Ijma and Its Authority

The doctrine of ijma' — scholarly consensus — is among the most theologically significant and practically contested concepts in Islamic legal theory. Abu Zahrah's treatment is characteristically thorough, addressing the theological foundation of ijma's authority, the conditions for its valid establishment, its types, and the significant scholarly differences about its scope and bindingness that have persisted throughout Islamic intellectual history.

The theological foundation of ijma' is the hadith: 'My ummah will not unite upon an error' — and similar narrations. If the Prophet guaranteed the collective inerrancy of the Muslim scholarly community on points of agreement, then a ruling on which all qualified scholars have agreed is protected from error by prophetic promise. This gives ijma' a binding authority that, in the classical theory, places it beyond legitimate challenge once established. The Quran also grounds this concept: 'And whoever opposes the Messenger after guidance has been made clear to him, and follows a path other than that of the believers — We will give him what he has chosen and drive him into Hellfire.' The 'path of the believers' (sabil al-mu'minin) is interpreted by many scholars as including the consensus of the scholarly community.

The conditions for valid ijma' require: the qualified scholars (mujtahids) of a particular era must agree on a ruling; this agreement must encompass all qualified scholars without a single dissenter; the agreement must be on a matter of Islamic law (not a factual or empirical question); and the agreement must be explicitly expressed or clearly implied from the absence of recorded disagreement after the question was publicly deliberated. These conditions are demanding, and Abu Zahrah acknowledges that genuinely established ijma' meeting all conditions is limited to a relatively small number of core Islamic rulings — the obligation of the five prayers, the permissibility of certain foods, the obligation of zakah, and similar foundational matters.

Abu Zahrah examines the important distinction between 'ijma' of the companions' and subsequent ijma'. The companions' consensus carries the most weight, given their unique position as direct witnesses of the prophetic era. Their agreements on legal questions — compiled in works on sahabah opinions — are treated by many scholars as particularly strong evidence, sometimes approaching the force of mutawatir Sunnah.

The concept of 'sukuti ijma'' (silent or tacit consensus) — where a ruling was expressed by some scholars and no other scholars of the era explicitly disagreed — is accepted as a weaker form of ijma' by some schools and rejected by others. The Hanbali school is particularly cautious about accepting this form, preferring to treat it as strong scholarly opinion rather than binding consensus. Abu Zahrah's balanced presentation of these scholarly differences provides the reader with a realistic picture of how ijma' operates in practice — less frequently as a formal constraint than as an indicator of the strength of scholarly agreement on core issues.