Anaxagoras, Empedocles, Leucippus, and Democritus

Anaxagoras, 5th century BCE. Anaxagoras moved to Athens, was an associate of Pericles, and may have been prosecuted and convicted for impiety in about 450 BCE.

"Do you think you are accusing Anaxagoras, my dear Meletus, and do you so despise these gentlemen and think they are so unversed in letters as not to know, that the books (βιβλία) of Anaxagoras the Clazomenian are full of such utterances? And forsooth the youth learn these doctrines from me, which they can buy sometimes (if the price is high) for a drachma in the orchestra [part of the ἀγορά in Athens] and laugh at Socrates, if he pretends they are his own..." (Plato, Apology 26d).

A "drachma" (δραχμή) was the daily wage of a hoplite (Thucydides, History of the Peloponnesian War VII.27).

A "hoplite" (ὁπλίτης) is an armed foot soldier. Hoplites take their name from the "shield" (ὅπλον) they carried.

The Chigi vase The Chigi vase (650 BCE), found in an Etruscan tomb at Monte Aguzzo. National Etruscan Museum, Villa Giulia.

Empedocles, 5th century BCE. Empedocles writes in verse, as did Xenophanes and Parmenides.

Leucippus, 5th century BCE.

Democritus, 5th to 4th century BCE. Democritus says that he was young when Anaxagoras was old (DK 68 B 5). He was still alive when Aristotle was in the Academy.

These Presocratics are mixed geographically. Empedocles came from Acragas in southern Italy, but the others were from the east. Anaxagoras came from Clazomenae. Democritus came from Abdera. Clazomenae is north of Miletus, and Abdera is further north and east. Leucippus is an obscure figure whose life and place of birth is unknown.
Anaxagoras, Empedocles, and Leucippus and Democritus (the ancient atomists) are inquirers into nature. They take the underlying nature to consist in a plurality of objects.

The relationship of these inquirers into nature to the Milesians and to Parmenides is uncertain, but the ontology in Democritus and Leucippus (and also Anaxagoras and Empedocles) provide a means to defend the inquiry into nature against the threat Parmenides posed.

In this way, the new tradition of philosophy (which first arose out the external demand for a new kind of explanation of the world and human beings) was becoming mature enough that new positions developed in response to older positions from within the tradition.

Leucippus and Democritus

According to Democritus and Leucippus, atoms and void are the nature of things.

On the existence of the ordinary objects salient in experience, Democritus and Leucippus may have different views. The evidence for what Leucippus thinks is less certain, but Democritus seems to think the ordinary objects salient in experience are how the atoms in the void appear to humans beings. Democritus seems to think that belief in the existence of these objects and the traditional conception of reality generally is a product of sense-experience, that sense-experience is a "bastard" form of judgment, that this form of judgment is not knowledge, that the ordinary objects salient in experience are the way arrangements of atoms in the void appear, and that only the "legitimate" judgment of reason provides knowledge of what exists.

The traditional way to think about ordinary objects is to suppose that they come into existence, persist through various changes, and eventually go out of existence, but Democritus seems to think that this way of thinking mistakes appearance for reality. He accepts Parmenides' conclusion that nothing comes into or goes out of existence. The atoms exist and move in the void, but the atoms do not come into or go out of existence. They become arranged in various ways as they move aimlessly through the void, but these transient arrangements are not themselves objects and hence are not objects that come into or go out of existence.

Knowledge, Reason, and Experience

"Democritus sometimes does away with what appears to the senses, and says that none of these appears according to the truth but only according to opinion. The truth in real things is that there are atoms and void. 'By custom,' he says, 'sweet, bitter, hot, cold, color; but in truth, atoms and void'" (Sextus Empiricus, Against the Logicians I.135; DK 68 B 9).

"He says that there are two kinds of knowing, one through the senses and one through the intellect. Of these he calls the one through the intellect 'legitimate,' attesting its trustworthiness for the judgment of truth, and that through the senses he names 'bastard,' denying it inerrancy in the discrimination of what is true. To quote his words: 'Of knowing there are two forms, one legitimate, one bastard. To the bastard belong all this group: sight, hearing, smell, taste, touch. The other is legitimate and separate from that'" (Sextus Empiricus, Against the Logicians I.138; DK 68 B 11).

"The principles of the totality of things are atoms and the void, everything else is the object of convention (νενομίσθαι). ... Nothing comes into being from what does not exist nor is it destroyed into what does not exist. And the atoms are unlimited in magnitude and number and they move in the whole, whirling around" (Diogenes Laertius, Lives of the Philosophers IX.44).

Sextus Empiricus lived in the 2nd or 3rd century CE. He is the primary source for Democritus' epistemology. He discusses Democritus in Against the Logicians I (M VII).

"The Greeks do not conceive correctly either what it is to come to be or what it is to be destroyed. For no thing comes to be or is destroyed; but rather, out of things that are, there is mixing and separation. And so, to speak correctly, they would have to call coming to be ‘mixing’ and being destroyed ‘separating'" (Anaxagoras DK 59 B 17. Simplicius, Commentary on Aristotle’s Physics).

"[O]f nothing is there birth, among all mortal things, nor is there an ending coming from baleful death, But only mixture and exchange of things mixed exist, and ‘birth’ is a name given by mortal humans" (Empedocles, DK 31 B 8. Pseudo-Plutarch, De Placita Philosophorum 1.30.1).

Pseudo-Plutarch is the conventional name of the unknown author of works that were but now are no longer attributed to Plutarch. De Placita Philosophorum (Περὶ τῶν ἀρεσκόντων φιλοσόφοις φυσικῶν δογμάτων, On the physical doctrines held by the philosophers) abridges a longer work ascribed to Aëtius (first to second century CE).
Democritus seems to think that the traditional conception of reality as consisting of objects that come into and go out of existence is a "custom" or "convention" that has its basis in the senses. It is a "bastard" judgment, not a "legitimate" judgment in terms of reason. Human beings typically rely on their senses for their beliefs, and it is through this reliance that human beings form their belief in the traditional but mistaken conception of reality in which there are objects that come into and go out of existence. Democritus accepts Parmenides' injunction to "judge by reason (κρῖναι δὲ λόγῳ)," and "not [to] let habit born from much experience (πολύπειρον) compel" belief about existence in terms of a "sightless eye and sounding ear and tongue."

A Defense of the Inquiry into Nature

Democritus, with his version of Atomism, provides a means to defend the inquiry into nature against Parmenides' argument by showing that the inquiry into nature may be understood so that it is consistent with his conclusion that nothing comes into or goes out of existence.

Thales and the Milesian inquirers into nature may follow a "backward-turning" method, as Parmenides suggests. They may think objects exist in terms of changes in the nature of reality, but this ontology is not essential to the inquiry into nature. The ordinary objects salient in experience do not exist, according to Democritus, and so do not exist in terms of the nature of reality. These objects, however, according to Democritus, seem to exist because the traditional conception of reality is how reality appears to human beings who to know the truth rely on sense-experience rather than the "legitimate" judgment of reason. In this way, according to Democritus, the inquiry into nature relies on reason to show how changes in the objects in the traditional and customary way to conceive of reality are in fact a matter of changes in the locations of atoms in the void. As Democritus says, in a fragment Sextus Empiricus preserves, "[b]y custom, sweet, bitter, hot, cold, color; but in truth, atoms and void" (DK 68 B 9).

The Inquiry into Nature goes to Athens

At some point in Democritus' lifetime, the inquiry into nature became fashionable in intellectual circles in Athens. Aristophanes makes fun of this new way of thinking in his play the Clouds. This play was performed in 423 BCE as part of an annual festival in Athens to honor the god Dionysus, so the ideas must have been in Athens prior to that.

Socrates certainly knew and may initially have had an interest in and even possibly pursued the inquiry into nature in his youth, but his primary place in the ancient philosophical tradition is part of the new focus of intellectual discussion in Athens on questions about how to live.

Diogenes Laertius (3rd century CE) structures his Lives of the Philosophers (in ten books) lines of succession.
"Archelaus, the son of Apollodorus, or as some say of Midon, was a citizen of Athens or of Miletus; he was a pupil of Anaxagoras, who first brought natural philosophy from Ionia to Athens. Archelaus was the teacher of Socrates. He was called a physicist inasmuch as with him natural philosophy came to an end, as soon as Socrates had introduced ethics. It would seem, though, that Archelaus himself also treated of ethics, for he has discussed laws and goodness and justice; Socrates took the subject from him and, having improved it to the utmost, was regarded as its inventor" (Diogenes Laertius, Lives of the Philosophers, II.16).

Perseus Digital Library:

Henry George Liddell, Robert Scott, A Greek-English Lexicon:
ἄτομος, (ἀ + τέμνω), atomos, adjective, "uncut"
νόος, noos, noun, "intellect"
νομίζω, nomizō, verb, "to hold as a custom, use customarily"
νόμος, nomos, noun, "that which is in habitual practice, custom"

Arizona State University Library. Loeb Classical Library:
Early Greek Philosophy, Volume V: Western Greek Thinkers, Part 2
Early Greek Philosophy, Volume VI: Later Ionian and Athenian Thinkers, Part 1
Early Greek Philosophy, Volume VII: Later Ionian and Athenian Thinkers, Part 2
Sextus Empiricus, Against the Logicians

"[O]nce a discipline of philosophy was established, it naturally came to respond to two different sets of needs or demands: the external ones, which originally gave rise to the practice of philosophy, and also internal demands as to what counted as acceptable or good practice in terms of the discipline. Both demands or needs wold ensure that the discipline would change over time. As the culture evolved, the external needs would change, and with it the discipline, to the extent that it continued to be responsive to them. And the internal demands would also force change. New answers would raise new questions, and the answers to these questions could force a revision of the answer to the original ones" (Michael Frede, "The Philosopher," 3. Greek thought: A Guide to Classical Knowledge, 3-16).

"[H]ow does it come about that, if reality is the way Parmenides describes it, we nevertheless perceive it the way we do? "Medicine, according to Democritus, cures the illnesses of the body, but wisdom frees the soul from passions (παθῶν)" (Clement of Alexandria, Pedagogue 1.2).

Clement of Alexandria (first to second century CE) was a Greek Christian theologian and head of the catechetical school of Alexandria (the city on Mediterranean Sea in Egypt that Alexander the Great founded in 331 BCE).
It was Democritus who took up this problem, and, in taking it up, had to face the question of the relative roles of thought and perception in cognition. He thus, instead of having a vague and indefinite notion of some cognitive power of thought, came nearer to having a notion of reason by trying to determine more precisely the relative role of thought in cognition" (Michael Frede, "Introduction," 21-22. Rationality in Greek Thought, 1-28).

Michael Frede's A Free Will is a partially revised version of his Sather Lectures delivered in 1997/98 at the University of California, Berkeley. Frede died (in 2007 while swimming at Agios Minas, a cove east of Itea on the Gulf of Corinth in Greece) before releasing his lectures for publication. "[There can be a temptation for us to think] that Democritus must have thought that the atoms move, collide, or rebound according to fixed laws of nature. But it is perfectly clear that Democritus has no idea of such laws. He is concerned, rather, to resist the idea that the apparent regularity in the behavior of objects be understood as the result of their being designed to behave in this fashion; for in Greek thought regularity of behavior as a rule is associated with design by an intellect. The planets are taken to be supremely intelligent, if not wise, because they move with an extreme degree of regularity. If an object is not intelligent but displays regularity in behavior, it is readily thought to do so by design of an intelligent agent. Democritus's point is that the apparent regularity of the world is not a work of design, say, by an Anaxagorean cosmic intellect but a surface phenomenon produced by the aimless, random motion of the atoms" (Michael Frede, A Free Will. Origins of the Notion in Ancient Thought, 13).

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