Sources of the Law, According to the Ancient Rabbis

The rabbis recognize several sources of halakhah, including interpretation, legislation, and custom. The fecundity of scripture as a source of law through interpretation is evident in m. Avot 5:22, although the pressure to anchor existing halakhah in scripture led some scholars—most famously the school of R. Akiva—to offer contrived interpretations based on semantically insignificant textual features, as illustrated by the two passages from the Sifra (attributed to the school of R. Akiva) here. When derivation from scripture was difficult, a law might be designated “a halakhah of Moses from Sinai” in an effort to establish its antiquity. The rabbis were aware that their methods of study and argumentation could generate multiple conflicting interpretations, as illustrated in b. Eruvin 13b. Disputes over the correct interpretation of the law might be settled by a decision to adopt the teachings of a particular authority (e.g., Hillel, R. Akiva, or R. Judah) or the view of the majority, as in m. Shabbat 1:4.

Legislative sources of law include the takanah, a rabbinic decree designed to prevent or correct an inequity or social harm arising from the observance of the law, as illustrated in m. Rosh Hashanah 2:1–2, 5, and in amoraic times the gezerah, a protective measure designed to prevent violations of a Torah law, seen in b. Sukkah 42b regarding a potential violation of the Sabbath laws of carrying in public. Indeed, the halakhah generated by the rabbis was often seen as a “fence” around the Torah, as is the case in b. Sanhedrin 46a regarding flogging for certain violations. Local custom and popular practice were other sources of halakhah, as seen in the rules in m. Avodah Zarah 1:6 regarding the sale of animals to non-Jews and in deference to common practice regarding a particular blessing in b. Eruvin 14b. Finally, the rabbis’ disciples scrutinized their masters’ actions as a source of halakhah. In b. Berakhot 11a, one sage takes pains not to send the wrong halakhic message about the proper position for prayer through his actions.