The four Jurists (Imāms) who are accepted by the entire Sunnī world of Islām, are thus agreed in giving an important place in legislation to Ijtihād, and the Shī‘as attached to it an even greater importance.3 In fact, the sphere of Ijtihād is a very wide one, since it seeks to fulfil all the requirements of the Muslim community which are not met with expressly in the Holy Qur’ān and the Ḥadīth. The great jurists of Islām have endeavoured to meet these demands by various methods, technically known as qiyās (analogical reasoning), istiḥsān (equity), istiṣlāh (public good), and istidlāl (inference). Before proceeding further, a brief description of these methods may be given to show how new laws are evolved by adopting them.4
The most important of these methods, and the one which has almost a universal sanction, is qiyās5 which may be described as ‘reasoning based on analogy’. A case comes up for decision, which is not expressly provided for either in the Holy Qur’ān or in the Ḥadīth. The jurist looks for a case resembling it in the Holy Qur’ān or in Ḥadīth, and, by reasoning on the basis of analogy, arrives at a decision. Thus it is an extension of the law as met with in the Holy Qur’ān and Ḥadīth, but it is not of equal authority with them, for no jurist has ever claimed infallibility for analogical deductions, or for decisions and laws which are based on qiyās; and it is a reorganized principle of Ijtihād that the jurist may err in his judgment. Hence it is that so many differences of juristic deductions exist even among the highest authorities. From its very nature the qiyās of one generation may be rejected by a following generation.
Istiḥṣān,6 in the terminology of the jurists, means the exercise of private judgment, not on the basis of analogy but on that of public good or the interest of justice. According to the Ḥanafī school, when a deduction based on analogy is not acceptable either because it is against the
3 Ijmā‘, of which I shall speak later, and which means really the Ijtihād of many, and Ijtihād, are thus looked upon as two more sources of the Islāmic law along with the Holy Qur’ān and the Sunnah, though only the latter two regarded as al-adillat al-qaṭ‘iyya or absolute arguments or authorities, the former two being called al-adillat al-ijtihādiyya or arguments obtained by exertion.
4 Sir ‘Abd al-Raḥīm has very ably dealt with this subject in his Muḥammadan Jurisprudence where he has referred to original authorities. I am indebted to him for the material used here.
5 Literally, measuring by or comparing with, or judging by comparing with, a thing, while the jurists apply it to “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” (MJ).
6 Literally, considering a thing to be good or preferring a thing.