In rabbinic Judaism, the Torah is understood as both a written text and an accompanying oral tradition, with the latter elucidating how the written commandments are to be observed. That claim raises an important internal question in light of the biblical prohibition against adding to or subtracting from the commandments, as stated in Deuteronomy 4:2: "You shall not add to the word which I command you, nor shall you subtract from it, to keep the commandments of the Lord your God which I command you." A similar injunction appears in Deuteronomy 13:1 (numbered Deuteronomy 12:32 in many Christian Bibles). The tension, then, is not merely whether later Jews found the Torah difficult to apply, but whether rabbinic tradition can coherently maintain that Oral Torah and later rabbinic legislation are authorized interpretation rather than forbidden addition.
The Prohibition in Deuteronomy
Deuteronomy 4:2 and 13:1 articulate a clear directive against altering the divine commandments. Classical Jewish commentators usually treat this as the prohibition known as bal tosif (adding) and bal tigra (subtracting). Rashi's comments are concrete rather than abstract: one may not change a commanded ritual form by, for example, making five compartments in tefillin, adding a fifth species to the lulav, or adding an extra tzitzit. Ramban likewise reads the verses as protecting the commandments from being altered or supplemented as Torah. This matters because the rabbinic defense does not deny the prohibition; it argues that interpretation, judicial application, and openly rabbinic safeguards are not the same as announcing a new commandment as part of the Written Torah.
The Oral Torah at Sinai
Rabbinic tradition, however, maintains that alongside the Written Torah, an Oral Torah was also given at Sinai. Pirkei Avot opens with the statement: "Moses received the Torah from Sinai and transmitted it to Joshua." In rabbinic interpretation, this transmission includes authoritative explanation, not only the written scroll. Rambam (Maimonides), especially in his introductions to the Mishneh Torah and to the Mishnah, presents the Oral Law as a chain of received explanations and legal principles necessary for fulfilling the commandments. At the same time, Rambam distinguishes received Mosaic interpretation from later rabbinic decrees, enactments, and customs. That distinction is essential: not every rule in rabbinic literature is claimed to be a verbatim Sinaitic command.
A major rabbinic argument for an oral component is that several written commandments are not fully specified in the written text. Deuteronomy 12:21 says that animals are to be slaughtered "as I have commanded you," yet the Torah does not preserve a detailed written slaughter procedure; rabbinic tradition sees this as pointing to received instruction. Deuteronomy 6:8 commands Israel to bind the words as "a sign on your hand" and "frontlets between your eyes," while rabbinic tradition specifies the boxes, scrolls, passages, straps, and placement of tefillin. The Sabbath is also a strong example: the Torah prohibits melakhah ("work") and gives some examples, but it does not provide a complete written taxonomy; Mishnah Shabbat 7:2 famously enumerates thirty-nine categories of labor, linked by rabbinic interpretation to the labors of the Tabernacle. These examples do not by themselves prove that every later rabbinic ruling is Sinaitic, but they do show why the rabbinic claim of inherited practical interpretation is not a superficial answer.
Internal Tensions
The sharper internal difficulty concerns not the claimed oral explanation of biblical commandments, but self-consciously post-biblical rabbinic legislation. The categories of takkanot (enactments) and gezerot (protective decrees) are openly acknowledged as rabbinic measures, not as newly discovered verses in the Torah. They address new situations, regulate communal life, or build a "fence around the Torah" (Pirkei Avot 1:1). The question is therefore precise: when do such rules remain legitimate rabbinic authority, and when would presenting them as divine Torah cross the line into "adding"?
Hanukkah is a useful test case, but it should not be described simply as a new biblical festival. The Torah does not command Hanukkah, and it is not one of the Torah's pilgrimage festivals. The Talmud in Shabbat 21b discusses its establishment after the Hasmonean victory and the practice of lighting lamps; Shabbat 23a then asks how one can bless God "who commanded us" concerning a rabbinic command and answers by appealing to the Torah's command to heed authorized judgment (Deuteronomy 17:11) and to respect ancestral instruction (Deuteronomy 32:7). This is the rabbinic model in miniature: Hanukkah is treated as binding rabbinic law, not as an added Torah festival. A critic may still question whether Deuteronomy 17 can bear that much authority, but the rabbinic position is more precise than a bare "addition to the biblical festivals."
Balancing Tradition and Authority
Jewish scholars and communities have answered these tensions in different ways. Rambam's approach is especially important: in Hilkhot Mamrim 2:9 he insists that a court must not present a rabbinic decree as if it were written Torah. If the court says a rabbinic rule is rabbinic, it may be binding under the Torah's grant of judicial authority; if it falsely labels it biblical, that is a serious error. Karaites, by contrast, reject the rabbinic Oral Torah as a binding Sinaitic tradition, though they are not interpretation-free; they rely on the written Tanakh together with their own exegetical methods and communal traditions.
In modern times, Jewish movements approach these issues differently. Orthodox Judaism generally affirms the divine authority of the Oral Torah and the binding force of halakhah as developed through rabbinic tradition. Conservative Judaism typically regards halakhah as binding but historically developing through authorized interpretation. Reform Judaism generally does not treat halakhah as legally binding in the same way, emphasizing ethical monotheism, communal practice, and individual religious responsibility. These differences show that the question is not only ancient; it continues to shape Jewish self-understanding.
Ultimately, Deuteronomy's prohibition against adding or subtracting should be handled with careful distinctions. A strong internal critique cannot simply equate every rabbinic practice with forbidden addition, because rabbinic Judaism has a serious answer: oral explanation, authorized courts, and rabbinic fences are not claimed to rewrite the Torah. The more focused question is whether that answer succeeds in each category, especially when a rabbinic command is treated as religiously obligatory. Framed that way, the issue becomes a substantive debate about textual authority, legal transmission, and the limits of interpretation within Jewish thought.