Our daf today concerns the permissibility of cooking and heating food on Shabbat, a discussion that began yesterday with the opening mishnah of chapter three. Yesterday’s mishnah articulated fairly strict restrictions on heating food over Shabbat: first, the food must be already cooked, and second, the fuel used to light the stove must either be mostly burned down before Shabbat begins, or one must have actively cooled it down prior to Shabbat.
Why? The issue at hand, as Rashi notes in his commentary, is not actually cooking per se, but the concern that our desire for the food to cook will lead us to stoke the coals of the fire and come to violate the Biblical law against igniting flame. In other words, this mishnah is creating a fence around the biblical prohibition against lighting a flame. But, the Gemara wonders, how high must this fence really be?
Despite the mishnah’s ruling that we cannot leave food on a hot fire before Shabbat, today’s Gemara says this:
Rav Shmuel Bar Yehudah says that Rabbi Yochanan says: with regard to a stove that was lit with pomace (pulp that remains from sesame seeds, olives, etc. after the oil is squeezed from them) or wood, one may leave a fully cooked dish or hot water upon it even if it is the sort of food that is improved by extra cooking.
This is a lenient ruling in two ways. First, Rabbi Yochanan allows one to leave food on a fire that has not been cooled in any way (contra our mishnah). And second, he allows this even in a situation where the food itself would be improved (throughout Shabbat) by additional cooking — meaning that one who places it on the fire before Shabbat would almost certainly want the heat that the fire provides to not only warm but actually continue to cook the food. (This assumes that the food is at least edible when Shabbat begins.) Rabbi Yochanan, it seems, is not concerned that allowing such an action will lead someone to inadvertently violate the biblical law by stoking the flames.
The Talmud then relates that one of the sages immediately challenged Rav Shmuel bar Yehudah, who related Rabbi Yochanan’s lenient ruling, reminding him that Rav and Shmuel (different sages!) both agreed that placing food on a stove before Shabbat was prohibited. Rav Shmuel bar Yehudah retorts that he knows what Rav and Shmuel said, he was reporting the position of Rabbi Yochanan. The back-and-forth ends with an amazing statement of what we might call halachic pluralism:
Rav Ukva from Meishan said to Rav Ashi: you are close to the place of Rav and Shmuel should act in accordance with their ruling, while we will act according to Rabbi Yochanan.
In other words, which ruling you follow is a matter of geography.
Halachic pluralism has been with us for a long time. For generations, the Ashkenazi and Sephardi communities have disagreed about the prohibition against eating kitniyot — foodstuffs that in some times and places could have been mistaken for prohibited foods — on Passover. As we see on our daf today, different sages felt differently about the need for such fences, and their varying answers to the question of “how careful should we be?” led to very real differences in how Jewish law was practiced.