Avicenna: Philosophy, Quotes & Legacy

Biography

Abu Ali al-Husayn ibn Abd Allah ibn Sina, known in the West as Avicenna, was born in 980 CE near Bukhara, in the region of present-day Uzbekistan, then part of the Samanid Empire. His father was a local governor from the town of Balkh, and the family had connections to the Ismaili movement, though Avicenna himself followed the mainstream Sunni tradition and devoted himself to the Peripatetic philosophy of Aristotle as transmitted and interpreted in the Islamic world. He was a child prodigy of legendary proportions: he claimed to have memorized the Qur'an by the age of ten, and by sixteen he had mastered logic, mathematics, physics, and medicine, studying the works of Aristotle and the commentaries of the Islamic philosophers who had preceded him, notably al-Farabi.

Avicenna's life was shaped by the political instability of his time. He served as a physician and administrator to a succession of rulers — the Samanid court at Bukhara, then the courts of various Buyid and local princes in Persia — and he was frequently forced to move as dynasties rose and fell. His service as a physician gave him access to libraries and patrons, and his medical reputation became legendary. He wrote on almost every subject of the knowledge of his age: logic, natural philosophy, psychology, metaphysics, theology, astronomy, music, and above all medicine, where his Canon of Medicine (al-Qanun fi al-Tibb) became the standard textbook in European universities for six centuries.

Avicenna died in 1037 in Hamadan, in present-day Iran, of a colic complicated by his legendary lifestyle of overwork. He was fifty-seven years old. By the time of his death he had produced an enormous corpus — over four hundred works, of which about two hundred survive — and had established a philosophical system that dominated the Islamic East for centuries and shaped the Latin scholastic tradition through the translations of the twelfth and thirteenth centuries, where he was known simply as "the Prince" or "the Chief."

Historical Context

Avicenna wrote at the culmination of the first great period of Islamic philosophy. The Abbasid caliphate had sponsored the translation of the Greek philosophical and scientific corpus into Arabic in the eighth and ninth centuries, and by the tenth century a distinct Islamic philosophical tradition had emerged, represented above all by al-Kindi and al-Farabi. Al-Farabi had established the program: reconcile Aristotle with the requirements of Islamic monotheism, and defend the rational study of philosophy against its religious critics. Avicenna inherited this program and transformed it into a complete system.

The intellectual context was shaped by two pressures. The first was internal to philosophy: the need to make sense of Aristotle's metaphysics, especially the obscure doctrine of the Unmoved Mover, in terms compatible with the Islamic doctrine of a creator God. The second was external: the rise of theological orthodoxy (kalam) and of movements suspicious of Greek philosophy, which would culminate in al-Ghazali's attack on the philosophers a generation after Avicenna's death. Avicenna's system was designed to answer both: a metaphysics that could ground the existence of God without compromising God's transcendence, and a philosophical psychology that could accommodate the Islamic doctrine of the individual soul.

Core Ideas

The Flying Man

Avicenna's most famous contribution to philosophy is the flying man argument, presented in the De Anima of his Book of Healing. The thought experiment asks the reader to imagine a person created all at once, fully formed, but suspended in the air with all senses blocked — no sight, no hearing, no touch. Would such a person still be aware of himself? Avicenna answers yes: the person would affirm "I exist" even with no sensory input whatsoever. The argument establishes two claims: that self-awareness is immediate and not derived from the senses, and that the self is not identical with the body. The flying man has been recognized since the nineteenth century as a striking anticipation of Descartes's cogito, and it makes Avicenna a founding figure of the philosophy of self-awareness.

Essence and Existence

Avicenna's central metaphysical innovation is the distinction between essence (mahiyya) and existence (wujud). In created things, the two are distinct: a thing's essence — what it is — does not entail its existence — that it is. The essence of a horse does not guarantee that any horse exists. This distinction, which Avicenna made explicit and systematic, became one of the most important doctrines of medieval philosophy, East and West. It also grounds his proof of God: if existence is not contained in essence, then whatever exists does so through something else — an efficient cause — and the chain of causes must terminate in a being whose essence is identical with its existence, a being that exists necessarily. This is Avicenna's God: the Necessary Existent (wajib al-wujud), the first cause whose essence is existence itself.

The Necessary Existent

Avicenna's metaphysics culminates in the doctrine of the Necessary Existent. Everything other than God is contingent: it might not have existed, and its existence must be explained by a cause. But the chain of contingent causes cannot be infinite; it must terminate in a being that does not need a cause — a being whose existence is necessary. This being is unique, simple, and perfect: it is pure existence, without matter, without potentiality, without composition. Avicenna's proof of God is cosmological in structure but distinctive in its use of the essence-existence distinction. It became the standard proof of God's existence in the Islamic philosophical tradition and, through the Latin translations, one of the sources of Thomas Aquinas's own cosmological arguments.

The Soul and the Intellect

Avicenna's psychology is the other pillar of his system. The human soul is a substance, not merely a form of the body: it is the principle of life and cognition, and it is separable from the body. Its highest faculty is the intellect, which has two operations: the abstractive intellect, which draws universals from particulars given by the senses, and the agent intellect, the cosmic principle that illuminates the mind and makes abstraction possible. On this Neoplatonic-cum-Aristotelian model, human knowledge is a participation in a cosmic intellectual order. The individual soul, being immaterial, survives the death of the body — a conclusion that aligned Avicenna's philosophy with the Islamic doctrine of the afterlife while remaining philosophically controversial.

Philosophy

Avicenna's philosophy is best understood as a systematic synthesis of Aristotle and Neoplatonism, organized for the purposes of monotheistic theology. From Aristotle he took the framework: logic, the categories, the physics of matter and form, the psychology of the faculties, and the metaphysics of substance. From the Neoplatonic tradition, transmitted through the so-called Theology of Aristotle (actually a paraphrase of Plotinus), he took the hierarchical cosmology of emanation and the theory of the agent intellect. His genius was to weld these elements into a system in which philosophy and religion are not rivals but two expressions of a single truth.

The system rests on the essence-existence distinction, which does the double work of explaining createdness and grounding the proof of God. Everything that exists, other than God, is a composite of essence and existence: its essence is a possibility that has been actualized. God alone is existence without essence, pure act. The universe flows from God through a series of ten intellects, each of which emanates a sphere and its soul, down to the agent intellect that illuminates human minds. The human being is the point of juncture: embodied in the physical world, the soul ascends through knowledge toward the intelligible order, and its happiness consists in the perfection of the intellect — the vision of the truth.

Major Works

Avicenna's two great encyclopedias dominate his corpus. The Book of Healing (Kitab al-Shifa), written around 1027, is a vast philosophical encyclopedia covering logic, natural philosophy, mathematics, and metaphysics; its De Anima contains the flying man argument. The Canon of Medicine (al-Qanun fi al-Tibb), completed around 1025, is the most influential medical textbook ever written: it systematized the medicine of Galen and the Islamic physicians and remained the standard European medical authority until the seventeenth century. The Book of Deliverance (Kitab al-Najat) and the Book of Guidance (Kitab al-Hidaya) are summaries of his philosophy for students, and the Pointers and Reminders (al-Isharat wa al-Tanbihat), written late in his life, presents his philosophy in its most condensed and most personal form. His famous autobiography, completed by his student al-Juzjani, is one of the great intellectual self-portraits of the Middle Ages.

Famous Quotes

Avicenna's most famous philosophical passage is the flying man argument, which asks whether "one of us" suspended in the air with no senses would still affirm his own existence. His most famous metaphysical formulation is the claim that "existence is an accident of essence" — the doctrine that for everything other than God, existence is added to essence from outside. And his epitaph, in the autobiographical account, captures his restless ambition: "I have never been able to sleep a whole night through in the course of my life; and I have never done anything in my life that has given me more satisfaction than the writing of my books."

Related Thinkers

Avicenna stands at the head of the classical Islamic philosophical tradition. He transformed the program of al-Farabi, whose commentary on Aristotle he mastered as a youth, and his system was attacked by Al-Ghazali in the Incoherence of the Philosophers and defended by Averroes in the Decisive Treatise — the three together define the great debate of medieval Islamic philosophy. His relation to Aristotle is the foundation of everything: he was the Islamic world's greatest interpreter of the Philosopher, and through the Latin translations his commentaries shaped the reading of Aristotle in the medieval West, where he influenced Thomas Aquinas and Duns Scotus as much as any Islamic thinker.

Sources

• Stanford Encyclopedia of Philosophy, "Ibn Sina" (plato.stanford.edu/entries/ibn-sina)
• Internet Encyclopedia of Philosophy, "Avicenna (Ibn Sina)" (iep.utm.edu/avicenna-ibn-sina)
• Avicenna. The Book of Healing, De Anima. Trans. F. Rahman, Avicenna's Psychology. London: Oxford University Press, 1952.
• Goodman, Lenn E. Avicenna. London: Routledge, 1992.