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Ibn Bājja, Ab

Ibn Bājja, Abū Bakr Muḥammad Ibn Yaḥyā Ibn Al-ṣa’igh

also known as Avempace or Avenpace

(b. Saragossa, Spain, end of the 11th century; d. Fez, Morocco, 1138/1139)


Ibn Bājja was a Muslim philosopher who wrote in Arabic. Besides Saragossa and Fez, he lived and worked in Seville and Granada. He is said to have been a vizier serving an Almoravid prince and to have been poisoned by physicians who were jealous of his medical skill. Ibn Bājja is often described as the earliest Arabic Aristotelian in Spain, which is correct but rather less significant than a characterization made by a friend and editor of his work, Abu’l-Hasan ’Alī of Granada, who indicates that Ibn Bājja had a preeminent part in establishing in Spain a systematic method for the study of the philosophical sciences. Such a method was already in existence in the Muslim East, but not in the peripheral Muslim West.

It can be taken as certain that, in working out his curriculum, Ibn Bājja, like the philosophers of the East, attached the greatest importance to the study of the corpus Aristotelicun. In spite of far-reaching doctrinal divergences he appears to have modeled his philosophical method on that of al-Fārābī rather than on that of Ibn Sīnā (Avicenna), whose influence was at that time predominant in the eastern centers of learning. In this and in various other respects he seems to have been responsible for the distinctive character of Spanish Aristotelianism, which counts among its representatives Ibn Rushd (Averroës)and Moses Maimonides. Among his extant works are the following:

Tabbīr al-mutawaḥḥid (“The Regimen of the Solitary”). The work deals with the various categories of men—those interested only in the bodily functions, those swayed by such “spiritual” faculties as imagination, and those governed by reason—in relation to man’s final end, which is intellectual perfection; with various regimens; and with the position that the philosopher should adopt in relation to the imperfect communities in which he has to live (the reference is to the Islamic states of the time). In the absence of any hope for the creation of a perfect philosophical body politic (the conception of which goes back to Plato), the philosopher should regard himself as a stranger in his own community and as a citizen of the ideal State constituted by the happy few, i.e., the men, in whatever country they live, who in the past or the present have attained intellectual perfection.

A treatise on the union of man with the Active Intellect.

Rishālat al-widā‘ (“The Epistle of Farewell”). The work treats some of the themes discussed in the Tadbīr.

A book on the soul.

Commentaries and notes on some works or parts of works belonging to the corpus Aristotelicum, including treatises of the Organon(there is also a commentary on Porphyry’s Isagoge), the Physics, De generatione et corruptione, the Meteorologica, and The Book of Animals. There is also a “Book of Plants.”

In a letter to Abū Ja’far Yūsuf Ibn Ḥasday, Ibn Bajja gives some details concerning his intellectual biography. After having learned the art of music, he studied astronomy; he then went on to study Aristotle’s Physics. In astronomy Ibn Bājja rejected the theory of epicycles as being incompatible with the (Aristotelian) physical doctrine (see Maimonides, The Guide of the Perplexed, II, 24). He thus seems to have been one of the initiators of the tendency—which, after him, came to the fore in Muslim Spain—to reject and attempt to replace the Ptolemaic system.

Ibn Bājja’s dynamics, as set forth in his notes on the seventh book of Aristotle’s Physics, may inter alia, be regarded as an attempt to unify the Aristotelian theory of movement by replacing the multiform concept of cause with the notion of force. The Arabic term used by Ibn Bājja is a translation of the Greek dynamis, but in the context it seems to have an exclusively active sense (which the term also has in Book VII of Aristotle’s Physics, in certain texts of pagan Neoplatonic philosophers, and in John Philoponus’ writings); it is in no way a potentiality. The unifying function of Ibn Bājja’s concept of force may to some extent be classified by a consideration of the notion of “fatigue” (a term used in somewhat similar but not identical contexts by Alexander of Aphrodisias and by John Philoponus), which in Ibn Bājja’s doctrine is associated with it. According to Ibn Bājja’s the force of a mover may become “fatigued” (1)by the mere fact that it is exerted in moving a body and (2) because of the reaction of the body that is moved, when this body is other than the mover.

In relation to the first factor Ibn Bājja’s statements give rise to some perplexity. One of them seems to purport that the “natural” motions of simple bodies do not cause fatigue, the reason being that in these motions there is no opposition between the mover and the moved body. It would thus appear that factor (1) causes fatigue only when it is accompanied by factor (2). The latter factor produces fatigue because a body moved by another body (and also a living being moved by its soul) causes in its turn (apparently in proportion to its fatigue) motion in its mover and thus fatigue the latter. In other words, there are an action and a reaction, the two being essentially comparable. While this view can be regarded as a development of some conceptions implicitly contained in the seventh book of Aristotle’s Physics, it does not agree with other Aristotelian texts, which tend to assimilate the relation between a mover and a moved body to the relation between an agent and the thing acted upon or between a cause and an effect; that is to say, to relations that from the Peripatetic point of view do not lend themselves easily, and perhaps do not lend themselves at all, to being quantified. As against this, there is no theoretical difficulty about the quantification of the relation of action and reaction postulated by Ibn Bājja.

This view could, as it seems, be expressed in the following formula (whose validity would, however, be restricted to the instant in which a given body is moved): M = F1 – F2, M being the motion, F1 the force of the mover, and F2 the force of the moved body. This formula does not take into consideration the progressive weakening, or in Ibn Bājja’s terminology “fatigue,” of the force of the mover, which in all probability (although this is not explicitly stated by Ibn Bājja) is directly proportional to the duration of the motion.

It is indicated in a rather vague way that in accordance with the formulas of Book VII of the Physics, the distance covered by a body in motion is directly proportional to the relation between the force of the mover and the force of the moved body. The formula breaks down, however, in the case of a moved body that weighs too little “to fatigue,” i.e., to move, its mover.

In the case of descent on an inclined plane, the fatigue (perhaps the slowing down) of the falling body is proportional to the angle formed by the inclined plane and a perpendicular drawn to the surface of the earth from the point on the plane at which the falling body happens to be. Ibn Bajja is possibly the earliest author known to us who has outlined, admittedly in a very summary way, a dynamic theory of descent on an inclined plane.

In his explanation of the motion of projectiles, Ibn Bājja follows Aristotelian lines. According to him, the continued motion of an arrow shot from a bow and of a stone thrown by the hand is due to their being pushed by particles of air, the motion of which is, in the last analysis, due to air’s being pushed by the action of the hand or the bow. He seems to ignore the theory of violent inclination, similar to the theory of impetus, which was propounded by such philosophers of the Muslim East as Ibn Sīnā. As an Aristotelian philosopher, Ibn Bājja believed that a projectile moves more quickly at the middle of its course than at its beginning.

In Ibn Bājja’s view a magnet does not directly cause a piece of iron that is not immediately contiguous to it to move; the latter’s motion is occasioned by the air, or some other body, such as a peice of copper or silver, that is placed between the magnet and the piece of iron. In another context Ibn Bājja refers to, but rejects, the belief that an attraction of the earth, similar to the attraction exerted upon a piece of iron by a magnet (rather than the tendency to reach their natural place), is the cause of the downward motion of heavy bodies.

In Latin Europe, the most influential of Ibn Bājja’s physical theories was the one sometimes described as the doctrine concerning the original time of motion. This theory attacks the Peripatetic conceptions concerning the role of the resistance of the medium (air or water), regarded as one of the factors determining the velocity of a moving body. According to the Aristotelians, the function of this factor is such that, in the absence of any resistance on the part of a medium, i.e., in a vacuum, the velocity of a moving body must become infinite. The impossibility of this proves that there is no vacuum. Although Ibn Bājja did not hold a brief for the existence of a vacuum, he refuted the Aristotelian argumentation. His view on this question is similar to a doctrine set forth by his contemporary Abu’l-Barakat al-Baghdadi as well as by John Philoponus, by whom Ibn Bājja may have been influenced, but it also derives in a logical way from Ibn Bajja’s theory concerning the relation between a mover and a moved body. As Stated above, it is this relation that determines the velocity of a moved body. Ibn Bājja contends that, in the absence of a medium, the body would move with this original velocity, which is clearly finite. This velocity would decrease in proportion to the resistance of a medium. As has been shown by E. A. Moody, this theory, which was known in Latin Europe through the exposition of Ibn Rushd, who refuted, it, influenced Thomas Aquinas, Duns Scotus, and other Schoolmen.


I. Original Works. Miguel Asin Palacios has provided the Arabic text and Spanish translation of the following works by Ibn Bājja: “Avempace Botánico” (“Book of Plants”), in Al-Andalus, 5 (1940), 259-299; “Tratado de Avempace sobre la uniõon del intelecto con el hombre” (“The Union of Man With the Active Intellect”), ibid., 7 (1942), 1-47; “la carta de adiõs de Avempace” (“The Epistle of Farewell”), ibid., 8 (1943), 1-85; and El régimen del solitario (“The Regimen of the Solitary”; Madrid-Granada, 1946), English trans. by D.M. Dunlop in Journal of the Royal Asiatic Society (1945), 61-68.

II. Secondary Literature. Further information on Ibn Bājja can be found in E. A. Moody, “Galileo and Avempace,” in Journal of the History of Ideas, 12 (1951), 163-193, 375-422; and S. Pines, “La dynamique d’Ibn Bājja,” in Mélanges Alexandre Koyré, I, L’aventure de la science (Paris, 1964), 442-468.

Shlomo Pines

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Ibn Tufayl, Abü Bakr Muhammad


(Latin, Abubacer )

(b. Guadix, Spain, before 1110; d. Marrakesh, Morocco, 1185)

medicine, philosophy.

Ibn Tufayl was a Spanish Muslim who received a broad education in the religion of Islam and the Arabic secular sciences. His professional career was that of a physician, first at Granada, Ceuta, and Tangier, and later (1163–1182) as court physician to the Almohad sultan of Morocco and Andalusia. He introduced Ibn Rushd to the sultan (ca. 1169) and commissioned him to write his commentaries on the works of Aristotle.

Ibn Tufayl is best known for his philosophical book Hayy ibn Yaqzān (“The Living, Son of the Wakeful”). After a valuable introduction surveying the rise of philosophy in western Islam, the author presents Neoplatonic philosophy in the form of a myth. Hayy is a boy born on a desert island and reared by a doe. As he grows up he teaches himself, entirely by his own observation and reasoning, some practical arts and the rudiments of the empirical sciences. In his adult life he proceeds by reasoning and intuition to an understanding of metaphysics and theology and to an ascetic practice, all of which culminate in mystical visions by his intellect of God, the Necessary Being and Cause of the world. In later experiences he converses with a devout Muslim, and they agree that there is no difference in doctrine between Hayy’s philosophy and the revealed religion of Islam, but that it is useless to teach philosophy to most people, for whom only the simplest practice of Islam is helpful.

The main aims of the myth appear to be to show (1) that the Neoplatonic philosophy is that which a rational man, undistracted by social interests or prejudices, will naturally arrive at, and (2) that the practice implied in this philosophy leads to the supreme happiness for man, which is the mystical state of the soul. In details Ibn Tufayl generally follows Ibn Sīnā, but there are some differences. For example, Ibn Tufayl thinks it unproved that the world is eternal rather than created in time, and holds that intelligibles are abstracted by the human intellect, not presented to it by an external Active Intellect.

Hayy ibn Yaqzän has always been widely read in Arabic, and appeared in several European translations from 1671 onward; it probably influenced Defoe’s Robinson Crusoe (1717).

Another work by Ibn Tufayl, Rajaz tawīl fīlit al-tibb (“Long Poem in Rajaz Meter onMedical Science”), was discovered recently in manuscript at Rabat. He is also known to have influenced his pupil al-Bitrū jī to abandon the Ptolemaic astronomy of eccentrics and epicycles in favor of a more Aristotelian system, but no astronomical writings by the master have survived.


Texts of Ibn Tufayl’s Hayy ibn Yaqzān include the French ed. and trans. of L. Gautheir (2nd ed., Beirut, 1936); that of Ahmad Amīn (Cairo, 1952); a partial English trans. by G. N. Atiyeh, in R. Lerner and M. Mahdi, Medieval Political Philosophy (Chicago, 1963), 134 – 162, and an English trans., intro., and notes by L. Goodman, Ibn Tufayl’s Hayy ibn Yaqzān (New York, 1971).

For studies of Ibn Tufayl and his work, see M. Cruz Hernandez, Historia de la filosofia Hispano-musulmana, I (Madrid, 1957), ch. 11; L. Gauthier, Ibn Thofaīl, sa vie, ses oeuvres (Paris, 1909); A.-M. Goichon, “Hayy b. Yakzān,” and B. Carra de Vaux, “Ibn Tufayl,” both in Encyclopaedia of Islam, new ed. (Leiden, 1960 – ), III: G. F. Hourani, “The Principal Subject of Ibn Tufayl’s Havy b. Yaqzān,” in Journal of Near Eastern Studies. 15 (1956), 40 – 46: A. Pastor, The Idea of Robinson Crusoe (Watford, 1930); T. Sarnelli, “Primauté de Cordoue dans la médecine arabe d’Occident,” in Actas del Primer Congreso de Estudios Arabes y Islamicos (Madrid, 1964), 441 – 451, describing the medical poem; and S. S. Hawi, Islamic Naturalism and Mysticism, a Philosophic Study of Ibn Tufayl’s Hayy ibn Yaqzān (Leiden, 1974).

George F. Hourani

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Abu Bakr Muhammad ibn Tufayl

Abu Bakr Muhammad ibn Tufayl

Abu Bakr Muhammad ibn Tufayl (ca. 1110-1185) was a Spanish Moslem philosopher and physician, author of the celebrated allegorical tale "Hayy Ibn Yaqzan."

Known to medieval Christian scholastics as Abubacer (from Abu Bakr), Ibn Tufayl was born in the town known in modern times as Guadix near Granada. He was trained as a physician but also followed the career of a government functionary, serving as secretary to the governors of Granada, and later of Ceuta and Tangier in North Africa (1154). Ultimately, he became court physician to the Almohad sultan Abu Yaqub Yusuf, who ruled in Marrakesh from 1163 to 1184.

Ibn Tufayl used his considerable influence at court to forward the career of the young Averroës; the Sultan seems to have taken a lively interest in philosophy, and Averroës wrote his commentary on Aristotle at the Almohad court, encouraged by Ibn Tufayl. After the latter's retirement as court physician, Averroës took his place. Ibn Tufayl died in Marrakesh.

"Alive, Son of Awake"

Little of Ibn Tufayl's work has survived except for Hayy Ibn Yaqzan, whose title means "Alive, Son of Awake," although medieval Arabic bibliographies credit him with an additional two books on medicine and some writings on astronomy. The title is borrowed from Avicenna, but the ideas put forward in Ibn Tufayl's work are quite contrary to Avicenna's.

The setting of the narrative is an island in the Indian Ocean, inhabited solely by a youth named Hayy, who grew up there quite alone, suckled as a child only by a gazelle, and completely cut off from humanity. Despite this cultural deprivation, Hayy stays alive and even thinks through and evolves a system of philosophy and metaphysics of the most refined order. Through fasting and meditation, moreover, he seeks and attains mystical experiences.

Ibn Tufayl then introduces into the narrative a devout man named Asal, from a neighboring island, who is seeking an uninhabited retreat from the world. He meets Hayy, teaches him to speak, and is astonished to find that the natural youth has evolved—all untaught—a system comparable but superior to Asal's own philosophy.

Hayy and Asal return to civilization, determined that Hayy's aperçus will be shared with mankind. The attempt fails, however, and the two philosophers return to the desert island and leave the common people to the undisturbing practice of their ancestral religion.

Translated into Latin in 1671, Ibn Tufayl's work has evoked interesting speculations. Translations into English and European languages soon followed, and it has been suggested that Defoe's Robinson Crusoe, which was published in 1719, may have been inspired by the English translation of 1708. The interpretations of scholars of the meaning of the allegory have varied greatly, although all agree, at least, that it is a tour de force intended to show the almost limitless capabilities of the human intellect.

Further Reading

The 1708 English translation, revised by A. S. Fulton, The History of Hayy Ibn Yaqzan, by Abu Bakr Ibn Tufayl (1929), presents Ibn Tufayl's philosophical romance on the "awakening of the soul." Z. A. Siddiqi, Philosophy of Ibn Tufayl (1965), is a study of Ibn Tufayl's work. □

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Ibn Tufayl, Abu Bakr

Ibn Tufayl, Abu Bakr (d. 1185 (AH 581)). Muslim philosopher and physician, known in the West as Abubacer. Born near Granada in Spain, he became wazīr and physician to the Almohads, introducing ibn Rushd to the court. He developed his philosophical views in Ḥayy ibn Yaqz̳an, (Alive, the Son of the Awake): Ḥayy represents humanity and Yaqz̳an God. Ḥayy grows up on a desert island, and using his powers of observation, reason and reflection, he arrives at the truth and experience in relation to God. The work was tr. into Lat. by E. Pococke in the 17th cent. (Philosophicus Auotodidactus) and was influential in the development of the idea of ‘the noble savage’ (Dryden) and of Rousseau's argument for a primitive simplicity which is corrupted by civilization. It may also have influenced Daniel Defoe's Robinson Crusoe.

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Ibn Tufayl

Ibn Tufayl (Ĭ´bən tōōfāl´), d. 1185/86?, 12th-century Spanish-Arab philosopher and physician, b. near Granada. His chief work was a philosophical romance, Hayy ibn Yaqzan, describing the development of a hermit, who, after long seclusion on an island, attains knowledge of the divine. He later comes into contact with a man trained in religion, the point of the work being the conflict between philosophy and religion. The book was translated into several European languages in the 17th cent. and was widely read. Ibn Tufayl, called Abubacer by Europeans, was famous as a physician.

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