If Rebbi didn't teach it, where would R' Chiya get it from? (Eruvin 92a)

This phrase
וכי רב לא שנאה, ר' חייא מנין לו
appears in a few places in Shas; I just saw it on Eruvin 92a. To me, it seems like a remarkable idea. It seems to work something like this, at least in Eruvin:
1) The amora makes a statement.
2) A mishnah is brought against his statement.
3) He explains how he would understand the mishnah to fit his statement.
4) The gemara then brings a beraisa (R' Chiya's collection) to show that that understanding of the mishnah is wrong.
5) At this point, the amora should be disproven: he is outranked by the tanna of the beraisa. However, he responds
וכי רב לא שנאה, ר' חייא מנין לו
In other words (I guess) the mishnah does not have any (internal) evidence for R' Chiya's reading over that of the amora, and therefore R' Chiya has no authority to tell us what it means.

That is a fascinating idea to me. I would have said: R' Chiya was a student of Rebbi, and learned the mishnah with him. Of course he knows what it means, whereas we are just trying to do our best to work it out. A couple of hundred years later, a disagreement has arisen on what was going on, and evidence from R' Chiya is ideally suited to settle it.
The gemara seems to be rejecting that point of view. If there is a later disagreement on how to understand the mishnah, and the mishnah does not lean either way - Rebbi must have written the mishnah in such a way as not to choose sides! R' Chiya has no business trying to settle an issue that Rebbi chose not to settle.

Or can someone explain this principle in another way? After all, the gemara is constantly bringing beraisos and ma'amarim from Rav or R' Yochanon which shift our understanding of a mishnah, and this objection is hardly ever raised. Do we know when to use it and when not?

I asked R' Mordechai Weisskopf shlit"a, and he sent me the following comment:
ז"ל הרשב"א שם: "וכי רבי לא שנאה ר' חייא מנין ליה. ואע"ג דהא דר"ח פירושא דמתני' היא וזמנין סגיאין דמאי דלא פי' במתני' פריש ברייתא אפ"ה אי איתא דאית ליה לרבי הכי הו"ל לפרושי כי הא במתני'" וכ"כ הריטב"א שם: "וכי רבי לא שנאה רבי חייא מנין לו. פירוש דכל כה"ג אילו סבר לה רבי לא סגיא דלא מפרש לה במתני', ואע"ג דאיכא מילי טובא דמאי דלא פריש במתני' פריש בברייתא"
That is, the glaring omission of this din (that they can only eat the fruit while on top of the wall) indicates that Rebbi disagreed with it. See also Shitah Mekubetzes to Beitzah 6b.

In practice, then, we have to be able to tell what is a glaring omission and what is not. There is no raaya against R' Chiyah (or whomever) if it is not truly omitted, but is alluded to in the Mishnah. (See hakdamah to Pe'as HaShulchan that Gra was able to show how the Toseftas are alluded to in the Mishnah. He even gives an example.) There is also no raaya if the omission is not glaring, i.e., it is not something that the Mishnah would necessarily have addressed if it were true.
MDW

Thank you, R' Mordechai. A couple of comments:
1) Tosefos in Niddah 62b says two p'shatim about this principle. The first sounds closer to what I was trying to say: R' Chiya cannot explain the mishnah unless there is actually a hint to his din in the mishnah itself. The second p'shat sounds closer to what you're saying, that the mishnah actually doesn't work as well according to R' Chiya's braisa's explanation.
2) While this is all pretty much a judgment call made by the gemara, not something that we can make ourselves, I guess I would have said that Rav Ashi's reading of the mishnah is actually much more difficult than R' Chiya's. It does have the advantage that R' Chiya's reading requires an אוקימתא - that an eiruv was made.
3) See also the language of Rabbeinu Chananel.

And I note that the Artscroll gemara also explains more-or-less the way I did: Rebbi intentionally left the ambiguity in the mishnah.

And he sent the following comment back to that (slightly paraphrased, I hope without doing violence to the meaning):

1. The second pshat is the same as Rashba et al. The first is different but not exactly what you seem to be saying, either. To wit, Tosafos says והך הוה פשיטא ליה לר"ל דלא רמיזא במתני'. That is, the lack of an allusion is itself proof that Rebbi did not hold of it, but it is not that we need the allusion in order to accept R Chiya's pshat, but that if we are ceratin that there is no such allusion then we proof against it. But I don't see anything about Rebbi not wanting to take sides - I think Tosafos mean that the lack of an allusion is proof that Rebbi did not hold of the din.

2. I'm not holding in the sugya well enough to comment. But the Rishonim claim that the Mishnah is mashma not like R Ashi

3. I think R Chiya means what I wrote above about Tosafos first pshat.

Artscroll writes (in Eruvin) that Rebbi purposely did not employ the Baraisa's phraseology. I think this leads to the conclusion that he disagreed with it, not that he was deliberately vague. But whatever the true pshat, there is nothing in Artscroll's lashon that indicates your pshat. And they cite R Chananel and Ritva, which are two different pshatim לענ"ד. In Niddah, Artscroll cites both pshatim of Tosafos and combines them. In Beitzah, they quote the Shittah who says like Rashba et al.

R’ Mordechai, I’m wondering if you were looking at Artscroll note 10., not note 9.

I still think I’m having trouble following your distinction here. If there is no allusion to the din in the mishnah – well, is there an allusion to Reish Lakish’s (or Rav Ashi’s in Eruvin) din instead? We are forced to choose one or the other. Since the second p’shat in Tosefos includes a positive allusion to Reish Lakish’s din, I would think that the first p’shat works even if there is no such allusion: the mishnah doesn’t say either way. But then your understanding is impossible; the mishnah can’t be taking sides, and I’d be back to my original point.
Michoel

And he sent back:

Tosafos second pshat is that there is a local raaya against R Chiyah. the first pshat is that there is no raaya to him - and this is itself the raaya against him. So its not that Rebbi was fence-sitting; he made it clear that he held of nothing not alluded to in his work. We thus must be certain that there is no such allusion, otherwise we have no proof against him.

Michoel,

I learned this gemara today. It seems to me that one can say the following idea here:

While there are 2 other places in Shas that I know of that this occurs: Nidah 62b and Yevamos 43a,
neither one is like this one. In Nidah there is a clear difference between the Mishna and the Braisa - i.e. whether it applies to Kesem or to know Dam Nidah. In Yevamos, the question is if there is a Machlokes in a Mishna (in general) and Stam in a Braisa, the Halacha goes like the Mishna, because if Rebbi does not teach it Stam, how can R' Chiya have the authority to do so.

In both those cases there is a clear indication that the Mishna is not like the Braisa. Here, this is not the case, because the Mishna says "Lematah" which could either mean taking the fruits into the Chatzer or into the house. Certainly it could mean into the Chatzer, which would fit with R' Chiya's braisa. So here we have a problem. How can the gemara say this over here?

To answer, this it occurred to me to say the following thought: R' Yochanan was known as a Baki in Mishna and Braisa. That is why he is one of very few Amoraim that authoritatively will reject versions of Mishna or Braisas. Here are 3 examples of Leshonos of R' Yochanan, which are almost not used by other Amoraim:

פוק תני לברא
This is said by R' Yochanan in 7 places in Shas (Eruvin 9a, Shabbos 106a, Yoma 43b, Beitzah 12a, Yevamos 77b, Baba Kama 34b, Sanhedrin 62a) as far as I know.

מוחלפת השיטה
This is an interesting one. Usually the Gemara uses a lashon of איפוך which is a more tentative statement - we need to reverse these opinions in order to fit with something else. Only someone who is an authority on Mishna and Braisa can say definitively מוחלפת השיטה. This appears 12 times in Shas, 9 times by R' Yochanan and 3 times by Rav. The 12 times are: (Eruvin 99a, Beitzah 3a, Yevamos 104a, Chulin 128a, Brachos 17b, Vrachos 49b, Pesachim 49b, Pesachim 55a, Beitzah 9b, Kesuvos 24a, Nedarim 61a, Kiddushin 64b.) The first 9 are R' Yochana, and the last 3 are Rav.

...איני יודע מי שנאן
R' Yochanan says this in Yevamos 27b

It is clear that R' Yochanan was an authority on the Mishna. Therefore, I wanted to say that when he says here "Lemata" means into the house, he does not mean that it can be read as into the house, but rather that it most certainly means "into the house" and does not mean "into the Chatzer". Therefore, R' Chiya is definitively arguing on Rebbi, and has brought a Braisa that is unfounded.

Of course, this limits the application of this idea (that R' Chiya cannot argue with Rebbi) only to cases where we clearly know that he is arguing with Rebbi, which I think is in line with What Tosafos says in Nidah 62b.

I hope this helps.

Thanks, R' Tzvi, that's a lot of information. You are taking into account that R' Yochanon didn't actually say any of this ("למטה לבתים", "וכי רבי לא שנאה"), etc.? It all seems to be Rav Ashi speaking on his behalf. So I'm having trouble understanding the conversation: how does Rav Ashi know that R' Yochonon is taking such a strong position? All he said was that halacha is like R' Shimon. Even if R' Yochanon has such expertise as to be able to reject ברייתות, doesn't he have to be the one to do it (as is perhaps the case in the other examples you brought)? Is there nowhere else in Shas where we bring a kashya from a b'raysa on R' Yochonon, without automatically responding, Well, he's such an expert, the b'raysa must be wrong!

I admit that I had read the Gemara quickly and failed to notice that this is a conversation between Ravina and Rav Ashi. However, on further reflection, I still like my original statement. It is entirely reasonable that Rav Ashi had a Mesora that this is Rabbi Yochanan's position. When the Gemara brings Rabbi Yochanan and Reish Lakish, or other earlier Amoraim, they clearly had this mesora that this is what the earlier Amoraim had said. We definitely do find Amoraim arguing on Rabbi Chiya.

By the way, I think it is possible to say that this statement is not generalizable. Obviously if a Braisa contradicts a Mishna, then it could be used, but my feeling is that it is similar to the Ramban's position on Ein Mukdam U'Me'uchar BaTorah - you only say it when the Gemara says it, but not elsewhere.

Let me know what you think. And thank you for raising this question!

As an addendum to my reply, I wanted to point out that the Gemara's usual answer to this question seems to be שני אמוראים אליבא דר' יוחנן.

The fact that they did not say so in this case makes me feel more strongly that Rav Ashi was answering based on actual Mesora, not just on his hypothesis that Rabbi Yochanan might have said this. Of course, by his knowing Rabbi Yochanan's general style he may just be suggesting a hypothetical answer here, but I feel it more likely that such a strong statement coming hundreds of years later is most likely based on Mesora.

See
https://gemaraboards.forumotion.com/t27-mesorah-in-the-gemara#77
I thought the topic merited a post of its own.