A Claim About Authority, Made as a Chain

The doctrine is stated as a genealogy. A tractate of the Mishnah opens by tracing the transmission of Torah from Moses at Sinai to Joshua, from Joshua to the elders, from the elders to the prophets, and from the prophets to the men of the great assembly, and then names the pairs of teachers who carried it down to the rabbis of the text's own day. The point of the list is not historical record but authorisation: it places the rabbis inside an unbroken succession and makes their rulings continuous with revelation. That is what the concept is for. Without it, rabbinic law is later human legislation about a written text; with it, the legislation is itself part of what was given. The distinction decides whether an interpretation can bind. The tradition was also aware of the paradox in its own name. Rabbinic sources discuss a prohibition on committing the oral Torah to writing, and yet the Mishnah, the two Talmuds and the midrashic collections are precisely that oral Torah written down.

Later authorities explain the outcome as a necessary concession to dispersion, persecution and failing memory rather than as a change in the material's nature, and the category survived the writing intact. That survival is informative in itself: the word oral was never really describing the medium, it was naming where the authority came from.