some of which are invalidated by revealed texts, while others are among those whose invalidity the early generations unanimously agreed upon (1). Yet the invalidity of much analogical reasoning does not entail the invalidity of all of it, just as the presence of falsehood in many hadith reports does not mean that all hadith reports are false.

Analogical reasoning hinges on the two cases being equivalent with respect to the grounds that necessitate and warrant the ruling (2). Whenever this is so, the analogy is undoubtedly sound. An analogist may, however, mistakenly suppose that something upon which the ruling does not turn is in fact the basis upon which it turns. Accordingly, for those who employ analogy, its soundness principally depends on demonstrating the legal efficacy of the shared attribute. They call this “answering the demand for proof.” The objection takes the following form:

“We do not concede that the effective cause of the ruling in the original case is the attribute shared by the original and subsidiary cases, such that the subsidiary case may be assimilated to the original. An analogy is not established as sound unless the two cases share (3) a common factor that entails (4) the ruling, whether that factor is the effective cause itself or evidence of the effective cause. This is established sometimes by identifying the common factor and sometimes by eliminating any material distinction. Once it is known that no legally consequential distinction exists between the two cases, it is known that they are equivalent (5) in their ruling, even if the precise common factor is not known.”

They uphold direct analogy, which assigns the subsidiary case the same ruling as the original because they share the basis upon which the ruling turns.

(* They also uphold inverse analogy, which denies that the ruling of the original case applies to the subsidiary because the bases upon which their respective rulings turn are different. *)

(6) This (7) distinguishes between them, because the effective cause establishing the ruling in the original case