The first philosophers: from Thales to Democritus

Almost nothing these thinkers wrote has come down to us directly. Scholars sort the evidence using the standard collection by Diels and Kranz: B marks fragments, the thinker’s quoted words, and A marks testimonia, reports about him; a newer collection by Laks and Most appeared in 2016. Those who quoted them chose what suited their own arguments. Aristotle, the main source for the earliest thinkers, describes them in his own vocabulary: in Metaphysics 983b he calls Thales ὁ τῆς τοιαύτης ἀρχηγὸς φιλοσοφίας, the founder of this kind of philosophy. That is Aristotle’s verdict, not Thales’ claim.

Both usual labels need care. «Presocratic» is not strictly chronological: Democritus, born about 460 BC, was a younger contemporary of Socrates, and some scholars avoid the term. «Philosopher» is also anachronistic, since these men probably did not use the word as Plato and Aristotle did. It remains defensible because Aristotle saw them as predecessors in one continuous inquiry.

Aristotle says these early thinkers looked for τινα φύσιν, some nature from which everything else comes, and he calls it an ἀρχή, a beginning or principle. For Thales of Miletus it was water. Aristotle’s reasons for this are guesses, marked by ἴσως, «perhaps» (983b), and it is doubtful that Thales wrote anything. Herodotus (1.74) says he foretold an eclipse to the Ionians, though only to the year. Modern reckoning dates it to 28 May 585 BC; how he could have done this is unknown, and some scholars doubt the story.

Anaximander, also of Miletus, chose τὸ ἄπειρον, the boundless; what he meant by it is disputed. One fragment of his book survives, in Simplicius (6th century AD), who follows Theophrastus and uses no quotation marks, so nobody knows exactly where the quotation begins and ends. It describes things passing away into what they came from, in the language of justice and penalty. Anaximenes preferred air, which changes by condensing and thinning.

Today’s Greek shows how unevenly words survive. Αρχή still means beginning, principle and authority, and ἀήρ became αέρας, from the accusative ἀέρα. But Thales’ ὕδωρ gave way to νερό, from νηρόν, «fresh», attested for water in late antiquity; ὕδωρ lives on in learned compounds such as υδρογόνο.

Heraclitus of Ephesus, active around 500 BC, opens his book with the λόγος, a word that can mean statement, account or reason. All things, he says, happen according to this λόγος (γινομένων γὰρ πάντων κατὰ τὸν λόγον τόνδε, B1), yet people fail to grasp it. In B30 he says that no god or human made this κόσμος, which always was, is and will be fire. Here κόσμος means an ordered world.

The slogan πάντα ῥεῖ is not among the surviving fragments. Plato gives πάντα χωρεῖ καὶ οὐδὲν μένει, «all things give way and nothing stays» (Cratylus 402a). Of three river sayings, the Stanford Encyclopedia of Philosophy accepts only B12, where different waters flow over those who step into the same rivers, and argues that Plato’s picture probably rests on a misreading of it.

Parmenides of Elea, born around 515 BC if Plato’s dialogue is reliable, took a different road. About 160 verses survive of a hexameter poem perhaps 800 lines long, mostly through later authors such as Sextus Empiricus and Simplicius. A goddess argues that what is cannot come from what is not: birth and destruction are ruled out, and reason, not the senses, is the test of truth.

Several later thinkers explained change as the mixing and separating of things that already exist. Empedocles of Acragas, whose work is dated to the mid-5th century BC, named four: earth, water, air and fire. His word was ῥιζώματα, roots; Aristotle calls them στοιχεῖα, elements (985a). Love brings them together and Strife drives them apart. Anaxagoras of Clazomenae, older than Empedocles but later in his works according to Aristotle (984a), set νοῦς, mind, over everything: in Plato’s Phaedo (97c) Socrates recalls hearing a reading from his book, that νοῦς is ὁ διακοσμῶν, what puts all things in order.

Aristotle (985b) names Leucippus and his companion Democritus together: for them the elements are τὸ πλῆρες and τὸ κενόν, the full and the empty. Leucippus is little known, and Democritus of Abdera seems to have systematised his views; Democritus’ work survives only in second-hand reports, some unreliable. Diogenes Laertius (9.72) quotes him: νόμῳ ψυχρόν, νόμῳ θερμόν, ἐτεῇ δὲ ἄτομα καὶ κενόν, by convention cold, by convention hot, in reality atoms and void. An ἄτομον is literally what cannot be cut, from ἀ- and τέμνω. Dalton’s chemical theory of 1808 took up the name, and experiments from 1897 revealed the electron, a part of every atom. The name stayed.