bluuebunny/crossref_metadata_2025 huggingface dataset:
Cosmopolitanism
Authors: Held David , Maffettone Pietro
Published: September 2018

Cosmopolitanism, in the broadest sense, is a way of thinking about the human condition. It portrays humanity as a universal fellowship. The unity to which cosmopolitans refer can be intellectual (we all share a capacity for reason), moral (we are all part of a single moral community), or institutional (we are all vulnerable to the same political evils and thus require shared collective solutions). The cosmopolitan intuition with its drive to highlight commonality is undoubtedly important. It understands that human beings are capable of an enormous range of good and bad, and attempts to embed human activity in a framework of common rules and norms; hence, it seeks to tame the potential for violent conflict. It tries to give us reasons to care for each other and to broaden our moral and intellectual universe beyond the remit of our personal ties and immediate environment. It offers a model of political action that confronts some of the most pressing challenges we face in the twenty-first century and does so by suggesting inclusive institutional solutions.

Yet, cosmopolitanism would not be an attractive philosophical position if it did not consistently strive to address some of its underlying tensions. One of the most intensely shared elements of the human experience is particularity, not unity. We come to the world from families and social and cultural groups, and often develop our moral sensibilities within the framework of public discourses based on specific political traditions. Critics often contend that cosmopolitanism downplays such particularity and is thus unable to reflect one of the most important aspects of persons’ lives. A second encompassing objection leveled at cosmopolitanism is its high degree of utopianism. Cosmopolitanism, its critics contend, is a flight from political reality. Its plans for institutional reform are too abstract to be credible and neglect the importance of power in human political relationships. Cosmopolitans should accept these challenges. Their aim should be to make cosmopolitanism more attractive by explaining the place of special ties in their moral outlook, and to make it more credible by detailing the urgency of cosmopolitan political reform. The enduring success of a cosmopolitan ethos is thus partly reliant on cosmopolitans’ ability to provide convincing answers to these alleged weaknesses.
Animal minds
Authors: Andrews Kristin
Published: September 2018

By examining the mind across species, we can make better progress on questions about the nature of the mind generally. While this has been acknowledged since ancient times, only recently has the philosophy of animal minds developed into a robust area of philosophical research. One wave of recent discussion focused on the nature and possibility of animal belief. Another wave of discussion focused on and the question of chimpanzee mindreading/theory of mind, or whether chimpanzees understand that other animals have mental states.

A more comprehensive investigation into the philosophy of animal minds came with the publication of the book Species of Mind (1997), written by philosopher Colin Allen and biologist Marc Bekoff. Given a commitment to the evolutionary continuity of mentality, just as we study other animals to better understand physical functions like disease or digestion, we can look at other animals to better understand consciousness, communication, memory, perception, and other aspects of mind. This approach raised methodological questions about how best to study animal minds. Anthropomorphism (the attribution of perhaps uniquely human traits to animals) and the use of anecdotes as data in animal cognition research were hotly debated. In the face of evidence suggesting that vervet monkeys have different alarm calls for different predators, philosophers investigated how best to interpret animal behaviour and communicative signals.

With advances in neurological and biological techniques, scientists started investigating animal consciousness, and philosophers often appealed to empirical research as part of their arguments about whether animals are conscious. Animals also started to gain more attention from ethicists, who often appealed to mental properties in their arguments for granting moral status to animals.

At the same time that the philosophical interest in animal minds has grown, many more findings in animal cognition have come from research in psychology, biology, and anthropology. In many cases, the philosophical and scientific discussions are tightly intertwined. This is apparent in the numerous philosophical articles that take empirical research into account as well as in the rich discussions about animal cognitive capacities that often arise from particular empirical findings.
Vision
Authors: Orlandi Nico
Published: September 2018

Why do things look to us as they do? This question, formulated by psychologist Kurt Koffka, identifies the main problematic of vision science. Consider looking at a black cat. We tend to see both the cat and its colour as the same at different times. Despite the ease with which this perception occurs, the process by which we perceive is fairly complex. The initial stimulation that gives rise to seeing, consists in a pattern of light that projects on the retina – a light-sensitive layer of the eye. The so-called ‘retinal image’ is a two-dimensional projection that does not correspond in any obvious manner to the way things look. It is not three-dimensional, coloured and shaped in a similar fashion to the objects of our experience. Indeed the light projected from objects is not just different from what we see, it is also both continuously changing and ambiguous. Because the cat moves around, the light it reflects changes from moment to moment. The cat’s projection on the retina correspondingly changes in size. We do not, however, see the cat as changing in size. We tend to see it as size-constant and uniformly coloured through time. How do we explain this constancy?

Along similar lines, the cat’s white paws cause on the retina a patch of light that differs in intensity from the rest. This patch could also be caused by a change in illumination. A black surface illuminated very brightly can look like a white surface illuminated very dimly. This means that the light hitting the retina from the paws is underdetermined – it does not uniquely specify what is present. But, again, we tend to see the paws as consistently white. We do not see them as shifting from being white to being black, but illuminated brightly. How do we explain this stability? A central aim of theories of vision is to answer these questions.

The science that attempts to address these queries is interdisciplinary. Traditionally, philosophical theories of vision have influenced psychological theories and vice versa. The collaboration between these disciplines eventually developed into what is now known as cognitive science. Cognitive science includes – in addition to philosophy and psychology – computer science, linguistics and neuroscience. Cognitive scientists aim primarily to understand the process by which we see. Philosophers are interested in this topic particularly as it connects to understanding the nature of our acquaintance with reality.

Theories of vision differ along many dimensions. Giving a full survey is not possible in this entry. One useful difference is whether a theory presumes that visual perception involves a psychological process. Psychological theories of vision hold that in achieving perception – which is itself a psychological state – the organism uses other psychological material. Opponents of psychological theories prefer to make reference to physiological, mechanical and neurophysiological explanations.
Metacognition
Authors: Proust Joëlle
Published: September 2018

It has often been claimed that metacognition should be defined as "cognition about one’s own cognition," "knowledge about one’s own knowledge," or "thinking about one’s own thinking" (Carruthers 2011; Nelson and Narens 1992; Perner 2012). These formulations, however, are now often seen as unduly restricting the scope of metacognition to a form of reflective judgment. There is evidence that agents with no concept of perception or knowledge, such as monkeys and young children, are nevertheless able to assess when they can confidently engage in a task (such as finding an object, discriminating visual patterns, or recognizing whether an item was already presented) (Hampton 2009). On an alternative definition, then, metacognition is the ability to evaluate whether one is likely to achieve a specific cognitive goal or to have successfully achieved it. These evaluations jointly contribute to the control of one’s actions. They allow agents to select contextually efficient cognitive actions, such as trying or not trying to remember the location of an object, and to decide whether or not to rely on a specific cognitive output to act on the world. In both cases, on this broader definition, agents may rely either on the degree of confidence that they experience (a noetic feeling), or on what they judge to be the case given their background beliefs and concept-based predictions (Arango-Muñoz 2011; Koriat and Levy-Sadot 1999; Proust 2007, 2013, 2015a). Metacognition so conceived is distributed in domain-specific abilities and involved in the regulation of mental actions, the distribution of resources between rival processes, and the regulation of one’s own emotions. Inter-agent metacognitive control is also exemplified in the pragmatic principles of conversation first explored by Paul Grice and in collective forms of epistemic investigation and decision-making (such as in scientific research).
Neuron doctrine
Authors: Hardcastle Valerie Gray
Published: September 2018

The neuron doctrine refers to the idea that neurons are the fundamental units of the nervous system and that understanding the activity of these cells is all that is needed to understand the brain. Importantly, the doctrine holds that not only are neurons structurally and functionally discrete, but they also have very specific connectivity, which determines how they signal one another. This notion has supported much of neuroscience research throughout the twentieth century, with its focus on uncovering the anatomical, physiological, and chemical properties of neurons central to their function. It also underlies most current approaches to neural network research, which assumes that discrete units connected in highly specific ways give rise to complex behaviors in biological and artificial nervous systems. However, we now know that the brain also uses patterns of neural activity averaged across groups of neurons to process information. In addition, information from genes, glial cells, and cellular structure affects neuronal responses. Our view of what it means to be a cell and how cells interact with the world has gotten much more complicated since the 1800s. But an approximation of the neuron doctrine remains useful in guiding research today.
Agrippa (1st/2nd century AD)
Authors: Hankinson R.J.
Published: September 2018

Agrippa, a Sceptic of the first or second century ad, compiled five general modes of Sceptical argument: the views of positive theorists are subject to endemic disagreement due to the relativity of appearances, and adjudication cannot succeed, since it will either be mere assertion (and hence will not command assent) or appeal to further considerations, which process will either be infinitely regressive or circular, or terminate in unfounded assumption.
Alexander of Aphrodisias (fl. c. AD 200)
Authors: Sharples R.W.
Published: September 2018

The Peripatetic philosopher Alexander was known to posterity as the commentator on Aristotle, until Averroes took over this title. His commentaries eclipsed most of those of his predecessors, which now survive only in scattered quotations. Used by Plotinus, Alexander’s commentaries were the basis for subsequent work on Aristotle by Neoplatonist commentators, and even though some themselves survive only in quotations by these later writers, Alexander’s interpretations of particular passages are still helpful and are cited by commentators today.

In addition to Alexander’s commentaries we have a number of monographs, and also collections of short discussions which are connected with themes in his writings, though some are probably by pupils rather than by Alexander himself. Alexander’s most influential and controversial doctrine has been his interpretation of Aristotle’s theory of soul and intellect; regarding the soul as the product of the mixture of the bodily elements, he has been seen as subordinating form to matter and as thereby misinterpreting Aristotle. Certainly his view excludes any immortality for individuals, but even if Aristotle himself allowed this it is arguable that to do so was incompatible with his definition of soul as the form of potentially living body. Alexander himself interpreted Aristotle’s ‘active intellect’ not as an immortal element in each individual, but as god, the unmoved mover, apprehended by our own intellects. Both on the question of soul and on that of the status of universals, Alexander gives a non-Platonizing reading of Aristotle, which accounts for some of the criticism to which he has been subjected by successors both ancient and modern. His treatment of the problem of free will has also been influential, though his criticisms of determinism are more telling than his own positive solution.

Seeing his task as interpreting Aristotle’s writings with the aid of one another and explaining apparent inconsistencies, Alexander contributed to the growth of Aristotelianism as a system; he does not criticize nor challenge Aristotle, and regards his own innovations as Aristotelian doctrine, developed in the context of new questions which Aristotle himself had not confronted in the same form. He was better at seeing the details than at comprehending the global picture, and the potential of some of his doctrinal contributions is most apparent in what they suggested to others; but there is still much to interest philosophers in his detailed argumentation on particular points and passages.
Archē
Authors: McKirahan Richard
Published: September 2018

Archē, or ‘principle’, is an ancient Greek philosophical term. Building on earlier uses, Aristotle established it as a technical term with a number of related meanings, including ‘originating source’, ‘cause’, ‘principle of knowledge’ and ‘basic entity’. Accordingly, it acquired importance in metaphysics, epistemology and philosophy of science, and also in the particular sciences. According to Aristotle’s doctrine of scientific principles, all sciences and all scientific knowledge are founded on principles (archai) of a limited number of determinate kinds.
Aretē
Authors: Sedley David
Published: September 2018

A pivotal term of ancient Greek ethics, aretē is conventionally translated ‘virtue’, but is more properly ‘goodness’ – the quality of being a good human being. Philosophy came, largely through Plato, to recognize four cardinal aretai: wisdom (phronēsis), moderation (sōphrosynē), courage (andreia) and justice (dikaiosynē). Others, considered either coordinate with these or their sub-species, included piety, liberality and magnanimity. The term generated many controversies. For example, is aretē a state of intellect, character or both? Does it possess intrinsic or only instrumental value? Is it teachable, god-given or otherwise acquired? Is it one thing or many? If many, how are they differentiated, and can you have one without having all?
Aristotle Commentators
Authors: Sorabji Richard
Published: September 2018

Aristotle’s school treatises were given renewed prominence by Andronicus of Rhodes in the first century bc, and from then on numerous commentaries were written on them. The main modern edition runs to 15,000 pages. They are not just commentaries, but represent the thought and classroom teaching on philosophy quite generally first of the Peripatetic (that is, Aristotelian) school, and then of the Neoplatonists between ad 200 and 600, with further activity from the ninth century in the Islamic world and from the eleventh in the Byzantine.
Callicles (late 5th century BC)
Authors: Hobbs Angela
Published: September 2018

Callicles, although known only as a character in Plato’s Gorgias (the dramatic date of which is somewhere between 430 and 405 bc), was probably an actual historical person. Employing a distinction between nature (physis) and convention (nomos), he argues eloquently that the naturally superior should seize both political power and a greater share of material goods: it is only a convention of the weak majority which labels such behaviour unjust. In private life the superior should indulge their desires freely: excess and licence are true virtue and happiness.
Chaldaean Oracles
Authors: Siorvanes Lucas
Published: September 2018

The Chaldaean Oracles were a collection of revelatory verses purportedly compiled in the second century ad. Along with the Orphic texts, Neoplatonists regarded them as divine words. When the Oracles appear in philosophical works, they lend support to select cosmological, metaphysical or psychological propositions which have already been formulated.
Cratylus (late 5th/early 4th century BC)
Authors: Long A.A.
Published: September 2018

Probably an Athenain, Cratylus was a radical Heraclitean, holding that the world is in constant and total flux. Through this doctrine he had a seminal influence on Plato. Cratylus also, for some time at least, defended the natural correctness of names.
Democritus (mid 5th–4th century BC)
Authors: Taylor C.C.W.
Published: September 2018

A co-founder with Leucippus of the theory of atomism, The Greek Philosopher Democritus developed it into a universal system, embracing physics, cosmology, epistemology, psychology and theology. He is also reported to have written on a wide range of topics, including mathematics, ethics, literary criticism and theory of language. His works are lost, except for a substantial number of quotations, mostly on ethics, whose authenticity is disputed. Our knowledge of his principal doctrines depends primarily on Aristotle’s critical discussions, and secondarily on reports by historians of philosophy whose work derives from that of Aristotle and his school.

The atomists attempted to reconcile the observable data of plurality, motion and change with Parmenides’ denial of the possibility of coming to be or ceasing to be. They postulated an infinite number of unchangeable primary substances, characterized by a minimum range of explanatory properties (shape, size, spatial ordering and orientation within a given arrangement). All observable bodies are aggregates of these basic substances, and what appears as generation and corruption is in fact the formation and dissolution of these aggregates. The basic substances are physically indivisible (whence the term atomon, literally ‘uncuttable’) not merely in fact but in principle; (1) because (as Democritus argued) if it were theoretically possible to divide a material thing ad infinitum, the division would reduce the thing to nothing; and (2) because physical division presupposes that the thing divided contains gaps. Atoms are in eternal motion in empty space, the motion caused by an infinite series of prior atomic ‘collisions’. (There is reason to believe, however, although the point is disputed, that atoms cannot collide, since they must always be separated by void, however small; hence impact is only apparent, and all action is at a distance.) The void is necessary for motion, but is characterized as ‘what-is-not’, thus violating the Eleatic principle that what-is-not cannot be.

Democritus seems to have been the first thinker to recognize the observer-dependence of the secondary qualities. He argued from the distinction between appearance and reality to the unreliability of the senses, but it is disputed whether he embraced scepticism, or maintained that theory could make good the deficiency of the senses. He maintained a materialistic account of the mind, explaining thought and perception by the physical impact of images emitted by external objects. This theory gave rise to a naturalistic theology; he held that the gods are a special kind of images, endowed with life and intelligence, intervening in human affairs. The ethical fragments (if genuine) show that he maintained a conservative social philosophy on the basis of a form of enlightened hedonism.
Diogenes of Oenoanda (c. 2nd century AD)
Authors: Erler Michael
Published: September 2018

The Epicurean philosopher Diogenes came from the Greek town Oenoanda in Lycia (Turkey). He is known exclusively for his massive philosophical inscription, erected in a colonnade there. Its remains contain sayings of Epicurus, plus Diogenes’ own writings, mainly on physics and ethics. His Epicureanism is largely traditional, but possible innovations include talk of a future Epicurean golden age.
Empedocles (c.495–c.435 BC)
Authors: Schofield Malcolm
Published: September 2018

Empedocles, born in the Sicilian city of Acragas (modern Agrigento), was a major Greek philosopher of the Presocratic period. Numerous fragments survive from his two major works, poems in epic verse known later in antiquity as On Nature and Purifications.

On Nature sets out a vision of reality as a theatre of ceaseless change, whose invariable pattern consists in the repetition of the two processes of harmonization into unity followed by dissolution into plurality. The force unifying the four elements from which all else is created – earth, air, fire and water – is called Love, and Strife is the force dissolving them once again into plurality. The cycle is most apparent in the rhythms of plant and animal life, but Empedocles’ main objective is to tell the history of the universe itself as an exemplification of the pattern.

The basic structure of the world is the outcome of disruption of a total blending of the elements into main masses which eventually develop into the earth, the sea, the air and the fiery heaven. Life, however, emerged not from separation but by mixture of elements, and Empedocles elaborates an account of the evolution of living forms of increasing complexity and capacity for survival, culminating in the creation of species as they are at present. There followed a detailed treatment of a whole range of biological phenomena, from reproduction to the comparative morphology of the parts of animals and the physiology of sense perception and thinking.

The idea of a cycle involving the fracture and restoration of harmony bears a clear relation to the Pythagorean belief in the cycle of reincarnations which the guilty soul must undergo before it can recover heavenly bliss. Empedocles avows his allegiance to this belief, and identifies the primal sin requiring the punishment of reincarnation as an act of bloodshed committed through ‘trust in raving strife’. Purifications accordingly attacked the practice of animal sacrifice, and proclaimed prohibition against killing animals to be a law of nature.

Empedocles’ four elements survived as the basis of physics for 2,000 years. Aristotle was fascinated by On Nature; his biology probably owes a good deal to its comparative morphology. Empedocles’ cosmic cycle attracted the interest of the early Stoics. Lucretius found in him the model of a philosophical poet. Philosophical attacks on animal sacrifice made later in antiquity appealed to him as an authority.
Epicurus (341–271 BC)
Authors: Sedley David
Published: September 2018

Epicurus of Samos founded the Epicurean school of philosophy. Initially a Democritean, he overhauled Democritus’ atomism so radically that his system was soon considered an independent one. He formed three Epicurean communities, the final one at Athens where his school, the Garden, became synonymous with Epicureanism. He and his three leading colleagues wrote voluminously, and their collective works became the school’s canonical texts in later generations. Those of Epicurus alone amounted to 300 books (scrolls), including his seminal treatise On Nature. Most were long and technical, but he also composed short digests as an aide memoire.
Gorgias (late 5th century BC)
Authors: Kahn Charles H.
Published: September 2018

The most important of the fifth-century bc Greek Sophists after Protagoras, Gorgias was a famous rhetorician, a major influence on the development of artistic prose and a gifted dabbler in philosophy. His display speeches, Encomium of Helen of Troy and Defence of Palamedes, are masterpieces of the art of making a weak case seem strong, and brilliant exercises in symmetrical and antithetical sentence structure. Of philosophical importance is his treatise On Not-Being, or On the Nature of Things, an elaborate reversal of the metaphysical argument of Parmenides, showing: (1) that nothing exists; (2) that if anything exists, it cannot be known; and (3) if anything can be known, it cannot be communicated. This nihilistic tour de force is probably a caricature rather than a serious statement of a philosophical position. Gorgias is a master of the persuasive use of logos (discourse), understood both as eloquence and as argumentative skill.
Hierocles (2nd century AD)
Authors: Inwood Brad
Published: September 2018

The Stoic philosopher Hierocles lectured and wrote on ethics. He is important for his defence of the theory of oikeiōsis (affiliation), a form of self-perception and self-love which becomes the foundation for human commitment to rationality and virtue. Observation of animal and human behaviour, he argues, shows that oikeiōsis is innate, rather than learned.
Homer (fl. c.700 BC)
Authors: Most Glenn W.
Published: September 2018

Author of the Iliad and Odyssey, the Greek poet Homer is probably the earliest surviving, and certainly among the greatest, of European poets. Down to the Renaissance he was considered the source of all scientific and philosophical wisdom; and he still supplies fruitful material for philosophical discussion of moral issues.
Lucian (c. AD 120–80)
Authors: Branham R. Bracht
Published: September 2018

Lucian of Samosata (in ancient Syria) was one of the most original and engaging figures of post-classical Greek culture. He produced a diverse and influential corpus comparable in size to that of Plato (consisting of seventy-six authentic libelli). Formally the dialogue (in both Platonic and Cynic forms) dominates (thirty-six of seventy-three prose works), but there are also satiric narratives, tall tales (for example, A True Story), ‘Cynic’ diatribes (for example, On Mourning), and multifarious lectures, or essays (for example, The Master of Rhetoric) in his singular oeuvre.
Melissus (mid or late 5th century BC)
Authors: Sedley David
Published: September 2018

Melissus was a Greek philosopher from the island of Samos. A second-generation representative of Eleatic metaphysics, he published one work, entitled On Nature or On That-Which-Is, which has been partially reconstructed by editors. It defends a version of Parmenides’ monism, but recast with terminology and arguments directly accessible to a readership schooled in the eastern Greek (Ionian) style of physical speculation, as distinct from Parmenides’ western Greek background. Although it is uncertain how important Melissus was to his own contemporaries, his prosaic but clear presentation of Eleatic concepts was more widely adopted by later writers than the enigmatic pronouncements of Parmenides.

Melissus argues that that-which-is is: (1) omnitemporal; (2) infinite in extent; (3) one; (4) homogeneous; (5) changeless, that is, without (a) reordering, (b) pain, (c) grief or (d) motion; (6) indivisible; and (7) bodiless. Here (1) – ‘it always was what it was, and always will be’ – is a departure from Parmenides, who had outlawed past and future in favour of a static present. Likewise (2) contrasts with Parmenides’ defence of spatially finite being. The remaining predicates are consonant with Parmenides, although (5) b–c suggest that the being Melissus has in mind is a living one, presumably a deity – an aspect not brought out by Parmenides. Melissus wrote ‘If there were many things, they ought to be such as I say the One is’ – a remark sometimes thought to have inspired his contemporaries the atomists.
Musonius Rufus (1st century AD)
Authors: Inwood Brad
Published: September 2018

Gaius Musonius Rufus was a Stoic philosopher who taught in Rome. Active on the margins of political life, he was twice exiled and recalled. His surviving work focuses on practical ethics. Besides his distinctive views on marriage, sexual morality and women’s education, Musonius is important for his influence on Epictetus.
Nous
Authors: Long A.A.
Published: September 2018

Commonly translated as ‘mind’ or ‘intellect’, the Greek word nous is a key term in the philosophies of Plato, Aristotle and Plotinus. What gives nous its special significance there is not primarily its dictionary meaning – other nouns in Greek can also signify the mind – but the value attributed to its activity and to the metaphysical status of things that are ‘noetic’ (intelligible and incorporeal) as distinct from being perceptible and corporeal. In Plato’s later dialogues, and more systematically in Aristotle and Plotinus, nous is not only the highest activity of the human soul but also the divine and transcendent principle of cosmic order.
Orphism
Authors: Burkert Walter
Published: September 2018

Orphism, a speculative trend within Greek religion, claimed the mythical singer Orpheus as founder and prophet. In changing forms, it is in evidence from the 6th century bc to the end of antiquity. Hexameter poems were attributed to Orpheus, especially a theogony about the origin of gods, world and mankind, and sectarian groups led an ‘Orphic life’, practising mystery cults supposedly founded by Orpheus. The main goal was salvation of the soul from evil, traced to ‘ancient guilt’, with a view to a blessed existence after death; this usually included the doctrine of transmigration
Parmenides (early to mid 5th century BC)
Authors: Sedley David
Published: September 2018

Parmenides of Elea, a revolutionary and enigmatic Greek philosophical poet, was the earliest defender of Eleatic metaphysics. He argued for the essential homogeneity and changelessness of being, rejecting as spurious the world’s apparent variation over space and time. His one poem, whose first half largely survives, opens with the allegory of an intellectual journey by which Parmenides has succeeded in standing back from the empirical world. He learns, from the mouth of an unnamed goddess, a dramatically new perspective on being. The goddess’s disquisition, which fills the remainder of the poem, is divided into two parts; the Way of Truth and the Way of Seeming.

The Way of Truth is the earliest known passage of sustained argument in Western philosophy. First a purportedly exhaustive choice is offered between two ‘paths’ – that of being, and that of not-being. Next the not-being path is closed off: the predicate expression ‘… is not’ could never be supplied with a subject, since only that-which-is can be spoken of and thought of. Nor, on pain of self-contradiction, can a third path be entertained, one which would conflate being with not-being – despite the fact that just such a path is implicit in the ordinary human acceptance of an empirical world bearing a variety of shifting predicates. All references, open or covert, to not-being must be outlawed. Only ‘… is’ (or perhaps ‘… is…’) can be coherently said of anything.

The next move is to seek the characteristics of that-which-is. The total exclusion of not-being leaves us with something radically unlike the empirical world. It must lack generation, destruction, change, distinct parts, movement and an asymmetric shape, all of which would require some not-being to occur. That-which-is must, in short, be a changeless and undifferentiated sphere.

In the second part of the poem the goddess offers a cosmology – a physical explanation of the very world which the first half of the poem has banished as incoherent. This is based on a pair of ultimate principles or elements, the one light and fiery, the other heavy and dark. It is presented as conveying the ‘opinions of mortals’. It is deceitful, but the goddess nevertheless recommends learning it, ‘so that no opinion of mortals may outstrip you’.

The motive for the radical split between the two halves of the poem has been much debated in modern times. In antiquity the Way of Truth was taken by some as a challenge to the notion of change, which physics must answer, by others as the statement of a profound metaphysical truth, while the Way of Seeming was widely treated as in some sense Parmenides’ own bona fide physical system.
Peripatetics
Authors: Sharples R.W.
Published: September 2018

The title ‘Peripatetics’ designates followers of the philosophical tradition founded by Aristotle: at first those who continued his inquiries, and in the Roman period those who interpreted and commented on his writings. The distinctive Peripatetic tradition was eventually absorbed into Neoplatonism. The adjective ‘Peripatetic’ is often used as an equivalent of ‘Aristotelian’. Peripatetic doctrines were marked by a rejection of the extreme views characteristic of Stoicism.
Philo of Alexandria (c.15 BC–c. AD 50)
Authors: Runia David T.
Published: September 2018

Philo of Alexandria is the leading representative of Hellenistic-Jewish thought. Despite an unwavering loyalty to the religious and cultural traditions of his Jewish community, he was also strongly attracted to Greek philosophy, in which he received a thorough training. His copious writings – in Greek – are primarily exegetical, expounding the books of Moses. This reflects his apologetic strategy of presenting the Jewish lawgiver Moses as the sage and philosopher par excellence, recipient of divine inspiration, but not at the expense of his human rational faculties. In his commentaries Philo makes extensive use of the allegorical method earlier developed by the Stoics. Of contemporary philosophical movements, Philo is most strongly attracted to Platonism. His method is basically eclectic, but with a clear rationale focused on the figure of Moses.

Philo’s thought is strongly theocentric. God is conceived in terms of being. God’s essence is unreachable for human knowledge (negative theology), but his existence should be patent to all (natural theology). Knowledge of God is attained through his powers and, above all, through his Logos (‘Word’ or ‘Reason’), by means of which he stands in relation to what comes after him. In his doctrine of creation Philo leans heavily on Platonist conceptions drawn from reflection on Plato’s Timaeus. The conception of a creation ex nihilo (‘from nothing’) is not yet consciously worked out. Philo’s doctrine of human nature favours the two anthropological texts in Genesis 1–2, interpreting creation ‘according to the image’ in relation to the human intellect. With regard to ethics, both Stoic concepts and peculiarly Jewish themes emerge in Philo’s beliefs. Ethical ideals are prominent in the allegorical interpretation of the biblical patriarchs.

Philo’s influence was almost totally confined to the Christian tradition, which preserved his writings. He was unknown to medieval Jewish thinkers such as Maimonides.
Physis and nomos
Authors: Hobbs Angela
Published: September 2018

In the fifth and fourth centuries bc a vigorous debate arose in Greece centred on the terms physis (nature) and nomos (law or custom). It became the first ethical debate in Western philosophy. Is justice simply a matter of obeying the laws, or does it have some basis in nature? If the laws conflict with my natural needs and desires, why should I submit to them? Is society itself ‘natural’, and what difference might the answer make to our evaluation of it? Both nomos and physis had their supporters, while some tried to dissolve the antithesis altogether.
Pneuma
Authors: Stead Christopher
Published: September 2018

Pneuma, ‘spirit’, derives from the Greek verb pneo, which indicates blowing or breathing. Since breathing is necessary for life and consciousness, pneuma came to denote not only wind and breath but various vital functions, including sensation and thought, and was understood by some philosophers as a cosmological principle. It became especially important in Stoicism, which explained the world in terms of matter and the rational structure exhibited in all its forms; this is established by rhythmical variations in the tonos or ‘tension’ of the pneuma.

In Hebrew tradition, where Greek was used, pneuma stood for life, consciousness, and for invisible conscious agents, angels or demons. In Christian thought it denotes divine inspiration, in particular the Holy Spirit acknowledged as a divine Person. At John 4:24 it is used, unusually, to describe God himself.
Presocratic philosophy
Authors: Sedley David
Published: September 2018

The Presocratics were the first Western philosophers. The most celebrated are Thales, Anaximander, Pythagoras, Heraclitus, Parmenides, Zeno of Elea, Empedocles, Anaxagoras and Democritus. Active in Greece throughout the sixth and fifth centuries bc, they concentrated on cosmogony and cosmology – the tasks of explaining the world’s origin and order, without recourse to mythology.
Pyrrho (c.365–c.275 BC)
Authors: Brunschwig Jacques
Published: September 2018

The Greek philosopher Pyrrho of Elis gave his name first to the most influential version of ancient scepticism (Pyrrhonism), and later to scepticism as such (pyrrhonism). Like Socrates, he wrote nothing, despite which – or thanks to which – he too became one of the great figures of philosophy. Although he has vanished behind his own legend, he must have helped nurture that legend: his unique personality palpably exercised an unequalled fascination on his acquaintances, and through them, on many others. We possess, thanks especially to Sextus Empiricus, extensive documentation of what can be called ‘Neo-Pyrrhonian’ scepticism, because from the time of Aenesidemus (first century bc) it invoked Pyrrho as its patron saint. But Pyrrho’s own thought is hard to recover. The documentary evidence for him is mainly anecdotal, and the principal doxography is more or less directly dependent on his leading disciple Timon of Phlius, who managed to present himself as Pyrrho’s mere ‘spokesman’, but who was in fact perhaps rather more than that. The main question, which is still unanswered, is whether Pyrrho was primarily or even solely a moralist, the champion of an ethical outlook based on indifference and insensibility, or whether he had already explicitly set up the weaponry of the sceptical critique of knowledge which underlies the epistemological watchword ‘suspension of judgment’.
Sophists
Authors: Kahn Charles H.
Published: September 2018

The Sophists were itinerant educators, the first professors of higher learning, who appeared in Greece in the middle and later fifth century bc. The earliest seems to have been Protagoras, who was personally associated with the statesman Pericles. The next most eminent was Gorgias, an influential author and prose stylist. The Sophists succeeded in earning very large sums for their instruction. They lectured on many subjects, including the new natural philosophy, but their most important teaching was in rhetoric, the art of influencing political assemblies and law courts by persuasive speech. In conservative circles their great influence was regarded with hostility, as corrupting the young.
Speusippus (c.410–339 BC)
Authors: Dillon John
Published: September 2018

The Greek philosopher Speusippus was the second head of the Platonic Academy. Succeeding his uncle Plato on the latter’s death, he developed his thought in interesting directions. He pursued further the tendency in the Academy to mathematicize reality that so annoyed Aristotle, postulating a complicated metaphysics, which started from a ‘One’ superior to being and all other qualities, and a material principle, ‘multiplicity’, from the union of which arose, first number, then geometrical entities, and then soul and the material world. In his hands, Plato’s doctrines of first principles, of Forms, and of the union of Forms with matter, suffered transformations of which we have only imperfect reports. His later influence was greater on Neo-Pythagoreanism than on ‘orthodox’ Platonism, until Plotinus.
Strato (d. c.269 BC)
Authors: Sharples R.W.
Published: September 2018

The third head of Aristotle’s school, from c.287 to c.269 bc, Strato has been regarded as substituting materialism for Aristotelian metaphysics, mechanism for teleology, atheism for theology and empiricism for intuition; and he has been blamed for the decline of Aristotle’s school, or (less often) praised for his adoption of a more scientific outlook, especially in psychology. However, on some issues at least it may be more a matter of a selective emphasis of certain parts of Aristotle’s teachings than of conscious and deliberate anti-Aristotelianism. None of Strato’s writings survives.
Thucydides (fl. c.400 BC)
Authors: Woodruff Paul
Published: September 2018

A Greek historian with philosophical interests, Thucydides wrote about the Peloponnesian War between Athens and Sparta (431–404 bc). He elaborates on the decisions of war in brilliantly reconstructed debates and speeches, reflecting his training under various Sophists. Many of these speeches take for granted that people care less for justice than for their own narrow interests. This dark view of human nature influenced Hobbes, while the style of the debates and speeches has had an enduring effect on public rhetoric. His account of Athenian democracy in action is cautionary, and his conservative political views anticipated Aristotle’s in some respects.
Timon (c.315–c.225 BC)
Authors: Brunschwig Jacques
Published: September 2018

Timon was a Greek philosopher-poet. The formative influence on his life was his meeting with Pyrrho, who was later hailed as the founder of Scepticism. He devoted his literary talents to eulogizing Pyrrho, and his satirical vigour to criticizing other philosophers. He, more than anyone else, carved the image of Pyrrho into what was to become its traditional form and placed it on its pedestal. In this, Timon seems to have been not only a fervent propagandist but also a major philosophical figure, exerting a decisive influence on the history and the very definition of neo-Pyrrhonian scepticism.
Xenocrates (396–314 BC)
Authors: Dillon John
Published: September 2018

The Greek philosopher Xenocrates was the third head of the Platonic Academy. Like his predecessor Speusippus, he further developed Plato’s philosophy, but along more orthodox lines. Indeed, Xenocrates contributed much to the formalization of Plato’s philosophy into dogma. Starting from a metaphysical system of Monad and Dyad, the former being a self-contemplating intellect on the Aristotelian model and the latter a material principle, he systematically derived the rest of creation, postulating first the generation of number, and then soul, defined as ‘self-moving number’. He is notable for a tendency towards triadic divisions of the universe, and a developed theory of daemons. He was probably responsible for the first definitive edition of Plato’s works.
Zeno of Citium (334–262 BC)
Authors: Sedley David
Published: September 2018

Zeno of Citium, a Greek philosopher from Cyprus, founded the Stoic school in Athens c.300 bc. His background and training lay in various branches of the Socratic tradition, including the Platonic Academy, but especially Cynicism. His controversial Republic was a utopian treatise, founded on the abolition of most civic norms and institutions. He laid the main foundations of Stoic doctrine in all areas except perhaps logic.
Antiochus (c.130–68 BC)
Authors: Barnes Jonathan
Published: September 2018

For most of his career the Greek philosopher Antiochus of Ascalon, a pupil of Philo of Larissa, was an orthodox ‘sceptical’ Academic. He then changed his philosophy: some called him a Stoic, but he himself claimed to be returning to the Old Academy of Plato and his immediate successors. He took a generous view of his new home, urging that the Peripatetics and the Stoics were not new schools of thought but mere modifications of Platonism, and the philosophical position which he advocated was a ‘syncretism’ – an amalgam of ideas and doctrines and arguments taken from several sources. To philosophy itself he contributed little, but he was a figure of considerable importance in the larger world, where he presented Greek philosophy to an educated Roman public.
Eudaimonia
Authors: Taylor C.C.W.
Published: September 2018

The literal sense of the Greek word eudaimonia is ‘having a good guardian spirit’: that is, the state of having an objectively desirable life, universally agreed by ancient philosophical theory and popular thought to be the supreme human good. This objective character distinguishes it from the modern concept of happiness: a subjectively satisfactory life. Much ancient theory concerns the question of what constitutes the good life: for example, whether virtue is sufficient for it, as Socrates and the Stoics held, or whether external goods are also necessary, as Aristotle maintained. Immoralists such as Thrasymachus (in Plato’s Republic) sought to discredit morality by arguing that it prevents the achievement of eudaimonia, while its defenders (including Plato) argued that it is necessary and/or sufficient for eudaimonia. The primacy of eudaimonia does not, however, imply either egoism (since altruism may itself be a constituent of the good life), or consequentialism (since the good life need not be specifiable independently of the moral life). The gulf between ‘eudaimonistic’ and ‘Kantian’ theories is therefore narrower than is generally thought.
Dissoi logoi
Authors: Burnyeat M.F.
Published: September 2018

Dissoi logoi (‘Twofold Arguments’) is the title scholars apply to a short anonymous collection of arguments for and against various theses. The work, in Greek, is (questionably) dated around 400 bc, and regarded as an interesting, if second-rank, product of the Sophistic age.
Immortality in ancient philosophy
Authors: Brennan Tad
Published: September 2018

In Greco-Roman philosophy immortality is discussed in two contexts: as an uncontroversial attribute of the gods and as a highly controversial attribute of human souls. Subdividing this latter topic, one may discern a more metaphysical question about whether every human soul as such is immortal in virtue of its nature or essence, and a more ethical topic about whether certain souls may enjoy a greater degree or share of immortality through adopting a certain mode of life. (This sub-topic is joined to the first main topic, to the extent that the virtuous agent’s approximation to immortality is part of their imitation of god or homoiōsis theōi).

Several Presocratic philosophers held that human souls are immortal, but it is Plato who first offers extensive arguments for this claim, as well as extensive reflections on the ethical import of personal immortality. Aristotle’s psychology leaves little room for the soul’s immortality, and it remains controversial whether he wished to leave any whatsoever. Discussions of immortality and its ethical consequences are similarly downplayed in surviving Stoic sources. The Epicureans gleefully argued the contrary view that a virtuous outlook depends on our conviction that we are irredeemably mortal. Only with the resurgence of Platonism in the Common Era does the soul’s immortality become once again a commonplace among philosophers. The connection between this and the Christian belief in resurrection is complicated. It is presumably due to the ascendancy of this double legacy that current popular usage counts it as nearly tautological that souls are immortal, but acknowledges a real question of whether human beings have souls, where ancient usage accepted as a near tautology that all living beings have souls, but admitted wide dispute over whether souls are immortal or not.