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Relation between religion and philosophy

During Averroes's lifetime, philosophy came under attack from the Sunni tradition, especially from theological schools like the Hanbali school and the Ashʾarites. In particular, the Ashʾari scholar al-Ghazali (1058–1111) wrote The Incoherence of the Philosophers, a scathing and influential critique of the Neoplatonic philosophical tradition in the Islamic world and against the works of Avicenna in particular. Among others, Al-Ghazali charged philosophers with non-belief in Islam and sought to disprove the teaching of the philosophers using logical arguments.

In Decisive Treatise, Averroes argues that philosophy—which for him represented conclusions reached using reason and careful method—cannot contradict revelations in Islam because they are just two different methods of reaching the truth, and "truth cannot contradict truth". When conclusions reached by philosophy appear to contradict the text of the revelation, then according to Averroes, revelation must be subjected to interpretation or allegorical understanding to remove the contradiction. This interpretation must be done by those "rooted in knowledge"—a phrase taken from surah Āl Imrān 3:7 of the Quran, which for Averroes refers to philosophers who during his lifetime had access to the "highest methods of knowledge". He also argues that the Quran calls for Muslims to study philosophy because the study and reflection of nature would increase a person's knowledge of "the Artisan" (God). He quotes Quranic passages calling Muslims to reflect on nature. He uses them to render a fatwa that philosophy is allowed for Muslims and is probably an obligation, at least among those who have the talent for it.

Averroes also distinguishes between three modes of discourse: the rhetorical (based on persuasion) accessible to the common masses; the dialectical (based on debate) and often employed by theologians and the ulama (religious scholars); and the demonstrative (based on logical deduction). According to Averroes, the Quran uses the rhetorical method of inviting people to the truth, which allows it to reach the common masses with its persuasiveness, whereas philosophy uses the demonstrative methods that were only available to the learned but provided the best possible understanding and knowledge.

Averroes also tries to deflect Al-Ghazali's criticisms of philosophy by saying that many of them apply only to the philosophy of Avicenna and not to that of Aristotle, which Averroes argues to be the true philosophy from which Avicenna has deviated.