Islamic philosophy

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Islamic philosophy is the tradition of rational inquiry that developed across the Islamic world from roughly the ninth century onward, working out the inheritance of Greek thought within a civilization shaped by the Qur’an. It is not the same as Islamic theology, though the two argued constantly; nor is it the philosophy of a single creed, since Jews and Christians wrote within the same Arabic intellectual culture. Its central strand carried a name of its own: falsafa, a loan from the Greek, and its practitioners were the falasifa — those who took up the project of Plato and Aristotle in a new language.

That strand — the reading of Aristotle and the Neoplatonists in Arabic — runs from al-Kindi in ninth-century Baghdad through al-Farabi and Avicenna to Averroes in the Muslim West, and it is the lineage that carried Greek rationalism into the Latin universities. But the wider tradition is not exhausted by it. It also takes in the theologians who turned the tools of logic back against the philosophers, the Jewish and Christian thinkers who reasoned in the same Arabic idiom, and the later eastern currents that fused argument with mystical sight. What unites them is less a shared method than a shared problem: how a created, contingent world stands to a single necessary God, and how far reason may go before revelation has the last word.

The translation movement

The whole enterprise rests on an act of translation. From the late eighth century, under the early Abbasid caliphs in Baghdad — a project that crowns the intellectual energy of the Islamic golden age — the Greek scientific and philosophical corpus was rendered into Arabic, often by way of Syriac and largely through Christian scholars trained in the older learning of the Near East. Aristotle came first and counted most, but with him came medicine, astronomy, mathematics, and a body of late-antique material whose provenance the translators did not always grasp. Two texts in particular bent the shape of what arrived. A paraphrase drawn from the Enneads of Plotinus circulated under the title The Theology of Aristotle; a compilation distilled from Proclus became the Book of Causes. Both were taken for Aristotle’s own work. The Aristotle the falasifa inherited was therefore already an Aristotle fused with Neoplatonism, a philosopher in whom the cosmos descends by emanation from a single first principle — recognizably the One renamed, and the seed of the Islamic Neoplatonism that would run through the whole tradition. This misattribution had consequences that lasted centuries; the Greek-into-Arabic project was not a neutral pipeline but a furnace in which the inheritance was recast.

Four names along the spine

The classical line of falsafa is conventionally drawn through four figures, and each marks a stage in the argument rather than a mere succession of teachers.

Al-Kindi, faylasuf al-ʿArab, the Philosopher of the Arabs, is counted the first. Working at the heart of the translation movement in ninth-century Baghdad, he did not himself read Greek but directed and revised the translators, and from their labor built a vast body of writing on metaphysics, optics, music, and the mathematical sciences. His ambition was to show that the wisdom of the Greeks and the truth of Islam were one — an argument he pressed against theologians who held that revelation needed no help from pagan reason. Where Aristotle taught the world’s eternity, al-Kindi broke with him and sided with scripture, arguing for a universe created in time. He gave falsafa its first vocabulary in Arabic before that vocabulary could be taken for granted.

Al-Farabi — later honored as the Second Teacher, the first being Aristotle — built the first full system. From the First, the necessary being beyond all multiplicity, he derived a descending series of separate intellects, each turning a celestial sphere, down to the tenth, the Active Intellect, which governs the sublunar world and illuminates the human mind so that it can think. Onto this emanationist cosmos he grafted a politics drawn from Plato’s Republic: in The Principles of the Opinions of the People of the Virtuous City the well-ordered community mirrors the well-ordered cosmos, and is ruled best by a philosopher-prophet who unites theoretical wisdom with the craft of legislation. His most consequential move was to place prophet and philosopher on one continuous ladder. The prophet, on his account, reaches the same truths the philosopher reaches by demonstration, but receives them through a perfected imagination, in images the multitude can grasp. Later readers found this either illuminating or dangerous, and the danger was not lost on the theologians.

Avicenna — Ibn Sina — produced the most ambitious synthesis the tradition would know, and the one that became the common air later thinkers breathed. At its center lies a distinction scholarship credits him with making decisive: between what a thing is and that it is, essence and existence. Everything in the world, he argued, is in itself merely possible; its existence is something added, received from beyond itself. Follow the chain of what depends on another, and it must terminate in a being whose existence is not received but belongs to it by its very nature — the Necessary Existent, wajib al-wujud, the one being in which essence and existence are wholly identical. From this single source the orders of being emanate in a graded series, the heavens turning through their hierarchy of intellects. So thoroughly did Avicenna’s system absorb and reorganize the inheritance that the centuries after him are sometimes called the Avicennan turn: thinkers in the eastern Islamic lands defined themselves by absorbing, criticizing, or recasting him for the better part of a millennium.

Averroes — Ibn Rushd (1126–1198), born at Córdoba into a family of jurists and himself a judge and physician under the Almohad caliphate — stands at the western edge of the line. He devoted his life to Aristotle, producing short, middle, and long commentaries on nearly the whole corpus, and earned thereby the title the Latin schools gave him: the Commentator. Against the layered Neoplatonism the East had read into Aristotle, he labored to recover what he took to be the genuine Aristotle beneath the accretions. His own most contested doctrine — that the material intellect is a single, eternal, separate substance shared by all human beings, so that what is immortal in thought is not the individual — would scandalize the Latin West under the name of Averroism. But it was his exchange with al-Ghazali that fixed his place in the larger argument of the tradition.

Falsafa and kalam: reason against revelation

That argument was joined from the start. The falasifa held that reason and revelation, rightly read, could not finally conflict, since both issued from one truth; philosophy and prophecy were different routes to the same end. The theologians — the mutakallimun, practitioners of kalam, the discipline of reasoned theology — did not all agree. Kalam had its own genealogy, older in some respects than falsafa: the rationalist Muʿtazila of Basra and Baghdad, who made God’s justice and unity the axioms of a created Qur’an, and the Ashʿarites who answered them, building a world of discrete atoms and instants in which God alone holds causal power. Between this theology and the philosophy of the Greeks there was both rivalry and exchange; each borrowed the other’s weapons.

The decisive blow came from a man trained in both. Al-Ghazali (c. 1056–1111), born at Tus in northeastern Iran, a jurist and Ashʿarite theologian who held the most prestigious teaching chair of his day at the Nizamiyya in Baghdad, mastered the philosophers’ own methods in order to turn them against the philosophers. In The Incoherence of the Philosophers (Tahafut al-falasifa) he singled out three of their doctrines as not merely mistaken but as crossing into unbelief: the eternity of the world, which denied creation in time; the claim that God knows particulars only in a universal way, which seemed to strip providence of its reach into the individual; and the denial of bodily resurrection. On a wider front he attacked the philosophers’ confidence in necessary causation, arguing that the bond between a cause and its effect is not necessary at all — that fire does not of itself burn, that what we read as cause and effect is a habitual conjunction God sustains. His own passage through this crisis, out of the paralysis of doubt and toward a knowing grounded in direct experience, he set down in the autobiography Deliverer from Error; his turn from the lecture hall toward the inner life of Sufism is recorded there, and the confessions and the lamp-light theology of his later years survive in the library’s editions of his work. The Incoherence did not settle which side was right so much as fix the terms a later philosophy would have to answer to.

Averroes answered it directly, and the title of his reply was a deliberate echo: The Incoherence of the Incoherence (Tahafut al-tahafut), a line-by-line rebuttal in which he defended demonstration as the highest road to truth and charged al-Ghazali with misunderstanding what the philosophers had actually taught. In a companion work, the Decisive Treatise, he set out his settlement between philosophy and the revealed law: truth does not contradict truth, and where the literal sense of scripture seems to clash with what reason demonstrates, the law itself licenses the philosopher to read the text allegorically. He thereby reserved demonstration for the few capable of it while leaving the plain sense intact for the many — a hierarchy of understandings rather than a single public doctrine.

Older textbooks read this exchange as the death of philosophy in Islam: the theologians won, falsafa fell silent. That verdict has been set aside. Philosophical activity did not stop; it migrated and changed form. In the Sunni West the Averroist line thinned, but in the eastern and Persianate lands the Avicennan synthesis was absorbed into the curriculum, criticized in its details, and rebuilt — often by men who were theologians and philosophers at once, and who would not have recognized the neat border the older story drew between the two.

The inquiry across creeds

The tradition was never the property of one religion. Jewish philosophers worked in the same Arabic culture and on the same questions, and the strand has its own weight in the history of thought; the Jewish philosophy that grew in the Islamic world reaches its peak in Maimonides, who praised al-Farabi’s logic above all others and whose Guide of the Perplexed applies the philosophers’ tools to the reading of scripture, building a negative theology of a God beyond every positive name. Through Latin and Hebrew translation the whole enterprise reshaped Christian scholasticism. Avicenna and Averroes, rendered into Latin at Toledo and in Sicily from the twelfth century, gave the medieval West a fuller Aristotle than it had possessed and a set of arguments it could not ignore; the essence-and-existence distinction, the proof from contingency, the doctrines on soul and intellect became material that Thomas Aquinas, Duns Scotus, and their contemporaries took up, adapted, and contested. The Book of Causes, that Arabic distillation of Proclus, was set as required reading in the arts faculty at Paris and drew a commentary from Aquinas himself once its true source was recognized.

The eastern turn: light and transcendent wisdom

In the eastern Islamic lands the tradition did not end but turned inward, toward a philosophy in which disciplined reasoning and direct vision were meant to arrive together — a direction with no real parallel in the Latin West.

Suhrawardi (1154–1191) recast metaphysics as a philosophy of light. Trained in the dominant Avicennan Aristotelianism, he turned against part of it, beginning with a critique of the very procedure of Aristotelian definition: every definition, he argued, sorts a thing under prior terms that are themselves undefined, so the procedure never reaches the thing itself. Against it he set al-ʿilm al-huduri, knowledge by presence — the soul’s immediate awareness of itself, requiring no intervening form — and on that footing built a metaphysics in which the fundamental reality is not being but light. At the summit stands the Light of Lights; below it descends an unbroken order of lesser lights, each illuminating and governing what lies beneath, the dimmer knowing the brighter by being present to it. He framed his philosophy of illumination — hikmat al-ishraq — not as invention but as the recovery of an ancient wisdom shared by the sages of Greece and of pre-Islamic Iran, a genealogy that draws on the older Sasanian-Iranian wisdom tradition. He was executed at Aleppo in 1191, around the age of thirty-six, on charges his followers disputed; the tradition called him al-Maqtul, the slain.

Alongside the Illuminationist current ran a metaphysics born from Sufi contemplation rather than from the schools. Ibn ʿArabi (1165–1240), the Andalusian master his readers called al-Shaykh al-Akbar, the Greatest Master, articulated a vision later condensed under the phrase wahdat al-wujud, the unity of being. Only the Real possesses being in the full sense; everything else is its self-disclosure, a theophany through which the one Being shows itself in endless particular forms. The systematic shape of the doctrine owes much to his stepson and chief interpreter, Sadr al-Din al-Qunawi, through whom the Akbarian school passed into the Persian, Turkish, and Indian Islamic worlds.

These streams converged in the School of Isfahan, the flowering of philosophy in the Safavid capital across the late sixteenth and seventeenth centuries. Its greatest figure, Mulla Sadra (Sadr al-Din al-Shirazi, c. 1571–1636), gathered the whole post-classical inheritance — Avicennan metaphysics, Suhrawardi’s presential knowing, Ibn ʿArabi’s monism, and Twelver Shiʿi theology — into a single current he named al-hikma al-mutaʿaliya, the transcendent wisdom. He reversed the Avicennan order of priorities, holding that existence rather than essence is the fundamental reality (asalat al-wujud); that being is a single reality graded by intensity from the most deficient existent to the divine fullness (tashkik al-wujud); and that substances themselves are caught in a ceaseless motion of becoming (al-haraka al-jawhariyya), so that the soul does not merely change its states but grows in being across its life. His vast al-Asfar al-arbaʿa, the Four Journeys, maps the stages of philosophical argument onto the stages of the soul’s ascent, treating philosophy itself as a way of becoming, not a body of conclusions. Through his commentators his transcendent wisdom became the backbone of advanced religious education in Iran, where it is studied and disputed to this day — a current whose modern interpreters, Henry Corbin foremost among them, read it as the living afterlife of a philosophy the West had written off as dead.

Texts, editions, and the modern study of the field

The recovery of Islamic philosophy as a discipline in its own right rests on a body of critical scholarship and on the primary texts themselves, several of which the library holds in their early translations.

• The reference frame most readers now consult is the Stanford Encyclopedia of Philosophy, whose suite of signed articles maps the field: Thérèse-Anne Druart, “Al-Farabi,” and the entries on al-Kindi, Avicenna, and Averroes set the figures in current scholarship. plato.stanford.edu/entries/al-farabi
• Frank Griffel’s “Al-Ghazali” (SEP, revised 2026) reconstructs the argument of the Incoherence, the three condemned doctrines, and the critique of necessary causation, and corrects the long-standing caricature of al-Ghazali as philosophy’s executioner. plato.stanford.edu/entries/al-ghazali
• Sajjad H. Rizvi’s “Mulla Sadra” (SEP) sets out the primacy of existence, the gradation of being, and substantial motion, and situates the transcendent wisdom within the School of Isfahan. plato.stanford.edu/entries/mulla-sadra
• For the Latin afterlife, the SEP survey of Arabic and Islamic philosophy’s influence on the Latin West tracks the translation channels at Toledo and in Sicily, the diffusion of the Book of Causes, and the transformation of nearly every scholastic discipline. plato.stanford.edu/entries/arabic-islamic-influence
• Dimitri Gutas, Greek Thought, Arabic Culture: The Graeco-Arabic Translation Movement in Baghdad and Early ʿAbbasid Society (Routledge, 1998), is the standard account of why the translation movement happened — a sustained social and ideological project, not an accident of curiosity. Gutas’s Avicenna and the Aristotelian Tradition (Brill, 1988; 2nd ed. 2014) anchors the reading of Ibn Sina.
• Peter Adamson, Philosophy in the Islamic World: A History of Philosophy Without Any Gaps, Volume 3 (Oxford University Press, 2016), is the fullest accessible narrative survey, treating falsafa, kalam, and the later traditions together.
• Majid Fakhry, A History of Islamic Philosophy, 3rd ed. (Columbia University Press, 2004), remains a durable single-volume overview of the whole tradition.
• The primary texts available here in the public domain include al-Ghazali’s spiritual autobiography in Claud Field’s translation, The Confessions of al-Ghazzali (1909), held in the library at /library/sufi/field-confessions-ghazali, and his treatise on the lights of God, the Mishkat al-Anwar, in W. H. T. Gairdner’s translation (1924), at /library/sufi/gairdner-mishkat-al-anwar.

Older European scholarship treated this tradition mainly as a conduit that preserved Greek learning for the Latin West, a holding-pen between antiquity and the scholastics. That reading has fallen away. These thinkers are read now as philosophers in their own right, posing and answering questions the Greeks had not — the contingency of a created world, the reach of providence into particulars, the standing of prophecy beside demonstration. The argument between philosophy and faith they conducted is one the later West inherited without always knowing where it came from.

→ In the library: Al-Ghazali — The Confessions (Field, 1909) · Al-Ghazali — Mishkat al-Anwar (Gairdner, 1924)

→ Related: Islamic Falsafa · Arabic Falsafa Islamic Philosophy · Al Kindi · Al Farabi · Avicenna · Suhrawardi · Ishraqi Illuminationism · Maktab I Isfahan · Akbarian Sufism Wahdat Al Wujud · Islamic Neoplatonism · Islamic Golden Age · Islamic Prophetology Doxography · Islamic Sufism · Jewish Philosophy · Thomas Aquinas · Theology