Al-Ghazali

Abu Hamid Muhammad al-Ghazali was a Persian Muslim theologian, jurist and mystic of the late eleventh and early twelfth centuries, and one of the most influential thinkers in the history of Islam. He studied the Greek-inspired philosophy of his day more closely than almost any theologian before him, attacked its claims about God and the world in The Incoherence of the Philosophers, and then gave Sufi mysticism a respected place within mainstream Sunni learning.

Al-Ghazali was born in Tabaran, one of the two towns of the district of Tus in Khurasan, north-eastern Iran, not far from modern Mashhad. Later Muslim historians give his birth year as 1058 or 1059, but remarks in his own letters and autobiography suggest he may have been born two or three years earlier. He and his younger brother Ahmad, who became a well-known preacher and Sufi, were educated in Tus after their father's death. Muhammad then went to Nishapur to study at the Nizamiyya college under al-Juwayni, the leading theologian of the Ash'arite school, which defended traditional Sunni belief with rational argument.

His teacher's circle put him in contact with the court of the Seljuk Empire, the Turkish dynasty that then dominated the eastern Islamic world, and with its powerful vizier Nizam al-Mulk, who founded and funded the Nizamiyya colleges. In 1091 Nizam al-Mulk appointed al-Ghazali to the chair of the Nizamiyya in Baghdad, the most prestigious teaching post in the Sunni world. In his thirties he was a celebrated lawyer and theologian, close both to the Seljuk court and to the caliph of the Abbasid Caliphate.

In 1095, at the height of his fame, al-Ghazali gave up his position and left Baghdad. In his autobiography, The Deliverance from Error, written years later, he describes a crisis that had built up over about two years. He had come to doubt whether any of the knowledge he taught was certain, and he feared that his pursuit of status and wealth was endangering his soul. For a time, he writes, he lost the ability to speak and lecture. Reading Sufi authors convinced him that true knowledge of God came through experience and a purified life rather than through argument alone, and that serving sultans and viziers made a scholar complicit in their rule.

He travelled to Damascus and Jerusalem, and at the tomb of Abraham in Hebron he vowed never again to serve political rulers or teach in state-funded schools. After making the pilgrimage to Mecca in 1096 he returned home to Tus, where he set up a small private school and a Sufi lodge. In 1106, under pressure from the Seljuk court and convinced that the start of a new Islamic century called for a renewer of religion, he broke his vow and taught again at the Nizamiyya in Nishapur. Critics accused him of having absorbed too much from the philosophers, but the Seljuk governor Sanjar cleared him. He died in Tus in December 1111.

The philosophers whom al-Ghazali engaged, known in Arabic as the falasifa, followed Aristotle as read through late Greek Neoplatonism. Their greatest representatives were Al-Farabi and above all Avicenna. Al-Ghazali first wrote a clear, neutral summary of their views, The Aims of the Philosophers, and then a refutation, The Incoherence of the Philosophers, completed around 1095.

In the Incoherence he examined twenty of their teachings. He argued that on most of them the philosophers could not prove what they claimed, even by their own standards of demonstration. Three positions he judged to be unbelief: that the world has always existed and was not created in time, that God knows only universal truths and not individual events, and that the soul alone, not the body, survives death. Holding these, he wrote, put a Muslim outside the faith. He did not reject everything the philosophers taught. He accepted their mathematics and much of their natural science, and he regarded Aristotelian logic as a neutral tool, writing manuals on it and encouraging theologians and jurists to use it.

His best-known argument concerns cause and effect. When cotton touches fire, we see the cotton burn, but, al-Ghazali argued, we observe only that one event follows the other, never that the fire itself produces the burning. The link between them is not logically necessary. In his view God creates each event directly, and the regular order of nature is the result of God's habit, not of powers built into things. This position, called occasionalism, left room for miracles, which the philosophers' necessary chain of causes seemed to rule out. Centuries later, David Hume made a similar point about causation for different reasons, and historians often compare the two.

Al-Ghazali's largest work, The Revival of the Religious Sciences, written after he left Baghdad, is a long guide to the Muslim life in forty books. It covers worship, everyday conduct, the vices that destroy the soul and the virtues that save it, and ends with love of God, death and the afterlife. Its aim was to show that law and outward observance needed to be joined to sincere inner devotion, and that the Sufi path was compatible with Sunni orthodoxy. The work was controversial at first, and was even burned in parts of the Almoravid west, but it became one of the most widely read books in Islam. He also wrote The Niche of Lights, a mystical commentary on the Light Verse of the Qur'an, and many works on law and on the errors of the Ismaili Shia.

Al-Ghazali's influence on Sunni Islam was immense. He helped to fold both logic and Sufism into the curriculum of the religious schools, and later Muslims honoured him with the title Proof of Islam. A common modern claim that he single-handedly ended science or philosophy in the Islamic world is rejected by most historians: philosophy, much of it shaped by Avicenna, continued to flourish, particularly in Iran, for centuries after him. In al-Andalus, Averroes replied to him in The Incoherence of the Incoherence.

In Latin Europe, The Aims of the Philosophers was translated in the twelfth century without the preface explaining that it was a summary, so medieval scholars knew "Algazel" as a faithful follower of Avicenna rather than his critic. He is one of the central figures of Islamic and Jewish philosophy.