Alexander of Aphrodisias

“Alexander was a Peripatetic philosopher and commentator, active in the late second and early third century CE. He continued the tradition of writing close commentaries on Aristotle’s work established in the first century BCE by Andronicus of Rhodes, the editor of Aristotle’s ‘esoteric’ writings, which were designed for use in his school only. This tradition reflected a gradual revival of interest in Aristotle’s philosophy, beginning in the late second century BCE, and helped to reestablish Aristotle as an active presence in philosophical debates in later antiquity. Aristotle’s philosophy had fallen into neglect and disarray in the second generation after his death and remained in the shadow of the Stoics, Epicureans, and Academic skeptics throughout the Hellenistic age. Andronicus’ edition of what was to become the Corpus Aristotelicum consolidated a renewed interest in Aristotle’s philosophy, albeit in a different form: active research was replaced by learned elucidations of The Philosopher’s difficult texts. The commentaries themselves served as material for the exposition of Aristotle’s work to a restricted circle of advanced students. Hence each generation of teachers produced their own commentaries, often relying heavily on their predecessors’ work. Thus, the ‘scholastic’ treatment of authoritative texts that was to become characteristic of the Middle Ages had already started in the first century BCE. Alexander, due to his meticulous and philosophically astute exegesis of a wide range of Aristotle’s texts, in logic, physics, psychology, metaphysics and ethical topics, became known as the exemplary commentator throughout later antiquity and the Arabic tradition. He is often referred to simply as ‘The Commentator’ (ho exêgetês), later sharing this title with Avicenna or Averroes. Because there is little evidence on Alexander’s life and activities, his commentaries and his short treatises on topics related more or less closely to Aristotelian doctrine provide all the information we have about him as a philosopher and a man. As these writings show, his main contemporary opponents were the Stoics, but there is also some evidence of a controversy with Galen. Alexander is not only regarded as the best of the ancient commentators but also as the last strictly Aristotelian one, whose aim was to present and defend Aristotle’s philosophy as a coherent whole, well suited to engage contemporary philosophical discussions. The later commentators were members of the Neoplatonist schools and were concerned to document the substantial agreement of Platonic and Aristotelian thought, and to integrate Aristotle’s work into their Neoplatonist philosophical system. But they continued not only to consult, discuss, but also to criticize, Alexander’s work, a fact that probably accounts for its survival.


As the list of his work shows, Alexander was a prolific writer. His writings comprise both commentaries (hupomnêmata) on the works of Aristotle and several systematic treatises of his own (including works on ‘problems’, consisting of series of essays on different Aristotelian texts and topics). Of the commentaries, the following are extant: On Prior Analytics I, Topics, Metaphysics, Meteorologica, and On Sense Perception. Of the commentary on the Metaphysics only the first five books are by general consent accepted as genuine; the remaining nine books are attributed to the late commentator Michael of Ephesus (11th-12th century CE.). The commentary on the Sophistical Refutations, ascribed to Alexander in some manuscripts, is considered spurious. References by later commentators show that Alexander’s commentaries covered all of Aristotle’s theoretical philosophy, including his physical writings (with the exception of the biological works). The list of his lost work is long: there are references to commentaries on the Categories, De interpretatione, Posterior Analytics, Physics, and On the Heavens, as well as On the Soul and On Memory. Alexander did not write commentaries on Aristotle’s Ethics or Politics, nor on the Poetics or the Rhetoric. That he had quite some interest in ethical problems, however, is witnessed by the discussions in his own treatises. Among the extant short systematic writings the following are regarded as genuine: Problems and Solutions, Ethical Problems, On Fate, On Mixture and Increase, On the Soul and a Supplement to On the Soul (‘Mantissa’ lit. ‘make-weight’) that not only contain discussions of questions concerning psychology but also problems in physics, ethics, vision and light, as well as fate and providence. The ‘Mantissa’ may not be by Alexander but a compilation of notes by his students. The rest, Medical Questions, Physical Problems, and On Fevers are considered spurious. Of his lost works some have been preserved in Arabic because they were highly influential (see D’Ancona & Serra 2002): On the Principles of the Universe, On Providence, Against Galen on Motion, and On Specific Differences. Because of Alexander’s prestige and authority as an interpreter of Aristotle, many of his works now lost were incorporated in the commentaries of his successors, whether they name him or not. Nothing certain is known about the relative chronology of his writings, but this is not an issue of much importance, since his commentaries may well represent the results of many years of teaching, with later insertions and additions, in a way quite similar to Aristotle’s own texts. This would explain the lack of any attempt at elegance and the occurrence of inconsistencies or unclear transitions in Alexander.

In general, Alexander goes on the assumption that Aristotelian philosophy is a unified whole, providing systematically connected answers to virtually all the questions of philosophy recognized in his own time. Where there is no single, clearly recognizable Aristotelian point of view on some question, he leaves the matter undecided, citing several possibilities consistent with what Aristotle says. Sometimes Alexander tries to force an interpretation that does not obviously agree with the text, but he avoids stating that Aristotle contradicts himself and, with rare exceptions, that he disagrees with him. Readers will not always be convinced by his suggestions but they will often find them helpful and informative where Aristotle is overly compressed and obscure. As a remark in his commentary on the Topics shows, Alexander was quite aware that his style of philosophic discussion was very different from that of the time of Aristotle (In top. 27,13): “This kind of speech [dialectic refutation] was customary among the older philosophers, who set up most of their classes in this way — not on the basis of books as is now done, since at the time there were not yet any books of this kind.” As this explanation indicates, however, he seems to have regarded the bookishness of his own time as an advantage over the dialectic style rather than a disadvantage.

Like the other commentaries in the ancient tradition, Alexander’s derive from his courses of lectures (‘readings’) on Aristotle’s works. In commenting, Alexander usually refrains from giving comprehensive surveys. He generally starts with a preface on the work’s title, its scope and the nature of the subject matter. He then takes up individual passages in rough succession by citing a line or two (this provides the ‘lemma’ for the ensuing discussion) and explaining what he considers as problematic (in explanatory paraphrases, clarifications of expressions, or refutations of the views of others), often in view of what Aristotle says about the issue elsewhere. This procedure clearly presupposes that the students had their own texts at hand and were sufficiently familiar with Aristotle’s philosophy as a whole. Alexander does not generally go through the text line by line, but chooses to discuss certain issues while omitting others. Paraphrases are interrupted by clarifications of terminology, and sometimes, at crucial points, by notes on divergent readings in different manuscripts and a justification of his own preference concerning Aristotle’s original words. Decisions on such philological problems are based on what makes better sense in conforming with Aristotle’s intentions here or elsewhere. As Alexander indicates, such philological explorations were considered as part of the commentator’s work (cf. On Aristotle Metaphysics A, 59, 1–9): “The first reading, however, is better; this makes it clear that the Forms are causes of the essence for the other things, and the One for the Forms. Aspasius relates that the former is the more ancient reading, but that it was later changed by Eudorus and Euharmostus.” Alexander’s concern with textual problems makes him a valuable source for textual criticism, as can be seen from Kotwick’s (2016) monograph on the text of Aristotle’s Metaphysics.

Though Alexander follows the Aristotelian texts quite conscientiously, he often concentrates on special points and the respective passages while passing over others with brief remarks. Thus in his comments on the first book of Aristotle’s Metaphysics he devotes more than half of his exegesis to the two chapters in which Aristotle attacks Plato’s theory of Forms (Metaph. A, 6 & 9). Since Aristotle there focuses on Plato’s attempt to connect the Forms with numbers, a theory that is not elaborated in the dialogues, Alexander’s disquisition turns out to be our most valuable source on the vexed question of Plato’s Unwritten Doctrine and also on the impact of this doctrine on the members of the Early Academy (see Harlfinger & Leszl, 1975; Fine 1993). Though on the whole Alexander adopts Aristotle’s critical stance towards Plato’s separate Forms, he sometimes at least indicates the possibility of dissent. When, for instance, Aristotle claims that Plato recognizes only two of his own four causes, the formal and the material cause, Alexander refers to the demiurge’s activities in the Timaeus as an example for an efficient cause acting for the sake of a final cause. But then he adds a justification to explain why Aristotle acknowledges neither of the two causes in his report on Plato (59,28–60,2): “The reason is either because Plato did not mention either of these in what he said about the causes, as Aristotle has shown in his treatise On the Good; or because he did not make them causes of the things involved in generation and destruction, and did not even formulate any complete theory about them.”

The idea that discrepancies in Aristotle’s texts are due to the development of his philosophy was as alien to Alexander as it was to all other thinkers in antiquity. Instead, he treats Aristotle’s philosophy as a unitary whole and tries to systematize it by forging together different trains of thought, and smoothing over inconsistencies. Thereby he contributed to the emergence of what was to become the canonical ‘Aristotelianism’ that was attacked in early modern times as a severe obstacle to new ideas and scientific development. Though Alexander indicates that he was aware of changes at particular points (he regarded the Categories as Aristotle’s earliest work and notes that it does not yet observe the systematic distinction between genus and species), he does not consider the possibility that there were different phases with substantial changes in the Master’s work. If such conservatism surprises us in view of the fact that Alexander’s own work shows traces of revisions and improvement, we must keep in mind that in the eyes of ‘The Commentator’ Aristotle was an authority quite outside the common order. The doctrine of the Master was not the product of an ordinary human mind, subject to trial and error, but a magisterial achievement in a class of its own.

As a philosopher, Alexander presents in his writings an Aristotelian point of view that reflects in many ways the conditions of his own time, on questions that were not or not extensively discussed by Aristotle himself. His Problems and Solutions (Quaestiones), in three books, are collections of short essays, which were apparently grouped together in different books already in antiquity. As their Greek title (phusikai scholikai aporiai kai luseis. lit. ‘School-discussion of problems and solutions on nature’, cf. Sharples 1992, 3) indicates, these three books address problems in natural philosophy in the broadest sense. The fourth collection, Problems of Ethics (êthika problêmata) proceeds in a similar way. As the lists of the essays’ titles at the beginning of each book show, the collections contain a hodgepodge of topics, arranged in a quite loose order. The intellectual level of these discussions is uneven and the titles of the treatises are sometimes misleading. Some of essays do present problems and solutions, but others contain exegeses of problematic passages in Aristotle’s texts. There are also mere paraphrases or summaries of certain texts, collections of arguments for a certain position, and sketches of larger projects that were never worked out. It is unclear when and by whom these collections were put together.

The attempt to ‘naturalize’ crucial concepts in Aristotle’s philosophy is typical of Alexander’s philosophical stance in general. He regards universals as inseparable from particulars and as secondary to them, and stresses the unity of matter and form. Similarly, he treats the human soul as the perishable form imposed upon the bodily elements to constitute a living human being. He argues that the intellect develops from an embodied intellect (that is focused upon the material world) to a state that eventually contains forms that are not embodied. He rules out personal immortality by identifying the active intellect with pure form and with God, the Unmoved Mover (see On the Soul and Caston 2012). In his emphasis on a naturalist point of view he appears remarkably free from the increasingly spiritualistic and mystical tendencies of his own time. In the treatise On Mixture and Increase Alexander expands on problems that Aristotle touched upon only briefly in On Generation and Corruption I 10, but his main concern is — as it is in his On Fate — to prove that the Stoic position of a ‘thorough’ mixture of two substances cannot be maintained. These treatises suggest that at the beginning of the third century philosophical discussions between the traditional schools were still lively. We have, of course, no other evidence on that issue. But there would be little point in proving the superiority of the Peripatetic doctrine, as he does in On Fate, to the emperors if the issue was by general consent regarded as obsolescent. It is unlikely, therefore, that Alexander’s polemics are only a kind of shadow-boxing against long-gone adversaries.

Scholars nowadays continue to make use of his commentaries, not only for historical reasons but also because his suggestions are often worth considering in their own right. Because in recent years much more attention has been paid to the philosophers in late antiquity, not only to the Neo-Platonists, Alexander’s work has come under detailed scrutiny in various respects by specialists, as witnessed by an increase in publications both on general and on special aspects of his exegetical and philosophical work. The accessibility of most of his writings in English translations will make apparent to a more general readership that Alexander’s work is not only relevant for specialists in the history of philosophy, but opens up an interesting age of transition in the history of philosophical and scientific ideas.”


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