Thanks so much as in the past for this great chesed of answering our questions!
On Sotah 31b, in Rashi DH "Amar Lach R' Chiya":
He says "The fact that R' Chiya doesn't say that the metsiata (1 'attacked' by 2) is talking about a case of zeh achar zeh is because R' Chiya makes a diyuk from the fact that the eidim who are trying to be machchish are saying "No you didn't see that", which implies that they are coming along at the same time as the first eid/im".
But I don't understand: Did Rashi mean to say that R' Chiya could have said zeh achar zeh instead of coming onto the chiddush of psulei eidush? It seems to me there are two questions here. 1: If I have the reisha of chad vechad I can learn the seifa, so why do I need it. 2: I know 1vs2, 2 wins - so the seifa is obvious and why do I need it?
So Ulla answers Q1 by saying that the reisha is chad vechad must be LO haytah shotah, so then I couldnt have learned the seifa from it. And Q2 he answers by saying that it's needed to infer to the reisha that it is indeed LO haytah shotah (and not HAYTAH shotah like R' Chiya).
And R' Chiya says the seifa is a chiddush, so you (1) couldn't have learned it from the reisha and (2) it's not in and of itself obvious.
But how would zeh achar zeh have helped R' Chiya? Fine, it would have answered (1), since if the reisha is bevas achas and the seifa is zeh achar zeh then you couldn't learn seifa from reisha. But how would that answer up Q2? For Ulla the exact problem with Q2 is with zeh achar zeh, since he learns the whole mishnah is zeh achar zeh. What did Rashi mean that R' Chiya could have answered by saying the case of 1 vs 2 (metsiata/reisha of seifa) is zeh achar zeh: you still have the problem that it is obvious since "2 always beats 1"?
(The only answer I could really begin to think of was that R' Chiya is arguing with Ulla about the following point: Fine, 2 eidim always beat 1 eid. But when you have an eid echad believed as 2 vs 2 eidim, then we're not sure: Did the Torah still give the eid echad the status of 2 even in the face of 2 regular eidim, in which case this isn't 2 vs 1 which is obvious but 2 vs 2.
Maybe Ulla says it's obvious that the Torah only believes an eid echad like 2 when there's no contradictory eidus, but R' Chiya says that's not so obvious and the Mishnah needed to tell us.)
Thanks in advance for your answer!
BH, London, UK
You certainly picked a tough Sugya to ask about! Let's see if we can shed some light on it:
1. Your question seems similar to the question of Tosfos (DH Ha) who writes that the reason why the Gemara did not answer that the Metzi'asa is referring to Zeh Achar Zeh is that the Diyuk from the Seifa would not work out. It is clear from Tosfos that the Seifa itself is obvious and does not need to be stated at all, so clearly the only reason the Seifa could have been stated is for the Diyuk that can be made from it, and thus if the Diyuk also does not tell us anything new, then this means the Seifa must be totally superfluos. So Tosfos' question seems to be equivalent to your's, namely, the Seifa is obvious, so why is it mentioned at all?
2. However, Rashi does not appear to learn like Tosfos, as you allude to, because Rashi suggests that the reason why the Gemara does not answer Zeh Achar Zeh is not because the Seifa would not make sense, but rather because the wording of the Mishnah suggests that the Edim came together, but not that logically it had to be like that. In addition, the Tosfos Shantz on the side of the page writes that the reason Rashi explains that the Metzi'asa is not Zeh Achar Zeh is that since we explained that the Reisha is Zeh Achar Zeh, we do not want to set up a different part of the Mishnah in a different way. Even though the way Tosfos Shantz cites Rashi is not exactly the way Rashi appears in our text, nevertheless one does see that the common factor in the different versions of Rashi is that the reason the Gemara did not answer Zeh Achar Zeh is that it does not fit with the words, and not because it does not fit with the logic.
3. Accordinglt, we will have to find another way to answer your question on Rashi. Rav Yosef ben Arza, in Yosef Da'as, refers to ha'Ma'or ha'Gadol to Maseches Sotah, printed at the end of the Rif in Kidushin (page 66 of the pages of the Rif). (This is not the Rishon who wrote the Ba'al ha'Me'or on the Rif, but rather it apparently is an Acharon.)
Ha'Ma'or ha'Gadol writes that there is no dispute in Halachah whatsoever between Rebbi Yitzchak in the Gemara and Rebbi Chiya. The only dispute between them is what the words of the Mishnah are. Rebbi Yitzchak learns that the Mishnah states, "Lo Haisah Shotah," and therefore learns that the Mishnah is Zeh Achar Zeh. In contrast, Rebbi Chiya learns that the Mishnah states, "Haisah Shotah," and therefore learns that the Mishnah is b'Vas Achas.
4. I suggest that this explanation of ha'Ma'or ha'Gadol explains Rashi (but does not apply to Tosfos). When Rashi implies that Rebbi Chiya could have said Zeh Achar Zeh, this refers only to the Metzi'asa, and if the Metzi'asa would have been Zeh Achar Zeh it would have read "Lo Haisah Shotah." The reason why the Metzi'asa is not referring to Zeh Achar Zeh is merely linguistic, as Rashi writes, because when the two Edim said, "You did not see it," this suggests that they came together.
5. However, even if the Metzi'asa would have been Zeh Achar Zeh, this would not have affected the Seifa at all, and the Seifa would still have said the Chidush of Pesulei Edus. Rashi does not mean to say that Rebbi Chiya could have said Zeh Achar Zeh instead of the Chidush of Pesulei Edus.