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Debate

Al-Ghazali and Averroes: Can Philosophy Prove What It Claims?

1095–1180 · Can the philosophers prove their teachings about God, the eternity of the world and the soul with the certainty of demonstration – and do causes in nature act by necessity, or does God create each event?

Around 1095 al-Ghazali, then teaching at the Nizamiyya college in Baghdad, published The Incoherence of the Philosophers. He attacked neither logic nor the sciences, but the claim of the philosophers in the tradition of Avicenna to have demonstrated twenty theses of metaphysics and natural philosophy; three of them, he concluded, amounted to unbelief. Some eighty years later, around 1180, Ibn Rushd (Averroes), judge in Seville and Córdoba and commentator on Aristotle, answered him point by point in The Incoherence of the Incoherence; in the Decisive Treatise, written about the same time, he argued that Islamic law itself commands the study of philosophy. Al-Ghazali’s approach shaped later Muslim theology, while Averroes’ writings found their widest readership in Hebrew and Latin. The exchange is still read as a model of the dispute between reason and revelation.

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Positions

The philosophers have not proved it

Al-Ghazali measured the philosophers by their own standard of demonstration (burhan) and found that their metaphysical proofs, such as those for a world without beginning, do not compel assent. Three teachings of Avicenna – that the world has no beginning, that God knows individual things only in a universal way, and that souls do not return to bodies after death – contradict revelation; in a brief legal opinion at the end of the book he declared those who teach them publicly to be unbelievers, while counting the other errors as innovations. In the seventeenth discussion he denied that the connection between what is called a cause and its effect is necessary: when fire touches cotton, it is God who creates the burning, through angels or directly.

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To deny causes is to deny reason

Averroes answered, in substance, that whoever denies causes denies the intellect, since knowledge is knowledge of things through their causes. Many objections, he argued, struck Avicenna rather than Aristotle. In the Decisive Treatise he held that the Law commands reflection on the world – citing verses such as 59:2, which calls on those who have vision to reflect – and, for those able to follow it, demonstrative study; where a demonstration and the literal sense of scripture seem to conflict, the text must be interpreted. Since there is no certain consensus of scholars on such theoretical questions, the charge of unbelief cannot be upheld, and on the eternity of the world the parties differ, he thought, almost only in names.

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After the dispute

The story that al-Ghazali put an end to philosophy in Islam was told by many European historians from the nineteenth century onwards, among them Ernest Renan; recent scholarship rejects it. Philosophy in the tradition of Avicenna continued in the East, now within theology: Fakhr al-Din al-Razi wrote a critical commentary on Avicenna’s Pointers and Reminders, and Nasir al-Din al-Tusi defended Avicenna against him in a commentary of his own. Frank Griffel (Al-Ghazali’s Philosophical Theology, 2009) argues that al-Ghazali himself adopted much of Avicenna’s thought and left open whether God creates events directly or through secondary causes, so that the seventeenth discussion is not simply a defence of occasionalism.

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As of 10/2026. Summaries for orientation – the sources give the full arguments. · How Agora is made

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