|Early Mu`tazilite theologians in the 2nd and 3rd centuries AH, in addition to theological issues, made the subject of their intellectual scrutiny matters relating to fiqh and juristic methodology. As the first instance of a theological view on the foundations of fiqhi reasoning reference should be made to the short comment by Wasil b. `Ata who notes that in case there is no evidence from the Qur’an or a hadith that may be viewed as proof (khabarun ja’a muj’i al-hujjah) the faqih should follow the guidance of sound reason. Though the brevity of Wasil’s assertion makes it difficult to determine the intended meaning of ‘sound reason” it may safely be deduced that, considering the popular atmosphere of the period, it refers to what in fiqhi circles was termed as ijtihad al-ra’y. It appears that Wasil has intentionally sidestepped the latter phrase and offered a more rational notion in order to avoid giving legitimacy to the idea of ra’y.
Among the Mu`tazilites of the later generation mention should be made of Ibrahim Nazzam whose theory on the sources of fiqhi reasoning may be deemed as an extension of Wasil’s view. In Nazzam’s opinion these naqli (transmitted, i.e. traditional) sources include the Qur’an and the type of hadith that definitely removes any pretext (for doubt). He also believed that the rules of all matters were intellectual when viewed from an abstract point of view, unless when there existed a definite rule of the above type. As regards ijma`, which had come to gain the status of the third traditional source of fiqhi reasoning, Nazzam’s position was one of opposition. In his book of al-Nakt, Nazzam deals with the notion of ijma` and questions the commonly held belief that it is impossible for the entire ummah to reach consensus on an incorrect issue. Perhaps the most objective assessment of his view is provided by Ibn Rawandi who notes that Nazzam was of the opinion that it was possible for the ummah of the Holy Prophet (PBUH) to arrive at a wrong conclusion through their reliance on ijma` and qiyas, but such possibility did not exist when it came to reports of the actual events (tanaqqal `an al-hawass). The same view of ijma` is found among the next generation, such as in Ja`far b. Mubashshir (d. 234 AH), who was known by the Mu`tazilites as the founder of a systematic school of fiqh.
From a historical point of view it may be noted that until the middle of the 3rd/9th century the Mu`tazilites, in spite of their rationalist leaning in theology, advocated close adherence to religious texts in matters of fiqh and lashed out against the followers of ra’y and qiyas throughout their writings. The general method of the early Mu`tazilites, known as istikhraj (extraction), entailed the selective restriction of fiqhi sources to what was asserted in the Qur’an as well as in hadiths which excluded all pretext for doubt, and, in rest of the cases, set aside all other methods such as adherence to variable traditions, ijma`, ra’y and qiyas and proceed directly to the use of reason.
The second half of the 3rd century AH witnessed a fundamental transformation in the fiqhi system of the Mu`tazilites, a development that brought the main principles of their fiqhi outlook much closer to the views of other mainstream juridical schools of the day. During this period, Abu al-Hasan Khayyat, the chief Mu`tazilite leader in Baghdad, was bent on a symbolic move to reconcile the fiqhi ideas of Nazzam and Ja`far with the new positions adopted by the movement. In the school of Basra, Abi `Ali Jubba`i came to embrace the authority of ijma` and qiyas and in spite of being an independent Mu`tazilite jurist differed widely with his Shafi`ite and Hanafite counterparts over the four sources of the Qur’an, the sunnah, ijma` and qiyas. In time, the fiqhi component of the Mu`tazilite movement as an independent school of thought was disintegrated and its members came to adopt the positions of common fiqhi schools such as Hanafism or Shafi`ism.
During this period, a particular fiqhi stance is seen among the followers of the notion of irja’, which owing to their views on `adl (justice), were considered as belonging to the Mu`tazilites. Bishr Murisi was a prominent member of this group who, in addition to believing in the Qur’an and sunnah as sources of fiqhi reasoning, placed special emphasis on the authority of ijma`. Here, the fact that the notions of irja’ and the authority of ijma` should come together within a single intellectual framework is worthy of investigation, however, the historical evidence clearly point to the fact that the Murji’ite advocates of `adl were staunch defenders of the authority of ijma` and had their own particular views regarding its nature. Bishr Murisi, who may broadly be viewed as a Hanafite, like the earlier members of the school, was a firm believer in the authority of ijma`, so much so that he accorded a consensual basis to analogy. He was of the opinion that “qiyas is secondary to the asl (principle)” and considered its practice to be permissible only if the ummah gave its consensual approval. According to Ahmad b. Hanbal, Bishr Murisi along with his contemporary Mu`tazilite Abu Bakr Asamm – whose views did not, in their entirety, meet with the approval of his fellow Mu`tazilites – were two scholars who devoted the most effort to the elaboration of the theory of ijma`. Abu `Imran Muways b. `Imran, as a representative of another branch of Murji’ite Mu`tazilites, was another advocate of the authority of ijma`. His position was underpinned by the belief that with regard to religious duties there was no difference between a divine rule and one that was arrived at by the scholars of the ummah, since they would not opt for other than what was in the interest (maslahah) of the community. This view of the ijma` may be the oldest interpretation of the subject which looks at consensus not as a means of arriving at what has been previously determined but as an independent source of legislation.