Skip to main content

Alexander of Aphrodisias°


ALEXANDER OF APHRODISIAS ° (end of second century–beginning of third century c.e.), Greek philosopher, commentator on the writings of *Aristotle, and author of independent works. Alexander was important for his systematization of Aristotle's thought and for the formulation of a number of distinct doctrines, especially in psychology. A number of his commentaries and independent works were translated into Arabic, and the views contained in them became an important part of medieval Islamic and Jewish Aristotelianism. The first book of Alexander's On the Soul was translated into Hebrew by Samuel ben Judah of Marseilles from the Arabic translation made by Ḥunain ibn Isḥaq. This translation, which contains brief annotations, was completed in 1323 in Murça and a revised version of it was finished in 1339–40 in Montùlimar.

Alexander, it was commonly thought, wrote a second book in psychology, called Treatise on the Intellect, and it circulated in Arabic translation. Averroes wrote a commentary to this work that was translated into Hebrew and is extant in manuscript only with the supercommentaries of *Moses b. Joshua of Narbonne (1344) and Joseph b. Shem Tov *Ibn Shem Tov (1454). H.A. Davidson edited the Averroean portions of the commentary themselves, without these supercommentaries, in 1988.

*Maimonides' estimation of Alexander may be gathered from a famous letter which he wrote to Samuel ibn *Tibbon. Evaluating the philosophical literature of the day, Maimonides advises his translator that for a correct understanding of Aristotle's teachings he should read, beside the commentaries of *Themistius and Averroes, also those of Alexander (A. Marx, in jqr, 25 (1934/35), 378). Maimonides used works by Alexander in the composition of his Guide, and Alexander's views formed part of Maimonides' own brand of Aristotelianism (for details see S. Pines, "Translator's Introduction," Guide of the Perplexed (1963), ixiv–ixxv). Maimonides cites Alexander as his source for his discussion of the factors which prevent man from discovering the truth (Guide 1:31), for his account of the celestial motions and intelligences (2:3), for his knowledge of the views of certain Greek philosophers (2:13), and for his discussion of God's knowledge (3:16). Alexander may also have influenced Maimonides' views on religion and political history, particularly the view that God used "wily graciousness" in bringing man from inferior forms of worship to more adequate ones (3:32).

Of special importance for Jewish philosophers was Alexander's doctrine of the intellect, discussed in detail particularly by *Gersonides (Wars of the Lord, Book 1). Aristotle's views (especially De Anima 3:5) were rather enigmatic. Central to Aristotle's discussion was the distinction between the agent intellect (nous poietikos) and the passive intellect (nous pathetikos). Interpreting Aristotle's views, Alexander held that the agent intellect did not form part of the individual human soul, but was identical with the intellect of God; while the passive intellect belonged to the soul as a mere predisposition or ability for thought. The passive intellect was also called material or hylic intellect (nous hylikos), and when actualized by the agent intellect became the acquired intellect (nous epiktetos) or intellect in habit (nous kath'hexin). The passive intellect, according to Alexander, being part of the individual human soul, is, like it, mortal; only the acquired intellect is immortal, insofar as the objects of its thought are the immaterial beings, in particular, God. While Alexander's doctrine of the intellect was more precise than that of Aristotle, it contained enough ambiguities to give rise to further refinements on the part of Islamic and Jewish philosophers.

Jewish, as Islamic, philosophers accepted Alexander's notion of the agent intellect, but instead of identifying it with God, they identified it with the lowest of the celestial intelligences, which, on the one hand, governs the sublunar world, and, on the other, is a causal agent in the production of human knowledge (see also *cosmology). The agent intellect is also important to Jewish Aristotelians for its roles in the production of prophecy. While there was general agreement about the nature of the agent intellect, there was disagreement about the nature of the passive one. Alexander's acquired intellect became a commonplace in Jewish philosophy, though the medievals refined this notion by distinguishing between the intellect in actuality, and the acquired intellect. Medieval philosophers disagreed about the exact nature of the acquired intellect, but it became important for their doctrine of the immortality of the *soul and the world to come (for details see *Intellect, Doctrines of).


P. Moraux, Alexandre d'Aphrodises, exégète de la noétique d'Aristote (1942); R. Walzer, Greek into Arabic (1962), index; Steinschneider, Uebersetzungen, index; idem, Die arabischen Uebersetzungen aus dem Griechischen (1893), 93–97; J. Finnegan, in: Mélanges de l'Université St. Joseph, 33 (1956), 159–62; E.I. Freudenthal, Die durch Averroes erhaltenen Fragmente Alexanders zur Metaphysik des Aristoteles (1885); A. Guensz, Die Abhandlung Alexanders von Aphrodisias ueber den Intellekt (1886). add. bibliography: A.P. Fotinis, The De Anima of Alexander of Aphrodisias (1979); A.H. Armstrong, The Cambridge History of Later Greek and Early Medieval Philosophy (1967), 117–23; H.A, Davidson, Alfarabi, Avicenna, and Averroes, on Intellect (1992), 20–24; idem, "Averroes' Commentary on the De Intellectu Attributed to Alexander," in: Shlomo Pines Jubilee Volume (1988), 205–17.

[Julius Guttmann /

Alfred L. Ivry (2nd ed.)]

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Alexander of Aphrodisias°." Encyclopaedia Judaica. . 18 Aug. 2018 <>.

"Alexander of Aphrodisias°." Encyclopaedia Judaica. . (August 18, 2018).

"Alexander of Aphrodisias°." Encyclopaedia Judaica. . Retrieved August 18, 2018 from

Learn more about citation styles

Citation styles gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, cannot guarantee each citation it generates. Therefore, it’s best to use citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

The Chicago Manual of Style

American Psychological Association

  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.