Our Gemara on Amud Aleph asks what the practical differences are in practice in a Jewish court between an oath that is obligated biblically or due to a rabbinic enactment. The Gemara endeavors to find distinctions.

Rav Yosef Engel in Gilyonei Hashas asks: There is a simpler difference between a biblical oath and a rabbinic oath. If there are two cases that need to be adjudicated, one involving a biblical oath and another involving a rabbinic oath, in the case involving a rabbinic oath, in essence, biblically, the case is dismissed and automatically adjudicated. No oath, no additional process is necessary. In contrast, the case that requires a biblical oath has an incumbent mitzvah deoraysa to administer it. Therefore, Beis Din should give precedence to this case, much in the same way that a biblical mitzvah takes precedence over a rabbinic mitzvah.

Rav Engel’s answer to this question is that since rabbinic laws are still Torah—such as studying the laws of Chanuka are no less Torah study than studying the laws of Shabbos—adjudication of the law is considered Torah study as well (based on Berachos 6a). The adjudication of either case equally constitutes a mitzvah of Torah study, and neither has precedence.

We take it as a given that studying rabbinic Torah is an equally valid mitzvah of Torah study as studying biblical mitzvos. The most striking example comes from maseches Eruvin, which is largely a discussion of a rabbinic solution to a rabbinic problem. In other words, one cannot carry in a “Carmelis” (a shared domain, or semi-public domain), and this is only forbidden rabbinically. However, an Eiruv permits carrying in a Carmelis, which is also a rabbinic construct to have it resemble a private domain. Keep in mind, an Eiruv is not a sufficient boundary to allow carrying in a public domain medoraysa. If so, most of Maseches Eruvin is not just Oral Torah but a study of minutiae of rabbinic edicts—a complex series of rabbinic solutions to rabbinic problems! Biblically, there is no problem nor a need for a solution. Yet, no authority ever saw Eruvin as less worthy of study than, say, Bava Metzia. We know this must be true, but what, then, is the definition of Torah that makes this understandable?

Avodah Zarah (19b) states: One should know that even the ordinary conversation of Torah scholars requires analysis, as it is stated: “And whose leaf does not wither.” This teaches that even the ordinary conversation of a Torah scholar, which is comparable to the leaves of a tree, has great significance, like the actual fruit of the tree. Notably, the Maharsha’s explanation is that even the ordinary talk of sages has Torah ideas embedded within. If so, we can argue Kal V’chomer: the enactments of the rabbis to support Torah and society contain gold nuggets of Torah wisdom.

Another explanation could be based on the Rambam’s opinion: every rabbinic mitzvah is really biblical, based on the commandment of lo sasur (Sefer Hamitzvos Shoresh Aleph, and Mamrim 1:2, as opposed to Ramban, Sefer Hamitzvos ibid, who does not hold there is a biblical commandment to follow rabbinic law). Therefore, study of every rabbinic mitzvah is part of studying how to fulfill lo sasur.

A more nuanced idea is that just as the rabbis can make a rabbinic mitzvah such as Chanuka candles and in the blessing we state, “who has commanded us,” even though, strictly speaking, God did not command, so too the rabbis can make a rabbinic mitzvah of Torah study (Gemara Shabbos 23a discusses this). So perhaps study of rabbinic mitzvos fulfills a rabbinic mitzvah of Torah study, just as the second day of Yom Tov fulfills a rabbinic mitzvah of Yom Tov.