The philosophy of the Greco-Roman world from the sixth century bc to the sixth century ad laid the foundations for all subsequent Western philosophy. Its greatest figures are Socrates (fifth century bc) and Plato and Aristotle (fourth century bc). But the enormously diverse range of further important thinkers who populated the period includes the Presocratics and Sophists of the sixth and fifth centuries bc; the Stoics, Epicureans and sceptics of the Hellenistic age; and the many Aristotelian and (especially) Platonist philosophers who wrote under the Roman Empire, including the great Neoplatonist Plotinus. Ancient philosophy was principally pagan, and was finally eclipsed by Christianity in the sixth century ad, but it was so comprehensively annexed by its conqueror that it came, through Christianity, to dominate medieval and Renaissance philosophy. This eventual symbiosis between ancient philosophy and Christianity may reflect the fact that philosophical creeds in late antiquity fulfilled much the same role as religious movements, with which they shared many of their aims and practices.
Only a small fraction of ancient philosophical writings have come down to us intact. The remainder can be recovered, to a greater or lesser extent, by piecing together fragmentary evidence from sources which refer to them.
1. Main features
‘Ancient’ philosophy is that of classical antiquity, which not only inaugurated the entire European philosophical tradition but has exercised an unparalleled influence on its style and content. It is conventionally considered to start with Thales in the mid sixth century bc, although the Greeks themselves frequently made Homer (c.700 bc) its true originator. Officially it is often regarded as ending in 529 ad, when the Christian emperor Justinian is believed to have banned the teaching of pagan philosophy at Athens. However, this was no abrupt termination, and the work of Platonist philosophers continued for some time in self-imposed exile (see Aristotle commentators; Neoplatonism §1; Simplicius §1).
Down to and including Plato (in the first half of the fourth century bc), philosophy did not develop a significant technical terminology of its own – unlike such contemporary disciplines as mathematics and medicine. It was Plato’s pupil Aristotle, and after him the Stoics (see Stoicism), who made truly decisive contributions to the philosophical vocabulary of the ancient world.
Ancient philosophy was above all a product of Greece and the Greek-speaking parts of the Mediterranean, which came to include southern Italy, Sicily, western Asia and large parts of North Africa, notably Egypt. From the first century bc, a number of Romans became actively engaged in one or other of the Greek philosophical systems, and some of them wrote their own works in Latin (see Lucretius; Cicero; Seneca; Apuleius). But Greek remained the lingua franca of philosophy. Although much modern philosophical terminology derives from Latinized versions of Greek technical concepts, most of these stem from the Latin vocabulary of medieval Aristotelianism, not directly from ancient Roman philosophical writers.
2. The sixth and fifth centuries bc
The first phase, occupying most of the sixth and fifth centuries bc, is generally known as Presocratic philosophy. Its earliest practitioners (Thales; Anaximander; Anaximenes) came from Miletus, on the west coast of modern Turkey. The dominant concern of the Presocratic thinkers was to explain the origin and regularities of the physical world and the place of the human soul within it (see especially Pythagoreanism; Heraclitus; Anaxagoras; Empedocles; Democritus), although the period also produced such rebels as the Eleatic philosophers (Parmenides; Zeno of Elea; Melissus), whose radical monism sought to undermine the very basis of cosmology by reliance on a priori reasoning.
The label ‘Presocratic’ acknowledges the traditional view that Socrates (469–399 bc) was the first philosopher to shift the focus away from the natural world to human values. In fact, however, this shift to a large extent coincides with the concerns of his contemporaries the Sophists, who professed to teach the fundamentals of political and social success and consequently were also much concerned with moral issues (see Sophists). But the persona of Socrates became, and has remained ever since, so powerful an icon for the life of moral scrutiny that it is his name that is used to mark this watershed in the history of philosophy. In the century or so following his death, many schools looked back to him as the living embodiment of philosophy and sought the principles of his life and thought in philosophical theory (see especially Socratic schools).
3. The fourth century bc
Socrates and the Sophists helped to make Athens the philosophical centre of the Greek world, and it was there, in the fourth century, that the two greatest philosophers of antiquity lived and taught, namely Plato and Aristotle. Plato, Socrates’ pupil, set up his school the Academy in Athens (see Academy). Plato’s published dialogues are literary masterpieces as well as philosophical classics, and develop, albeit unsystematically, a global philosophy which embraces ethics, politics, physics, metaphysics (see FORMS, PLATONIC), epistemology (see INNATENESS IN ANCIENT PHILOSOPHY), aesthetics and psychology.
The Academy’s most eminent alumnus was Aristotle, whose own school the Lyceum came for a time to rival the Academy's importance as an educational centre. Aristotle’s highly technical but also often provisional and exploratory school treatises may not have been intended for publication; at all events, they did not become widely disseminated and discussed until the late first century bc. The main philosophical treatises (leaving aside his important zoological works) include seminal studies in all the areas covered by Plato, plus logic, a branch of philosophy which Aristotle pioneered. These treatises are, like Plato’s, among the leading classics of Western philosophy.
Platonism and Aristotelianism were to become the dominant philosophies of the Western tradition from the second century ad at least until the end of the Renaissance, and the legacy of both remains central to Western philosophy today.
4. Hellenistic philosophy
Down to the late fourth century bc, philosophy was widely seen as a search for universal understanding, so that in the major schools its activities could comfortably include, for example, biological and historical research. In the ensuing era of Hellenistic philosophy, however, a geographical split helped to demarcate philosophy more sharply as a self-contained discipline (see Hellenistic philosophy). Alexandria, with its magnificent library and royal patronage, became the new centre of scientific, literary and historical research, while the philosophical schools at Athens concentrated on those areas which correspond more closely to philosophy as it has since come to be understood. The following features were to characterize philosophy not only in the Hellenistic age but also for the remainder of antiquity.
The three main parts of philosophy were most commonly labelled ‘physics’ (a primarily speculative discipline, concerned with such concepts as causation, change, god and matter, and virtually devoid of empirical research), ‘logic’ (which sometimes included epistemology) and ‘ethics’. Ethics was agreed to be the ultimate focus of philosophy, which was thus in essence a systematized route to personal virtue (see Arete) and happiness (see Eudaimonia). There was also a strong spiritual dimension. One’s religious beliefs – that is, the way one rationalized and elaborated one’s own (normally pagan) beliefs and practices concerning the divine – were themselves an integral part of both physics and ethics, never a mere adjunct of philosophy.
The dominant philosophical creeds of the Hellenistic age (officially 323–31 bc) were Stoicism (founded by Zeno of Citium) and Epicureanism (founded by Epicurus) (see Stoicism; Epicureanism). Scepticism was also a powerful force, largely through the Academy (see Arcesilaus; Carneades), which in this period functioned as a critical rather than a doctrinal school, and also, starting from the last decades of the era, through Pyrrhonism (see Pyrrhonism)
5. The imperial era
The crucial watershed belongs, however, not at the very end of the Hellenistic age (31 bc, when the Roman empire officially begins), but half a century earlier in the 80s bc. Political and military upheavals at Athens drove most of the philosophers out of the city, to cultural havens such as Alexandria and Rome. The philosophical institutions of Athens never fully recovered, so that this decentralization amounted to a permanent redrawing of the philosophical map. (The chairs of Platonism, Aristotelianism, Stoicism and Epicureanism which the philosopher-emperor Marcus Aurelius (§1) established at Athens in ad 176 were a significant gesture, but did not fully restore Athens’ former philosophical pre-eminence.) Philosophy was no longer, for most of its adherents, a living activity within the Athenian school founded by Plato, Aristotle, Zeno or Epicurus. Instead it was a subject pursued in small study groups led by professional teachers all over the Greco-Roman world. To a large extent, it was felt that the history of philosophy had now come to an end, and that the job was to seek the correct interpretation of the ‘ancients’ by close study of their texts. One symptom of this feeling is that doxography – the systematic cataloguing of philosophical and scientific opinions (see Doxography) – concentrated largely on the period down to about 80 bc, as did the biographical history of philosophy written c. ad 300 by Diogenes Laertius.
Another such symptom is that a huge part of the philosophical activity of late antiquity went into the composition of commentaries on classic philosophical texts. In this final phase of ancient philosophy, conveniently called ‘imperial’ because it more or less coincides with the era of the Roman empire, the Hellenistic creeds were gradually eclipsed by the revival of doctrinal Platonism, based on the close study of Plato’s texts, out of which it developed a massively elaborate metaphysical scheme. Aristotle was usually regarded as an ally by these Platonists, and became therefore himself the focus of many commentaries (see Platonism, Early and Middle; Peripatetics; Neoplatonism; Aristotle Commentators). Despite its formal concern with recovering the wisdom of the ancients, however, this age produced many powerfully original thinkers, of whom the greatest is Plotinus.
6. Schools and movements
The early Pythagoreans constituted the first philosophical group that can be called even approximately a ‘school’. They acquired a reputation for secrecy, as well as for virtually religious devotion to the word of their founder Pythagoras. ‘He himself said it’ (best known in its Latin form ‘ipse dixit’) was alleged to be their watchword. In some ways it is more accurate to consider them a sect than a school, and their beliefs and practices were certainly intimately bound up in religious teachings about the soul’s purification.
It is no longer accepted, as it long was, that the Athenian philosophical schools had the status of formal religious institutions for the worship of the muses. Their legal and institutional standing is in fact quite obscure. Both the Academy and the Lyceum were so named after public groves just outside the walls of Athens, in which their public activities were held. The Stoics too got their name from the public portico, or ‘stoa’, in which they met, alongside the Athenian agora. Although these schools undoubtedly also conducted classes and discussions on private premises too, it was their public profile that was crucial to their identity as schools. In the last four centuries bc, prospective philosophy students flocked to Athens from all over the Greek world, and the high public visibility of the schools there was undoubtedly cultivated partly with an eye to recruitment. Only the Epicurean school kept its activities out of the public gaze, in line with Epicurus’ policy of minimal civic involvement.
A school normally started as an informal grouping of philosophers with a shared set of interests and commitments, under the nominal leadership of some individual, but without a strong party line to which all members owed unquestioning allegiance. In the first generation of the Academy, for example, many of Plato’s own leading colleagues dissented from his views on central issues. The same openness is discernible in the first generations of the other schools, even (if to a much lesser extent) that of the Epicureans. However, after the death of the founder the picture usually changed. His word thereafter became largely beyond challenge, and further progress was presented as the supplementation or reinterpretation of the founder’s pronouncements, rather than as their replacement.
To this extent, the allegiance which in the long term bound a school together usually depended on a virtually religious reverence for the movement’s foundational texts, which provided the framework within which its discussions were conducted. The resemblance to the structure of religious sects is no accident. In later antiquity, philosophical and religious movements constituted in effect a single cultural phenomenon, and competed for the same spiritual and intellectual high ground. This includes Christianity, which became a serious rival to pagan philosophy (primarily Platonism) from the third century onwards, and eventually triumphed over it. In seeking to understand such spiritual movements of late antiquity as Hermetism, Gnosticism, Neo-Pythagoreanism, Cynicism (see Cynics §4) and even Neoplatonism itself, and their concern with such values as asceticism, self-purificaton and self-divinization, it is inappropriate to insist on a sharp division between philosophy and religion.
‘Ancient philosophy’ is traditionally understood as pagan and is distinguished from the Christian Patristic philosophy of late antiquity (see Patristic philosophy). But it was possible to put pagan philosophy at the service of Judaism (see Philo of Alexandria) or Christianity (see for example Clement of Alexandria; Origen; Augustine; Boethius; Philoponus), and it was indeed largely in this latter capacity that the major systems of ancient philosophy eventually became incorporated into Medieval philosophy and Renaissance philosophy, which they proceeded to dominate.
This extensive overlap between philosophy and religion also reflects to some extent the pervasive influence of philosophy on the entire culture of the ancient world. Rarely regarded as a detached academic discipline, philosophy frequently carried high political prestige, and its modes of discourse came to infect disciplines as diverse as medicine, rhetoric, astrology, history, grammar and law. The work of two of the greatest scientists of the ancient world, the doctor Galen and the astronomer Ptolemy, was deeply indebted to their respective philosophical backgrounds.
A very substantial body of works by ancient philosophical writers has survived in manuscript. These are somewhat weighted towards those philosophers – above all Plato, Aristotle and the Neoplatonists – who were of most immediate interest to the Christian culture which preserved them throughout the Middle Ages, mainly in the monasteries, where manuscripts were assiduously copied and stored. Some further ancient philosophical writings have been recovered through translations into Arabic and other languages, or on excavated scraps of papyrus. The task of reconstituting the original texts of these works has been a major preoccupation of modern scholarship.
For the vast majority of ancient philosophers, however, our knowledge of them depends on secondary reports of their words and ideas in other writers, of whom some are genuinely interested in recording the history of philosophy, but others bent on discrediting the views they attribute to them. In such cases of secondary attestation, strictly a ‘fragment’ is a verbatim quotation, while indirect reports are called ‘testimonia’. However, this distinction is not always rigidly maintained and indeed the sources on which we rely rarely operate with any explicit distinction between quotation and paraphrase.
It is a tribute to the philosophical genius of the ancient world that, despite the suppression and distortion which its contributions have suffered over two millennia, they remain central to any modern conspectus of what philosophy is and can be.
Citing this article:
Sedley, David. 'Ancient philosophy'. Routledge Encyclopedia of Philosophy 1998: Accessed (July 28, 2016). https://www.rep.routledge.com/articles/ancient-philosophy/v-1/. doi:10.4324/9780415249126-A130-1
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