Philosopher · Medieval
Avicenna (Ibn Sina)
980–1037 · Islamic Neoplatonic Aristotelianism (falsafa)
The philosopher St. Thomas cites most after Aristotle and Augustine; his distinction of essence and existence is the ground of Thomas's own.
Physician and philosopher whose “Book of Healing” and “Canon of Medicine” ruled East and West for five centuries. He proved God as the Necessary Existent from whom all possible beings receive existence, distinguished essence from existence in creatures, taught the soul's immateriality by the “floating man,” and held that the world emanates from God necessarily and eternally through the intelligences.
Why he matters: Without him there is no Thomism: the essence–existence distinction, the Necessary Being, and the analysis of the soul all come through him. He is also where the Church met Islam as philosophy rather than as arms.
Where to be careful
Necessary emanation denies free creation; God knows only universals; and the resurrection of the body is doubted. Al-Ghazali condemned him on these three points, and so, with more care, did the Church through Thomas.
Documented positions
Where this thinker stands on each dispute the test covers.