Scholarly Consensus (Ijma'): Theory and Scope

Ijma', the scholarly consensus of the Muslim community, occupies a distinctive position in the hierarchy of Islamic legal sources. Unlike the Quran and Sunnah, which are direct divine communications, and unlike qiyas, which is a human inferential process, ijma' derives its authority from prophetic traditions guaranteeing that the Muslim community collectively cannot err in matters of religion. Al-Razi addresses this source with characteristic thoroughness in the Mahsul, examining both the theoretical basis for ijma's authority and the practical conditions that must be met for a claimed consensus to be genuinely binding. His treatment is among the most philosophically sophisticated in the classical usul literature, engaging with the difficult questions of who counts as a qualified participant in consensus formation and what counts as genuine agreement versus mere silence or acquiescence.

The definition of whose agreement constitutes binding ijma' was a matter of substantial disagreement among classical scholars. The most common position, and the one al-Razi defends, holds that binding consensus must include all qualified legal scholars (mujtahidun) of a given age. A second position, associated with Ahmad ibn Hanbal and some of his followers, restricted binding consensus to the agreement of the Companions of the Prophet specifically, given their unique closeness to the sources of revelation. A third position, associated with some Maliki scholars, gave special weight to the consensus of the scholars of Medina on the grounds that they inherited and preserved the continuous practice of the Prophet's city. Al-Razi systematically examines the textual evidence for each position, ultimately defending the broader formulation while acknowledging the special evidential weight of Companion agreement.

One of the most theoretically challenging issues in ijma' theory concerns how consensus can ever be established in practice. How can one verify that every qualified scholar in the Muslim world at a given time agrees on a point? Al-Razi discusses the mechanisms by which consensus is recognized: explicit agreement expressed in writing or speech, tacit agreement indicated by the absence of objection when a ruling is publicly proposed, and transmitted consensus reported by later scholars who had access to the complete picture of their predecessors' views. He acknowledges the practical difficulty of achieving verified consensus on contested questions, which is why most claimed instances of ijma' in the classical literature concern either foundational matters (the obligatory nature of the five prayers, the prohibition of intoxicants) or questions that had simply never generated serious scholarly disagreement.

Al-Razi gives careful attention to the relationship between ijma' and qiyas. Some scholars argued that ijma' and qiyas operate as complementary sources: when direct textual evidence is unavailable, the jurist first attempts analogical reasoning, and if the resulting ruling is then accepted without dissent by all qualified scholars, it acquires the additional authority of consensus. Al-Razi examines whether a consensus based on qiyas carries the same absolute authority as a consensus based on Quranic or Sunnah evidence, ultimately arguing that the authority of ijma' is independent of its evidential basis: once genuine consensus is established, the ruling is binding regardless of whether its original foundation was textual or analogical. This position reflects the Mahsul's broader commitment to treating the formal properties of legal sources, rather than merely their content, as the key to establishing the strength and permanence of legal rulings.