We have previously discussed the purpose of an Oral Torah and some arguments in favor of the reliability of the Oral Torah. Before we turn to understanding the philosophy of the Oral Torah, I will now briefly deliniate it's categories.
Halakha l'Moshe m'Sinai
Halakha l’Moshe M’Sinai are laws or explanations of laws which, as the name suggests, were given to Moshe and are only known through tradition; as the Rambam in Hakdma l'Peirush ha'Mishnayot makes clear there is no source for Halakhot l'Moshe m'Sinai in the Written Torah. However, the Megillat Esther on Sefer Ha’Mitzvot, shoresh aleph (see Encyclopedia Talmudit pg. 366), distinguishes between a “remez galuy” [a clear hint in a verse] and a “remez b’nistar” [a masked hint in a verse]. A Halakha l’Moshe M’Sinai can have the latter. It may be possible to bring a remez from Nakh for a Halakha l’Moshe M’Sinai (see Moed Katan 5a). Sometimes the Talmud will give an asmachta – a supporting verse – for a Halakha l’Moshe M’Sinai. This asmachta can also come from Nakh.
The Maharatz Chayes (Mevo l'Talmud) points out that a Halakha l’Moshe m’Sinai can either provide the details for laws found in the Torah or be the sole source for a law (for example, Sukkah 44b, Sanhedrin 81b or Nazir 4:6).
The Rambam counts about thirty-three instances of Halakhot l’Moshe M’Sinai. Interestingly, Chanoch Albeck writes that there are only three times in the Mishna that it appears – Peah 2:6; Edeyot 8:7; and Yadayim 4:3. Sometimes, however, the Talmud uses the term Halakha l’Moshe M’Sinai imprecisely; it applies this term to certain rabbinic laws. The Rash in Yadayim 4:3 explains that it means Halakha K’Moshe M’Sinai, it is as clear as if given at Sinai (see Tos, Yom Tov in Yoma perek bet, siman yud bet; the Rash, Rosh, Bartenura, Turei Even in Chagiga 3:2; Pesachim 110b; Rosh at the end of Nidda; the R”I in Hikhot Mikvaot, siman aleph). R. Soloveitchik (Shiurim l’zecher Abba Mori, Mesorah) interprets Halakha l’Moshe M’Sinai, presumably only in these cases, to mean that the halakha was received without any reason given, just like a real Halakha l’Moshe M’Sinai.
The Talmud states in many places that certain Halakhot l’Moshe M’Sinai were forgotten and later reconstituted (usually by the prophets). There is an opinion that these halakhot in their reconstituted state lost their status as a Halakha l’Moshe M’Sinai (Marahap, Shabbat 1:4).
A point of considerable controversy is the Rambam's statement (Hakdama l’Peirush ha'Mishnayot) that Halakhot l'Moshe m'Sinai are not subject to disagreement. See Encyclopedia Talmudit, pg. 370 for a list of Rishonim/Achronim who seem to hold like this. This opinion is difficult for the following reasons:
A) The Ramban on Sefer haMitzvot (shoresh aleph), and Chavot Yair point out that there are many instances where there is disagreement regarding a Halakha l’Moshe M’Sinai (For example, see Temurah 15a-16a). In fact, the Chavot Yair lists eight instances of disagreement out of the Rambam’s own list of thirty-three! Furthermore, he lists fifty Halakhot l’Moshe m’Sinai that the Rambam did not list which are subject to disagreement. In fact, the Rambam himself mentions a Halakha l’Moshe m’Sinai that was forgotten due to the “many years that passed and many exiles” – the instructions for correctly sounding the Shofar (Hilkhot Shofar 3:2; also see the Ran on Rosh Hashana 34a).
B) The aggadita discusses the pervasiveness of forgetfulness (even by Moshe himself!). It is likely that forgetfulness is inherent in the transmission of an oral tradition, especially under oppression and exile.
C) R. Zvi Lampel (Dynamics of Dispute) points it this way: the origin of a law does not affect its remembrance. Why should telling the people that a certain law had been explicated by Hashem and is without any supporting verse in the Torah make them less liable to forget it than had the law come through a hermenutical principle? Furthermore he asks “Is it reasonable to construct a scenario…that even though a law is remembered, its origin could have become obscure, none knowing for certain if it had originated as a law told to Moshe at Sinai, or as a rabbinical law, or as the result of a drash?” The Dor Revi”i (Hakdma l'Chullin) asks a similar question: Just because we haven’t found dissenting opinions in regard to a Halakha l’Moshe M’Sinai that does not mean that there were never any dissenting opinions!
A common approach in defending the Rambam is to state that that Rambam holds that there can be arguments over minute details of a Halakha l’Moshe M’Sinai but there will never be a case where one says “permissible” and the other says “forbidden.” There is no disagreement about matters of fundamental importance. See Aurch ha’Schulkhan on Hilkhot Mamrim, 64. R. Zvi Lampel argues that this answer is too vague for what constitutes a major or minor issue?
Maharatz Chayos (Torat HaNevi’im, as developed by R. Zvi Lampel) defends the Rambam by reversing our understanding of what the Rambam said. He did not mean that the “Sinaitic laws remained extant and clear because they were basic, but the reverse: Simply that those Sinaitic teachings that happened to remain extant, precisely because they were known to be extant Sinaitic teachings, stood as the uncontested prime material to be subject only to analysis and analytical debate and not challenge.” When the Rambam says “eyn bo makhloket” he means that no Sage contested any laws that were known to have originated with Moshe, not that there are
no Sages who disagreed about such laws. The Rambam in Peirush ha’Mishnayot (Edeyot 8:7) seems to say this excplicitly. The Rambam was reacting to the Karaite challenge that the existence of disagreement demonstrates that there is no Oral Law transmitted from Sinai. The Rambam responded that indeed there is disagreement, even about Halakhot l’Moshe m’Sinai but all agree that it is a Halakha l’Moshe m’Sinai!