AVERROES (Ibn Rušd, Abū 'l-Walid Muḥammad b. Ahmad b. Muḥammad; Latin Averroes). — While in the East, after Avicenna, Arabic philosophy rapidly declined, in Spain, in contact with Jews and Christians, the Arabs, from the 10th century onwards, gave rise to a flourishing philosophical school of which A. was the most distinguished representative.
He was born in 1126 (520 A.H.) in Córdoba and died at Marrakesh in Morocco on 10 December 1198 (595 A.H.). Like his father and grandfather, he served as a qāḍī in his native city and as physician to the caliph. He enjoyed the favor of the great until, accused of heterodoxy, he was exiled to Lucena (Córdoba). He cultivated law, astronomy, medicine, philosophy, and theology. About seventy titles of his works are known to us, only partially preserved and almost all not in the original Arabic but in Hebrew and Latin translations. A.'s writings can be grouped into two broad categories: original works and commentaries on Aristotle. Among the original works, noteworthy are: the famous medical treatise *Colliget*, several treatises on astronomy, jurisprudence, and on the relationship between faith and reason; questions on the metaphysics of Avicenna, a summary of the *Organon*, questions on physics, a reply to al-Ghazālī titled *Destructio destructionis*, well-known along with the treatise *De animae beatitudine* among Jews and Christians in the Middle Ages; an interesting *Epistula de connexione intellectus abstracti cum homine* and the *De substantia orbis*.
But A. owes his renown above all to his commentaries on almost all of Aristotle's works. A certain number of these commentaries have been lost. For the Stagirite, A. professed boundless admiration, going so far as to call him “regula in natura et exemplar quod natura invenit ad demostrandam ultimam perfectionem humanam” (In libr. De Anima, cap. 2, ed. Venice 1550, f. 169, l. 59). In the Middle Ages in the West he was known as the Commentator by antonomasia. A.'s commentaries fall into three groups: the large, the middle, and the abbreviations and paraphrases. In the first, A. reproduces the entire text, accompanied by extensive elucidation; in the second, the text is partially quoted, but the commentary is more concise and rich in original developments; in the third, the text is abandoned and A. condenses, sometimes with great freedom, the material treated by Aristotle. For the *Posterior Analytics*, the *Physics*, the *Metaphysics*, and the treatises *On the Soul* and *On the Heavens*, all three types of commentary survive in Latin translations; the *Organon* is perhaps the work most faithfully commented upon in the second and third types.
A. did not know Greek and was far removed from the spirit of Hellenism, and although he had to work from translations, far from perfect, made by Syriacs, he nonetheless always managed to astonish the world of scholars by his great fidelity to Aristotle, or at least by the acumen with which he penetrated the philosopher's system. His interpretation greatly influenced all Latin Aristotelians of the 13th century.
The philosophical positions that most characterize A.'s thought can be summarized as follows. God is pure act and can be demonstrated rationally. Among the arguments he adduces to prove His existence are those of Avicenna, the passage from the contingent to the necessary, and from the imperfect to the perfect, but formulated more appropriately. St. Thomas Aquinas drew near to this formulation in his third and fourth proofs of God's existence. God created prime matter and the intelligences that inform it from eternity (Aristotelian thesis) and directly (contrary to Avicenna). Hence, the creation *ex nihilo* and the creation of the world in time, which St. Thomas deemed beyond dispute only on faith, are denied. Creation is not a one-time act: prime matter, coeternal with God, is not the empty receptacle where all forms are projected (Neoplatonism), but, as medieval Latins expressed it, the *latitatio formarum*, that is, a pure indeterminacy, a universal potentiality of forms. God, pure act, continuously draws forms from this matter, from potentiality to actuality. The generation of these is necessary (determinism) and eternal both *a parte ante* and *a parte post*.
All the intelligences, unequal in perfection, are extrinsically united to spheres. The heavens are composed of multiple spheres; the first sphere is informed and moved by the Prime Mover and communicates its motion to the second; this to the third,