What is the difference between reason and revelation in Islamic thought?

One of the singular distinctions of Islam is the balance maintained between ‘aql and naql, that is, between human rational thought and revealed scripture.

Certain people admit the intellect alone to be the source of knowledge, whether in the realm of the manifest or the hidden. Others hold transmitted or revealed knowledge alone to be the font of all truths. Others yet take a position between these two, granting each of them an authoritative status. Given that we will expound on these relationships at length, it behooves us to first note some terms and delimit their scope.

Reason (‘aql)
The dictionary al-Mu’jam al-wasit, published by the Arabic Language Academy in Cairo, defines reason as what responds to the natural instincts; what enables thought and reasoning and composition and illustration and attestation; and what distinguishes the beautiful from the repulsive, good from evil, and truth from falsehood. The term is derived from the root ‘ayn qaf lam, its essential meaning being prevention. It so named because reason prevents its bearer from what does not correspond to it, unlike beasts, which act according to their appetites.

The dictionary al-Qamus al-muhit defines reason (‘aql) as knowledge, that is, of the qualities of good and ill, perfection and imperfection, the ability to recognize the best of goods and the most evil of evils, or matters in general.

A precise and clearly delimited definition of the intellect is difficult, as it is a disputed term in the lexicon of Islamic thought: the philosophers, mutakallimun, legal theorists, and others all held different conceptions. The philosophers, for just their part, offered a wide variety of sometimes contradictory opinions. Their concern was focussed on the very existence of the intellect, which is a question that cannot be understood as a matter of fact, being rather a mystery among the Divine mysteries, like the existence of the soul. Each effort to seek a clear definition of the intellect was itself affected by a broader theoretical background and method. Thus the intellect was held to be sensible, according to the mutakallimun, legal theorists, and jurists; subtle and esoteric, according to the sufis; and both, according to the philosophers. The grand debate on the conception of the intellect and its implications among Muslim thinkers included such questions as the status of the intellect, the difference between intellect, self, and soul, and the distinction between intellect and knowledge, among others.

It is evident that this definition of the intellect is active, not substantial. Hence we may say that it is the power that enables distinguishing between good and evil. The author of the Qamus offers further definitions, including that it is a spiritual light by which the self perceives the necessary and theoretical disciplines and that it has embryonic origins and develops until maturity (others say: until the age of forty).

Al-Raghib al-Asfahani defined reason in his Mufradat al-Qur’an as the power that enables knowledge.

The commentator on the Qamus observes: People differ regarding the intellect: does it have a reality? If so, is it essential or accidental? Is its locus in the head or the heart? Are intellects equal or unequal? Whether power or substance, it is the immaterial degree by which God distinguished humans from beasts. Through it, humans reckon and contemplate, internally and the world around them; understand discourse and attain knowledge; begin new things and criticize old ones; understand and relate to the past, live and develop the present, and anticipate and plan for the future; distinguish good from evil, virtuous from vicious acts, correct from mistaken positions, and true from false creeds; distinguish the better of good options and the worse of bad options; compare and contrast things and characters and thoughts; and reflect on their lives and afterlives. Or we might say, through reason humans ponder the origins and ends of existence, and our existence with it, and the prophecies we have received. In other words, reason searches out satisfactory answers to the enduring questions that humans have asked since time immemorial, namely: who am I? And where am I going? And why?

Revelation (naql)
This term can fruitfully be compared to reason. It is the knowledge that emerges from Divine revelation or a Prophetic source. This knowledge is inherited through the generations, being transmitted by one to another; it cannot be attained through empirical observation or experience or theoretical reasoning or deduction. It is passed from one to another, through solid chains of transmission, even unto its Divine revelation to the Prophet. Those who transmitted it affirmed its holy origin and embraced its incontrovertible foundations, even while they had the right to use their rational faculties in understanding, commenting upon, and explaining its derivation. There is no doubt that the greatest minds of the Umma worked in its service and sanctification, due to whose efforts we now have the various disciplines of exegesis, hadith, fiqh, sufism, theology, and theoretical sciences necessary for these such as legal theory, the principles of commentary, and hadith methodology.

This domain of revealed knowledge is sometimes synonymously known as that of “obedience”, “divine legislation”, “religion”, or “textual sources”, while the domain of the rational faculties is sometimes known synonymously as that of “wisdom” or “philosophy”. Much of these matters are encompassed in such complementary formulations as “law and wisdom” (as employed by Ibn Rushd in his Fasl al-maqal fi ma bayn al-shari‘a wal-hikma min al-ittisal) or the phrases “religion and philosophy”, “creed and thought”, and “ratiocination and obedience”. The complementary and intended meaning of each of these phrases is clear.

The Two Meanings of Revealed Knowledge (Naql) in Islamic Thought
- The general meaning, denoting simply the primary sources of Islam: the Qur’an and Prophetic practice
- The specific meaning elaborating on these sources, which is the focus of much debate in Islamic thought. Indeed, most of the polemics between the different methodologies and schools hinge on how to interpret revealed knowledge, including on the issues of the createdness of the Qur’an among the Mu‘tazilites, the gnostic elements of Sufism, the active intellect of philosophy, and the Imamate of the Shi‘is.

How to understand the Prophetic practice was more widely disputed than how to understand the Qur’an. It can be broadly delineated into the Sunni and Shi‘i approaches, for their varying methodologies and authorities in establishing and investigating even what comprises the Prophetic practice.