Part I

Ijma or Consensus of Jurist's Opinions

Ijma is defined as [the] agreement of Muslim jurists in a particular age on a question of law.  Its authority as a source of law is based on certain Quranic and traditional texts. A Hadith says, 'Whatever the Muslim holds to be good is good before God.' Some of the other Ahadith are:  'My followers will never agree on what is wrong." "It is incumbent upon you to follow the most numerous body." "The (protecting) hand of God is over the entire body and no account will be taken of those who separate themselves."

Some of the Quranic verses are: "Do not be like those who separated and divided after they had received clear proofs." "What lies outside the truth is an error," "Obey God and obey the Prophet and those amongst you who have authority." "If you yourself do not know, then question those who do so." "Today We have completed your religion."

According to all the four Sunni Schools of Law, Ijma is a valid source of law and there was a unanimity of opinion on this point amongst the Companions. If any rule of law is not explicitly laid down in the Quran or Hadith, it must be capable of being deduced from them and concurrent opinion of the jurists carries valid authority and it is also infallible as, according to Islam, truth is one and all besides it is error. All the Sunni schools are unanimous [in] that only Muslim Mujtahids or jurists alone have a voice in Ijma. 

The non-Muslims are excluded from juristic deliberations, for Muslims alone have been given this authority by the Quran and the Hadith and the non-believers. who do not accept the authority of the Law-giver cannot be expected to arrive at the truth in matters of law and religion. Naturally, this authority amongst the Muslims vests only in the learned for they alone can make analogical deductions in the light of the Quranic and traditional texts. In the Quranic text "Obey God and obey the Prophet and others amongst you who are in authority," the words "those in authority" refers to the learned, for the rulers and governors may or may not be learned and fully conversant with the science of interpretation of the Quran and Hadith or the rules and methods of analogical deduction.

In order that a valid ljma may be reached, it is not necessary, according to the Hanafis and the Malikis that the number of jurists participating in the deliberation should be large. According to some, the number must not be less than three and according to others it can be even two. The ljma may be based on the text of the Quran or of Hadith or on analogy.

Juristic Deduction
Analogy

All four Sunni schools are agreed that in matters which have not been provided for by a Quranic text or Hadith nor determined by consensus of opinion, the law may be deduced from what has been provided by any of these authorit[ies] by the use of Qiyas (analogy).

The Hanafis define Qiyas as "an extension of law from the original text to which the process is applied to a particular case, by means of a common illat or effective cause, which cannot be ascertained merely by interpretation of the language of the text".' The Malikis define it as "the accords of a deduction with the original text in respect of the illat or effective cause of its laws."' The Shafi'is define it as "the accord of a known thing with a known thing by reason of the equality of the one with the other in respect of the effective cause of its laws."

Thus Qlyas is a process of deduction by which the law of a text is applied to cases which though not covered by the language, are governed by the reason of the text. As a source of law analogy is subordinate and subsidiary to the Quran the Traditions and the Ijma. It is different from interpretation which means application of a text to cases covered by its language while the function of analogy is to extend the law of the text to casts not falling within the purview of its terms: It does not amount to establishing a new rule of law. It merely helps us to discover the law and not to establish a new law. By application of analogy the law embodied in a text may be widened generally but it has no application to pure inferences of facts.

Rules of law deduced analogically do not as authority rank as high as those laid down by a text of the Quran or Hadith or Consensus of opinion. The analogical deduction, if agreed by the learned as a body, assumes a higher legal aspect. 

Authority for analogy is taken from a tradition of the Prophet. While sending Muadh to Yemen as its Governor, the Prophet asked him, "How are you going to decide cases?" Muadh replied, By the light of what is in the Book of God". The Prophet then asked, "And if you do not find anything in the Quran to guide you (in the matter)?" Muadh said, "I will decide in the way the Prophet has been doing". The Prophet next inquired , "If you do not find any precedent from me, what then?" He said, "I will do my best by exercising my judgment". The Prophet thereupon exclaimed, "Praise be to God who has so disposed the delegate of His Prophet as to be able to satisfy him." 

This Hadith gives a general authority for application of reason and experience in developing and applying the law of the Quran. The Prophet and his Companions resorted to analogy [the] for purposes of legal deduction.

There are certain limitations in making analogical deductions:

(1) The law enunciated in the text to which [the] analogy is sought to be applied must not have been intended to be confined to a particular state of affairs

(2) The law of the text must not be such that its raison d'être cannot be understood by human intelligence nor must it be in the nature of an exception to some general rule.

(3) According to the Hanafis and the Malikis ananalogical deduction can be founded on the law established either by a text of the Quran or Hadith, which has not been repealed, or by a unanimous decision of the learned and according to Shafi'is and the Hanbalis it can be based on another analogical deduction.

(4) The deduction must not be such as to involve a change in the law embodied in the text.

It is not generally permissible for a jurist to make deductions merely from the broad policy of the law. The general rule is that from what is deduced must be definite and perceptible.