So a Reform correspondent and I are talking about the nature of Oral Law. Beyond our grundnorms of Divine-originated vs. human-originated Oral Law, I got into some discussion of how I have come to understand the different types of Oral Law.
S____:
> I understand that people have to interpret a document. I understand that
> specifics have to be laid down for some laws. However, how is something
> like "don't eat shellfish" need any further explanation? How is that
> "irrelevant [another commentator's characterization of our correspondent's
> argument]", You say that "oral Torah" begins at Sinai. We disagree
Well, from what I can see of the Oral Torah process, a lot of it has to do with places where we [including Our Sages in that "we", since they're the main body of people who actually worked out the derivations] know there's a rule, but it's not entirely clear how it fits with the Torah text. We know they have to be related, that's part of the definition of the system, but the exact relationship is unclear, whether through loss of tradition, or linguistic shift, or whatever.
Take the shellfish, [please].
First the Biblical passage:
9 These shall ye eat of all that are in the waters: whatsoever hath snapir and kaskeset in the waters, in the seas, and in the rivers, them shall ye eat.
10 And all that have not snapir and kaskeset in the seas, and in the rivers, of all that move in the waters, and of any living thing which is in the waters, they shall be an abomination unto you:
11 They shall be even an abomination unto you; ye shall not eat of their flesh, but ye shall have their carcases in abomination.
12 Whatsoever hath no snapir nor kaskeset in the waters, that shall be an abomination unto you.
We know, for instance, a rule, as you say, "don't eat shellfish". Our ancestors presumably knew this rule too. But there's no actual verse that says "don't eat shellfish." There is a verse that says "whatsoever hath snapir and kaskeset in the waters, in the seas, and in the rivers, them shall ye eat".
Then ensues a whole discussion on what do those two words mean. Once it's decided that it means "fins & scales", which word means which, etc., then we look at the fish, and find there are 4 kinds of scales. And that's where we get into rabbinically legislated details: Which kinds of scales are kosher (there are 4, of which 2 are kosher)? The Talmud itself says that "everything with kaskeset also has snapir", impying that they knew about the different types of scales, and only the 2 kosher varieties were called kaskeset. What about species where the scales are only present at one stage of the life cycle, but not at the stage where the fish is harvested? etc.?
But establishing the Torah's meaning in relation to known rules, this is also part of Oral Torah, and is presumed to have originated at Sinai. There's no way to prove it, of course, but rules that are universally (pre-1800) accepted, and are general rules, and are known to be based on verses, rather than explicit rabbinic legislation, are treated as if they originated at Sinai, because at that point, there's really no difference - universal ratification being equivalent in force to Divine transmission.
I've been thinking of it as a 2x2 matrix. Say, Written/Oral along one axis and Biblical/Rabbinic along the other
Written Torah is the Five Books of Moses, that's it.
Oral Torah is practically everything else, from the Prophets and Writings, down through the implications of the 4QMMT in the Dead Sea Scrolls, and the Fast Scroll (both being Hasmonean-period documents), through the Mishnah, Midrashim, Talmuds, and all their further interpretations and elaborations.
Within that, you have Biblical and Rabbinic Law. Biblical Law is rules that can be derived from verses using the 13 Hermeneutical Rules of Rabbi Ishmael (plus possibly some others). Now, we don't know which (or whether any) of those derivations are actually Sinaitic, but we assume that if they can be derived from verses, and were not otherwise legislated, they are treated AS IF they had come down from Sinai. [Yes, I know we say that certain of the rules require a Sinaitic component, but that's a different discussion, and one which is also hard to prove to someone who simply denies Divine origin to Talmudic law.] Because they're part of the interpretive system that began at Sinai.
Rules that are legislated similarly should have some tenuous connection to a verse, to demonstrate that they're within the Torah's system, and not total inventions, but there the textual derivation can be much weaker, because there's no need to prove a strong connection to the Divine.
So yes, even a simple rule like "don't eat shellfish" requires the Talmud, requires an Oral Torah, wherever that tradition is sourced, to turn it into practical law. AND to link it to the correct verse and phrases in the Written Torah to demonstrate the rule's Biblical nature.
The Rambam (Maimonides) further breaks down the Oral Law into different degrees of relatedness to the posited Divine origin, but that's another post.