Hakdama Rambam 8

Therefore the types of laws that were established in the Torah, upon these principles that we have prefaced, are divided into five divisions:

The first division are explanations transmitted from the mouth of Moshe and they have a hint in Scripture and it it possible to extrapolate them by way of reasoning. And about this there is no disagreement; if one says, "So has it been transmitted to me," there is nothing to say about it.

The second division are the laws about which it is said, a 'law of Moshe from Sinai.' And there are no proofs about them as we have mentioned. Likewise here, none disagree with [such a law].

The third division are the laws that they extrapolated by the ways of reasoning and a disagreement about them occurred, as we have mentioned – and the law was decided in them according to the majority. And this happens, when the investigation is given to divergence. And because of this, they say (Yevamot 76b), "If it is a [transmitted] law, we will accept it; but if it is a law [that is deduced], there is a rebuttal."