Question: Rav already taught this. Why would he have to teach both of these?

Answer: Had he taught only that teaching (a Mavoy needs houses...), one might have thought that Dirah of a Nochri is Dirah. Therefore he taught this teaching (a Nochri in a Mavoy) to teach that it is not Dirah;

Had he taught only this teaching, we would not know how many houses are required. The other teaching teaches that two are required [to open to each Chatzer].

Now that Rav taught that [that one may not be Me'arev through windows] even regarding a Chatzer [with a Nochri on one side], we know that his reason is because one may not live alone with a Nochri [lest he learn from his ways. Therefore, one may not be Me'arev through windows, in order that no Yisrael will be with Reuven in the Mavoy with the Nochri, and Reuven will fear to be there].

Rav Yosef: R. Tavla was saying 'Nochri, Nochri.' I did not understand this until now. (He alluded to the Isur to be Me'arev when there is a Nochri on one side of a Mavoy or a Chatzer.)

(Mishnah): If there is an inner Chatzer and an outer Chatzer:

If only the inner Chatzer was Me'arev, it is permitted [to transfer between its houses and the inner Chatzer], and the outer Chatzer is forbidden;

If only the outer Chatzer was Me'arev, both are forbidden.

If each was Me'arev by itself, each is permitted by itself [but one may not transfer from one Chatzer to the other];

R. Akiva forbids the outer Chatzer due to Drisas ha'Regel of the inner Chatzer;

Chachamim say, Drisas ha'Regel does not forbid it.

If an outer person forgot to be Me'arev, the inner Chatzer is permitted, and the outer Chatzer is forbidden;

If an inner person forgot, both Chatzeros are forbidden;

If both Eruvin were put in one place (this will be explained), and someone forgot to be Me'arev, whether he is in the inner or outer Chatzer, both Chatzeros are forbidden;

If each Chatzer had only one resident, they need not be Me'arev.

Version #1 (Gemara - Rav Dimi citing R. Yanai): The Reisha is R. Akiva's opinion, who says that even people who are permitted in their place (Chatzer) forbid elsewhere. Chachamim say, just like people permitted in their place do not forbid [elsewhere], also people forbidden in their place do not forbid.

Question #1 (Mishnah): If only the outer Chatzer was Me'arev, both are forbidden.

Question: Who taught this clause?

It cannot be R. Akiva. He says [in the Seifa] that even people permitted in their place forbid. He need not teach that people forbidden in their place forbid!

Answer #1: It is Chachamim.

Answer (and Answer #2 to Question (1)): Really, it is R. Akiva. Indeed, he teaches a small Chidush and then a larger Chidush [which encompasses the smaller Chidush].

Question #2 (Mishnah): If each was Me'arev by itself, each is permitted by itself.

Inference: They are permitted only because both of them were Me'arev. However, had one not been Me'arev, both would be forbidden.

The Tana holds that permitted people (i.e. when each was Me'arev by itself) do not forbid, yet forbidden people (who were not Me'arev) forbid!

R. Akiva did not teach this. He holds that permitted people forbid. It must be Chachamim!

Also, since the Seifa is R. Akiva, the Reisha is not R. Akiva!

Answer: Really, also the Reisha is R. Akiva. The Mishnah is abbreviated. It means as follows:

If each was Me'arev by itself, each is permitted by itself;

This is when there is a small door between the Chatzeros. If not, the outer Chatzer is forbidden due to Drisas ha'Regel of the inner.

This is the opinion of R. Akiva, who forbids the outer due to Drisas ha'Regel.

Chachamim say, Drisas ha'Regel does not forbid.

Question #3 (Rav Bivi bar Abaye - Seifa): If each Chatzer had only one resident, they need not be Me'arev.

Inference: If [either] Chatzer had more than one person, they would need to be Me'arev.

This shows that someone permitted (when each Chatzer had only one resident) does not forbid, but someone forbidden (when a Chatzer has more than one resident) forbids!

Question #4 (Ravina - Mishnah): If an outer person forgot to be Me'arev, the inner Chatzer is permitted, and the outer is forbidden. If an inner person forgot, both are forbidden.

Inference: If no one forgot, both are permitted.

This shows that someone permitted (e.g. when no one forgot) does not forbid, but someone forbidden (e.g. when an inner person forgot) forbids!

Version #2 (Ravin citing R. Yanai): There is a three-way argument among the Tana'im. The first Tana holds that forbidden people forbid, but permitted people do not. R. Akiva holds that even permitted people forbid. The latter Chachamim hold that just like permitted people do not forbid, also forbidden people do not. (Ritva - the entire Reisha is R. Akiva, like we answered before. The Chachamim who say 'Drisas ha'Regel does not forbid' hold that it never forbids. The Tana of the Seifa (when someone forgot) holds that forbidden people forbid, but people permitted do not. According to this, Ravin answers Questions 3 and 4 for Rav Dimi. However, this is unlike our text, which says 'the first Tana holds that forbidden people forbid, but permitted people do not' - PF.)

(Mishnah): If the Eruv [for both Chatzeros] was put in one place, and anyone forgot to be Me'arev [both Chatzeros are forbidden].

Question: What is the meaning of 'in one place'?

Answer (Rav Yehudah): It means the outer Chatzer.

Question: Why is it called 'in one place'?

Answer: It is the one place that both of them use.

Support (Beraisa - R. Akiva): If the Eruv was put in the outer Chatzer, and anyone forgot to be Me'arev, both Chatzeros are forbidden;

If the Eruv was put in the inner Chatzer, whether an inner or outer person forgot to be Me'arev, both are forbidden;

Chachamim say, if an outer person forgot, the inner Chatzer is permitted, and the outer is forbidden.

Question (Rabah bar Rav Chanan): Presumably, Chachamim permitted the inner Chatzer when an outer person forgot, because they can close the door and use their Chatzer by themselves. R. Akiva should agree with this!

Answer (Abaye): They have Drisas ha'Regel in the Chatzer because their Eruv is there.

Question: Chachamim should agree that they have Drisas ha'Regel due to their Eruv!

Answer: The inner people say 'we were Me'arev with you only for our benefit, not for our detriment!'

Question: R. Akiva should agree with this!

Answer: R. Akiva holds that the outer Chatzer can be Mevatel Reshus to the inner (this permits the inner, so it (the Eruv) is not detrimental to them. He forbids only before Bitul);

Chachamim hold that Bitul does not work from one Chatzer to another. (If not, they would agree and forbid before Bitul.)

Suggestion: Shmuel and R. Yochanan argue like Chachamim and R. Akiva:

Shmuel (68a) holds that Bitul does not work from one Chatzer to another, like Chachamim. R. Yochanan holds that it works, like R. Akiva!

Rejection #1: Even R. Akiva could hold like Shmuel. R. Akiva only allows Bitul from one Chatzer to another when they forbid each other. He could agree that when neither forbids the other (each has its own opening to Reshus ha'Rabim) that Bitul does not work;

Rejection #2: Even Chachamim could hold like R. Yochanan (Bitul works from one Chatzer to another. Here [the Eruv does not join the Chatzeros for this would be detrimental,] the inner Chatzer would be forbidden until Bitul. (Therefore the Eruv permits just the inner Chatzer, and Bitul is not needed.)

(Mishnah): If each Chatzer had only one resident, they need not be Me'arev.

(Rav Yosef - Rebbi - Beraisa): If there were three [residents among the two Chatzeros, even if two are in the outer Chatzer], it (the outer Chatzer) is forbidden (Rashi. R. Chananel - if there were three [Chatzeros, one inside the other], all are forbidden.)

Rav Bivi: Do not heed Rav Yosef [who says that this is a Beraisa]. I taught it to him in the name of Rav Ada bar Ahavah;

They are forbidden because Rabim (three) use the outer Chatzer (R. Chananel. Rashi - when Rabim (two) are in the outer Chatzer, we decree to forbid due to when there are Rabim in the inner Chatzer. (Since they forbid themselves without an Eruv, their Drisas ha'Regel forbids the outer Chatzer.))

Rav Yosef: Indeed, this is what I heard. I confused '[since they are a] Rabim' with 'Rabi', and therefore attributed it to Rebbi. (The proper pronunciation of 'Rebbi' is actually 'Rabi'.)

(Shmuel): They are permitted unless there are two in the inner Chatzer.

(R. Elazar): A Nochri is like a Rabim. (If he is in the inner Chatzer, and there are two (Rashi; R. Chananel, according to Milchamos Hash-m - even one) Yisrael(im) in the outer, the Nochri forbids. This is like Shmuel.)

Question: A lone Yisrael [inside] does not forbid [for there is no need to decree]:

People who know that he is alone know that he himself is permitted. (They will not conclude that Drisas ha'Regel of someone forbidden does not forbid.) People who think that there are more than one inside will assume that they were Me'arev;

Likewise, a lone Nochri should not forbid. People who know that he is alone understand why he does not forbid. People who think that Yisraelim live with him will assume that they rented his Reshus!

Answer: If a Nochri rented his Reshus he would publicize this. (If one thinks that Yisraelim live with him, since he did not hear about a rental, he will mistakenly conclude that Drisas ha'Regel never forbids).

(Rav Yehudah): If there are 10 houses, one inside the other, it suffices for the innermost one to be Me'arev with the Chatzer. (Since the innermost resident walks through the others, they are like Batei Sha'ar which need not be Me'arev - 85b);

(R. Yochanan): Even the outer[most] house [must be Me'arev].

Objection: All the other houses pass through it. Surely it is like a Beis Sha'ar!

Correction: He refers to the house outside the innermost one [must be Me'arev].

Question: What do they argue about?

Answer: Rav Yehudah holds that a Beis Sha'ar of an individual (only the innermost house has Drisas ha'Regel through the second) is considered a Beis Sha'ar. R. Yochanan holds that it is not.