From myth to reason: who were the Presocratics?
The Presocratics are Greek thinkers who lived before Socrates (and some at the same time), roughly from 600 to 400 BCE. They worked in Greek cities around the Aegean Sea and in southern Italy. Few of their books survive, only short quotes and reports by later writers such as Aristotle.
Before them, most people explained storms, earthquakes and the seasons with myths about gods. These thinkers tried to explain nature by reason (logos): a cause you can think about and argue over, not a story about a god's mood. This is why many people say philosophy and science began here.
India had its own early thinkers too, who talked about five elements and about atoms (in the Vaisheshika school), so these questions are shared across the ancient world.
The first principle (arche)
The big question was: what is the arche (first principle)? The arche is the starting stuff that everything comes from, is made of and returns to.
- Thales of Miletus (about 600 BCE): water. Water is everywhere, living things need it and it can be solid, liquid or gas.
- Anaximander: the apeiron, the boundless or unlimited. It is not any one known stuff, so it can give rise to all opposites like hot and cold, wet and dry.
- Anaximenes: air. When air gets thin and loose it becomes fire. When it is pressed and condensed it becomes wind, cloud, water, earth and stone. So all change is just thinning and thickening of one stuff.
- Pythagoreans: number: they saw patterns (music, geometry) as the base of everything.
- Empedocles: four "roots" (earth, air, fire, water) mixed and separated by Love and Strife.
Notice the shared idea: the world has one order that we can understand, and the differences we see come from one source.
Change and permanence: Heraclitus and Parmenides
If everything comes from one stuff, how can things change at all? Two thinkers gave opposite answers.
- Heraclitus of Ephesus (about 500 BCE): everything flows. His famous idea is that you cannot step into the same river twice, since new water keeps coming. Fire is his sign: a flame stays a flame while its fuel and gas change every moment. But he did not say there is only chaos. He taught there is a logos, an order or measure, behind the change, and that opposites like day and night depend on each other.
- Parmenides of Elea (about 500 BCE): what is, is. Nothing can come from nothing and nothing can become nothing, so being cannot begin, end or change. It is one, whole and still. Change and many things are only what our senses seem to show, not truth. Truth must be reached by reason.
- Zeno of Elea, a follower, built puzzles to show that motion leads to contradictions. In Achilles and the tortoise, the fast runner can never catch the slower one, because he must first reach where the tortoise was, and by then it has moved on a little.
Reconciling the two: atoms and the birth of science
Later thinkers wanted to keep Parmenides' rule (nothing comes from nothing) and still explain the change we see.
- Empedocles and Anaxagoras said real stuff does not appear or vanish. It only mixes and separates.
- Leucippus and Democritus (about 400 BCE): the world is made of atoms ("uncuttable" bits) and void (empty space). Atoms are unchanging, so Parmenides is right about what exists. But atoms can move and join in new patterns, so Heraclitus is right that things change. A cake can be cut into smaller and smaller pieces, but in Democritus' idea the cutting must end at atoms.
Why it matters: they asked "what is it made of?" and "why does it change?" with reasons, not stories. They also showed that thinkers can argue with each other, and that is how knowledge grows. Their questions led to Socrates, Plato and Aristotle, and later to chemistry and physics.
Try it: a candle and a cup
Light a small candle (with an adult). 1. Watch the flame. Is it the same flame from moment to moment? Which side of Heraclitus does this support? 2. Now hold a cold steel spoon over it: soot (carbon) collects. Where did the candle go? Has anything disappeared? 3. Half-fill a cup with water, mark the level, leave it a few days. Where did it go? Then use the 3D to try each thinker's idea and write one sentence on what each would say about your candle.
Key formulas and definitions
- Arche = the first principle: the stuff all things come from
- Thales: water; Anaximander: apeiron (boundless); Anaximenes: air; Heraclitus: fire/flux; Parmenides: One Being; Democritus: atoms + void
- Anaximenes: thin air β fire; thick air β wind, cloud, water, earth, stone
- Zeno sum (Achilles): 100 + 10 + 1 + 0.1 + β¦ = 100 Γ· (1 β 0.1) β 111.1 m
- Key terms: arche, logos, apeiron, flux, being, atom, void
Worked examples
1. Match each Presocratic with his first principle: Thales, Anaximenes, Heraclitus.
Thales: water. Anaximenes: air. Heraclitus: fire (a sign of constant change), together with the ordering logos.
2. Anaximenes says all things are air. Explain how one stuff can become water and stone.
He used thinning and thickening. Thin, loose air becomes fire. Pressed (condensed) air becomes wind, then cloud, then water, then earth, and the most pressed becomes stone. The stuff is the same and only its closeness changes.
3. What does Heraclitus mean by 'you cannot step into the same river twice'?
Water keeps flowing, so the water you touch now is not the water you touched a moment ago, and you too have changed. The river keeps its form and name, yet it is made of new water. So things stay recognisable only through constant change.
4. State Parmenides' reason for saying change is impossible.
To change would mean something comes from nothing or becomes nothing. But nothing cannot be, so it cannot be the source or the end of anything. So what is cannot begin, end or change. He concluded that the changing world our senses show is not the real truth.
5. In Achilles and the tortoise, Achilles runs at 10 m/s and the tortoise at 1 m/s and starts 100 m ahead. When does Achilles catch up, and how far does he run?
Gap closes at 10 β 1 = 9 m/s, so time = 100 Γ· 9 β 11.1 s. Distance = 10 Γ 11.1 β 111.1 m. Zeno's steps are 100 m, 10 m, 1 m, 0.1 m, β¦, infinitely many but their sum is 100 Γ· (1 β 0.1) = 111.1 m, a finite number, so he does catch up.
6. How do Democritus' atoms answer both Heraclitus and Parmenides?
Atoms do not come into being or vanish and do not change, which agrees with Parmenides. But atoms move in the void and join in different patterns, so the world we see keeps changing, which agrees with Heraclitus. Change is a change of arrangement, not of the atoms themselves.
Common mistakes
- Thinking the Presocratics came after Socrates. 'Pre' means mostly before him.
- Thinking Heraclitus said the world is pure chaos. He believed in a logos, an ordering rule behind the flow.
- Thinking Thales meant only drinking water. He meant water as the one stuff that takes many forms.
- Thinking Zeno proved motion is impossible in real life. His paradoxes are puzzles about infinity; the sum of the steps is finite.