In the debate between al-Ghazālī and Ibn Rushd concerning the limits of demonstration: was al-Ghazālī's position fideistic in the sense of modern fideism, or did it have its own logic within the kalām framework?

This question touches upon one of the deepest debates in the history of Islamic thought, whose echoes still reverberate in contemporary discussions about the relationship between reason and revelation. The traditional Orientalist reading—from Renan to De Boer—portrayed al-Ghazālī as the "destroyer of philosophy" and "pioneer of irrationalism," while Ibn Rushd was the "champion of rationalism." However, contemporary studies (Griffel, Marmura, al-Jabiri, Taha Abdel Rahman) reveal a much deeper complexity.

Inadequate Responses to Be Avoided

From some defenders of al-Ghazālī:

"Al-Ghazālī never opposed reason; he only opposed the philosophers." This is an inadequate simplification. Al-Ghazālī had a deep epistemological critique of the limits of rational demonstration in metaphysics, and this goes beyond merely criticizing the persons of the philosophers. The issue is methodological, not personal.

"Al-Ghazālī's position is entirely rational; he used logic against the philosophers." A half-truth. It is true that al-Ghazālī used Aristotelian logic skillfully, but he used it to demonstrate the limits of demonstrative reason in attaining certainty in divine matters. There is a difference between using reason and believing in its absolute sufficiency.

"Al-Ghazālī was a Sufi, and Sufism transcends rational argumentation." A reductionist view. The Sufi al-Ghazālī does not cancel out the theologian and legal theorist al-Ghazālī. His mystical experience influenced his epistemological outlook, but it did not eliminate his commitment to the Ashʿarite theological method.

From some defenders of Ibn Rushd:

"Ibn Rushd saved rationalism from al-Ghazālī's irrationalist attack." An outdated Orientalist reading. Ibn Rushd himself did not see al-Ghazālī as an enemy of reason, but as a theologian with a different method of dealing with demonstration. The disagreement is methodological, not about the value of reason.

"Ibn Rushd proved that philosophy and sharīʿa are in complete agreement." An exaggeration. Ibn Rushd acknowledges the existence of different levels of understanding (demonstrative, dialectical, rhetorical) and that harmony requires careful interpretation. The matter is not as simple as it is portrayed.

"If Ibn Rushd had triumphed, the Islamic world would have been more advanced." Counterfactual history that cannot be proven. Ibn Rushd's greatest impact was in Latin Europe, and the historical factors of progress and decline are more complex than the mere victory of a philosophical school.

Why These Responses Are Inadequate

They share a failure to understand the epistemological framework within which both al-Ghazālī and Ibn Rushd operated. Both worked within an epistemological paradigm different from modern paradigms, and projecting modern concepts such as "rationalism" and "fideism" distorts our understanding of their positions.

Al-Ghazālī's Position: Between Kalām and Philosophy

Al-Ghazālī in "Tahāfut al-Falāsifa" was not attacking reason, but was attacking the philosophers' claim to achieve demonstrative certainty in twenty metaphysical issues, including the eternity of the world, God's knowledge of particulars, and the denial of bodily resurrection. His basic argument: rational demonstration requires certain premises, and in metaphysics we do not possess such premises.

In "al-Munqidh min al-Ḍalāl," al-Ghazālī clarifies his epistemological journey: he began with methodical doubt (five centuries before Descartes), went through a deep epistemological crisis in which he doubted even sensory perceptions and primary rational principles, then found certainty not in rational demonstration alone, but in "a light that God casts into the heart." This is not a rejection of reason, but a recognition of its limits.

His position on logic reveals the complexity of his stance: in "Miʿyār al-ʿIlm" and "Miḥakk al-Naẓar" he defends Aristotelian logic as a tool, even integrating it into legal theory in "al-Mustaṣfā." However, he distinguishes between logic as a formal tool and demonstration as a path to metaphysical certainty.

The Special Logic of al-Ghazālī's Theological Position

Al-Ghazālī operates within the Ashʿarite framework, which has its own logic:

First, Ashʿarite epistemology distinguishes between necessary knowledge (which requires no investigation) and theoretical knowledge (acquired through reasoning). In divine matters, rational investigation is obligatory but insufficient to reach all truths.

Second, the Ashʿarite concept of causation (which al-Ghazālī defended in issue 17 of the Tahāfut) denies inherent necessity in natural causation. This is not a denial of reason, but a refoundation of rationality on a different basis: God is the true agent, and natural causes are habits, not necessities.

Third, the distinction between demonstration and persuasion. Al-Ghazālī does not deny the value of demonstration in mathematics and logic, but he denies the possibility of achieving the same level of certainty in metaphysics.

Ibn Rushd's Position: Defending Demonstration

Ibn Rushd in "Tahāfut al-Tahāfut" does not merely defend the philosophers, but defends the possibility of demonstrative knowledge in philosophy. His central argument: al-Ghazālī confuses different levels of discourse (demonstrative, dialectical, rhetorical). What is valid in dialectical discourse for the masses is not valid in philosophical demonstration for the elite.

In "Faṣl al-Maqāl," Ibn Rushd establishes the harmony between wisdom and sharīʿa: truth does not contradict truth but agrees with it and testifies to it. If contradiction appears, the solution lies in demonstrative interpretation of the text.

However, Ibn Rushd is not "rationalist" in the modern sense. He operates within an Aristotelian-Islamic framework that sees human reason as connecting with the Active Intellect, and that true knowledge comes from this connection.

The Difference from Modern Fideism

Modern fideism—from Tertullian ("I believe because it is absurd") to Kierkegaard ("the leap of faith")—is based on radical opposition between reason and faith, choosing faith against reason.

Al-Ghazālī's position is radically different:

First, he does not see absolute opposition between reason and revelation. For him, reason is light, and sharīʿa is light, and "light upon light" as he says in "Mishkāt al-Anwār." The problem lies in claiming to be satisfied with one without the other.

Second, reason is necessary for understanding revelation. In "al-Iqtiṣād fī al-Iʿtiqād" he affirms that reason is the basis of moral obligation, and without it faith is invalid. This is the opposite of fideism, which demands faith despite reason or against it.

Third, mystical experience for him is not against reason but above it. Intuitive knowledge (maʿrifa dhawqiyya) complements rational knowledge and does not cancel it, just as sight perceives what hearing does not perceive without contradicting it.

The Debate in Contemporary Context

The al-Ghazālī-Ibn Rushd debate echoes in contemporary discussions:

In the Islamic world, some see in al-Ghazālī a model for transcending rational modernity (Taha Abdel Rahman in "Tajdīd al-Manhaj"), while others see in Ibn Rushd a model for reconciling tradition and modernity (al-Jabiri in "Naḥnu wa-l-Turāth").

In contemporary Western philosophy, al-Ghazālī's critique of causation is compared to Hume, and his position on the limits of reason to Kant. Some contemporary philosophers of religion (Plantinga, for example) develop positions resembling al-Ghazālī's in criticizing atheistic reason's claims.

Evaluation from the Perspective of Rational Preponderance

From the angle of rational preponderance (rajḥān ʿaqlī) adopted by this site:

Al-Ghazālī was correct in criticizing the claim of demonstrative certainty in metaphysics. His skeptical arguments remain strong, and contemporary philosophy (especially after Kant) tends toward recognizing the limits of theoretical reason.

Ibn Rushd was correct in defending the value of philosophical inquiry and the necessity of harmonizing wisdom and sharīʿa. Complete rejection of philosophy impoverishes religious thought.

The optimal position perhaps combines al-Ghazālī's epistemological caution with Ibn Rushd's philosophical ambition: using reason to its utmost limits while recognizing these limits, and remaining open to other epistemological sources (revelation, spiritual experience) without falling into irrationalism.

Where We Stand in This Debate Today

The al-Ghazālī-Ibn Rushd debate is no longer confined to the history of Islamic philosophy but has become present in multiple research fields between 2020 and 2026. Griffel's later studies (2021-2023) reframed al-Ghazālī as a philosopher practicing philosophy with its own tools rather than merely an external critic of it, weakening the long-standing "al-Ghazālī against philosophy" dichotomy. Conversely, the works of Catarina Belo and Richard Taylor broadened understanding of Ibn Rushd as a thinker more complex than the "pure rationalist," revealing theological and spiritual dimensions in his project.

In the contemporary Arab context, ideological exploitation of the debate continues: currents raising al-Ghazālī as a symbol of authenticity opposing Westernization, and others raising Ibn Rushd as a symbol of enlightenment. However, serious research—such as that of Abu Yaʿrub al-Marzuqi and others—transcends this polarization toward an integrative reading benefiting from both positions.

The philosophically sound position today: the debate is not settled in favor of one side. Al-Ghazālī provided an epistemological critique of demonstrative claims in metaphysics that remains valid after Kant and Wittgenstein, and Ibn Rushd provided a defense of the necessity of systematic rational inquiry that remains indispensable. Real progress lies not in choosing one of them but in building an epistemological framework that accommodates the caution of the first and the ambition of the second—and this is precisely what the method of cumulative rational preponderance seeks: no absolute certainty in metaphysics, but no resignation from reason either, rather cumulative preponderance from multiple evidence.

For Reading

- Al-Ghazālī, Tahāfut al-Falāsifa (ed. Sulaymān Dunyā)
- Al-Ghazālī, al-Munqidh min al-Ḍalāl (ed. Jamīl Ṣalībā and Kāmil ʿAyyād)
- Ibn Rushd, Tahāfut al-Tahāfut (ed. Sulaymān Dunyā)
- Ibn Rushd, Faṣl al-Maqāl (ed. Muḥammad ʿAmāra)
- Frank Griffel, Al-Ghazali's Philosophical Theology (Oxford UP, 2009)
- Dimitri Gutas, Ibn Rushd as Philosopher (Brill, 2014)
- Taha Abdel Rahman