Question: How does the Gemara learn Sh'tuki be'Yisrael from the extra "Kahal"?

Answer: It compares "Mamzer" to "Kahal" - Just as "Kahal" precludes Safek Kahal, so too, does "Mamzer" preclude Safek Mamzer.

Question: This implies that it is obvious that he is permitted to her, whereas in Perek ha'Choletz (Yevamos, Daf 37a) Rava himself holds like Rebbi Elazar in our Mishnah, who forbids Safek be'Safek.

Answer: Rava there is stating his own opinion, whereas here, when he asked 'Why did they say a Sh'tuki is Pasul?', he is asking according to all opinions.

Introduction to Question: This implies that the reason for not being concerned is because the Arusos are a minority, and we don't know for sure that he was born to one of them ...

Introduction to Question (cont): ... but that if we knew that he was, we would establish him a Mamzer ...

Question #1: But this is not correct, since even if we knew that he was the son of an Arusah, he would not be a Mamzer ...

Source: ... seeing as the Gemara says further on (on Daf 75a) 'If an Arusah becomes pregnant, the child is Kasher'?

Question #2: Furthermore, why does the Gemara say ' ... and a minority whose husbands went overseas'? There too, we ought to declare the child Kasher, because perhaps her husband came back using Hash-m's Name and was intimate with her? ...

Source: Like the case (cited in the Yerushalmi) of Shmuel's father who went overseas, and returned using the Name of Hash-m and was intimate, as a result of which Shmuel was born?

Answer #1: Here there is a disadvantage in that she threw the baby out. Consequently, if we knew that she was an Arusah, we would establish him as a Vaday Mamzer - because had she been pregnant from her betrothed, she would not have thrown him out.

Answer #2: Alternatively, we will not rely on the fact that her husband returned using the Name of Hash-m unless she actually said so, but with the current Asufi, seeing as his mother does not testify, we cannot rely on it.

Explanation #1: Rashi explains that the onus is on him to take note, seeing as he will be subject to a 'Mi she'Para' in the event that he retracts and returns the money to the one who paid him ...

Explanation #1 (cont.): ... but once the object is no longer in his hands - because they are both holding it, he is no longer believed, because, since the onus is not on him any more, he is not careful to remember who paid him ...

Explanation #1 (cont.): The Gemara then asks 'Let's see from whom he took the money?'

Clarification: According to Rashi, this refers to where the object is no longer in his hands ...

Proof: ... since he explains 'The Gemara thinks that he only took the money from one of them, so he is bound to remember from which one it was' ...

Proof (cont.): ... and it answers 'That he took the money from both of them, and it is not known from which one ... '.

Explanation #1 (concl.): According to this, even if he claims that he knows (from which one ... ), he will not be believed - seeing as the onus is no longer on him to take note. Rashi.

Introduction to Question: And what he explains - that the Gemara's question refers to where the object is no longer in his hands, where is not believed, and the question is that we should see from whom he took the money, since that is definitely the one to whom he agreed to sell it ...

Question: ... poses a Kashya - Since why should we believe him any more than any other single witness, because, seeing as the object is no longer in his hands, he does not have a Migu with which to believe him?

Explanation #2: Therefore Rabeinu Tam explains that it is only if the object is still in his hand that he is believed ...

Reason: ... with a Migu that he could have said that he did not sell it! or that he bought it back ...

Reason (cont.): ... but if it is not, he is not believed, since Migu is then not applicable.

. Explanation #2 (cont.): The Gemara then asks 'Let's see from whom he took the money?' - Granted, the object is in his hand, why is he believed when he says that he agreed to sell it to the one who did not give him the money - since it implies that he is believed in any event ...

Explanation #2 (cont.): Why is he believed? Why is it not a Migu against witnesses, seeing as we are witnesses that he agreed to sell it to the one who paid him? And the Gemara answers that he took money from both of them ... .

Clarifying Text: In that case, the text reads 've'Lo Yada' (and he does not know), and not 've'Lo Yedi'a' (and it is not known) ...

Reason: ... since that would imply that we do not contend with his knowledge - when in fact, we certainly would contend with it if he knew.

Explanation #2 (concl.): Consequently, we must explain that he did not know, because if he did, we would assume that he is the one to whom he agreed to sell.

Sugya in Bava Metzi'a: However at the beginning of Bava Metzi'a (Daf 2b) regarding the case of two people who are holding a cloak

Explanation #1: ... which Rashi explains according to his explanation here.

Explanation #1 (cont.): Furthermore Rashi writes there that even though the Gemara says in the last Perek of Kidushin that if the object is not in the seller's hands he is not believed, and here (in Bava Metzia) it is not in the sellers hands, since both buyers are holding the cloak, so why does the Gemara (in Bava Metzia) ask that the seller should be believed...

Explanation #1 (cont.): ...the Gemara there (in Kidushin) establishes that the seller is not believed when he took money from both purchasers but if he took from only one he is believed, and the Gemara (in Bava Metzia) currently thinks that the seller only took money from one of the purchasers.'

Question: There is a Kashya however, on Rabeinu Tam - Why does the Gemara ask there 'Let's see from whom he took the money?', since according to him, he is not believed even assuming he took the money from one of them, as Tosfos explained?

Explanation #2: We must therefore explain that when the Gemara asks there 'Let's see from whom he took the money?', it is asking how the Mishnah requires each one to swear that he does not own less than half of the object ...

Explanation #2 (cont.): Why do we not ask the seller from whom he received the money, and let him be a single witness, to exempt the one he supports - even from a Shevu'as Hesses, and let the other one swear a Shevu'ah d'Oraysa?

Explanation #2 (cont.): ... but it is obvious that he is not believed to extract money from one to give to the other - only in the way we just explained.

Explanation #2 (concl.): And the Gemara answers that 'He took money from both of them'.

Conclusion: Also according to this explanation the correct text reads 'He does not know - because if he did, it is obvious that we would contend with his knowledge to obligate the one a Shevu'ah d'Oraysa, as Tosfos explained.