Connecting the dots TB Eruvin 57

Today’s daf TB Eruvin 57 defines a karpef (קַרְפֵּף) differently than we did previously. Before we described it as an enclosed backyard. Although everybody agrees that a karpef is 70 2/3 amot long, Rabbi Meir and the Rabbis disagree what is the karpef’s purpose. Rabbi Meir describes it as a city’s buffer area; consequently according to him, a city’s tekhum is actually 2070 amot. The Rabbis hold that a karpef can unify as one tekhum cities or villages that are no more than a karpef apart.

 “MISHNA: One allocates a karpef to every city, i.e., the measure of a karpef, which is slightly more than seventy cubits, is added to every city, and the two thousand cubits of the Shabbat limit are measured from there; this is the statement of Rabbi Meir. And the Rabbis say: They spoke of the addition of a karpef only with regard to the space between two adjacent cities. How so? If this city has seventy cubits and a remainder vacant on one side, and that city has seventy cubits and a remainder vacant on the adjacent side, and the two areas of seventy-plus cubits overlap, the karpef combines the two cities into one.” (Sefaria.org translation)

 How close to the two cities have to be unified into one tekhum according to the Rabbis? Of course, the Gemara cites a disagreement between Rav Huna and Hiyya bar Rav. “It was stated that the amora’im disagreed with regard to this issue. Rav Huna said: One allocates a karpef to this city and a karpef to that city, so that the two cities together are granted a total of slightly more than 141 cubits. Ḥiyya bar Rav said: One allocates only one common karpef to the two of them.” (Sefaria.org translation)

 This discussion becomes relevant how far a person may walk when they are two adjacent different incorporated suburbs. In other words, where does the tehum Shabbat begin? Because tekhum Shabbat is a rabbinic injunction, poskim have ruled leniently. Even though the Shulkhan Arukh rules in favor of the Rabbis position (Orekh Hayyim, 398:5), Rabbi Moses Isserles, who wrote the gloss on the Shulkhan Arukh for Ashkenazi Jews, ruled leniently according to Rabbi Meir. Similarly, the halakha follows Rav Huna allowing the two cities, villages, or suburbs to be two karpefs apart or 141 1/3 amot apart. So go ahead and walk. It’s good for you.