In the eyes of Imāmī jurists, the Qur’an, Sunna, ijmāʿ (consensus), and ʿaql (intellect) are the four sources used to derive religious rulings. Intellect is a religious tool that all Imāmī scholars, except the scholars of the Akhbārī school of thought, are at one over its validity for deriving religious rulings.

The issue of intellect, its realm, and the level of its validity has been one of the preoccupations of Shīʿī scholars throughout history. They examine intellect from four important angles:

1. What is the definition of the rule of intellect?
2. Does reason have the capacity to discover religious rulings? In other words, when the intellect deduces a ruling in a definite form, can it be said that the sharīʿa also has such a view?
3. If the answer is yes, can it compel a mujtahid to issue a fatwā accordingly?
4. What are the reasons for the Akhbārī opposition to the role of intellect in revealing religious rulings?

This article aims to address these four angles in detail.

KEYWORDS: sharīʿa, induction (istiqrāʾ), analogy (tamthīl), logical deduction (qiyās-i manṭiqī), independent dictates of reason (al-mustaqilla al-ʿaqliyya), non-independent dictates of reason (ghayr al-mustaqilla al-ʿaqliyya) understanding of benefits and harms (maṣāliḥ wa mafāsid).