The Principle of Ijtihad in Islam
Ayatullah Murtadha Mutahhari
What is Ijtehad
It is not for the believers to go forth all together; but why should not a party of every section of them go forth, to become learned in religion, and to warn their people when they return to them, that they may beware. (9:122) 
The question of ijtihad is a very topical one these days. Many people ask, either aloud or to themselves, what form ijtihad takes in Islam, and from where Islam got the concept. Why should one practice taqlid? What are the conditions for ijtihad? What are the duties of a mujtahid?
Broadly speaking, ijtihad has the meaning of being an authority in the matters of Islam; but there are two ways of being an authority and deriving opinions in the matters of Islam in the eyes of us Shi`i Muslims: one which is in accordance with the shari`a, and one which is forbidden by it. Similarly, taqlid is of two kinds: one which is in accordance with the shari`a, and one which is forbidden.
The kind of ijtihad which is forbidden by the shari’a.
Now, the kind of ijtihad which, in our opinion, is forbidden is that which means “legislating” or “enacting the law”, by which we mean that the mujtahid passes a judgement which is not in the Book (the Qur’an) or the Sunna, according to his own thought and his own opinion – this is technically called ijtihad alra’y. According to Shi`i Islam, this kind of ijtihad is forbidden, but in Sunni Islam it is permitted. In the latter the sources of legislation, and the valid proofs for determining the shar`ia, are given as the Book, the Sunna and ijtihad. The Sunnis place ijtihad, which is the ijtihad alra’y explained above, on the same level as the Book and the Sunna.
This difference takes its origin in the fact that Sunni Muslims say that the commands which are given in the shari`a from the Book and the Sunna are limited and finite, whereas circumstances and events which occur are not, so another source in addition to the Book and the Sunna must be appointed for the legislation of Divine commands – and that source is the very same as we have defined as ijtihad alra’y. Concerning this matter, they have also narrated hadiths from the Prophet, and one of them is that when the Prophet sent Mu`adh b. Jabal to the Yemen, he asked him how he would issue commands there. He replied: “In conformity with the Book.” “And if it is not to be found in the book?” “I will make use of the Sunna of the Prophet.” “And if it is not to be found in the Sunna of the Prophet?” “Ajtahidu ra’ yi, ” he replied, which means: I will employ my own thought, ability and tact. They also narrate other hadiths in connection with this matter.
There is a difference of view among Sunni Muslims as to what ijtihad al-ra’y is, and as to how it is to be conceived. In his famous book, the “Risala”  which was the first book to be written on the principles of Islamic jurisprudence (usul alfiqh), (…) alShafi`i insists that the only valid ijtihad according to hadith is qiyas [reasoning by analogy]. Qiyas, briefly, is the taking into account of similar cases, and ruling in a case from one’s own opinion by comparing it with these other similar cases.
But some other Sunni fuqaha [experts in fiqh, sing.: faqih] did not recognize ijtihad alra’y as being exclusively qiyas; they also counted istihsan [“finding the good” by one’s own deliberations] as valid. Istihsan means to see, quite independently, without taking similar cases into account, what is nearest to the truth and to justice, and to give one’s opinion according as one’s inclination and intellect approve. Similarly with istislah [determining what is in the interests of human welfare by one’s own deliberationsl, which means the seeming of one thing as more expedient than another, and ta`awwul in which, although a ruling may have been reached in one of the nusus [the textual bases for a precept of the shari`a sing.: nass], in a verse from the Qur’an or in a hadith from the Prophet, one still has the right, for some reason, to dispense with the contents of the nass and to give priority to one’s own independent opinion (ijtihad alra’y). Each of these requires explanation and a detailed account, and the Shi`iSunni debate is relevant to such an account. Many books have been written both for and against this idea, viz., that ijtihad is on a par with textual evidence, and the best of them is the treatise written recently by the late `Allama, the Sayyid Sharaf alDin, called “alNass wa lIjtihad”.
Now, according to Shi`i Muslims, such a kind of ijtihad is not permitted by the shari`a. In the view of Shi`i Muslims and their Imams, the first basic principle of this matter, i.e., that the rulings of the Book and the Sunna are not adequate and that it is therefore necessary to practice ijtihad alra’y, is not correct. There are many hadiths relevant to this discussion, and, in general, [they tell us that] there exist rulings for every eventuality in the Book and the Sunna. In “alKafi” , after the chapter on bid`a [innovation] and maqa’is [measurements], there is a chapter with the title: “Chapter on referring to the Book and the Sunna – and there is no halal [permitted thing] or haram [forbidden thing] or anything which the people need which does not come in the Book or the Sunna.” The Imams of the ahl albayt have been known since the earliest days as opponents of qiyas and ra’y.
Of course, the acceptance or nonacceptance of qiyas and ijtihad alra’ y can be studied from two angles. Firstly, from the aspect from which I have looked at it; that is to say, we count qiyas and ijtihad alra’y as one of the sources of Islamic legislation, and place it alongside the Book and the Sunna, and say that there are cases which have not been ruled upon by revelation and which mujtahids must explain using their own opinion. Or alternatively, [we can study it] from the aspect that ( . . . ) qiyas and ijtihad al-ra’y [arel a means for deriving the real rulings, just as we use the other ways and means such as khabar alwahid. In other words, it is possible to perceive qiyas as either a substantive (mawdu`iya) [element in law], or a methodological (tariqiya) [principle].
In Shi`i fiqh, qiyas and ra’y are invalid in both of the above senses. In the first sense, the reason is that we have no ruling which is not given in the Book and the Sunna; and in the second case, the reason is that qiyas and ra’y are kinds of surmise and conjecture which lead to many errors. The fundamental opposition of Shi`i and Sunni legists in the matter of qiyas is in the first sense, although the second aspect has become more famous among the scholars of usul (the principles and methodology of fiqh).
The right of ijtihad did not last for long among the Sunnis. Perhaps the cause of this was the difficulty which occurred in practice: for if such a right were to continue [for any great length of time], especially if ta`awwul and the precedence of something over the texts were to be permitted, and everyone were permitted to change or interpret according to his own opinion, nothing would remain of the way of Islam (din alislam). Perhaps it is for this reason that the right of independent ijtihad was gradually withdrawn, and the view of the Sunni `ulama became that they instructed people to practice taqlid of only the four mujtahids, the four famous Imams – Abu Hanifa [d.150/767], alShafi`i; [d.204/820], Malik b. Anas [d.179/795] and Ahmad b. Hanbal [d.241/855] – and forbade people to follow anyone apart from these four persons. This measure was first taken in Egypt in the seventh hijri century, and then taken up in the rest of the lands of Islam.
9. The translation of Qur’anic verses and hadiths has been made in accordance with the author’s own Persian translation except where this is more an interpretation than a translation, in which case a more literal English translation is given
10. This address was given on 1 Urdibihisht 1340 Sh. (21 April 1961), three weeks after the death of Ayatullah Burujirdi.
11. (Cairo, 1940) The main work in jurisprudence by Abu `Abdillah Muhammad b. Idris al-Shafi`i (150/767 ¬ 204/820), the founder of the Shafi`iya legal school. He laid the foundations for the systematic treatment of qiyas.
12. The Sayyid `Abd al¬Husayn al¬Musawi Sharaf al¬Din (1290/1873¬4¬ 1377/1957¬8), born in Kazimayn, educated in Najaf, but subsequently resident mostly in the Lebanon. He is popularly famous for his ”al¬Muraja`at” (Sayda, 1355/1936¬7; frequently reprinted), which contains his detailed correspondence with the Egyptian scholar Salim al¬Bishri in defense of Shi`ism. His “Al¬Nass was l¬Ijtihad” was published in Najaf in 1375/1955¬6, and has also been reprinted several times. He is also the author of “Abu Hurayra” (Sayda, n.d.), a book about the controversial narrator of hadith.
13. “Al¬Kafi fi `Ilm al¬Din”, (ed `A. A. Ghaffari, 8 vols., Tehran, 1377¬9) the first and largest of the Shi`i collections of hadith, compiled by Muhammad b. Ya`qub b. Ishaq al¬Razi al-Kulayni (d. 328/939). It contains over 16,000 traditions from the Prophet and the Imams covering all aspects of the usul (the ‘roots’, mainly theological) and the furu` (the ‘branches’, mainly preceptual) of the religion.
14. The khabar al¬wahid is that kind of tradition which has not reached the status of tawatur, i.e., has not been narrated by so many traditionalists that there is no doubt about its validity. Under certain conditions, such traditions are admissible as proof (hujja) in the derivation of precepts.