Methodology

Cicero, Academica 1.43–6

(1) Then Varro said: ‘It is now up to you, as one who deviates from the philosophy of the ancients and approves the innovations of Arcesilaus, to explain what the schism was and why it took place, so that we can see whether your desertion is adequately justified.’ (2) I [Cicero] then said: ‘It was with Zeno, so we have heard, that Arcesilaus began his entire struggle, not out of obstinacy or desire for victory – in my opinion at least – but because of the obscurity of the things which had brought Socrates to an admission of ignorance; and before him already, Democritus, Anaxagoras, Empedocles, and almost all the ancients, who said that nothing could be grasped or cognized or known, saying that the senses are restricted, the mind weak, the course of life short, and that (to quote Democritus) truth has been submerged in an abyss, with everything in the grip of opinions and conventions, nothing left for truth and everything in turn wrapped in darkness. (3) So Arcesilaus was in the practice of denying that anything could be known, not even the one thing Socrates had left for himself – the knowledge that he knew nothing: such was the extent of the obscurity in which everything lurked, on his assessment, and there was nothing which could be discerned or understood.

Scepticism

Diogenes Laertius 9.61–2 (Caizzi 1A, 6, 7, 9)

(1) Pyrrho of Elis was the son of Pleistarchus, as Diocles also records. According to Apollodorus in his Chronicles, he was first a painter, and was instructed by Bryson son [or pupil?] of Stilpo, as Alexander says in his Successions. Later he studied under Anaxarchus and accompanied him everywhere, with the result that he even associated with the Naked Philosophers in India and with the Magi. (2) In consequence he seems to have practised philosophy in a most noble way, introducing that form of it which consists in non-cognition and suspension of judgement… (3) For he would maintain that nothing is honourable or base, or just or unjust, and that likewise in all cases nothing exists in truth; and that convention and habit are the basis of everything that men do; for each thing is no more this than this. (4) He followed these principles in his actual way of life, avoiding nothing and taking no precautions, facing everything as it came, wagons, precipices, dogs, and entrusting nothing whatsoever to his sensations. But he was looked after, as Antigonus of Carystus reports, by his disciples who accompanied him. Aenesidemus, however, says that although he practised philosophy on the principles of suspension of judgement, he did not act carelessly in the details of daily life. He lived to be nearly ninety.

Why to suspend judgement

Diogenes Laertius 9.106–7

(1) Aenesidemus, in the first of his Pyrrhonist discourses, says that Pyrrho determines nothing in doctrinaire fashion, because of the opposition of arguments, but follows appearances. He says the same in his Against wisdom and On inquiry … (2) Hence according to the Sceptics it is what appears that serves as a criterion, as Aenesidemus also says … (3) As end the Sceptics name suspension of judgement, upon which freedom from disturbance follows like a shadow, as the followers of Timon and Aenesidemus put it.

Diogenes Laertius 9.78

Pyrrhonist discourse is a kind of recollection of appearances, or of ideas of any kind, on the basis of which they are all brought into confrontation with each other and, when compared, are found to present much disparity and confusion. This is what Aenesidemus says in his Outline introduction to Pyrrhonism.

Photius, Library 169b 18–170b3

(1) I read Aenesidemus' eight Pyrrhonist discourses. The overall aim of the book is to establish that there is no firm basis for cognition, either through sense-perception, or indeed through thought. (2) Consequently, he says, neither the Pyrrhonists nor the others know the truth in things; but the philosophers of other persuasions, as well as being ignorant in general, and wearing themselves out uselessly and expending themselves in ceaseless torments, are also ignorant of the very fact that they have cognition of none of the things of which they think that they have gained cognition.

THE SCHOOLS

If Aristotle could have returned to Athens in 272 b.c., on the fiftieth anniversary of his death, he would hardly have recognized it as the intellectual milieu in which he had taught and researched for much of his life. He would have found there new philosophies far more diverse and more self-consciously systematic than those on offer in his own day. Some of the central issues, and much of the technical terminology in which they were being discussed, would have seemed unfamiliar.

How had this change come about? Aristotle might have perceived it as one aspect of the radical transformations effected throughout the greater part of the known world by the conquests of his delinquent pupil Alexander the Great. Alexander's hellenization of the east Mediterranean and beyond had generated a new excitement about Greek culture among people with primarily non-Greek backgrounds. For those who were attracted by Greek philosophy in particular, Athens was their natural Mecca, both because it still housed the schools founded by Plato and Aristotle, and because such literary masterpieces as Plato's Socratic dialogues, which will have afforded many their first taste of the subject, lent Athens an unfading glamour as the true home of philosophical enlightenment. Thus in the new Hellenistic age philosophy flourished at Athens as never before. And many of her new breed of philosophers hailed from the eastern Mediterranean region.

The philosophical curriculum

Aetius 1, Preface 2 (SVF 2.35)

The Stoics said that wisdom is scientific knowledge of the divine and the human, and that philosophy is the practice of expertise in utility. Virtue singly and at its highest is utility, and virtues, at their most generic, are triple – the physical one, the ethical one, and the logical one. For this reason philosophy also has three parts – physics, ethics and logic. Physics is practised whenever we investigate the world and its contents, ethics is our engagement with human life, and logic our engagement with discourse, which they also call dialectic.

Diogenes Laertius 7.39–41

(1) They [the Stoics] say that philosophical discourse has three parts, one of these being physical, another ethical, and another logical. This division was first made by Zeno of Citium in his book On discourse, and also by Chrysippus in his On discourse book 1 and in his Physics book 1 … and by Diogenes of Babylon and Posidonius. (2) Apollodorus calls these parts ‘topics’, Chrysippus and Eudromus ‘species’, and others ‘genera’. (3) They compare philosophy to a living being, likening logic to bones and sinews, ethics to the fleshier parts, and physics to the soul. They make a further comparison to an egg: logic is the outside, ethics what comes next, and physics the innermost parts; or to a fertile field: the surrounding wall corresponds to logic, its fruit to ethics, and its land or trees to physics; or to a city which is well fortified and governed according to reason.

This work is a collection and discussion of the primary sources for Hellenistic philosophy. By presenting the material both in its original languages and in translation, we aim to give classicists and philosophers direct access to the surviving evidence on the Stoics, Epicureans, Pyrrhonists and Academics, whose thought dominated philosophy in the three centuries after the death of Aristotle in 322 b.c. There has been a remarkable upsurge of interest in these philosophies over the last few decades, but up to now the original texts have not been collected in any single book with the comprehensiveness and detail we have sought to provide.

In its scope and purpose our book closely resembles G. S. Kirk, J. E. Raven, and M. Schofield, The Presocratic Philosophers (ed. 2, 1983), but we divide the material between two volumes. Vol. 1 is entirely in English, offering translations of texts, accompanied by philosophical commentary. It is presented in a manner which we hope will make it usable by those with no historical background in the classical world. With its glossary and set of indexes, it is designed to be entirely self-sufficient. But the expectation is that our classical readers will use it in conjunction with vol. 2. This latter supplies (sometimes in longer excerpts) the texts translated in vol. 1, together with critical apparatus, information on their original contexts, supplementary commentary on technical matters and points of detail, and some additional texts.

PHYSICS

The principles of conservation

Epicurus, Letter to Herodotus 38–9

(1) Having grasped these points, we must now observe, concerning the non-evident, first of all that nothing comes into being out of what is not. For in that case everything would come into being out of everything, with no need for seeds. (2) Also, if that which disappears were destroyed into what is not, all things would have perished, for lack of that into which they dissolved. (3) Moreover, the totality of things was always such as it is now, and always will be, (4) since there is nothing into which it changes, (5) and since beside the totality there is nothing which could pass into it and produce the change.

Lucretius 1.15 9–73

(1) For if things came into being out of nothing, every species would be able to be produced out of everything, nothing would need a seed. (2) Men, to start with, would be able to spring up out of the sea and scaly fish from the land, and birds hatch out of the sky. Cattle and other livestock, and every species of wild animal, would be born at random and occupy farmland and wilderness alike. Nor would the same fruits stay regularly on the same trees, but would change over: all trees would be able to bear everything.

The earliest surviving record of a clash between the two cosmologies is in Plato's Phaedo – perhaps an unexpected place to find it, since the Phaedo is not about the natural world, but about the human soul, its destination after death, and the implications of immortality for the life of man or earth. And yet Plato's discussion of the issue gains an important dimension from its unexpected context, as we shall see, although he himself does not explicitly draw attention to the point.

Socrates is sitting in an Athenian prison waiting for the death sentence to be carried out. He talks with friends and explains the ground for his confidence that a man's soul survives his death. They listen and are convinced – but two of them express lingering doubts. The first doubt is quickly disposed of, but the second, says Socrates, is more troublesome. The first part of his attempt to allay it contains the critique of other philosophers that interests us. We shall return later to the doubt itself and the role of this critique in putting it to rest.

In his youth, Socrates says, he was an avid student of the philosophy of nature. ‘It seemed to me a superlative thing – to know the explanation of everything, why it comes to be, why it perishes, why it is’ (96a).

The kind of question he considered then, he says, was whether the growth of animals came from a fermentation of the hot and the cold, and whether the blood, or air, or fire,

The educational tradition of the Western half of the world has fairly recently adopted a new picture of the physical universe and man's place in it. We are now brought up to believe that we live on one of the planets that move in orbits around a rather minor star, itself a member of one galaxy among a vast number of others. We are taught that our planet is not eternal, but had an origin and will have an end; that it has grown into its present condition through a long evolutionary process, in which the minerals developed first, before any life appeared, and then the complex living species that we see around us, including man, evolved over a very long period of time through the processes of mutation, natural selection, and inheritance.

This picture has largely, though not entirely, replaced an earlier one that held the field for many centuries. According to that, the earth is stationary at the center of the cosmos. The stars, planets, sun, and moon revolve around the earth. The cosmos is finite, being bounded by the outermost sphere of the heavens, and is unique. This cosmic order, according to the prevalent, Judaeo-Christian version of the picture, was determined and brought into being at a certain point of time by God, who adopted it because it is a good order. He also created all the living species that now exist and arranged them in a hierarchical order of decreasing complexity or excellence, with man at the top of the scale.

Aristotle vigorously attacked the Atomists and their predecessors for their theories of the elementary material components of the physical world. He himself held a theory that there are such elements, but it differed from all that had come before: he does not even spare Empedocles, who anticipated him at least in picking out earth, water, air, and fire as the elements. His criticisms are directed at the character given to the elements, and the use made of these elements in explaining the phenomena.

We shall examine these criticisms of early theories of the material elements in the second section. First, we must look at a more fundamental criticism – a criticism of materialism itself. Aristotle argues that an account of the material elements is a necessary part of explanation in the study of the natural world, but it is not sufficient for explanation, except in a minority of less important cases. He accuses his philosophical predecessors of a crucial failure, in that they virtually ignored form and finality in nature. This takes us right to the heart of the differences between Atomism and Aristotelianism.

The failure of Presocratic explanations

The subject under discussion is nature, physis. At the beginning of the second book of his Physics, Aristotle makes some very general remarks, which then form the basis for his criticisms of the Presocratics.

The four roots

It is customary to regard the Sicilian Empedocles as a particularly archaic and reactionary thinker, but I believe that is a mistake. Like Parmenides, he wrote in hexameter verse, and he chose the language of myth. He adopted the Pythagorean idea of metempsychosis, and wrote of himself as a fallen daimon, one who had been ‘a bird, a bush, and a dumb sea-fish.’ Historians of science find it hard to take someone like that seriously. Nevertheless, he was responsible for three innovations of great importance to the history of science: the invention of elements, the postulation of two physical forces, qualitatively different from each other, and the first statement, so far as we know, of the concept of natural selection by survival of the fittest.

His theory of elements claimed that there are just four substances in the physical world: earth, water, air, and fire. There is a finite and unvarying quantity of each of them, and between them they make up all the material objects that there are, by mixing in different proportions. Empedocles gives an idea of how the theory works by offering a comparison with fourcolor painting:

In chapter 2 we have already taken a preliminary look at Plato's first observations on the cosmology of his predecessors. He gave us an unforgettable picture of Socrates reviewing his life of philosophizing, as he sat in prison with friends on the last day of his life. The main target of his criticism of earlier philosophy was its neglect of the question ‘to what end?’ or ‘what is the good of this?’ The physicists gave him nothing but a story of matter in motion, of how, not why, things come to be as they are. This Socrates found so unsatisfying that he turned to a quite different kind of philosophy.

Plato returned to criticism of materialism in works written later than Phaedo, and that is the subject of this chapter. First we must observe that Plato seldom names the targets of his criticism. Of the ‘physicists’ we have reviewed in earlier chapters, Plato mentions Thales, but not Anaximander or Anaximenes; Anaxagoras several times, but Empedocles only twice; and Leucippus and Democritus not at all. The omission of the last two has surprised the commentators from ancient times to the present day. There is a story in the biography of Democritus in Diogenes Laertius (ix.40) that Plato wanted to burn all of Democritus' books that he could collect, but was prevented by two Pythagoreans. It was no use, they said, the books were too widely published.

The crucial importance of Parmenides of Elea in the history of cosmology has been explained. We must now turn to his followers, who reinforced his arguments with contributions of their own. Some of these played an extraordinary and fascinating part in the development of Atomism, and their authors have an assured place in history. It happens that these connections have been fairly thoroughly explored in recent literature, especially in the English language, and this chapter will accordingly be relatively brief.

We hear of two followers of Parmenides, each about one generation younger than he was. Zeno came from Parmenides' home town of Elea, Melissus from the Aegean island of Samos, the birthplace of Pythagoras. Their work can be dated about the middle of the fifth century. There is no doubt about their allegiance. For Zeno, we have Plato's authority: his dialogue called after Parmenides presents Parmenides, as a man of sixty-five, with Zeno as a companion then aged about forty, in conversation with Socrates, at the time still very young. The occasion itself is probably fictitious, but the relative ages are likely to be about right, and when Plato has Zeno say that his book was in support of Parmenides' argument, he may be believed. Against those who ridiculed Parmenides' thesis ‘One thing is,’ Zeno is made to say, he wrote to show that still more ridiculous things follow from the contrary thesis, ‘Many things are’ (Parmenides 128b–c).

This volume tells one side of the story of ancient Greek cosmology, and takes it as far as the criticisms directed by Aristotle at his materialistic predecessors. The book is to be completed in a second volume, The Teleological World Picture and its Opponents. In that I shall give an account of the cosmology of Plato's Timaeus and Aristotle's works on the philosophy of nature, followed by the attempted rehabilitation of the atomic theory of the universe by Epicurus and his followers. Then I shall try to describe the arguments of philosophers of the Hellenistic period and later, including the Stoics and the later Peripatetics. I hope to take the story as far as the time of Simplicius and Philoponus, in the sixth century A.D.

I have tried to make the book readable by those with no specialized knowledge of Greek philosophy, and no Greek. Although it is not designed to be a course textbook, in writing it I have kept in mind the students to whom I lecture every year in Princeton University in a course called ‘Introduction to Ancient Philosophy’. They include some who are taking a major in Classics or Philosophy, but also many who have never before studied the ancient world or read anything of the Greek philosophers. I have tried to keep the philological technicalities to a minimum.

On some subjects I have adopted positions that need more detailed defense than I have been able to give in this context. I have sometimes argued the case in articles that have been published separately in the professional journals, or in papers that are not yet published.

In response to Parmenides, Anaxagoras worked out the astonishing theory that all physical change is nothing more than an emerging into view of something previously latent. Thus, we have no need to speak about what is not, but only about what we do not yet see.

The interpretation and assessment of Anaxagoras put forward here differ substantially from what is found in most contemporary histories of philosophy, in at least three respects. I believe Anaxagoras' theory is quite independent of Zeno, and that Zeno, in fact, criticized him. I also think that Anaxagoras did not criticize and modify Empedocles' theory of elements, but represents a more primitive stage of response to Parmenides than Empedocles. Moreover, my interpretation of his theory of matter is not quite the same as any other that I have read. These are all controversial positions, which cannot be defended in detail here.

Anaxagoras

Anaxagoras began his book with a striking affirmation that at once made clear his opposition to Parmenides:

Parmenides had agreed that what is is invariant in time, so that only ‘it is,’ and not ‘it was’ or ‘it will be,’ is correct, and that it is uninterrupted in space by any interval or change of density.

The men and their books

The writers of the ancient world were confident that Leucippus and Democritus were the founders of the atomic theory, but they were not at all careful in allocating the credit between the two of them. Attempts have been made by modern scholars to isolate the contribution of Leucippus – the earlier and less well-known of the two – but their arguments, if not demonstrably wrong, are too tenuous to rely on. Little attempt will be made in this book to distinguish their doctrines, at least with regard to the physical world; on the subject of human society and ethics, it appears that Democritus was very much the major contributor.

The early Atomists are associated with the remote country town of Abdera, on the northern Greek mainland close to the island of Thasos. Democritus lived and worked there; probably Leucippus did so too, although ancient biographers were uncertain whether to connect him with Abdera, Elea, or Miletus. Democritus had a long life – some say he lived to be a hundred. His precise dates are not known. He himself wrote in The Small World Order, according to Diogenes Laertius (IX.41), that he was forty years younger than Anaxagoras. Probably he was born about 460 b.c., and Leucippus was somewhat older. The atomic theory, then, must date from about the time of the Peloponnesian War, in the last decades of the fifth century; it is approximately contemporary with Socrates' philosophical activity, and with the birth of Plato.