POINT BY POINT OUTLINE OF THE DAF
prepared by Rabbi Pesach Feldman of Kollel Iyun Hadaf, Yerushalayim
Rosh Kollel: Rabbi Mordecai Kornfeld
ERUVIN 90 (28 Sivan) - Dedicated in memory of Hagaon Rav Yisroel Zev (ben Rav Avrohom Tzvi) Gustman, zt"l, Rosh Yeshiva of Yeshivas Netzach Yisrael-Ramailes (Vilna-Brooklyn-Yerushalayim), author of "Kuntresei Shi'urim" and renowned Dayan in pre-war and post-war Vilna, on his Yahrzeit. Dedicated by Harav Avraham Feldman of Yerushalayim, Dr. Yehoshua Daniel of Efrat, and Rabbis Eliezer and Zalman Stern of New York, who merited to study under the Rosh Yeshiva zt"l in Yerushalayim.
1) CARRYING ON AND BETWEEN ROOFS
(a) Question (Rami bar Chama): [According to Rav, according to Chachamim,] may one transfer between his roof and a pillar [in Reshus ha'Rabim]?
1. Question: Does he ask about transferring from a Karmelis to Reshus ha'Yachid?! (Surely, it is forbidden! Rashi - one may not carry more than four Amos on the roof. It is like a Karmelis. The pillar is 10 tall and four wide, so it is a Reshus ha'Yachid. R. Tam - the roof is Reshus ha'Yachid (one could carry there if he made an Eruv). The pillar is a Karmelis (it is less than 10 tall).)
2. Answer: Amidst his sharpness [he rushed to ask, and] he was not careful [to ask about the proper scenario].
(b) Correction: Rather, he meant to ask [about a case when there is no problem of transferring from a Karmelis to Reshus ha'Yachid, e.g.] whether one may transfer between his roof and the roof of an Achsadra (Rashi - a roof supported by four poles, without walls. It belongs to someone else. Tosfos (94a-b) - it has three walls, and few Diyurin.)
1. Perhaps since neither is proper for Dirah, they are like one Reshus;
2. Or, perhaps it is forbidden, just like from roof to roof is forbidden [because they are different Reshuyos]!
(c) Question (Rav Bivi bar Abaye): May one transfer between his roof and a ruin (Rashi; Tosfos - the roof of a ruin)?
(d) Rav Kahana: You ask [a question equivalent to] Rami bar Chama's question!
(e) Rav Bivi: Do not suspect me of doing so! The Achsadra is not proper for Dirah. (It does not have four walls.) We cannot learn to a ruin which [with simple renovations] is proper for Dirah. (Rami bar Chama asked about a pillar, and the Gemara said that he should have asked about an Achsadra! Perhaps Rav Bivi bar Abaye later heard that Rami himself asked about an Achsadra - Ga'on Yakov.)
(f) Question: Since a ruin is proper for Dirah, this is obvious! (Rashi - it is unlike a roof. Surely, it is like another Reshus! Tosfos - since a ruin is proper for Dirah, its roof is just like a roof of a house. Chachamim forbid transferring from one roof to another.)
(g) Answer: His question depends partially on Rami's question:
1. If you will say that (Tosfos - the roof of) the Achsadra is not proper for Dirah [and therefore one may transfer between his roof and the Achsadra's roof], perhaps we forbid regarding a ruin, for it is proper for Dirah;
2. Or, since no one dwells there, it is permitted!
(h) This question is not resolved.
(i) (Rav): According to R. Meir, if [the heights of adjacent] roofs are within 10 Tefachim of each other, and according to Chachamim when there is an isolated roof [no roof adjoins it], one may carry on all of it [even according to R. Meir. We shall refer to the roofs in the singular, for they are like one Reshus);
(j) (Shmuel): One may carry only within four Amos.
(k) Question: Rav contradicts himself! (Rashi - above, he permits only four Amos because the roof is totally open to a Reshus to which it is forbidden, i.e. another roof. Also here, it is totally open to Reshus ha'Rabim! Tosfos ha'Rosh - since Rav does not say Gud Asik, the roof should be like Karmelis, for it has no Mechitzos!]
(l) Answer: Above, the Mechitzos [between houses] are not Nikarim [on the roof, therefore Rav does not say Gud Asik]. Here, the Mechitzos (the walls of the house(s) on the outside) are Nikarim.
(m) Question: Shmuel contradicts himself! (Above, he permits the entire roof.)
(n) Answer: Above he permits only when each roof is at most Beis Se'atayim. Here, he forbids when the area of the roof exceeds Beis Se'atayim;
1. The walls below were made for the house(s), and not for [Dirah on] the roof. [Even if we consider the roof to be enclosed due to Gud Asik,] the roof is like a Karfef more than Beis Se'atayim which was not Hukaf l'Dirah, so one may carry only within four Amos.
2) CARRYING IN A BOAT
(a) (Rav): One may carry anywhere within a boat;
(b) (Shmuel): One may carry only within four Amos [if the boat is more than Beis Se'atayim].
(c) Rav permits the entire boat because it has Mechitzos, (It is considered Hukaf l'Dirah);
(d) Shmuel forbids, because the Mechitzos are [not for Dirah, rather, only] to keep the water out.
(e) Version #1 (Rav Ashi) Question (R. Chiya bar Yosef, to Shmuel): Is the Halachah like you, or like Rav?
(f) Answer (Shmuel): The Halachah follows Rav.
(g) (R. Chiya bar Yosef): Rav agrees that if one flipped [the boat] over, one may carry [on what is now on top] only within four Amos.
(h) Question: Why did he flip it over?
1. If it was in order to dwell underneath it, [this is like remaking the Mechitzos l'Shem Dirah], it should be just like a roof! (Even though the Mechitzos were l'Shem Dirah below, also above is considered Hukaf l'Dirah, and even more than Beis Se'atayim is permitted.)
(i) Answer: He flipped it over in order to tar it.
(j) Version #2 (Rav Acha brei d'Rava): R. Chiya bar Yosef asked [Shmuel if the Halachah follows him or Rav] regarding an Achsadra:
1. (Rav): One may carry anywhere in an Achsadra in a valley. (It has a roof supported on poles in the corners, but no walls);
2. (Shmuel): One may carry only within four Amos.
3. Rav permits the entire Achsadra. We say Pi Tikra Yored v'Sosem;
4. Shmuel permits only within four Amos. We do not say Pi Tikra Yored v'Sosem.
3) TRANSFERRING BETWEEN RESHUYOS WITH DIFFERENT USES
(a) Question: According to Rav, R. Meir should permit transferring between a roof and a Chatzer! (Since one may carry anywhere on the roof, it is a proper Reshus ha'Yachid, like the Chatzer)!
(b) Answer: He decrees not to, like the decree of R. Yitzchak bar Avdimi. (When there are two adjacent similar Reshuyos, one may not transfer between them, lest one adjust a load on a mound 10 tall and four wide (a Reshus ha'Yachid) in Reshus ha'Rabim.)
(c) Question: According to Shmuel, Chachamim should permit transferring between a roof and a Karfef! (Rashi - both of them are more than Beis Se'atayim. Both are like Karmelis, for one may carry only within four Amos. Ri - both are at most Beis Se'atayim. A Karfef resembles a roof more than a Chatzer does, and one may transfer between a roof and a Chatzer!)
(d) Answer (Rabah bar Ula): They decree not to, lest the roof be diminished [from Beis Se'atayim and it will be a Reshus ha'Yachid, but one will still transfer between them - Rashi. Ri - perhaps part of the roof will cave in and the roof will be used more, and it will be considered Hukaf l'Dirah, unlike the Karfef.]
(e) Question: If so, they should also decree not to transfer between two Karfifos [above Beis Se'atayim], lest (Ri - the wall of) one of them be diminished!
(f) Answer: If a Karfef is diminished, this will be evident [because it has real Mechitzos]. If the roof is diminished, it will not be evident. (Ri - its change in status will not be evident even to people on the roof.)