1) IS SWEEPING THE FLOOR ON SHABBOS A "DAVAR SHE'EIN MISKAVEN"?
QUESTION: Rebbi Eliezer maintains that one who sweeps the floor on Shabbos is Chayav to bring a Korban Chatas. The Gemara concludes that since the Halachah follows the opinion of Rebbi Shimon, who says that a Davar she'Ein Miskaven is permitted, one may sweep the floor on Shabbos. This implies that Rebbi Eliezer prohibits it because he maintains that a Davar she'Ein Miskaven is forbidden.
This is difficult to understand. Even if sweeping the floor is a Davar she'Ein Miskaven, and even according to the opinion of Rebbi Yehudah who says that a Davar she'Ein Miskaven is prohibited, a Davar she'Ein Miskaven is prohibited only mid'Rabanan and l'Chatchilah; it is not Asur mid'Oraisa and it does not obligate a person to bring a Korban Chatas. How, then, can Rebbi Eliezer say that one is Chayav to bring a Korban?
ANSWER: TOSFOS (DH Mechabed) answers that the Gemara means to say that when Rebbi Eliezer and the Rabanan argue with regard to sweeping, their argument is based on whether sweeping is a "Pesik Reshei." Rebbi Eliezer maintains that it is a "Pesik Reshei," and therefore it is forbidden whether or not a Davar she'Eino Miskaven is prohibited. The Halachah follows the view that it is not a "Pesik Reshei," and thus according to Rebbi Yehudah it is forbidden, but one is not Chayav to bring a Korban, and according to Rebbi Shimon it is permitted. Since the Halachah follows Rebbi Shimon with regard to a Davar she'Eino Miskaven, one is permitted to sweep the floor on Shabbos (see following Insight).
2) HALACHAH: MAY ONE SWEEP THE FLOOR ON SHABBOS
OPINIONS: The Gemara discusses whether one may sweep the floor with a broom on Shabbos. What is the Halachah in practice?
(a) The BEHAG (cited by Tosfos DH v'Ha'idna), RIF, and RAN permit one to sweep any type of floor, because the Gemara concludes that it is a Davar she'Ein Miskaven, and the Halachah follows Rebbi Shimon who permits a Davar she'Ein Miskaven.
However, there seems to be another problem that should prohibit one to sweep the floor on Shabbos. The dust which one moves around as he sweeps is Muktzah, because it has no use on Shabbos. The Rishonim suggest either that the dust has the status of a Geraf Shel Re'i (Rashba to Shabbos 143a), or that the Rabanan were lenient for the sake of the enjoyment of Shabbos (Ran), and they therefore permitted one to move Muktzah indirectly (Tiltul Min ha'Tzad) in order to clean the house.
(b) The RAMBAM (Hilchos Shabbos 21:3) permits one to sweep only a tiled floor, as the Gemara here states. If the floor is not tiled, one may not sweep it because a person inevitably smoothes grooves in the dirt floor as he sweeps (and thereby transgresses the Melachah of Boneh), and the act of Melachah is a "Pesik Reshei." The BEIS YOSEF (OC 337) infers that this is also the opinion of Rashi (124b, DH Shel Temarah).
(c) The SEFER HA'TERUMAH prohibits one to sweep even a tiled floor. He maintains that it is prohibited either because the Rabanan prohibited sweeping a tiled floor lest one mistakenly assume that he is also permitted to sweep a dirt floor, or because even when the floor is tiled, there are cracks between the tiles, and when one sweeps he makes the floor even by filling in those cracks (HAGAHOS MAIMONIYOS, Hilchos Shabbos 21).
(d) TOSFOS and the ROSH prohibit one to sweep even a tiled floor because of the problem of Tiltul Muktzah, since one moves the dust when he sweeps. When the Gemara says that one is permitted to clean the floor, it refers only to sprinkling the floor but not to sweeping.
HALACHAH: The SHULCHAN ARUCH (OC 337:2) first cites the opinion of the RAMBAM and RIF (who permit one to sweep only tiled floors). He cites the BEHAG's opinion (that one may sweep even a dirt floor) as "Yesh Matirin." The REMA cites the SEFER HA'TERUMAH who is stringent and prohibits one to sweep even tiled floors. However, the Rema permits one to sweep a dirt floor with a soft cloth, because a soft cloth does not smooth the grooves in the floor.
The Rema concludes that one should be stringent in this matter and not sweep even tiled floors, as the Sefer ha'Terumah rules. The BI'UR HALACHAH, however, points out that the Sefer ha'Terumah prohibits one to sweep only because of a Gezeirah, as mentioned above, or because one might fill in the cracks between the tiles. Consequently, in a town where most of the floors have no cracks, such as floors made of wooden or cement (and not tiles), the Gezeirah does not apply and one is permitted to sweep. Nevertheless, one should be careful not to use a broom which has bristles that break easily, lest he break them on Shabbos (Rema ibid.).