Rabbi Yochanan vs. Reish Lakish (article preview)

A somewhat cryptic Mishna on Kiddushin 28a seems to discuss chalipin, such as exchanging a donkey for an ox and when each is acquired. The gemara mentions the positions of Rav Sheshet and Rav Nachman (bar Yaakov), third-generation Babylonian Amoraim, and how they can reconcile with second-generation Rav Yehuda’s understanding of the Mishnah.

Rav Sheshet (A) maintains that chalipin works not just for vessels, but for produce and animals as well. Rav Nachman (B) restricts chalipin to vessels. In an entirely separate dispute, Rabbi Yochanan (X) says that Biblically, paying money effects an acquisition of moveable objects, and only by Rabbinic law is pulling the item (meshicha) required, lest the seller receive the money and then tell the buyer “your wheat was burned in the loft”. Rabbi Shimon ben Lakish (Y) says that pulling, meshicha, is explicit in the Torah, so money alone cannot acquire the moveable object. The gemara analyzes these positions, aligning Rav Nachman with Rabbi Yochanan (A → X) and Reish Lakish with Rav Sheshet (Y → B).

In the parallel sugya (Bava Metzia 46b), the Rif discusses the halachic fallout. This alignment demonstrates that we rule like Rav Nachman, for we generally rule like Rabbi Yochanan over Reish Lakish.