Evidence and the Permissibility of Ijtihad upon what is decisive

Firstly, it should be known that the evidences found in the Qur’an and Sunnah is divided into four categories:

1) Evidence which is decisive (Qat’i) both in respect of authenticity (of its transmission) and meaning,

2) Evidence which is decisive in authenticity of transmission but speculative in meaning,

3) That which is of probabilistic/speculative in authenticity (Zanni), but definite and decisive in meaning,

4) Evidence which is probabilistic/speculative, both in authenticity of transmission and meaning.

One must also remember here that all the evidences in the Qur’an are decisive in authenticity of transmission, yet not all are decisive in meaning. The evidences in the Sunnah can be from all four categories.

Ijtihad does not apply to the first of the abovementioned four categories, such as the clear texts concerning the prescribed penalties (Hudud).

However, Ijtihad is valid and permissible for those qualified to exercise it, in regard to any of the remaining three types of evidences.

This shows that if there is an evidence in the Qur’an (which is obviously decisive in authenticity of transmission), but the meaning of the verse is probabilistic in what it indicates (according to the standards of the science of legal methodology (usul al-fiqh)), then Ijtihad is valid.

Example of this is the text in Surah al-Baqara, where Allah Most High says:

“The divorced woman must observe three ‘Quru’ upon herself (for the waiting period).” (2:228)

There is no doubt concerning the authenticity (in transmission) of this text as every verse of the Qur’an is decisive in its establishment. However, the precise meaning of the word ‘Quru’ is open to interpretative difference.

Imam Abu Hanifa and Imam Ahmad ibn Hanbal (Allah have mercy on them both) are of the view that the meaning is ‘menstruation’, while Imam Shafi’i and Imam Malik (Allah have mercy on them both) regard the meaning as ‘Tuhr’ (Period of being clean between menstrual periods).

Therefore, Ijtihad can be carried out on matters such as these. However it can not be exercised on matters such as the obligatory status of the pillars of Islam or the prohibition of murder, theft and adultery, etc…, for those are established through explicit and decisive primary texts.

This has (more or less) been mentioned in most of the books written on the principles of Islamic Jurisprudence, (see: al-Mustasfa of Abu Hamid al-Ghazali, al-Wusul by Imam al-Tumurtashi, Usul al-Fiqh by Shaykh Abu Zahra and others).

And Allah Knows Best