believed to say, "believe me that I really never owed you any money, as I simply made a mistake and thought I owed you money, because I could have claimed that I paid you (since yesterday)?" The implication of the Gemara is therefore that a Migu claim is not believed when the person has to say that he made a mistake.

Implied Question: What was Rav Nachman's reason for quoting the law of Ma'amad Shelashtan?

Answer: Rav Nachman thought that the person simply wanted to retract what he said he would give, aside from the reason that he realized he should not have had to give anything in the first place. (Note: Therefore Rav Nachman told him that Ma'amad Shelashtan is a binding commitment equal to a regular Kinyan.)

Implied Question: Why is the Gemara deducing from here that Shmuel holds "Holech Lav k'Zchi" if Shmuel himself said a different reason for his law?

Answer: The Gemara at this point understands that the reason that Shmuel gives, that being that the sender is still responsible for the money he must be able to retract, is not the main reason for his position.

We similarly find that this is the case regarding one who takes wine from Kusim (and has to take off Terumos and Ma'asros). Originally the Gemara (25a) wanted to say that the reason that Rebbi Yehudah holds this way (that one cannot choose the status of the grain in the way discussed in the Gemara there) is because he does not hold of Breirah (that a person can choose to establish a status retroactively, see Gemara there at length). This is despite the fact that they (Rebbi Yehudah and those who hold like him) said to Rebbi Meir, "Don't you agree that there is a possibility that the jug will break etc" (see 26a). (Note: This shows that their concern was that the jug with the Terumos and Ma'asros will break, not Breirah.) There are other similar examples of this (throughout the Gemara).

Opinion (#1): Rashi explains that if the case was where a present was sent, meaning that the sender is not held liable if the present does not reach its destination, Shmuel would agree that the sender cannot retract the present.

Question: This does not seem to be correct, as we do not apply the concept of "Holech k'Zchi" regarding the giving of presents, as explained earlier (12a).

Opinion (#2): Rather, if a lender is given an exemption from his being responsible that the money he is lending gets to the borrower, or regarding the sending of a Get that frees a slave, Shmuel would agree that the sender cannot retract.

Observation: This implies that they could not force him (Rav Yosef bar Chama) to return it to them according to the law.

Implied Question: This is despite the fact that they were not known to be people who would deny that they had the object. (Note: Being that this was the reason given before for the first Shomer being unable to force the return of the object, and this is inapplicable here, what is the Gemara's reasoning in our case?)

Answer: This is because Rav Yosef bar Chama really was the messenger of Rav Sheshes, and he therefore could not say, "I do not want my object in the hands of another."

Implied Question: Even though the intended receiver died in the lifetime of the giver, and he only acquired after the death of the giver, the inheritors still acquire. (Note: Why?)

Answer: The mindset of the giver is that being that the intended receiver is alive when he sends the present, either the receiver or his inheritors should eventually receive the present.

This is even if the inheritors of the receiver were not born yet until after the giver's death.

Implied Question: This is even according to the opinion that if someone acquires something for a fetus, the fetus (and eventual child) has not acquired anything.

Answer: This is because the words of a Shechiv Meira when he dies are as if he has given the item to the receiver from the time he gave it over or from the time of his proclamation that they should be given.

Implied Question: (Note: Rebbi holds this way here) even though Rebbi states (63a) that if someone says, "go and give to her/acquire for her/accept for her," he cannot retract because saying "go and give" is tantamount to saying acquire. (Note: How can we reconcile this seeming contradiction?)

Answer: This is because the messenger there said to him, "Your wife asked me to accept the Get for her." The assumption is that a husband gives the Get to such a messenger with the intent that he is indeed a Shliach l'Kabalah, as long as he does not explicitly state otherwise.

Opinion (#1): Every time the Gemara says "Teiku," Rabeinu Hai Gaon states in his work "Shea'rim" that the money is split between the two parties.

Opinion (#2): It does not appear to the Ri that this is correct. Rather, wherever we find explicitly that because of the Teiku they split, they split, but otherwise we say that the money should remain in the hands of the one who currently has it.

Observation: Rabeinu Tam deduces from here that one should not explain the concept of "Shuda d'Deini" as does Rashi in Kesuvos (85b). The Gemara there discusses what to do in a case where the ruling is Shuda d'Deini and both people involved are relatives, neighbors, or Torah scholars. Rashi explains that the judge's job is to try to assess who the person in question liked better, and to whom he wanted to give the money in question.

Rashi explains that this is what this means in our Gemara as well.

Opinion: Rather, Shuda d'Deini means that the judge should give the money to whomever he wants. This is like the implication of our Gemara which says that whatever the messenger wants to do he should do, and the Gemara calls this Shuda (d'Deini).

Text: Rabeinu Tam understands that our text should read Rebbi Elazar (not Rebbi Eliezer).

This is evident from the second part of the Mishnah in Bava Basra (156a) where Rebbi Eliezer and Rebbi Yehoshua argue. Rebbi Eliezer says that his words are upheld on Shabbos, but not during the week. Rebbi Yehoshua says etc. However, in the first part of the Mishnah it is clear that they argue whether it is Shabbos or during the week, as they did not mix the two parts of the Mishnah.

Additionally, the fact that the Rabbanan ask Rebbi Elazar a question from the mother of the sons of Rochel and Rebbi Elazar does not answer that perhaps it took place on Shabbos (when he agrees to the Chachamim) indicates that this is because the second part of the Mishnah is Rebbi Eliezer (not Rebbi Elazar).

Additionally, the Gemara there (Bava Basra 156b) says that one can acquire from a Shechiv Meira, even on Shabbos, and not to worry about Rebbi Elazar's statement. If it would be Rebbi Eliezer this would not be understandable, as Rebbi Eliezer agrees that on Shabbos his words are upheld.

Rebbi Meir said there that according to Rebbi Eliezer during the week his words are upheld, but not on Shabbos (and therefore iii. would not be a proof if the Gemara were using Rebbi Meir's understanding of Rebbi Eliezer).

The Gemara there (quoted in iii.) is not referring to Rebbi Meir's understanding of Rebbi Eliezer, but rather the Mishnah's understanding of his opinion (which Rebbi Meir clearly argues on).

Additionally, the Gemara here says that Rebbi Meir holds like Rebbi Eliezer, and the case of "take a Manah" implies that it is on a weekday. Rebbi Meir indeed holds in Bava Basra (156b) that Rebbi Eliezer holds that during the week his words are upheld. Rather, there are certainly three separate opinions in this argument. (Note: The three opinions are Rebbi Eliezer in the Mishnah (only on Shabbos), Rebbi Meir's understanding of Rebbi Eliezer (only during the week), and Rebbi Yehoshua (both on Shabbos and during the week (see bottom of Bava Basra 156b).)