Avicenna (980-1037)

Key dates

Bukhara, the child prodigy

Avicenna was born around 980^[18] at Afshana, a village near Bukhara, then the capital of the Samanid dynasty and one of the great intellectual centers of the Muslim Iranian world. His father, Abdallah, from Balkh and won over to Ismaili ideas, held an administrative office in the province; his mother was named Setareh^[19]. The exact date of his birth remains debated among academic historians: tradition retains the year 980, but some studies place it in the preceding decade; the uncertainty is unresolved and must be honestly flagged rather than presented as certain^[20].

The autobiography Avicenna dictated in his mature years to his disciple and companion al-Juzjani, completed by the latter for the following years, is the richest source available on his youth^[21]. It describes a child of rare precocity: at ten, he knew the Qur'an by heart along with a good part of classical Arabic literature^[22]. He first studied arithmetic with an herbalist merchant, then logic and the rudiments of philosophy with a teacher named Abu Abdallah al-Natili^[23]. But very quickly the pupil outgrew the master: at fourteen he studied Hippocrates and Galen on his own; at sixteen he completed his medical training; at seventeen he was already teaching in a Bukhara hospital^[24]. By his own account, it was Aristotle's metaphysics that resisted him longest: he says he read the text forty times without fully understanding it, until a commentary by al-Farabi, found by chance at a bookseller's, finally revealed its meaning to him^[25].

The library of the Samanids: the healing of Emir Nuh ibn Mansur

The most famous episode of Avicenna's youth is his healing of the Samanid emir Nuh ibn Mansur, afflicted with an illness the court physicians could not cure. The young Avicenna, called in consultation, diagnosed and successfully treated the illness^[26]. As a reward, he asked for neither title nor fortune, but access to the royal library of the Samanids, one of the richest manuscript collections of his time:

"I was admitted to a building which had many rooms; in each room there were chests of books piled one on top of the other." — Avicenna, Autobiography dictated to al-Juzjani, ed. and trans. W. E. Gohlman, The Life of Ibn Sina, State University of New York Press, Albany, 1974, English trans. pp. 35-37, sentence quoted p. 37^[27]

In eighteen months, he claims to have gained knowledge of all the ancient authors then available^[28]. Shortly afterwards, a fire destroyed part of this library, a fact which some later detractors, according to biographical tradition, interpreted as Avicenna's way of hiding the true extent of his sources, an accusation modern historiography does not retain as founded^[29].

The fall of the Samanids and the wandering years

In 999, the Samanid dynasty collapsed under the twin pressure of the Karakhanids from the north and the Ghaznavids from the south^[30]. Avicenna, now without a stable protector, began a period of wandering across eastern and central Iran: he stayed at Gorgan, on the shores of the Caspian Sea, where he met the man who would become his disciple and biographer, al-Juzjani^[31], then at Rayy (near present-day Tehran), in the service of the Buyid regent Sayyida Shirin and her son Majd al-Dawla^[32]. It was during these years of forced mobility that he began writing his two great works: the Canon of Medicine, begun around 1012-1014^[33], and the Book of Healing, whose composition spans roughly 1014 to 1027^[34].

Physician then vizier to Shams al-Dawla

In 1014, Avicenna entered the service of the Buyid emir Shams al-Dawla at Hamadan, first as personal physician, then, as his reputation grew, as vizier, that is chief minister of the emirate^[35]. This dual role, very rare for a scholar, shows the breadth of the talents the Buyid court recognized in Avicenna: administrator by day, he wrote by night the chapters of his philosophical and medical work, an activity he himself describes, according to the received biographical tradition, as carried on in a state of permanent exhaustion and strain.

Imprisonment in the fort of Fardajan

On the death of Shams al-Dawla in 1021, Avicenna's position became fragile. Suspected of keeping up a secret correspondence with the rival emir Ala al-Dawla of the Kakuyid dynasty, he was arrested and imprisoned for about four months in the fortress of Fardajan, near Hamadan^[36]. It was during this captivity, according to several modern scholarly studies of the genesis of his works, that he is said to have written or developed one of his most famous philosophical arguments, the "Flying Man", on the immateriality of the soul^[37], a circumstance which lends this meditation on self-consciousness independent of the body a particular biographical resonance.

Isfahan: the last years with Ala al-Dawla

Freed, Avicenna finally joined, around 1023-1024, the court of the Kakuyid emir Ala al-Dawla Muhammad at Isfahan, whom he would serve as physician and adviser until his death, for fourteen years^[38]. It was at Isfahan that he wrote his last great philosophical work, the Pointers and Reminders (al-Isharat wa l-tanbihat), composed between 1030 and 1034 approximately^[39], a denser text, more allusive and more personal in tone than the Shifa, in which some interpreters have claimed to detect the lineaments of a philosophical spirituality close to mysticism, though specialists are not agreed on this point.

Death at Hamadan (1037)

Avicenna fell ill during a military expedition led by Ala al-Dawla toward Isfahan, seized by a chronic intestinal ailment whose exact nature remains debated: amoebic dysentery, colon cancer and poisoning have all been proposed by different historians of medicine^[40]. He died in June 1037 at Hamadan, at about fifty-seven years of age^[41], having, according to biographical tradition, distributed his goods to the poor and freed his slaves in his last days. He is buried at Hamadan, where his mausoleum, rebuilt in the 20th century, remains today a national memorial in Iran.

The Book of Healing (Kitab al-Shifa)

The Book of Healing (Kitab al-Shifa, literally "the Healing", of ignorance, the title specifies, not of the body) is Avicenna's philosophical masterpiece, an encyclopedia in several volumes covering logic, the natural sciences (physics, biology, mineralogy, psychology), mathematics and metaphysics^[42]. Its metaphysical section, the al-Ilahiyyat ("the divine science"), written for the most part between 1014 and 1020^[43], is the text that would exercise the most lasting influence on medieval Latin philosophy, through its translation made at Toledo in the 12th century^[44].

The Canon of Medicine (al-Qanun fi l-tibb)

Composed for the most part between 1012 and 1024^[45], the Canon of Medicine (al-Qanun fi l-tibb) is the most systematic medical treatise of late Antiquity and the Islamic Middle Ages, synthesizing Galenic medicine, Greco-Arab pharmacology and its author's personal clinical observation in five books: general principles, materia medica, localized pathologies, general diseases and specific affections, pharmaceutical formulary^[46].

Translated into Latin by Gerard of Cremona at Toledo between 1150 and 1187^[47], the Canon became the reference manual of the medical faculties of Europe, Montpellier, Bologna, Padua, and remained taught there, in whole or in part, until the 17th century^[48], a pedagogical longevity almost without equivalent in the history of Western medicine.

The Pointers and Reminders (al-Isharat wa l-tanbihat)

A work of maturity, written at Isfahan around 1030-1034^[49], the Pointers and Reminders take up, in a tighter and more personal form, the great metaphysical and psychological theses of the Shifa. The text would enjoy a considerable scholarly posterity within the Islamic world itself, notably through the critical commentary the theologian Fakhr al-Din al-Razi would devote to it a century and a half later^[50].

The lost "Eastern Philosophy"

In several of his writings, Avicenna mentions the existence of a distinct work, the Hikmat al-mashriqiyya ("Eastern Philosophy" or "of the Easterners"), which he presents as a more personal philosophy, freed from the pedagogical constraints imposed by the official Peripatetic tradition^[51]. This text, for the most part lost (tradition reports that a large part of it is said to have vanished during the sack of Isfahan in 1034^[52]), nourished, in the 20th century, an academic debate over the possible existence of a second, esoteric "Avicenna", distinct from the Peripatetic philosopher of the great summas. This line of reading, associated notably with the works of Henry Corbin, remains a minority and disputed view among contemporary Avicenna specialists, who stress the fragmentary and largely speculative character of the sources adduced in its support.

Grasping the point: why distinguish what a thing is from the fact that it exists

Before entering into technical detail, the starting intuition must be grasped, in the simplest possible terms: one can perfectly understand what a horse is, or a man, or a mountain of gold, without knowing whether such a being really exists anywhere. This shows, according to Avicenna, that the essence of a thing (what it is) and its existence (the fact that it really is) are not the same thing: existence is not included in the mere definition of the essence; it is added to it as a distinct fact, for every reality that is not God^[53]. It is this intuition, made precise and formalized, that structures the whole metaphysics of the Shifa.

The essence/existence distinction

Avicenna establishes a real distinction between essence (mahiyya, what a thing is) and existence (wujud, the fact that it is): for every created being, essence does not by itself imply existence, which must be conferred on it by an external cause^[54]. This thesis makes it possible to divide all beings into two fundamental categories: beings possible in themselves (mumkin al-wujud), whose existence depends on an external cause, and the being necessary in itself (wajib al-wujud), whose essence is identically existence, and which needs no cause in order to exist^[55]. Only this Necessary Being, according to Avicenna, fully deserves the name of God.

The "Proof of the Truthful" (burhan al-siddiqin)

From this distinction, Avicenna builds a famous demonstration of God's existence, known in the Islamic tradition as the Proof of the Truthful (burhan al-siddiqin): it proceeds by conceptual analysis of the notion of "existent" alone, without recourse to any particular empirical datum, neither motion nor efficient causality observed in the sensible world, unlike the classical Aristotelian ways^[56]. Every possible being, Avicenna shows, requires a cause that makes its existence actual; if that cause is itself possible, it in turn requires a cause; an infinite regress of merely possible causes cannot, in his view, explain why anything really exists rather than nothing. There must therefore be, at the end of the chain, a being whose existence is owed to nothing other than itself: the being necessary in itself^[57]. The Ignispedia article on the argument from contingency develops this argumentative structure in detail, including its adoption by Saint Thomas Aquinas in the third way of the Summa Theologiae; the article on "If God created everything, who created God?" explains why this distinction dissolves the popular objection that asks for a cause of the Necessary Being itself.

The emanation of the ten separate intelligences: a point of tension with the Catholic faith

On how the world proceeds from the Necessary Being, Avicenna adopts an emanationist scheme inherited, via al-Farabi, from Neoplatonism: from the necessary One flows, through a process of self-thinking, a first separate Intelligence, which in turn engenders, through an analogous movement, a second Intelligence and the corresponding celestial sphere, and so on down to ten Intelligences, the last being the Active Intellect which governs the sublunary world^[58].

This process, Avicenna insists, is not free in the sense that God might have chosen not to create, or to create otherwise: it flows necessarily from the very nature of the Necessary Being, so that the world, while depending ontologically on God at every instant, is coeternal with Him in time^[59].

It is precisely on this point that Avicenna's metaphysics departs most clearly from the Catholic doctrine of free creation ex nihilo, according to which God creates the world by a sovereignly free act of will, under no inner necessity constraining Him to do so, and in time rather than from all eternity. The historian of medieval philosophy Étienne Gilson, who devoted a large part of his work to tracing the Christian reception and critique of Avicenna, stresses that Latin scholasticism would take up the essence/existence distinction with enthusiasm, while firmly rejecting the necessitarian and emanationist framework in which Avicenna had set it^[60], a point developed further in this article and in the Ignispedia article on Étienne Gilson.

The "Flying Man" argument: the soul without the body

To establish that the human soul is an immaterial substance distinct from the body, Avicenna proposes, in the psychological section of the Shifa, a thought experiment that has remained famous as the "Flying Man" (al-insan al-ta'ir)^[61]:

"To establish the existence of the soul (...) one must imagine that one of us were created in a single stroke, whole and complete, but with his sight veiled so that he could not directly observe the things of the external world. He is created as if floating in the air or in the void, with the air not supporting him in any way he could feel, and the limbs of his body spread out and separated from one another, so that they do not come into contact or touch." — Avicenna, Kitab al-Shifa, De Anima (psychology), I, 1, English trans. Jon McGinnis and David C. Reisman, Classical Arabic Philosophy: An Anthology, Hackett Publishing, Indianapolis, 2007^[62]

Deprived of all sensation, sight, touch, even the perception of his own body, this suspended man would nonetheless affirm, without hesitation, the existence of his own self^[63]. Since he knows nothing of his body but cannot be unaware of the existence of his soul, Avicenna concludes, the soul must be a reality distinct from the body, not identical with it. The argument, often compared with the Cartesian cogito formulated six centuries later, has prompted renewed philosophical debate down to the present day. The contemporary Thomist philosopher Edward Feser, to whom the Ignispedia article is devoted, grants it real epistemological force, superior on some points to the Cartesian argument because it does not presuppose that sensory experience is impossible without a body, while observing that it requires, to be fully conclusive, further metaphysical commitments on the nature of self-knowledge which Avicenna does not fully establish in this passage alone^[64].

The theory of prophecy and the Active Intellect

Avicenna also develops an original theory of intellectual knowledge and prophecy: according to him, the human mind reaches universal truths through a form of conjunction with the Active Intellect, tenth and last of the separate Intelligences, which "illuminates" the human intellect and enables it to grasp in a flash, by intuition (hads), the middle term of a syllogism^[65]. In the most gifted minds, the prophets, this faculty of intuition reaches so high a degree that it allows an immediate and almost total knowledge, without prior discursive learning: this is how Avicenna explains philosophically, without seeing in it a miracle properly speaking, the phenomenon of prophetic revelation^[66].

Does God know particular things?

A controversial consequence of this system is the thesis that God knows the world in a universal way, not through direct knowledge of each particular thing taken in its concrete and changing singularity^[67]. For Avicenna, God's knowledge of individual things takes place "in a universal manner", through knowledge of the causes and general laws that produce them, rather than through immediate perception of each singular event, in the way God perceives what changes over time in traditional Islamic theology^[68]. It is precisely this thesis, judged incompatible with the idea of a divine providence attentive to each creature, that al-Ghazali would denounce as one of the gravest errors of Avicennian philosophy.

The Tahafut al-Falasifa: twenty theses refuted, three judged heretical

A generation after Avicenna's death, the theologian and mystic al-Ghazali (1058-1111) published The Incoherence of the Philosophers (Tahafut al-Falasifa), a systematic refutation of twenty theses of Islamic Peripatetic philosophy, drawn chiefly from al-Farabi and Avicenna^[69]. Seventeen of these theses are described as blameworthy innovation (bid'a); three, judged incompatible with the very foundations of the Muslim faith, are explicitly condemned as unbelief (kufr)^[70]:

This controversy, peculiar to the Islamic world, illuminates by contrast an issue Catholic theology meets in a related form: the need to hold together the metaphysical rigor borrowed from Greek philosophy and fidelity to a Revelation which affirms a personally provident God and a world freely created in time, a tension Latin scholasticism would face, a century later, confronted with the same Avicennian corpus.

Averroes defends the philosophers

A century after al-Ghazali, the Andalusian philosopher Averroes (Ibn Rushd, 1126-1198) would reply point by point in his own Tahafut al-Tahafut ("the Incoherence of the Incoherence"), defending the legitimacy of the philosophical enterprise against al-Ghazali's theological objections, while himself severely criticizing, on several points of doctrine, Avicenna's own positions, which he judges insufficiently faithful to authentic Aristotelianism. This discussion, central to understanding the history of classical Islamic philosophy, is developed in the Ignispedia article on Averroes.

Gerard of Cremona and the Toledo translation

The Canon of Medicine and a large part of the Shifa were translated into Latin at Toledo, in the 12th century, chiefly by Gerard of Cremona (d. 1187), a central figure of the school of translators which transmitted to the Latin West most of the Greco-Arab scientific and philosophical corpus^[71]. These translations circulated in Latin Europe from the late 12th century and the early 13th, even before the complete translation of Aristotle himself, so that, for a generation of Latin readers, Aristotle's metaphysics was first read through the prism of Avicenna^[72].

"Latin Avicennism": William of Auvergne, John of La Rochelle

In the first decades of the 13th century there developed, among several Parisian masters, the bishop William of Auvergne (d. 1249), the Franciscan John of La Rochelle, a current of thought which historians of medieval philosophy call Latin Avicennism: a Christian theology which massively borrows Avicenna's vocabulary and conceptual distinctions, notably on essence, existence and the soul, while striving to purge them of their emanationist and necessitarian implications incompatible with the Christian faith^[73]. William of Auvergne, in particular, explicitly takes up the Avicennian distinction between possible being and Necessary Being to build his own proof of God's existence, while firmly rejecting the eternity of the world and the necessity of emanation.

The Paris condemnations of 1210 and 1215

In 1210, the provincial synod of Sens, on which the bishop of Paris depended, forbade under pain of excommunication the public teaching at Paris of Aristotle's books on natural philosophy "and of their commentaries"^[74]. The formula targeted notably the Arab commentators, foremost among them Avicenna. This prohibition, strictly local in scope and limited to the faculty of arts, was renewed and made more precise in 1215 by the papal legate Robert of Courçon, who restructured the Paris university curriculum to limit students' exposure to the theses judged riskiest^[75]. It did not concern theologians, free to read these texts in order to refute them, and its real application remained uneven, but it attests the vigilance of the Latin ecclesiastical authorities in the face of the rapid spread of a metaphysics whose consequences (eternity of the world, necessitarianism, limits on providence) seemed directly to offend revealed faith, exactly as they had offended, a century earlier, al-Ghazali's theology in the Muslim world.

Albert the Great and Thomas Aquinas: taking over without espousing

It is in this climate of wary caution that Saint Albert the Great and his disciple Saint Thomas Aquinas worked, a generation later. Both read Avicenna attentively (Albert quotes him abundantly, notably on the theory of the Active Intellect creating the universality of concepts^[76]), and both take over, for its properly metaphysical core, the essence/existence distinction which would become in Thomas one of the pillars of his own doctrine of being. In his youthful treatise On Being and Essence, Thomas significantly opens his reflection by referring to Avicenna:

"Being and essence are what the intellect conceives first of all, as Avicenna says at the beginning of his Metaphysics." — Saint Thomas Aquinas, De Ente et Essentia, prologue, c. 1252-1256^[77]

But Thomas profoundly transforms what he receives. Where Avicenna makes existence something "added" from outside to an essence otherwise already fully intelligible in itself, a model sometimes described as "accidentalist" by commentators, Thomas makes the act of existing (actus essendi) the most intimate and most radical perfection of every being, not a mere superadded accident^[78].

Still more fundamentally, Thomas entirely rejects Avicenna's emanationist and necessitarian framework: for him, God creates the world not by a necessity of nature, but by a free act of His almighty will, and the world is not coeternal with God, even though Thomas admits, moreover, that unaided philosophical reason cannot by itself decide apodictically whether the world was created from all eternity or created in time, clearly distinguishing this point of faith from what natural reason can demonstrate. The Ignispedia article on the Summa Theologiae and the one on Saint Thomas Aquinas develop the Thomist third way and the doctrine of ipsum esse subsistens which arise, in part, from this critical rereading of Avicenna.

The judgment of the Catholic Encyclopedia (1907)

The assessment of Avicenna offered by the first great modern Catholic synthesis devoted to the history of philosophy, the 1907 Catholic Encyclopedia, sums up the classical position well: his thought is described as an "Aristotelianism mixed with Neo-Platonism"^[79], whose principles the scholastics admired while rightly mistrusting his exposition of Aristotle as a whole, in particular because of its pantheizing tendencies inherited from the emanationist scheme:

"The Scholastics, apparently, know nothing of the special work on pantheism; they were, however, aware of the pantheistic tendencies of Avicenna's other works on philosophy, and were, accordingly, reluctant to trust in his exposition of Aristotle." — William Turner, article "Avicenna", Catholic Encyclopedia, New York, Robert Appleton Company, 1907^[80]

Structure and method

The Canon of Medicine stands apart from earlier Galenic treatises by its systematic ambition: it organizes the whole of Greco-Arab medical knowledge in a single logical order, from the most general (physiology, anatomy, causes of diseases) to the most particular (pathologies localized organ by organ, formulary of compound medicines)^[81]. This rigorous architecture, allied with a style of remarkable pedagogical clarity for the period, largely explains its lasting success in teaching.

Reception in Europe: from the medieval universities to Vesalius

Translated and diffused in Latin Europe from the late 12th century, the Canon quickly became a pillar of the medical curriculum in Western universities, alongside the works of Galen and Hippocrates. It was printed at Venice between 1493 and 1495^[82], went through many Latin and Hebrew reeditions up to the 16th century, and remained taught, in whole or in part, in several European medical faculties, notably at Montpellier, until the middle of the 17th century^[83]. This prolonged authority did not exempt it from criticism: in the 16th century, the anatomist Andreas Vesalius, on the strength of direct dissections, corrected several anatomical errors transmitted by the Galeno-Avicennian tradition, while the Swiss physician Paracelsus broke spectacularly, symbolically by burning a copy of the Canon, with the whole of medieval Greco-Arab medical authority^[84], two classic milestones in the birth of modern medicine, which measure, in negative, the extent of the authority Avicenna's work had exercised for nearly six centuries.

A considerable scientific and philosophical legacy

Beyond theological controversy, Avicenna's contribution to the history of thought remains considerable and widely recognized, including by his most rigorous doctrinal adversaries: encyclopedic systematization of ancient medical knowledge, rigorous formalization of Aristotelian logic, the essence/existence distinction which still structures a good part of classical metaphysics today, the "Flying Man" argument which continues to nourish contemporary philosophy of mind. Few non-Christian thinkers have left so deep and so lasting an imprint on the Western understanding of being and of God.

What the Catholic faith retains, what it cannot receive

An honest Catholic view of Avicenna must hold together two equally necessary judgments. On the one hand, the essence/existence distinction, once purified of its necessitarian framework by Saint Thomas Aquinas, has become one of the most precious conceptual tools of classical theism, that of Augustine, Anselm, Thomas and, in his own way, Maimonides, for thinking God as subsistent Being itself (Ipsum Esse Subsistens), by contrast with the more fragile representations of a God conceived simply as one cause among others^[85]. On this precise point, the Ignispedia article on Edward Feser recalls how alive this classical metaphysical heritage remains in contemporary philosophical apologetics.

On the other hand, the emanationist and necessitarian framework in which Avicenna sets this distinction, a world which proceeds from God by necessity of nature, coeternal with Him, governed by intermediate intelligences rather than directly provided for with regard to each singular creature, is irreducibly distinct from the Catholic doctrine of free creation ex nihilo and of God's particular providence over each person. This is exactly the point denounced, from inside Islam itself, by al-Ghazali; it is also the point which Latin scholasticism, in taking up the essence/existence distinction while rejecting its emanationist packaging, discerned with remarkable intellectual lucidity. Receiving Avicenna's metaphysical rigor without espousing its cosmological conclusions incompatible with Revelation: such was, on this precise dossier, the approach of the greatest doctors of the Church, and it remains, eight centuries later, the model of a demanding dialogue between philosophical reason and revealed faith.

• The argument from contingency — the demonstrative structure which Avicenna's Necessary Being/possible being shares with Aristotle, Anselm and Thomas Aquinas
• "If God created everything, who created God?" — why the Necessary Being through itself dissolves this popular objection
• Why could there not be several gods? — divine uniqueness demonstrated by necessity of existence
• The Summa Theologiae of Saint Thomas Aquinas — the five ways and the doctrine of ipsum esse subsistens
• Saint Thomas Aquinas — the life and work of the doctor who takes up and transforms Avicenna's essence/existence distinction
• Maimonides — another great medieval reader of the Shifa, on negative theology and divine uniqueness
• Étienne Gilson — the historian who contributed most to tracing the Latin reception of Avicenna
• Saint Albert the Great — one of the first great scholastic readers of Avicenna
• Rémi Brague — on the transmission of Greek philosophy through the Arabo-Muslim world
• Edward Feser — classical theism today, and the contemporary appreciation of the "Flying Man" argument
• Ibn Arabi — another great name of medieval Islamic thought, a Sufi mystic distinct from Avicenna in period and in doctrine