Presocratics

The Presocratics were philosophers who lived before Socrates.
They are a convenient starting point for studying the history of science because they left behind written sources.
These Greeks were the cornerstone of scientific inquiry in Western Europe.

Ancient Greece is typically dated from around 800 BCE (after the fall of the Mycenaeans) to 146 BCE (the Roman conquest).
The focus is on a science-dense period from around 600 to 400 BCE.
The Greeks lived in small towns, were comfortable at sea, traded and fought with each other, and sometimes dealt with invading Persians.
They worshipped nature, but their land was deforested and eroded.
They established colonies throughout the Mediterranean and the Black Sea.
There was no public support for modern science, nor schools to study it.
The Greeks practiced natural philosophy, meaning "self-conscious inquiry into nature."
A central question of their philosophy was: "What is stuff?"

"Science" can be divided into a "body of knowledge" and a "set of methods."
The Presocratics weren't scientists in the modern sense; they didn't create detailed, accurate knowledge of nature based on observation.
However, they came up with theories that attempted to explain why things are the way they are.
Their theories explored themes that would drive centuries of further inquiry, such as the divide between the abstract and the material and identifying the smallest possible particle of stuff.
They developed first drafts of many of the methods we still use and value today.
Natural philosophy became a quest for abstract knowledge.
The Presocratics started making general claims about the real world—laws that would apply in every situation, not only specific instances.
The Presocratics developed "schools" of thought that spread their ideas around geographically and down the centuries.
These schools operated as individuals who took credit for their ideas, which were passed down.
A key method was rational debate.

Natural philosophers used reason, logic, and observation to attack others' theories and bolster their own.
Some historians argue there’s a link between rational debate about political constitutionality and rational debate about the constitution of nature.

The first European natural philosopher whose ideas survived to the present.
The first individual known to have proved a mathematical theorem—Thales’s theorem.
He separated the natural world from the divine.
He believed the world was something comprehensible by the human intellect; it became an object, a thing, like other things.
He held that wind, not a god, caused the Nile to flood.
He believed that all things have a god, or soul, within them.
He was the founder of the first European "school" of philosophy, the Milesian school.
The Milesian school was known for its theory of matter, which held that water was the primary substrate.
The Earth floats on water like a ship.
Earthquakes happen when the water rocks back and forth.
The soul of things may not have been material, but their stuffness was water.
Plato and Aristotle criticized Thales, claiming he used his philosophy for personal gain by predicting an upcoming harvest to corner the market on olive oil.

Thales’s student.
Thought to have been the first European philosopher to write down his own ideas.
Like Thales, he believed that nature is ruled by discoverable laws.
He rejected Thales’s watery universal substrate, proposing instead a formless initial state called the apeiron.
He proposed that this primal formlessness would then devolve into opposite properties that could be experienced—hot/cold, dry/wet, heavy and light, etc.
He worked in astronomy, geography, and mathematics.
He introduced the gnomon (the part of the sundial that casts a shadow) to Greece.
He developed a model of the cosmos that envisioned heavenly wheels punctured by holes letting light through.

Influenced by Pythagoras and Parmenides.
He put forward the theory of the four classical elements: earth, air, fire, and water, mixed by two forces, Love and Strife.
By asking "What is Stuff?", the Milesians were moving away from mythology and toward modern physics.

The "Triangle Guy."
Studied the philosophy of the Milesians but was a more mystic thinker (a cult leader).
Believed in reincarnation and outlawed beans, seeing them as impure.
Introduced the notion of idealism to science: idealists generated abstract models of perfect stuff.
Unlike the Milesians, who were materialists (they started theorizing about actual stuff).
Shifted from practical arithmetic (inherited from Egypt and Mesopotamia) to a new, pure geometry.
For Pythagoras, numbers were not just a way of counting stuff; they were sacred.
Pythagoras loved whole numbers. He hated irrational numbers, such as the square root of two. He called the square root of two the alogon or “unutterable.”
Developed mathematical proof.
Egyptians and Babylonians knew about Pythagorean triplets—that is, whole number solutions to the Pythagorean theorem.
$a^2 + b^2 = c^2$
Pythagoras understood it (and proved it) in a purely abstract, purely mathematical way.

Associated with atomism, the theory that the world is made of particles you can’t divide any further.
Made heavy use of rational debate through dialogues.
Held that everything is made of atoms: indestructible, uncreated, always in motion, and infinite in number.
Atoms came in all kinds of shapes and sizes.
A materialist like the Milesians.
He is even credited with holding a bottle of air underwater to show that air is made of stuff.
Argued against other theorists—Parmenides and Zeno—using the void hypothesis.
Democritus: "Everything is made of little indivisible bits of stuff, I call them atoms."
Zeno: "But, Democritus my friend, what is between two atoms?"
Democritus: "Nothing, between atoms there is only a void."
Zeno: "You’re caught in a paradox, friend; if everything is made of atoms, and the void is a thing, then the void is made of atoms… but then… what is between the atoms of the void?"

The Presocratics elevated being curious about the world into natural philosophy.
The way they framed problems about stuff, change, nothingness, mathematical elegance, perception, truth, and the cosmos has echoed across the centuries.