Philosophy › Faith and reason › Philosophy in the Islamic world (falsafa)
Al-Ghazali, The Incoherence of the Philosophers
1058–1111· Philosopher· Reality, mind & God
Well documentedSolid records, texts or physical evidence.
Persian theologian whose Incoherence of the Philosophers (c. 1095) attacked Avicenna's Aristotelian system as contrary to Islam and beyond reason's reach.
See it on the Philosophy map →The idea
The idea: reason cannot prove what the philosophers claimed, and on key points they contradict revelation. Teaching in Baghdad, al-Ghazali first summarized Avicenna's system, then attacked it on 20 points, condemning three as unbelief: an eternal world, a God who knows no particulars, and no bodily resurrection. Most famously, he argued fire does not burn cotton by its own nature; God creates the burning each time, and we only see the two together. The main objection, pressed by Averroes: without real causes, science becomes impossible.
Why it matters
He set the terms of Islam's faith-versus-reason debate, made logic acceptable to theologians, and his doubts about causation anticipate Hume by six centuries.
Legacy and sources
His Incoherence, his earlier neutral summary The Aims of the Philosophers, and his autobiography Deliverance from Error all survive, along with Averroes' point-by-point reply.
Still debated
Whether he truly denied natural causes, or only that they act without God, is debated; the old claim that he killed Islamic philosophy is now largely rejected.
Connections (4)
▸Avicenna (Ibn Sina) was attacked by Al-Ghazali, The Incoherence of the PhilosophersWell documented
The connection
Avicenna had built Aristotle into a grand system: an eternal world flowing necessarily from God, a God who knows things only in general, and a soul that survives without the body. Al-Ghazali first summarized this system accurately, then refuted it on twenty points in The Incoherence of the Philosophers, branding three of them unbelief.
When and how
Baghdad, about 1094–1095, while al-Ghazali taught at the Nizamiyya college, some 60 years after Avicenna's death.
How we know
The Incoherence names al-Farabi and Avicenna as its main targets, and its arguments track Avicenna's works, which al-Ghazali had summarized in The Aims of the Philosophers.
Debates and open questions
Scholars debate how much al-Ghazali quietly absorbed from Avicenna; his later theology uses many Avicennan ideas.
▸Al-Ghazali, The Incoherence of the Philosophers was answered by Averroes (Ibn Rushd)Well documented
The connection
About 85 years later, Averroes wrote The Incoherence of the Incoherence, quoting al-Ghazali passage by passage and rebutting each. He argued that denying natural causes makes all knowledge impossible, and that al-Ghazali had attacked Avicenna's distortions rather than Aristotle himself. He also argued that Islamic law commands philosophy for those able to pursue it.
When and how
Al-Andalus, about 1180; Averroes, then a judge, wrote it around the time of his Decisive Treatise on faith and philosophy.
How we know
The Incoherence of the Incoherence survives in Arabic and in Hebrew and Latin translations, and quotes al-Ghazali's text directly.
Debates and open questions
Historians debate why Averroes's reply had little influence in the Muslim East yet great influence in Christian Europe.
▸Al-Ghazali, The Incoherence of the Philosophers anticipated the doubts about causation of David HumeMostly agreed
The connection
Al-Ghazali argued that we never see fire cause cotton to burn; we only see burning happen when fire touches it. The link is God's custom, not a necessity. Hume, six centuries later, also said we observe only regular sequence and that 'cause' is a habit, though he located the habit in our minds, not in God.
When and how
Al-Ghazali's Incoherence of the Philosophers, Baghdad, 1095, Discussion 17; Hume's Treatise (1739) and Enquiry (1748).
How sure are we?
The arguments are clearly parallel. Direct influence is undocumented, but Hume did read Nicolas Malebranche, who made a similar argument that God is the only true cause.
Debates and open questions
Some scholars suspect an indirect chain from al-Ghazali through Latin sources to Malebranche and Hume; no documentary link has been found.
▸Al-Ghazali, The Incoherence of the Philosophers challenged Philosophy in the Islamic world (falsafa)Well documented
The connection
Al-Ghazali charged the Aristotelian philosophers (falasifa) with overstepping reason and contradicting Islam on three points that he said amounted to unbelief. He kept their logic, even urging theologians to use it, but discredited their metaphysics. After him, philosophy in the Muslim East increasingly merged with theology and Sufi mysticism.
When and how
Baghdad, about 1095, at the Nizamiyya college; his works spread across the Muslim world within a few decades.
How we know
His Incoherence, Deliverance from Error and logic manuals survive; later theologians such as Fakhr al-Din al-Razi wrote in the blended style he encouraged.
Debates and open questions
The old claim that he ended Islamic philosophy is now widely rejected: philosophy continued in Persia, through Suhrawardi and Mulla Sadra, for centuries.