Aristotle and Philoponus on Light

Jean De Groot

• Publisher: Routledge
• Year: 2015
• Print ISBN: 9781138937055
• eBook ISBN: 9781317380627
• Edition: 1
• Topic: Philosophy
• Subtopic: Philosophy History & Theory

Originally published in 1991. Philoponus' long commentary on Aristotle's definition of light sets up the major concerns, both in optics and theory of light, that are discussed here. Light was of special interest in Neoplatonism because of its being something incorporeal in the world of natural bodies. Light therefore had a special role in the philosophical analysis of the interpenetration of bodies and was also a paradigm for the soul-body problem. The book contains much about the physiology of vision as well as the propagation of light. Several chapters investigate the philosophical theory behind what came to be known as 'multiplication of species' in medieval light theory. These issues in the history of science are placed within an analysis of Neoplatonic development of the distinction between Aristotle's kinesis and energeia. The book treats Philoponus' philosophy of mathematical science from the point of view of matter, quantity, and three-dimensionality.

Chapter One

Philoponus and Alexandria: An Historical Introduction

In 529, Justinian ordered that the school of pagan philosophy in Athens be closed. Teaching continued at a similar school in Alexandria until well into the seventh century. There has been considerable modern speculation about the significance of these events in Athens and Alexandria for evaluating the political and intellectual status of paganism at this late date in the Roman Empire. The situation is especially important for interpreting the role of philosophy in the conflict between paganism and Christianity, and for evaluating the extent to which pagan philosophy had been assimilated by Christian thinkers. For understanding the relation of Christianity to pagan philosophy, the role of John Philoponus in the school at Alexandria is of considerable importance. Philoponus, though a Christian, edited many of the commentaries of Ammonius, head of the Alexandrian school. In some cases, he made changes and added comments of his own. There were many Christian students in Alexandria who attended the classes of Ammonius, before going on to study law or rhetoric. However, Philoponus is the only Christian of whom we have knowledge, either at Athens or Alexandria, who pursued the masters of pagan philosophy so thoroughly as to publish commentaries under his own name. Consequently, his status in the school has puzzled scholars who have attempted to explain the survival of pagan philosophy at Alexandria.

This issue is of interest to the historian of science or philosophy because of what it might reveal about Philoponus’ attitude toward the pagan Neoplatonism that dominated late antique school philosophy. The historical and intellectual aspects of Philoponus’ relationship to the pagan philosophical tradition are closely allied, because of the nature of the commentary genre. The commentaries are the artifacts of the school tradition. They are our primary source of historical information about the schools, but at the same time, they embody the intellectual tradition, which we wish to evaluate for its own sake. In Philoponus’ case, separating the substance of original thought from the conventions of the lecture form is complicated by the difficulty of determining whether the ideas presented belong to him or to his teacher, Ammonius. Consequently, the historical interpretation of Philoponus’ relation to the Alexandrian school impinges upon the interpretation of his philosophical works. For this reason, the survival of the school of Alexandria, after the school at Athens had been closed, is an event of considerable interest to any student of late antique philosophy. A brief evaluation of the circumstances surrounding the survival of the school is therefore in order.

According to the testimony of the sixth century chronicler, John Malalas, in 529 Justinian sent an edict (prostaxis) to Athens forbidding the teaching of philosophy or law there.¹ There are a number of questions about Malalas’ report. In the first place, beside the evidence of this report, there is no reason to believe there was a law school at Athens. Secondly, there is nothing in Malalas’ report that suggests the edict was aimed at the pagan school of philosophy or at pagans in general. Remarks of members of the Academy at this time indicate they were refused the right to teach due to their pagan convictions.² However, if we assume the order was directed at the Neoplatonic Academy, it is difficult to understand why a particular edict was needed for them, since general laws against pagans were quite sufficient to outlaw their activities.³ It is possible that these general laws were more or less ineffective at a local level without specific imperial attention, and this may explain the special edict for Athens. However, in Athens, even after 529, Simplicius continued his philosophical research, and it is likely that he used the resources of the Academy library. Furthermore, Olympiodorus, writing after 529, said that despite many confiscations, enough of the school’s endowment remained to pay the diadochos.⁴ All we can say with assurance is that teaching ceased at the Academy in 529, ostensibly as a result of the special edict Malalas mentioned.

Whatever the nature of the special edict against Athens, it seems clear that the general laws against pagans should have applied as well to Alexandria as Athens. Ammonius, who held the chair of philosophy in Alexandria during this period, was pagan, as were his successors, Eutocius and Olympiodorus. The first Christian head of the school was Elias, Olympiodorus’ successor. Elias became philosophos at least forty years after teaching stopped at the Athenian school. Pagans had, therefore, been able to continue teaching philosophy in Alexandria in spite of the laws against them. And unlike Athens, once the pagan succession stopped, teaching did not cease, but rather was carried on by Christians.⁵

The Athenian philosophers testify that their academic activities were restricted because of their pagan beliefs. Athenian Neoplatonism was associated by its practitioners, as well as its opponents, with pagan religion.⁶ This association is lacking in the Alexandrian school of philosophy. We cannot be sure that the Alexandrians abjured the Iamblican Neoplatonism of Athens, with its theurgic practices, since we do not have their writings on metaphysics. However, we do have the testimony of Damascius, last diadochos at Athens, that Aristotle was the special interest of Ammonius, his counterpart in Alexandria.⁷ The professional philosophy of Aristotle lacked the religious overtones of Iamblichan Neoplatonism. Even Christians recognized the importance of Aristotelian logic, although they were uncomfortable with his natural philosophy.⁸ Damascius accused Ammonius of having compromised with the Christian authorities, and modern scholars have supposed this to be a reference to the conditions under which the Alexandrian school was allowed to continue.⁹ Damascius may have assumed the consummation of a deal where there existed, in fact, only an informal arrangement, based on a long-standing agreement. Nevertheless, there has been considerable speculation about the nature of a possible compromise between Ammonius and the Christian authorities.

The necessity for student contributions has been presented by both Tannery and Saffrey as partial reason for a compromise that Ammonius supposedly made with the patriarch, Athanasius. According to Tannery, for Ammonius to obtain Christian students

…il fallu que les maîtes se pliassent à certaines nécessités; ils durent éviter de blesser les croyances de leurs élèves et tout aussi bien se garder que l’évêque n’interdît leurs leçons à ses fideles.¹⁰

Saffrey endorsed this view and further suggested that Ammonius may have agreed to limit his exegesis to Aristotle, since Plato was probably less acceptable to the Christian authorities.¹¹ No doubt, there were Christian students in Ammonius’ classes. Zacharias of Mitylene, in his dialogue, Ammonius, recounted an exchange between Ammonius and some of his Christian students on the eternity of the world during the course of a lecture on the Physics. From Zacharias’ description of his own activities, Courcelle supposed that Zacharias meant the episode to be taking place in 486.¹² However, Saffrey does not even suggest that Ammonius made his deal with the patriarch until 495. Zacharias’ dialogue tells us that Christians were present in Ammonius’ classes long before the supposed compromise. Consequently, for this hypothesis to be plausible, Athanasius must have threatened to remove the paying Christian students from Ammonius’ lectures, or to use his influence with the imperial authorities in the city to prevent Ammonius from teaching. The latter alternative is the more reasonable choice. In any case, Athanasius’ tenure as patriarch ended long before Justinian’s laws against pagans took effect. Even if Ammonius made a compromise of sorts, it was not a response to the pagan persecutions that closed the Academy. Rather, such a compromise would reflect circumstances peculiar to Alexandria.

Damascius’ charge that Ammonius compromised with the authorities at least strengthens the very plausible idea that Ammonius’ attitude toward his Christian antagonists was relevant to the survival of his school. Some idea of Ammonius’ attitude toward Christian doctrines can be gained from Zacharias’ dialogue. He presented several discussions he had with Ammonius in class, concerning doctrines of Christianity such as the creation of the world and the Trinity.¹³ Ammonius appeared interested in Christian philosophical arguments and, to a certain extent, impressed by their cogency. From the dialogue, it appears that, unlike his Athenian counterparts, Ammonius was no antagonist to Christian doctrine. His own commitment to pagan philosophy did not make him intolerant of Christian arguments on the same issues, and he was willing to consider those arguments on their merits. Whether or not this tolerance was the result of necessity, it is nevertheless true that in practical terms Ammonius lacked the commitment to pagan culture as such which was always the natural concomitant of the teaching of philosophy in Athens. This conciliatory attitude is undoubtedly the heart of the homologia with which Damascius reproached his former teacher.

Although Ammonius’ attitude toward Christianity is undoubtedly important, it is also worthwhile to note the larger political climate of Alexandria that may have affected the survival of his school. Ever since Justin had become emperor in 518, it had been imperial policy to enforce in the east the results of the Council of Chalcedon (451) and to end the schism between the eastern and western churches. The Council of Chalcedon declared that Christ was of two natures, human and divine. However, Christians in Egypt and Syria had long held to the view that Christ had a single nature, the divine, and they were not prepared to renounce their view in favor of another, which they considered non-orthodox. Compromising additions to the two-nature statement, which might have brought the eastern churches into the fold, were not adopted by the Council. Both of the eastern emperors, Zeno and Anastasius, were sympathetic to the Monophysite cause. It was not until Justin became emperor that a policy of enforcing orthodoxy was established. Monophysite patriarchs held the Sees of Antioch and Alexandria. Severus, patriarch of Antioch, was replaced by an orthodox patriarch in 518. However, a Monophysite, Timothy IV, continued as patriarch in Alexandria, having succeeded Dioscorus II in 517. In fact, it was to Alexandria that Severus fled in 518, and there he remained the most powerful leader in the Monophysite movement.

During the reign of Justin, Egypt was excluded from the campaign of persecution against Monophysites throughout the rest of the eastern provinces.¹⁴ This imperial exemption was, for Alexandria, exercised in other matters as well. In 520–21, Justin put an end to the Olympic games in cities throughout the Empire and also to other spectacles and entertainments because of the riots caused by political factions. Such entertainments were allowed to continue in Alexandria, and A.A. Vasiliev suggested why:

The Alexandrian spectacles remained undisturbed by imperial decrees and continued to amuse and divert the population of the Egyptian capital, whose tranquillity and satisfaction were essentially important for the tranquillity and prosperity of the empire as a whole.¹⁵

Contributing to the economic reasons for maintaining tranquillity in Egypt was the deep-rooted Monophysism of Egyptian Christians, especially the monks, and the political power that traditionally resided in the Alexandrian patriarchate.¹⁶ Furthermore, by this time, the Alexandrian patriarchate was the rallying point for the Monophysite population still clinging to what they regarded as the orthodox faith. Both Justin and Justinian wished for a final reconciliation of the Monophysites to orthodoxy, but they both perceived the peril of insurrection that lay in attempting to force that reconciliation. Concessions were made to maintain peace in Egypt. Not all were strictly related to religious matters; some were aimed at placating the general population. The proscription against teaching by pagans, therefore, was not the only imperial edict not enforced in Alexandria, and it certainly was not the most important law that was ignored. The inability of the emperor to enforce his will in Egypt may have resulted in the survival of the school, either by negligence or because the Monophysites wished to see the school continue. At this juncture, the presence of Christian students in Ammonius’ classes may well have been important. The association of Philoponus with the school suggests its value to the Monophysites, beyond its function in training students destined for law or rhetoric. Philoponus was a Monophysite with a great interest in the application of Aristotelian philosophy to theology. The Monophysites needed to substantiate their position from a theological as well as a political standpoint.

When Saffrey presen...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Original Copyright Page
• Dedication
• Table of Contents
• Preface
• Chapter One Philoponus and Alexandria: An Historical Introduction
• Chapter Two Reconciling the Mathematical and Physical Aspects of Optics
• Chapter Three The Propagation of Light Without the Passage of Time
• Chapter Four The Propagation of Light, Impetus Theory, and Aristotle’s Physics III.3
• Chapter Five Reexamining the Case for Neoplatonic Influence on Philoponus’ Causal Theories
• Chapter Six The Physical Basis for Mathematical Demonstration in Optics
• Chapter Seven Mathematical Demonstration in a Mixed Science
• Chapter Eight Conclusion
• Appendices
• Bibliography
• Indices