Ibn Sina (c. 980-1037), known in the Latin West as Avicenna, was a Persian polymath whose works in philosophy, medicine, and natural science shaped both Islamic intellectual tradition and European scholasticism for several centuries. Born near Bukhara in the Samanid Empire (present-day Uzbekistan), he produced an estimated 450 works across medicine, logic, metaphysics, psychology, astronomy, and poetry. His two most influential texts - the Kitab al-Shifa (Book of Healing, a philosophical encyclopedia) and the Al-Qanun fi al-Tibb (Canon of Medicine) - remained standard reference works in both Islamic and European universities well into the 17th century.

Avicenna synthesized Aristotelian philosophy with Neoplatonism and Islamic theology, producing a systematic framework that later thinkers had to engage with or argue against. His metaphysics introduced a sharp distinction between essence and existence - the claim that existence is not part of what a thing is but is something added to it - an idea that influenced Thomas Aquinas and the broader scholastic tradition. His proof for the existence of God via the concept of the Necessary Being (wajib al-wujud) became a durable argument in both Islamic kalam and Christian natural theology.

His thought experiment of the “Flying Man” - imagining a person created in the air, deprived of all sensory input, who would nonetheless be aware of his own existence - anticipates later arguments about self-knowledge and the immateriality of the soul, and has been compared to Descartes' cogito. His psychology distinguished the rational soul from the body while attempting to account for its operations in naturalistic terms, a tension that later interpreters resolved differently.

The Canon of Medicine organized Greek, Islamic, and original medical knowledge into a structured system covering general principles, simple drugs, organ-specific diseases, systemic diseases, and compound drugs. It was translated into Latin in the 12th century and used as a medical textbook at European universities including Bologna and Montpellier. Avicenna's recognition of the contagious nature of some diseases, the role of soil and water in spreading illness, and the importance of quarantine placed him ahead of the prevailing humoral framework in several respects, though his work remained embedded in that framework overall.

Avicenna's reception has varied significantly by tradition and era. In the Islamic world, his philosophy was sharply criticized by al-Ghazali in The Incoherence of the Philosophers (1095), which charged that several Avicennan positions - including the eternity of the world and the denial of bodily resurrection - were incompatible with orthodox Islamic belief. Averroes later defended a stricter Aristotelianism against what he saw as Avicenna's Neoplatonist distortions. In Latin Europe, his works entered through the translation movement centered in Toledo, and his influence on scholastic philosophy was substantial, though later figures such as Aquinas adopted his ideas selectively and critically. See Avicenna - History for a fuller account of his life and the transmission of his work.

• Soul as Immaterial Substance - The view, associated with Avicenna himself and adopted by many scholastics, that the rational soul is a simple, immaterial substance not reducible to body or its functions.
• Naturalist Reading - Some historians of philosophy interpret Avicenna's psychology as a sophisticated attempt to explain mental phenomena in terms compatible with natural science, rather than as straightforwardly dualist.
• Islamic Orthodoxy Critique - The position, most forcefully advanced by al-Ghazali, that Avicenna's synthesis of Greek philosophy with Islamic thought introduced ideas irreconcilable with revealed religion.
• Avicenna as Proto-Modern - Some scholars read the Flying Man argument and the essence-existence distinction as anticipating modern philosophy of mind and existentialist themes; others reject this as anachronistic.

• Avicenna - History
• Avicenna - Debate
• Scholasticism
• Al-Ghazali
• Averroes
• Thomas Aquinas
• Islamic Philosophy
• Aristotle
• History of Medicine

1. Goichon, A.M. “Ibn Sina.” Encyclopaedia of Islam, 2nd ed. Brill, 1971.
2. Gutas, Dimitri. Avicenna and the Aristotelian Tradition. Brill, 1988.
3. McGinnis, Jon. Avicenna. Oxford University Press, 2010.
4. al-Ghazali. Tahafut al-Falasifa (The Incoherence of the Philosophers). Trans. Michael Marmura. Brigham Young University Press, 2000.
5. Siraisi, Nancy G. Avicenna in Renaissance Italy. Princeton University Press, 1987.
6. Hasse, Dag Nikolaus. Avicenna's De Anima in the Latin West. Warburg Institute, 2000.