We noted earlier (16a) that there is a difference of opinion regarding the status of liquids vis-à-vis the laws of tuma v’tahara (ritual purity). On our daf, Rav Pappa argues that even according to the opinion that liquids can become ritually defiled on a Biblical level, nevertheless the liquids found in the slaughterhouse in the Temple are not tameh, and hilkhita gemiri lah – we are taught it by way of an oral tradition handed down from Moshe at Mount Sinai (halakha le-Moshe mi-Sinai).
The Gemara brings a number of questions on Rav Pappa’s position. In the first one, Rav Huna brei d’Rav Natan asks Rav Pappa how he explains the baraita that appeared on the previous daf in the Gemara. In it, Rabbi Elazar argues that he learned the rule that liquids in general do not become tameh (ritually defiled) from Yosei ben Yo’ezer of Tzereida‘s testimony that the liquids in the slaughterhouse of the Beit haMikdash are considered tahor (ritually pure). If that rule is halakha le-Moshe mi-Sinai, then how are we able to learn other rules from it?
In general, a halakha le-Moshe mi-Sinai carries the same weight as laws written in the Torah or derived in more conventional ways. Such a tradition is strong enough for us to reinterpret passages in the Torah or even uproot them totally from their simple meaning. One of the basic differences between a law that is written in the Torah and one that is based on such a tradition is whether we can derive other laws from this one. A halakha that is written in the Torah can act as an archetype from which we can extrapolate to other, similar cases. A law that we follow based on halakha le-Moshe mi-Sinai is limited just to that specific case.
Following the questions posed on Rav Pappa’s position, the Gemara concludes with the word kashya – “it is difficult.” Nevertheless, Maimonides, in his Mishneh Torah, rules like Rav Pappa. Apparently, even if some of the opinions in the baraita cannot be reconciled with Rav Pappa, other tanna’im are understood to agree with him. Since the Gemara did not conclude with the expression tyuvta – “it is refuted” – Rav Pappa’s position is not entirely rejected.