Ammonius Hermiae (Greek: Ἀμμώνιος ὁ Ἑρμείου; c. 440-c. 520) was a Greek philosopher, and the son of the Neoplatonist philosophers Hermias and Aedesia. He was a pupil of Proclus in Athens, and taught at Alexandria for most of his life, writing commentaries on Plato, Aristotle, and other philosophers.
Ammonius' father, Hermias, died when he was a child, and his mother, Aedesia, raised him and his brother, Heliodorus, in Alexandria. When they reached adulthood, Aedesia accompanied her sons to Athens where they studied under Proclus. Eventually, they returned to Alexandria, where Ammonius, as head of the Neoplatonist school in Alexandria, lectured on Plato and Aristotle for the rest of his life. According to Damascius, during the persecution of the pagans at Alexandria in the late 480's, Ammonius made concessions to the Christian authorities so that he could continue his lectures. Damascius, who scolds Ammonius for the agreement that he made, does not say what the concessions were, but it may have involved limitations on the doctrines he could teach or promote. He was still teaching in 515, since Olympiodorus heard him lecture on Plato's Gorgias in that year. He also taught Asclepius of Tralles, John Philoponus, Damascius and Simplicius.
Of his reputedly numerous writings, only his commentary on Aristotle's De Interpretatione survives intact. A commentary on Porphyry's Isagogue may also be his, but it is somewhat corrupt and contains later interpolations.
In De Interpretatione, Ammonius contends that divine foreknowledge makes void the contingent. Like Boethius in his second Commentary and The Consolation of Philosophy, this argument maintains the effectiveness of prayer. Ammonius cites Iamblichus who said knowledge is intermediate between the knower and the known, since it is the activity of the knower concerning the known.
In addition, there are some notes of Ammonius' lectures written by various students which also survive:
* On Aristotle's Categories (anonymous writer)
* On Aristotle's Prior Analytics I (anonymous writer)
* On Aristotle's Metaphysics 1-7 (written by Asclepius)
* On Nicomachus' Introduction to Arithmetic (written by Asclepius)
* On Aristotle's Prior Analytics (written by John Philoponus)
* On Aristotle's Posterior Analytics (written by John Philoponus)
* On Aristotle's On Generation and Corruption (written by John Philoponus)
* On Aristotle's On the Soul (written by John Philoponus)
He was also an accomplished astronomer; he lectured on Ptolemy and is known to have written a treatise on the astrolabe.