Can a sukka be made without any roof at all?
This is the question debated in the Mishna on our daf. According to the Mishna, the Hakhamim allow a sukka that is built like a tzrif – a circular hut, or one that is built leaning against a wall. Rabbi Eliezer rules that such sukkot are no good because they have no roof.
The Gemara explains the position of the Hakhamim as stemming from their belief that the slanted wall of a tent is considered to be a roof – that is to say that a separate, clearly delineated roof is not necessary.
It is related: Abaye found Rav Yosef, his teacher, who was sleeping inside a netted bridal canopy [kilat hatanim], whose netting inclines down, inside a sukka. Ostensibly, Rav Yosef did not fulfill his obligation, as he slept in the tent formed by the canopy and not directly in the sukka. Abaye said to him: In accordance with whose opinion do you hold, that you do not consider this netting a tent? Is it in accordance with the opinion of Rabbi Eliezer, who maintains that a structure without a distinct roof does not have the legal status of a tent, and therefore the netting does not constitute a barrier between the roofing of the sukka and the person sleeping below? …Rav Yosef said to him: In the baraita, the opposite is taught. Rabbi Eliezer deems it fit and the Rabbis deem it unfit.
To Abaye’s challenge that the Mishna should be given more credence than a baraita, Rav Yosef answers that our Mishna is yehida’a – a version accepted only by one redactor.
When redacting the Mishna, Rabbi Yehuda HaNasi collected and edited the oral traditions that were available to them and established a single, reliable formulation that we use as a basic text to this day. Generally speaking, Rabbi Yehuda HaNasi included in the Mishna his own rulings, which he indicated by stating one opinion without attribution or as the opinion of the Sages generally – hakhamim omerim.
R. Moshe Bezalel Luria explains in his Emek Sukkot that, regarding our Mishna, Rabbi Yehuda HaNasi received an oral tradition from Rabbi Natan and chose to insert it into his edited mishnayot, even though he did not agree with its conclusion. Rav Yosef was aware of this, and chose, therefore, to follow the opinion that he knew to be Rabbi Yehuda HaNasi’s as preserved in the baraita.