Philosopher
Last reviewed:
c. 980–1037 · Islamic Aristotelianism · Medieval
Ibn Sina, known in Latin Europe as Avicenna, was a Persian philosopher and physician of the late tenth and early eleventh centuries. He wrote in Arabic on medicine, logic, metaphysics, and the soul. The Canon of Medicine shaped medical teaching far beyond the Islamic world. The Book of Healing is his philosophical summa, and inside its psychology sits the floating man, a thought experiment in which a person created in mid-air, seeing and touching nothing, would still affirm that he exists.
Ibn Sina uses the scene to argue that the self one affirms is not identical with a body one senses. He built on Aristotle as read through late antique commentators and through al-Farabi, and he developed a metaphysics of necessary and contingent existence that Latin scholastics both used and feared. He is not a mystic in the floating-man passage, and he is not an early Descartes.
The English of that passage in this library is a condensation of a longer argument, not a single canonical sentence, which is why his quotable page stays short.
The floating man in the Psychology of the Book of Healing is a thought experiment of several sentences, and the English already here is a condensation, not one canonical line. A card for the necessary existent would have to invent a short English for an argument in the Metaphysics. Further slogans would misrepresent both passages.
The floating-man passage in a full translation of the psychology, with a note on his metaphysics of the necessary existent
The experiment is the line people meet, and it is unintelligible as a selfie. The metaphysics explains what kind of soul he thinks the experiment reveals.
“One of us must imagine himself so as to be created all at once and perfect, but with his sight veiled so that he cannot see anything external, and floating in the air, so that he feels nothing. Would he affirm the existence of his self? He would not doubt the affirmation of his self.”
Ibn Sīnā (Avicenna) · Islamic Aristotelianism
“Medicine is the science by which we learn the various states of the human body, in health and when not in health, and the means by which health is likely to be lost and, when lost, is likely to be restored.”
Ibn Sīnā (Avicenna) · Islamic Aristotelianism
“The knowledge of anything, since all things have causes, is not acquired or complete unless it is known by its causes.”
Ibn Sīnā (Avicenna) · Islamic Aristotelianism
“The necessary existent is that which, when it is assumed not to exist, an absurdity results. The possible existent is that which, when it is assumed either to exist or not to exist, no absurdity results.”
Ibn Sīnā (Avicenna) · Islamic Aristotelianism
“We say: the soul is the first perfection of a natural body possessed of organs, which has life potentially.”
Ibn Sīnā (Avicenna) · Islamic Aristotelianism
Floating man
A mind cut off from every sensation would still affirm its own existence, so the self affirmed is not simply the body sensed.
Necessary existence
God is necessary existence itself, and everything else exists through another and is contingent.
Soul and intellect
The rational soul has an activity that is not the act of a bodily organ, which is why it can survive the body's dissolution on his account.
The Book of Healing (c. 1020s)
A philosophical encyclopaedia. The floating man is in the psychology, the book on the soul.
The Canon of Medicine (c. 1025)
The medical summa by which Latin and Islamic physicians knew him for centuries.
Pointers and Reminders (later in his career)
A tighter philosophical work, including the last sections on the knower's path, read with care about genre.
None of the lines this library files for Ibn Sīnā (Avicenna) is marked Questionable or Misattributed. That is only a fact about these cards. It is not a certificate that every popular sentence is theirs.
The floating-man passage in a full translation of the psychology, with a note on his metaphysics of the necessary existent The experiment is the line people meet, and it is unintelligible as a selfie. The metaphysics explains what kind of soul he thinks the experiment reveals.
This library does not measure fame, and it does not rank lines by how often they are shared. The first line it files for Ibn Sīnā (Avicenna) that is not marked Questionable or Misattributed is “One of us must imagine himself so as to be created all at once and perfect, but with his sight veiled so that he cannot see anything external, and floating in the air, so that he feels nothing. Would he affirm the existence of his self? He would not doubt the affirmation of his self.” (The Book of Healing, Psychology (Kitāb al-Nafs), the floating man, Paraphrase or translation).
None of the lines this library files for Ibn Sīnā (Avicenna) is marked Misattributed or Questionable. That is a fact about these cards, not a certificate that every popular sentence is theirs.
Floating man: A mind cut off from every sensation would still affirm its own existence, so the self affirmed is not simply the body sensed.