bluuebunny/crossref_metadata_2025 huggingface dataset:
Rorty, Richard McKay (1931–2007)
Authors: Voparil Christopher
Published: September 2018

Best known for his lively and provocative advocacy of pragmatism, Rorty was a wide-ranging and iconoclastic philosopher, whose influential, frequently decried work helped define some of the key intellectual debates of the late twentieth century. His broad training in the history of ideas, early exposure to pragmatism, and self-taught fluency in analytic philosophy combined in his landmark book, Philosophy and the Mirror of Nature (1979), to yield a profound anti-Cartesian and anti-Kantian critique of the foundationalist and representationalist assumptions of modern epistemology and metaphysics. Drawing insight and inspiration from novel juxtapositions and associations of thinkers – Wittgenstein, Heidegger, and Dewey; Quine, Sellars, and Davidson; Freud, Sartre, and Gadamer – Rorty set the terms of his decades-long project: what he called in Mirror the negative, "therapeutic" work of historicizing the purportedly timeless problems of traditional philosophy to highlight how they resulted from the adoption of contingent vocabularies, and the positive, "edifying" (1979) effort to think through what it would mean to move beyond "the entire cultural tradition which made truth…a central virtue" (1982, 35). In his most original work, Contingency, Irony, and Solidarity (1989), and across four volumes of philosophical papers and a collection of popular essays, Rorty elaborated the implications of this broader cultural and intellectual shift for our understanding of language, the self, community, politics, ethics, justice, and religion. Increasingly identifying with the pragmatist tradition, he engaged with leading philosophers around questions of truth, knowledge, justification, and relativism. Yet, the moral core of his project centered on asserting "the priority of democracy to philosophy" (1991a) and reorienting philosophical reflection away from the problems of philosophers and toward a political liberalism dedicated to the reduction of human cruelty and suffering.
Epistemic contrastivism
Authors: Baumann Peter
Published: September 2018

Contrastivism about knowledge is the view that one does not just know some proposition. It is more adequate to say that one knows something rather than something else: I know that I am looking at a tree rather than a bush but I do not know that I am looking at a tree rather than a cleverly done tree imitation. Knowledge is a three-place relation between a subject, a proposition and a contrast set of propositions. There are several advantages of a contrastivist view but also certain problems with it.
Equality of opportunity
Authors: Navin Mark
Published: September 2018

Equality of opportunity is a political ideal according to which participants in some cooperative systems should possess equal access to some advantages at some point in time. According to this ideal, distributive outcomes (e.g., of income, welfare, functionings) should not be fixed in advance, but should result from processes that treat all people equally. Equality of opportunity is an egalitarian ideal, but it focuses on the means by which people acquire advantages, rather than on outcomes. Diverse conceptions of equality of opportunity are distinguished by their different accounts of what it means to possess an equal opportunity, which sorts of advantages people ought to have an equal opportunity to acquire, and which kinds of cooperative activities ought to be regulated by this ideal. In particular, advocates of equality of opportunity disagree about whether equality of opportunity requires only a prohibition on discrimination (e.g., in employment), or whether it also requires efforts to mitigate the influences of some background conditions (e.g., family social status) on distributive outcomes. They also disagree about whether people ought to have an equal opportunity to acquire welfare, resources, functionings, or some combination of these kinds of goods. Finally, advocates of equality of opportunity disagree about whether this ideal should regulate individual choices or only institutional arrangements, and whether it applies only among members of the same society. The concept of equality of opportunity has widespread support across the political spectrum, and therefore most of the critical literature offers objections to particular conceptions of this ideal, rather than to the broader concept of equality of opportunity.
Aenesidemus (1st century BC)
Authors: Hankinson R.J.
Published: September 2018

Aenesidemus was a Greek philosopher of the first century bc who revived Pyrrhonian Scepticism, formulating the basic Ten Modes of Scepticism, or tropoi, and demonstrating that concepts such as cause, explanation, goodness and the goal of life engendered endemic and undecidable dispute; faced with this the Sceptic suspends judgment – and tranquillity follows.
Alcmaeon (c. early to mid 5th century BC)
Authors: Schofield Malcolm
Published: September 2018

Alcmaeon of Croton was a Greek thinker with philosophical and medical interests. His work focused on the nature of man. Health was the outcome of ‘equal rights’ between, for example, hot and cold, moist and dry, disease that of the ‘monarchy’ of one of them. ‘Passages’ linked the sense organs to the brain, which Alcmaeon took to be the seat of sensation and understanding. Plato followed him in this view, as also in his proof of the immortality of the soul from its continual motion.
Ammonius, son of Hermeas (c. AD 440–521)
Authors: Wildberg Christian
Published: September 2018

The Greek philosopher Ammonius, ‘son of Hermeas’ was an Alexandrian Neoplatonist. Educated by Proclus in Athens, he succeeded his father as head of the school in Alexandria, where he cultivated the tradition of learned commentary on Aristotle. Simplicius, Philoponus, Asclepius, Damascius and Olympiodorus ranked among his pupils.
Anaxagoras (500–428 BC)
Authors: Schofield Malcolm
Published: September 2018

Anaxagoras of Clazomenae was a major Greek philosopher of the Presocratic period, who worked in the Ionian tradition of inquiry into nature. While his cosmology largely recasts the sixth-century system of Anaximenes, the focus of the surviving fragments is on ontological questions. The often quoted opening of his book – ‘all things were together’ – echoes the Eleatic Parmenides’ characterization of true being, but signals recognition of time, change and plurality. Even so, Anaxagoras is deeply committed to the Eleatic notions that, strictly speaking, there can be no coming into being or going out of existence, nor any separation of one part of reality from any other. His main object is to show how the variety of the world about us is somehow already contained in the primordial mixture, and is explicable only on the assumption that latent within each substance are portions of every other. Whether or not he owed his conception of unlimited smallness to Zeno of Elea, he held that there could be no such thing as a magnitude of least size; and he claimed that there was accordingly no difference in complexity between the large and the small.

Mind, however, is a distinct principle; unlimited, autonomous, free from the admixture of any other substance. Hence Anaxagoras’ decision to make it the first cause of the ordered universe we now inhabit. Mind initiates and controls a vortex, which from small beginnings sucks in an ever-increasing expanse of the surrounding envelope. The vortex brings about an incomplete separation of the ingredients of the original mixture: hot from cold, dry from wet, bright from dark, and so on, with a flat earth compacted at the centre and surrounded by misty air and clearer ether above and below. Contemporaries were scandalized by Anaxagoras’ claim that sun, moon and stars were nothing but incandescent stones caught up in the revolving ether.

Later fifth-century physicists – notably Archelaus and Diogenes of Apollonia – developed revised versions of Anaxagoras’ system, but abandoned his dualism. His conception of mind excited but disappointed Socrates, and exercised a profound influence on Plato’s cosmology and Aristotle’s psychology. Aristotle was also fascinated by the complexities of the remarkable theory of ‘everything in everything’. Anaxagoras’ philosophy was never subsequently revived, but he was remembered as the mentor of the statesman Pericles and the poet Euripides. His reputation as a rationalist critic of religion persisted throughout antiquity.
Anaxarchus (c.380–c.330 BC)
Authors: Brunschwig Jacques
Published: September 2018

The Greek philosopher Anaxarchus of Abdera was a friend of Alexander the Great, teacher and friend of Pyrrho, and heroic victim of a tyrant. More a court philosopher than a school one, and an ambiguous personality, he seems to have mixed a highly original philosophical cocktail: a primarily ethical, cynically inclined outlook, combined with certain elements of Democritean ethics, epistemology and physics. His only attested work was a treatise On Kingship, his dominant interest perhaps being the theory and practice of relations between intellectual and ruler.
Anaximander (c.610–after 546 BC)
Authors: McKirahan Richard
Published: September 2018

The Greek philosopher Anaximander of Miletus followed Thales in his philosophical and scientific interests. He wrote a book, of which one fragment survives, and is the first Presocratic philosopher about whom we have enough information to reconstruct his theories in any detail. He was principally concerned with the origin, structure and workings of the world, and attempted to account for them consistently, through a small number of principles and mechanisms. Like other thinkers of his tradition, he gave the Olympian gods no role in creating the world or controlling events. Instead, he held that the world originated from a vast, eternal, moving material of no definite nature, which he called apeiron (’boundless’ or ‘unlimited’). From this, through obscure processes including one called ‘separation off’, arose the world as we know it. Anaximander described the kosmos (world) and stated the distances of the celestial bodies from the earth. He accounted for the origin of animal life and explained how humans first emerged. He pictured the world as a battleground in which opposite natures, such as hot and cold, constantly encroach upon one another, and described this process as taking place with order and regularity.
Apuleius (c. AD 125–180)
Authors: Dillon John
Published: September 2018

The Latin writer Apuleius of Madaura was a professional rhetorician, a novelist and an amateur Platonist. His handbook of Platonism and his essay on the guardian spirit of Socrates are valuable sources on Middle Platonism. The handbook is comparable to that of his probable contemporary Alcinous, but covers only physics (including metaphysics) and ethics.
Arcesilaus (c.316–c.240 BC)
Authors: Barnes Jonathan
Published: September 2018

Arcesilaus of Pitane came to Athens as a young man, and was seduced by Platonic philosophy. Around 265 he became head of the Academy. He turned the school in a sceptical direction, urging that Plato himself had been of a sceptical bent. He revived the Socratic practice of dialectical argument, in which he displayed remarkable logical skill and honeyed oratorical talent. His dialectical prowess led him to ‘suspend judgment about everything’; but the main target of his arguments was Stoicism, and in particular Stoic epistemology, which he claimed to reduce to incoherence. Recognizing that a sceptic must live and act, he introduced the notion of ‘the reasonable’ as a criterion of sceptical action.
Archytas (early to mid 4th century BC)
Authors: Schibli Hermann S.
Published: September 2018

Archytas of Tarentum (modern Taranto in southern Italy) was a contemporary and personal acquaintance of Plato, and the last of the famous Pythagoreans in antiquity. An ancient source (Proclus) chytas with those mathematicians ‘who increased the number of theorems and progressed towards a more scientific arrangement of them’ and ranks him among the predecessors of Euclid. His chief contribution in mathematics was to find a solution for the doubling of the cube. As a Pythagorean philosopher, Archytas gave mathematics universal scope: he viewed the four cardinal branches of Greek scientific knowledge – arithmetic, geometry, astronomy and music – as ‘sister sciences’ since they could be formulated mathematically. In both mathematics and music he emphasized the study of mean proportionals. He also conducted empirical investigations in acoustics and invented simple technical devices by which to illustrate the application of mathematical principles to mechanics. Archytas was able to combine his philosophical-scientific interests with an active political career; he was a leading statesman of Tarentum and served as a successful general.
Aristippus the Elder (c.435–c.355 BC)
Authors: Tsouna Voula
Published: September 2018

Aristippus of Cyrene was a member of Socrates’ entourage who after Socrates’ death (399 bc) founded the Cyrenaic school. He was primarily interested in practical ethics. He focused on the concepts of pleasure and pain, and classed them as bodily motions of which we are conscious. He considered pleasure a major component of happiness, but also attributed intrinsic value to virtue and emphasized the importance of study and exercise as means to self-control.
Hellenistic medical epistemology
Authors: Hankinson R.J.
Published: September 2018

During the Hellenistic period (323–31 bc), there arose, largely in Alexandria, a profound debate in medical methodology. The main participants were the Empiricists, committed to an anti-theoretical, practical medicine based on observation and experience and the various Rationalists, such as Herophilus, Erasistratus, and Asclepiades, who held that general theories of physiology and pathology were both attainable and essential to proper medical understanding and practice. Dispute about the nature of scientific inference and the status of causal explanation mirrored and to some extent conditioned the contemporary debate between Stoics and sceptics about epistemology.
Atomism, ancient
Authors: Sedley David
Published: September 2018

Ancient Greek atomism, starting with Leucippus and Democritus in the fifth century bc, arose as a response to problems of the continuum raised by Eleatic philosophers. In time a distinction emerged, especially in Epicurean atomism (early third century bc), between physically indivisible particles called ‘atoms’ and absolutely indivisible or ‘partless’ magnitudes.
Calcidius (c. 4th century AD)
Authors: Dillon John
Published: September 2018

The Platonist Calcidius (sometimes less correctly spelt Chalcidius) was the author of a Latin work containing a partial translation of, and partial commentary on, Plato’s Timaeus. Although of uncertain date, the doctrinal content of his commentary reflects the thought of the Middle Platonist era (c.50 bc–ad 200).
Carneades (214–129 BC)
Authors: Barnes Jonathan
Published: September 2018

The Greek philosopher Carneades was head of the Academy from 167 to 137 bc. Born in North Africa he migrated to Athens, where he studied logic with the Stoic Diogenes of Babylon; but he was soon seduced by the Academy, to which his allegiance was thereafter lifelong. He was a celebrated figure; and in 155 bc he was sent by Athens to Rome as a political ambassador, where he astounded the youth by his rhetorical powers and outraged their elders by his arguments against justice.

Under Carneades’ direction the Academy remained sceptical. But he enlarged the sceptical armoury – in particular, he deployed sorites arguments against various dogmatic positions. He also broadened the target of sceptical attack: thus he showed an especial interest in ethics, where his ‘division’ of possible ethical theories served later as a standard framework for thought on the subject. But his major innovation concerned the notion of ‘the plausible’ (to pithanon). Even if we cannot determine which appearances are true and which false, we are able to distinguish the plausible from the implausible – and further to distinguish among several grades of plausibility. It is disputed – and it was disputed among his immediate followers – how, if at all, Carneades’ remarks on the plausible are to be reconciled with his scepticism.
Celsus (late 2nd century AD)
Authors: Dillon John
Published: September 2018

The Greek philosopher Celsus of Alexandria was a Middle Platonist, known only for his anti-Christian work The True Account. The work is lost, but we have Origen’s reply to it, Against Celsus. In it Celsus defends a version of Platonist theology.
Cleanthes (331–232 BC)
Authors: Sedley David
Published: September 2018

The Greek philosopher Cleanthes of Assos played a leading role in the formation of Stoicism. He was at once the most physicalist and the most religious of the Stoics. Pupil, and eventual successor (in 262), of the school’s founder Zeno, he wrote numerous philosophical works, including some poetry. In particular, he developed the notion of fire as the world’s governing principle.
Cleomedes (c. 2nd century AD)
Authors: Todd Robert B.
Published: September 2018

Cleomedes was the author of On the Heavens, a Greek treatise on elementary astronomy surviving from a larger exposition of Stoic philosophy. Its account of measurements of the earth, and its applications of Stoic epistemology and philosophy of science, make it important evidence on poorly documented subjects.
Cyrenaics
Authors: Tsouna Voula
Published: September 2018

The Cyrenaic school was a Greek philosophical school which flourished in the fourth and early third centuries bc. It took its name from the native city of its founder, Aristippus of Cyrene, a member of Socrates’ entourage. His most important successors were his grandson, Aristippus the Younger, and Theodorus, Anniceris and Hegesias, the heads of three separate Cyrenaic sects.

The basis of Cyrenaic philosophy is physiological and psychological. It focuses on the individual feelings of pleasure and pain which are classed as pathē, experiences produced in a subject by its contact with an object. They are described, respectively, in terms of smooth and rough movements, of the flesh or of the soul. A third category of pathē, described as intermediate between pleasure and pain, is also defined as movements and related to one’s perception of individual properties or qualities. All pathē are short-lived and have no value beyond the actual time of their occurrence.

These physiological characteristics are encountered both in the ethics and in the epistemology of the school. Although the Cyrenaics differed in their ethical doctrines, all of them attributed a central role in their systems to the individual bodily pleasure experienced in the present moment, and some of them considered it the moral end: it is pursued for its own sake, whereas happiness, conceived as the particular collection of pleasures that one experiences during a lifetime, is sought for the sake of its component pleasures. The goodness of individual pathē of pleasure is supported by an elaborate epistemological doctrine whose central claims are that we are infallibly and incorrigibly aware of the occurrence and content of our own pathē, but that we cannot apprehend the properties of external objects. A striking feature of this doctrine is the neologisms designating the perception of qualities, such as ‘I am whitened’ and ‘I am affected whitely’. This, and other features of Cyrenaic subjectivism, anticipate some modern philosophical analyses of subjective experience.
Damascius (c.462–540)
Authors: Dillon John
Published: September 2018

The late Neoplatonist philosopher Damascius was the last head of the Platonist school in Athens. He largely accepted the metaphysical system of the Athenian School of Syrianus and Proclus, but subjected it to acute dialectical scrutiny in a series of commentaries, and especially in his treatise On First Principles. His philosophical position is not comprehensible without bearing in mind that of Proclus, although on certain issues, such as the nature of the first principle and of the soul, he prefers the solutions of the earlier Iamblichus.
Diodorus Cronus (late 4th–early 3rd centuries BC)
Authors: Denyer Nicholas
Published: September 2018

The most famous member of the Dialectical school, the Greek philosopher Diodorus Cronus maintained various paradoxical theses. He argued that any attempt to divide space, time or matter must end with little regions, periods or bodies that cannot further be divided; hence, he inferred, things cannot be in motion. Diodorus also contributed to the contemporary debate on conditionals: one proposition implies another, he held, if and only if it never has been possible, and is not now possible, to have the former proposition true and the latter proposition false. Diodorus is however most famous for inventing the master argument. The master argument relied on two assumptions: that every past truth is necessary, and that the impossible does not follow from the possible. It concluded, on these assumptions, that no proposition is possible unless it either is true or will be. The master argument was designed to support Diodorus’ definition of possibility: a proposition is possible if and only if it either is or will be true. This definition is not exactly tantamount to the fatalist doctrine that all truths are necessary, but it was felt to come too close to fatalism for comfort.
Epicharmus (c. early 5th century BC)
Authors: Most Glenn W.
Published: September 2018

One of the earliest Greek dramatists, Epicharmus wrote mostly comedies with mythological content in Sicily around 500 bc. A number of philosophical passages were attributed to him in antiquity; their authenticity, sometimes doubted even then, has remained controversial, but the quotations were widely influential and remain of interest.
Heraclides of Pontus (4th century BC)
Authors: Gottschalk H.B.
Published: September 2018

Heraclides, a pupil of Plato, was roughly contemporaneous with Aristotle. Best known in antiquity as a writer of dialogues on moral and religious themes, he also held interesting views about cosmology and the structure of matter. Only fragments of his works survive.
Hermetism
Authors: Procope John
Published: September 2018

A primarily religious amalgam of Greek philosophy with Egyptian and other Near Eastern elements, Hermetism takes its name from Hermes Trismegistus, ‘thrice greatest Hermes’, alias the Egyptian god Thoth. Numerous texts on philosophical theology and various occult sciences, ascribed to or associated with this primeval figure, were produced in Greek by Egyptians between roughly ad 100 and 300, and are a major document of late pagan piety. Reintroduced into Western Europe during the Renaissance, they provided considerable inspiration to philosophers, scientists and magicians of the fifteenth and sixteenth centuries.
Hippias (late 5th century BC)
Authors: Kahn Charles H.
Published: September 2018

The Greek Sophist Hippias of Elis is a familiar figure in Plato’s dialogues. He served his city as ambassador, and he earned a great deal of money from his lectures. His unusually wide range of expertise included not only rhetoric but also history, literature, mnemonics, mathematics and natural philosophy.
Hippocratic medicine
Authors: Hankinson R.J.
Published: September 2018

The Hippocratic corpus is a disparate group of texts relating primarily to medical matters composed between c.450 and c.250 bc and dealing with physiology, therapy, surgery, clinical practice, gynaecology and obstetrics, among other topics. The treatises are (for the most part) notable for their sober naturalism in physiological theory, their rejection of supernatural explanations for disease, and their insistence on the importance of careful observation. Although embodying a variety of different physiological schemes, they are the origin of the enormously influential paradigm of humoral pathology. In antiquity, the authorship of the entire corpus was mistakenly ascribed to the semi-legendary doctor Hippocrates of Cos (fl. c.450 bc).
Iamblichus (c. AD 242–327)
Authors: Siorvanes Lucas
Published: September 2018

The late ancient philosopher Iamblichus was, alongside Plotinus and Porphyry, a founder of Neoplatonism. He established a new curriculum for the teaching of philosophy and formulated many distinctions that pervaded later Neoplatonic metaphysics. He began to mathematize all fields of philosophical concern. Most of all, he asserted that acts of transcendence, not contemplation, secure union with the divine, because it can only be reached by an equally divine faculty, which is present in every individual. Matter, soul and mind contain images of the divine and so are genuine participants in salvation.
Katharsis
Authors: Most Glenn W.
Published: September 2018

One of the central concepts of Aristotle’s Poetics, katharsis (’purgation’ or ‘purification’; often spelled catharsis) defines the goal of the tragic poet: by depiction of human vicissitudes so to provoke the spectators’ feelings of pity and fear that such emotions in them are finally purged.
Lucretius (c.94–c.55 BC)
Authors: Erler Michael
Published: September 2018

Titus Lucretius Carus was a Roman Epicurean philosopher and poet. About his life and personality little can be said with certainty, yet his only known work, ‘On the Nature of Things’ (De rerum natura), is of considerable size and one of the most brilliant achievements of Latin poetry. A didactic poem in six books, it expounds Epicurean physics. Its manifesto is to abolish the fear of gods and of death by demonstrating that the soul is mortal and the world not governed by gods but by mechanical laws.
Marcus Aurelius (AD 121–80)
Authors: Inwood Brad
Published: September 2018

Marcus Aurelius Antoninus, Emperor of Rome, was the author of a book of philosophical reflections written in Greek and known as the Meditations. These reflections are based primarily on Stoicism, but also reveal the influence of other currents of thought and of his experience as emperor. Marcus was deeply influenced by Epictetus and shares his interest in the inner mental life and the psychology of moral improvement. He combines a deep commitment to the providential cosmology traditional in the Stoic school with a more pronounced religious sensibility and a frequent emphasis on the insignificance of human life in space and time. The Stoic recognition of the irreducibly social character of human nature is obviously pertinent to an emperor whose career consisted largely of self-sacrificing public service.
Megarian school
Authors: Sedley David
Published: September 2018

The Megarians were a Greek ‘Socratic’ school of the fourth and early third centuries bc. After their founder Euclides, whose main doctrine was the unity of the good, the leading Megarian was Stilpo, best known for preaching the self-sufficiency of virtue. They propounded various puzzles and found objections to the possible–actual distinction, the copula and universals.
Neo-Pythagoreanism
Authors: Schibli Hermann S.
Published: September 2018

Neo-Pythagoreanism is a term used by modern scholars to refer to the revival of Pythagorean philosophy and way of life in the first century bc. It coincides with the redevelopment of Platonic thought known as Middle Platonism. Neo-Pythagoreans elaborated a mathematical metaphysics in which the highest level of being was occupied by a transcendent principle, equated with ‘the One’ or ‘the Monad’ and regarded as the source of all reality. Neo-Pythagorean anthropology reaffirmed the ancient Pythagorean belief in the immortality of the soul. Although Neo-Pythagoreanism is often indistinguishable from Middle Platonism, it is characterized by a tendency to see Pythagoras as the father of all true philosophers, including Plato. In the third century ad Neo-Pythagoreanism was absorbed into Neoplatonism.
Panaetius (c.185–c.110 BC)
Authors: White Stephen A.
Published: September 2018

Panaetius, a Greek philosopher from Rhodes, brought new vitality to Stoicism in the second century bc by shifting the focus of its ethical theory from the idealized sage to the practical problems of ordinary people. Working a century after Chrysippus had systematized Stoicism, Panaetius is often labelled the founder of ‘Middle Stoicism’ for defending new and generally more moderate positions on several issues. Because none of his writings survive, his influence is hard to gauge precisely and easily underrated. But his impact, especially in Rome where he was closely associated with many in the ruling elite, was profound. His emphasis on public service and the obligations imposed by power and high station probably helped shape the ideology of Roman imperialism. Through Cicero, whose writings preserve many of his ideas, he had lasting influence, especially on early modern moral and political thought.
Philodemus (c.110–c.40 BC)
Authors: Erler Michael
Published: September 2018

Philodemus of Gadara, a Greek epigrammatic poet, was also an influential Epicurean philosopher. Scrolls containing many of his works, buried by the eruption of Vesuvius in ad 79, have been partially recovered and deciphered. Their themes include epistemology, theology, ethics, philosophical history, poetics, rhetoric and music. He energetically defends Epicureanism against other philosophies, and his own interpretation of Epicureanism against rival factions. Although not a notably original thinker, Philodemus became highly regarded in educated Roman circles.
Philolaus (c.470–380/9 BC)
Authors: Schibli Hermann S.
Published: September 2018

The Greek philosopher Philolaus of Croton, a contemporary of Democritus and Socrates, was a pre-eminent Pythagorean. His book counts as the first written treatise in the history of Pythagoreanism. Surviving in fragments, it constitutes an important source for our knowledge of fifth-century Pythagoreanism and supplements the picture given by Aristotle of Pythagorean doctrine.

Like earlier Presocratics Philolaus sought to furnish a comprehensive cosmology. Arguing from logical propositions, he posited two pre-existing principles: ‘unlimited things’ and ‘limiting things’. United by harmony these two principles account for the formation of the cosmos and its phenomena. Since Philolaus also invokes number as an all-powerful explanatory concept, it is likely that he associated his first principles and the things originating from them with numbers. The emphasis on harmony and number accords with early Pythagoreanism.

Philolaus also wrote on musical theory and astronomy. A noteworthy feature of his astronomy is the displacement of the earth from the centre of the cosmos by fire, pictured as the ‘hearth’ of the universe. The fragments further attest Philolaus’ interest in embryology, the causes of diseases, and physiology combined with psychological functions.

It was not unusual for early Greek philosophers to treat such a wide variety of topics. The distinctive elements of the thought of Philolaus are the logical arguments evinced in the fragments and the epistemological role of number for understanding the structure of reality.
Plotinus (AD 204/5–70)
Authors: Emilsson EyjÓlfur Kjalar
Published: September 2018

Plotinus was the founder of Neoplatonism, the dominant philosophical movement of the Graeco-Roman world in late antiquity, and the most significant thinker of the movement. He is sometimes described as the last great pagan philosopher.His writings, the so called Enneads, are preserved as whole. While an earnest follower of Plato, he reveals other philosophical influences as well, in particular those of Aristotle and Stoicism. Plotinus developed a metaphysics of intelligible causes of the sensible world and the human soul. The ultimate cause of everything is ‘the One’ or ‘the Good’. It is absolutely simple and cannot be grasped by thought or given any positive determination. The One has as its external act the universal mind or ‘Intellect’. The Intellect’s thoughts are the Platonic Forms, the eternal and unchanging paradigms of which sensible things are imperfect images. This thinking of the forms is Intellect’s internal activity. Its external act is a level of cosmic soul, which produces the sensible realm and gives life to the embodied organisms in it. Soul is thus the lowest intelligible cause that immediately is immediately in contact with the sensible realm. Plotinus, however, insists that the soul retains its intelligible character such as nonspatiality and unchangeability through its dealings with the sensible. Thus he is an ardent soul-body dualist. Human beings stand on the border between the realms: through their bodily life they belong to the sensible, but the human soul has its roots in the intelligible realm. Plotinus sees philosophy as the vehicle of the soul’s return to its intelligible roots. While standing firmly in the tradition of Greek rationalism and being a philosopher of unusual abilities himself, Plotinus shares some of the spirit of the religious salvation movements characteristic of his epoch.
Prodicus (fl. late 5th century BC)
Authors: Kahn Charles H.
Published: September 2018

Prodicus was a Greek Sophist from the island of Ceos; he was active in Athens. He served his city as ambassador and also became prominent as a professional educator. He taught natural philosophy, ethics, and of course rhetoric, but he is best known as an authority on correct language, specializing in fine verbal distinctions. Prodicus’ greatest influence was due to his naturalistic interpretation of the traditional Greek gods; as a result, he later figured on the short list of famous atheists.
Psychē
Authors: Long A.A.
Published: September 2018

Conventionally translated ‘soul’, psychē is the standard word in classical Greek for the centre of an animal’s, and especially a human being’s, ‘life’. In its earliest usage (in Homer) psychē is a breath-like material persisting after death as a mere ghost. Its precise reference to the locus of thought and emotion only began under the influence of philosophy. From the beginning of the fourth century bc it became normal to pair and contrast psychē with ‘body’ (soma). The term generated sophisticated discussions. Leading questions include: Is psychē immortal? Is it corporeal or incorporeal? What are its parts or functions?
Ptolemy (c. AD 100–70)
Authors: Repellini Ferruccio Franco
Published: September 2018

The astronomer Ptolemy was one of the leading scientific figures of Graeco-Roman antiquity. His contributions to philosophy lie in his reflections on scientific activity. In knowledge, he distinguishes a perceptual stage, which provides the natural link between knowledge and things, from a further, rational stage, governing the transition to science. The move towards science consists of the progressive distinction between concepts, initially acquired through experience and methodical observation. Many components of his thought are derived from earlier philosophy, but he excludes those aspects which bear on more general philosophical issues.
Pyrrhonism
Authors: Hankinson R.J.
Published: September 2018

Pyrrhonism was the name given by the Greeks to one particular brand of scepticism, that identified (albeit tenuously) with Pyrrho of Elis, who was said (by his disciple Timon of Phlius) to have declared that everything was indeterminable and accordingly to have suspended judgment about the reality of things – in particular whether they were really good or bad. After Timon’s death Pyrrhonism lapsed, until revived by Aenesidemus. Aenesidemus held that it was inadmissible either to affirm or to deny that anything was really the case, and in particular to hold, with the Academic sceptics, that certain things really were inapprehensible. Instead, the Sceptic (the capital letter denotes the Pyrrhonists, who adopted the term, literally ‘inquirer’, as one of the designations for their school) should only allow that things were no more the case than not, or only so under certain circumstances and not under others. Aenesidemean Scepticism took the form of emphasizing the disagreement among both lay people and theoreticians as to the nature of things, and the fact that things appear differently under different circumstances (the various ways of doing this were systematized into the Ten Modes of Scepticism); the result was meant to be suspension of judgment about such matters, which would in turn lead to tranquillity of mind. Thus ‘Scepticism’ denotes a particular philosophical position, not simply, as in modern usage, that of any philosopher inclined towards doubt. Later Pyrrhonists, notably Agrippa, refined the Sceptical method and concentrated on undermining the dogmatic (that is, anti-Sceptical) notion of the criterion – there is no principled way to settle such disputes without resorting to mere assertion, infinite regress or circularity. We owe to Sextus Empiricus our most complete account of Pyrrhonian argument and the clearest exposition of the Pyrrhonian attitude. Faced with endemic dispute, Sceptics reserve judgment; but this does not render life impossible for them, since they will still react to the way things appear to be, although without believing in any strong sense that things really are as they seem. Furthermore, when Pyrrhonians describe their affective states, they do so undogmatically – and the Sceptical slogans (‘I determine nothing’, ‘nothing is apprehended’, and so on) are to be understood in a similar way, as merely reporting a state of mind and not expressing a commitment. Thus the slogans apply to themselves, and like cathartic drugs are themselves purged along with the noxious humour of dogmatism.
Pythagoreanism
Authors: Schibli Hermann S.
Published: September 2018

Pythagoreanism refers to a Greek religious-philosophical movement that originated with Pythagoras in the sixth century bc. Although Pythagoreanism in its historical development embraced a wide range of interests in politics, mysticism, music, mathematics and astronomy, the common denominator remained a general adherence among Pythagoreans to the name of the founder and his religious beliefs. Pythagoras taught the immortality and transmigration of the soul (reincarnation) and recommended a way of life that through ascetic practices, dietary rules and ethical conduct promised to purify the soul and bring it into harmony with the surrounding universe. Thereby the soul would become godlike since Pythagoras believed that the cosmos, in view of its orderly and harmonious workings and structure, was divine. Pythagoreanism thus has from its beginnings a cosmological context that saw further evolution along mathematical lines in the succeeding centuries. Pythagorean philosophers, drawing on musical theories that may go back to Pythagoras, expressed the harmony of the universe in terms of numerical relations and possibly even claimed that things are numbers. Notwithstanding a certain confusion in Pythagorean number philosophy between abstract and concrete, Pythagoreanism represents a valid attempt, outstanding in early Greek philosophy, to explain the world by formal, structural principles. Overall, the combination of religious, philosophical and mathematical speculations that characterizes Pythagoreanism exercised a significant influence on Greek thinkers, notably on Plato and his immediate successors as well as those Platonic philosophers known as Neo-Pythagoreans and Neoplatonists.
Seneca, Lucius Annaeus (4/1 BC–AD 65)
Authors: Inwood Brad
Published: September 2018

Lucius Annaeus Seneca, Roman statesman and Stoic philosopher, is the earliest Stoic of whose writings any have survived intact. Seneca wrote, in Latin, tragedies and a wide range of philosophical works. His philosophical and literary work was carried out in the intervals of an active political career. He is most important for his ethics and psychology, although natural philosophy was not neglected. Unlike many Stoics he showed little interest in logic or dialectic. His most influential work was on the psychology of the passions, the nature of the human will and techniques of moral education; he also wrote extensively on social and political issues from a distinctively Stoic perspective.
Sextus Empiricus (fl. c. AD 200)
Authors: Hankinson R.J.
Published: September 2018

Sextus Empiricus is our major surviving source for Greek scepticism. Three works of his survive: a general sceptical handbook (Outlines of Pyrrhonism), a partly lost longer treatment of the same material, and a series of self-contained essays questioning the utility of the individual liberal arts.
Socratic dialogues
Authors: Kahn Charles H.
Published: September 2018

After Socrates’ death in 399 bc, a number of his followers composed imaginary dialogues between Socrates and various persons, usually historical. In addition to the dialogues of Plato there were works by Antisthenes, Aeschines, Phaedo, Euclides and, somewhat later, Xenophon. Only the writings of Plato and Xenophon have survived intact. The portrayal of Socrates varied from author to author, but the charismatic personality and skilful questioner is recognizable in each version. The connection between love and Socratic philosophy was frequently illustrated in Socrates’ relationship to Alcibiades. The erotic theme was also represented in the role played by Aspasia, Pericles’ mistress, in at least four authors, including Plato. Historical fact and even chronological possibility were regularly disregarded. This was essentially a genre of fiction.
Theophrastus (c.372–c.287 BC)
Authors: Huby Pamela M.
Published: September 2018

Theophrastus, the pupil and successor of Aristotle, shared all the latter’s interests, and produced a large number of works on the same topics. Some, like the extant botanical works, went far beyond Aristotle, and Theophrastus is known as the Father of Botany; others amplified and criticized what Aristotle had done. The short Metaphysics, also extant, raises many questions about the nature and the possibility of metaphysics, but most of his work on logic, science, psychology, ethics, politics and religion survives only in fragments, some material coming from the Arabs, and some only from medieval Latin sources. His developments of modal logic and various forms of the syllogism were regarded as important, and his amplification of Aristotle’s account of the human intellect was studied in the Middle Ages in the West. His little Characters, an entertaining set of sketches of human peculiarities, has had considerable influence on later literature, and his surveys of earlier opinions, of which his On the Senses survives, influenced later doxographers. He was an older contemporary of Zeno, the founder of Stoicism, but his influence on Stoicism remains uncertain, and we also know little of his relationship with Epicurus.
Socratic schools
Authors: Tsouna Voula
Published: September 2018

For approximately one and a half centuries after Socrates’ death in 399 bc, several Greek philosophical schools and sects each claimed to be the true intellectual heirs of Socrates. Later doxographers emphasized the Socratic pedigree of each of these schools by establishing an uninterrupted succession (diadochē) between its alleged founder, who was invariably a member of Socrates’ own entourage, and the philosophers who succeeded him as leaders of the school.

Leaving aside Plato, the founder of the Academy, the members of the Socratic circle who left a succession behind them are Antisthenes, Aristippus of Cyrene, Euclides of Megara, and Phaedo of Elis, considered respectively the founders of Cynicism, and of the Cyrenaic, Megarian and Elian schools. It is these groupings, plus several of their offshoots, that are conventionally known as the ‘Socratic schools’. All can be seen as, in their own ways, developing Socrates’ ethical outlook, and several were concerned with exploring the logical and metaphysical implications of his dialectical principles.
Hypatia (c. AD 370–415)
Authors: Siorvanes Lucas
Published: September 2018

The Greek philosopher Hypatia was a Neoplatonist. She was famous for her public talks on philosophy and astronomy, and her forthright attitude to sex. Alhough concerned with higher knowledge, she was also a political animal and had a keen sense of practical virtue. She was killed by a Christian mob, and has remained since a martyr to the cause of philosophy.
Telos
Authors: Brennan Tad
Published: September 2018

Telos is the ancient Greek term for an end, fulfilment, completion, goal or aim; it is the source of the modern word ‘teleology’. In Greek philosophy the term plays two important and interrelated roles, in ethics and in natural science; both are connected to the most common definitional account of the telos, according to which a telos is that for the sake of which something is done or occurs.

In ethical theory, each human action is taken to be directed towards some telos (i.e. end), and practical deliberation involves specifying the concrete steps needed to attain that telos. An agent’s life as a whole can also be understood as aimed at the attainment of the agent’s overall telos, here in the sense of their final end or summum bonum (‘highest good’), generally identified in antiquity as eudaimonia (happiness). Rival ancient ethical theories are distinguished primarily by their rival specifications of the end; the Epicurean telos is pleasure, the Stoic telos is life according to nature, and so on.

In the natural science of Aristotle, the telos of a member of a species is the complete and perfect state of that entity in which it can reproduce itself (so, insects reach their telos when they become adults). The telos of an organ or capacity is the function it plays in the organism as a whole, or what it is for the sake of; the telos of the eye is seeing. Carrying on the tradition of Anaxagoras and Plato, Aristotle centres his scientific methodology around the claim that there are ends in nature, i.e. that some natural phenomena occur for the sake of something; Galen and the Stoics enthusiastically second this; Epicurus rejects it.
Prolēpsis
Authors: Scott Dominic
Published: September 2018

In post-Aristotelian Greek philosophy, the term prolēpsis (plural prolēpseis) was used, first by Epicurus and then by the Stoics, to refer to basic general concepts. These concepts were held to be preconditions of rational thought and language. For the most part, the Epicureans and Stoics thought that prolēpseis were formed by experience.
Abelard, Peter (1079–1142)
Authors: Tweedale Martin M.
Published: September 2018

Among the many scholars who promoted the revival of learning in western Europe in the early twelfth century, Abelard stands out as a consummate logician, a formidable polemicist and a champion of the value of ancient pagan wisdom for Christian thought. Although he worked within the Aristotelian tradition, his logic deviates significantly from that of Aristotle, particularly in its emphasis on propositions and what propositions say. According to Abelard, the subject matter of logic, including universals such as genera and species, consists of linguistic expressions, not of the things these expressions talk about. However, the objective grounds for logical relationships lie in what these expressions signify, even though they cannot be said to signify any things. Abelard is, then, one of a number of medieval thinkers, often referred to in later times as ‘nominalists’, who argued against turning logic and semantics into some sort of science of the ‘real’, a kind of metaphysics. It was Abelard’s view that logic was, along with grammar and rhetoric, one of the sciences of language.

In ethics, Abelard defended a view in which moral merit and moral sin depend entirely on whether one’s intentions express respect for the good or contempt for it, and not at all on one’s desires, whether the deed is actually carried out, or even whether the deed is in fact something that ought or ought not be done.

Abelard did not believe that the doctrines of Christian faith could be proved by logically compelling arguments, but rational argumentation, he thought, could be used both to refute attacks on Christian doctrine and to provide arguments that would appeal to those who were attracted to high moral ideals. With arguments of this latter sort, he defended the rationalist positions that nothing occurs without a reason and that God cannot do anything other than what he does do.