—it remains only a presumptive proof.

Al-Bazdawī and a number of Ḥanafī scholars said that ijmāʿ is of different ranks: the consensus of the Companions is on the same level as the Qur’an and a mutawātir report; the consensus of later generations is analogous to the mashhūr ḥadiths; and a consensus that was preceded by disagreement in an earlier age is comparable to a solitary report. Some of them held, in every one of these cases, that ijmāʿ obliges practice but does not yield certain knowledge. The views therefore became four: (1) it produces both knowledge and the duty to act; (2) it produces neither; (3) it produces knowledge where the authorities are unanimously agreed beyond doubt; and (4) it produces knowledge only in the consensus of the Companions.

The author of al-Taqwīm objected: “A consensus may be reached on the basis of an indicator (amārah); how, then, can certain knowledge arise from an ijmāʿ that itself branches out from conjecture?” His answer was that the factor producing certainty is its link with ijmāʿ, for the community is protected from error, so its connection is as though it were linked to the Messenger of Allah ﷺ and bore his tacit approval.

As for the claim that ijmāʿ belongs to the universal principles by which we rule upon the definitive proofs—the explicit texts of the Qur’an and the mutawātir sunnah—it must itself be definitive, for it is impossible for something non-definitive to override what is definitive.

Al-Ustādh Abū Isḥāq, in his Taʿlīqa, and al-Bandanījī, in al-Dhakhīrah, transmitted two opinions as to whether the term ijmāʿ is applied to both the definitive and the presumptive, or only to what is definitive. They both stated that the dispute is merely over wording.

I say: Some of these positions originate in the theologians’ claim that a solitary report yields only conjecture. This notion—that a single ḥadith, let alone ijmāʿ, provides no more than assumption—was unknown in the time of the Companions; it arose only with the emergence of kalām. The scholars of ḥadith and tradition, who built their religion on the foundations laid by the Companions, maintain that an authenticated solitary report imparts certain knowledge and obliges action.

Conditions for a valid ijmāʿ
First: the condition related to the status of those by whom the consensus is formed, and this comprises several issues.
Issue One – The authoritative consensus within each discipline.
Al-Zarkashī says in al-Baḥr al-Muḥīṭ (6/415): “For an ijmāʿ to be valid in any of the sciences, the view of every expert in that field in that era is required; the statement of anyone else would be without evidence, for they are ignorant of it. Thus, in a juristic matter the consensus of all jurists is required, and in …”