The third foundation of Islam. It literally means “collecting,” or “assembling,” and in Muslim divinity it expresses the unanimous consent of the Mujtahidun (learned doctors); or, as we should call it, “the unanimous consent of the Fathers.” A Mujtabid is a Muslim divine of the highest degree of learning, a title usually conferred by Muslim rulers. [MUJTAHID.] There are three foundations of Ijma': (1) Ittifaq-i-Qauli, unanimous consent expressed on declaration of opinion; (2) Ittifaq-i-Fi’li expressed in unanimity of practice; (3) Ittifaq-i-Sakula, when the majority of the Mujtahidun signified their tacit assent to the opinion or the minority by “silence” or non-interference.
The Mujtahidun capable of making Ijma’ must be “men of learning and piety, not heretics or fools, but men of judgment.”
There is great diversity of opinion as to up to what period in the history of Islam Ijma’ can be accepted. Some doctors assert that only the Ijma’ of the Mujtahidun who were Ashab (companions); others, that of those who were not only “companions” but “descendants” of the “Prophet”, can be accepted: whilst others accept the Ijma’ of the Ansars (helpers), and of the Muhajirun (fugitives), who were dwellers in al-Madinah with Muhammad. The majority of learned Muslim divines, however, appear to think that Ijma’ may be collected in every age, although they admit that, owing to the numerous divisions which have arisen amongst Muslims, it has not been possible since the days of the Taba’u t-Tabisin (i.e. the followers of the followers of the Companions).
The following is considered to be the relative value of Ijma’ : –
That of the Ashab (companions) is equal to Hadis Mutawatir. That which was decided afterwards, but in accordance with the unanimous opinion of the Ashab, is equal to Hadi-i-Khabar-i-Mashhur, and that upon which there was diversity of opinion amongst the Ashab, but has since been decided by the later Mujtahidun is equal to Hadis-i-Khabar-i-Wahid. (See Syud Ahmad Khan’s Essay.)
Some European writers confuse the term Ijma’ with Ijtihad is the deduction made by a single Muhrahid, whilst Ijam’ is the collective opinion of a council of Mujtahidun, or enlightened doctors.
Amongst the Shi’ahs, there are still Mujtahidun whose Ijma’ is accepted, but the Sunnis have four orthodox schools of interpretation, named after their respective founders – Hanafi, Shafa’i, Malaki, and Hambali. The Wahhabis for the most part reject Ijma’ collected after the death of “the Companions.”
It will be easily understood what a fruitful source of religious dissension and sectarian strife this third foundation of the rule of faith is. Divided as the Christian Church is by its numerous sects, it will compare favorably with Muslimism even in this respect. Muhammad it is related, prophesied that, as the Jewish Church had been divided into seventy-one sects! And the Christians into seventy-two! So his followers would be divided into seventy-three sects! But every Muslim historian is obliged to admit that they have far exceeded the limits of Muhammad’s prophecy; for according to ‘Abdu ‘l-Qadir al-Jilani, there are at least 150.
Based on Hughes, Dictionary of Islam