knew about nature.

Thales theorized that everything in the world is made of water.

Pythagoras was a mathematical-mystical vegetarian.

And Democritus, we all know and love as the Atom Guy…

Meet the Presocratics!

[Intro Music Plays]

The Presocratics were named for their leader, Presocrates.

That is a joke!

They were several different philosophers who lived before Socrates.

Why start with the Presocratics?

Since people have systematically made knowledge about the world for millennia, there's no

single starting point.

But a convenient place to get our footing is ancient Greece.

These Greeks were the cornerstone of scientific inquiry in western Europe.

Their theories had a terrific run.

Can you imagine coming up with a question about nature that puzzles people for more

than two thousand years?

I can't even decide what to have for breakfast.

A more practical reason to put on our thinking togas is that the ancient Greeks left behind

sources.

Writing stuff down makes history possible and here's a Pro tip: if you want to be remembered

in two thousand years, keep a diary!

Preferably on vellum with metallic ink.

Also, get super famous so that your students make plenty of copies.

Not all of the people we think of as “ancient

Greeks” actually lived in Greece.

Their culture stretched across a prosperous region called called Ionia.

And they weren't as ancient as some even ancient-er Greeks.

We typically date ancient Greece as starting around 800 BCE, after the fall of the Mycenaeans.

Those are the dudes who burned down troy because one of them got dumped.

Zero Chill.

“Ancient” Greece ends with the Roman conquest in 146 BCE.

We're focusing on a science-dense period from aroud 600 to 400 BCE.

These Greeks live in small towns and are very comfy out at sea.

They trade and fight with each other a lot, and they sometimes have to deal with invading

Persians.

They worship nature, but their land is deforested and eroded.

They love setting up new colonies all along the Mediterranean and the Black Sea.

There is no public support for anything like modern science.

There aren't even schools in which to study science…

The Greeks practiced natural philosophy, meaning

“self-conscious inquiry into nature.”

A lot of their philosophies were about answering our first running question: What is stuff?

I mean, really?

If you watched our first episode you'll know that we can divide “science” into

both a “body of knowledge” and a “set of methods.”

When you examine the work of these Presocratic philosophers, you can see two important things:

first, they weren't scientists in a modern sense.

They didn't make detailed, accurate knowledge of nature based on observation.

But they did come up with theories that tried to account for why stuff is the way it is.

In their wonky-sounding theories, we still find many of the themes that would drive centuries

of further inquiry: the divide between the abstract and the material, or identifying

the smallest possible particle of stuff.

Second, as these natural philosophers tried their best to separate Myth from Truth, they

developed first drafts of many of the methods we still use and value today.

Natural philosophy became a quest for abstract knowledge.

This is important because it means the Presocratics started making general claims about the real

world—laws that would apply in every situation, not only specific instances.

The Presocratics also developed “schools” of thought that spread their ideas around

geographically and down the centuries.

These weren't physical schools, but groups of teachers and students who thought about

the same problems.

One of the reasons we know about these schools, is because they operated as individuals, who

took credit for their ideas and whose names were passed down.

This practice differed from many other cultures of inquiry, and became a foundation for how

Europeans later systematically made knowledge.

But the big method, and the one we're going to focus on, was rational debate.

Between all those schools and individuals and abstract theories there was a lot of disagreement.

To convince people they were right: a natural philosopher had to use reason, logic, and

observation to attack the wrong-seeming theories of others and bolster his own awesomeness.

In fact, some historians argue there's a link between rational debate about political

constitutionality, or how humans should govern themselves, and rational debate about the

constitution of nature, or how the world governs itself.

There are more Presocratics than we could possibly mention, so here are some highlights:

this is our rogue's gallery of natural philosophers, who all had their own theories, and argued...

they rationally debated—themselves into the history of science.

The first European natural philosopher whose ideas survived down to the present was Thales,

the first individual known to have proved a mathematical theorem—Thales's theorem.

In fact, early historians attributed lots of firsts to Thales, making it hard to tell

exactly what he really accomplished.

Regardless, being the first at a whole way of doing thought is pretty unusual.

Thales set the natural world off as separate from the divine.

For him, the world was something comprehensible by the powers of the human intellect: it became

an object, a thing, like other things.

This meant leaving the gods out!

For example, Thales held that wind, not a god, caused the Nile to flood.

This was a general, natural explanation for a phenomenon.

Thales was not, however, irreligious.

He believed that all things have a god, or soul, within them.

Thales was also the founder of the first European “school” of philosophy, ---

The Milesian school was known for its theory of matter; theory of stuff.

This theory held that water was the primary substrate, or the most basic element.

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.

We'll come back to this essential dualism of soul versus matter in future episodes.

Later, Plato and Aristotle were dismissive of Thales, and part of their argument was

that Thales once predicted an upcoming harvest to corner the market on olive oil, using his

philosophy for personal gain.

Is that okay?

Depends on who you ask.

Thales's star student, was Anaximander.

He's thought to have been the first European philosopher to write down his own ideas.

Like Thales, Anaximander believed that nature is ruled by discoverable laws.

But Anaximander rejected Thales's watery universal substrate, proposing instead a formless

initial state called the apeiron.

Anaximader proposed that this primal formlessness would then devolve into opposite properties

that could be experienced—hot/cold, dry/wet, heavy and light, etc.

Anaximander worked in astronomy, geography, and mathematics.

One of his contributions was introducing the gnomon, the part of the sundial that casts

a shadow, to Greece.

These had already been used in China for two millennia.

The gnomon was good for more than just telling time, it helped people better understand the

movement of the sun, and it helped Anaximander develop a model of the cosmos that envisioned

heavenly wheels punctured by holes letting light through.

One of our earliest examples of natural philosophers trying to conquer the “Where are we” question.

The last great thinker associated with the Milesians was Empedocles.

(He was probably also influenced by Pythagoras and Parmenides.)

Almost every Greek philosopher had a book called On Nature; it's super confusing—In

Empedocles's “On Nature” he put forward the theory of the four classical elements:

earth, air, fire, and water, mixed by two forces, Love and Strife.

While this of course seems hopelessly misguided now, remember that simply by asking “What

is Stuff?”, the Milesians were moving away from mythology and toward modern physics.

Probably the Presocratic philosopher most well-known today is Pythagoras, that Triangle Guy.

Pythagoras studied the philosophy of the Milesians, but he was a more mystic thinker…

Which is a nice way of saying, Pythagoras was a cult leader.

He believed in reincarnation and outlawed beans, seeing them as impure.

Probably…

Historians love to debate the bean thing!

At least we're pretty sure he was a vegetarian.

How can you be a vegetarian without beans!?!?!?!

Pythagoras's focus on the pure dovetails with the fact that we think of him as having

introduced the notion of idealism to science: idealists generated abstract models of perfect stuff.

This was unlike the Milesians, who were materialists: they started theorizing about actual stuff.

In terms of math, Pythagoras's idealism meant a shift 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.”

To even know that the irrational numbers existed, you had to join the cult of the Pythagoreans

and work your way into the innermost circle.

... this is so great!

For our purposes, the thing that Pythagoras added to science is the role of the mathematical proof.

Egyptians and Babylonians knew about Pythagorean triplets—that is, whole number solutions

to the Pythagorean theorem.

That was useful...a practical guide that could be implemented by ancient engineers, but pythagoras

understood it (and proved it) in a purely abstract, purely mathematical way.

With Pythagoras, creating an elegant, abstract proof became a model for justifying a new

claim to knowledge.

Another major thread in Greek thought before

Socrates was atomism, the theory that the world is made of particles you can't divide

any further.

This was associated with democritus, who made heavy use of rational debate through dialogues, our “wonder”

of this period.

For this, he's the star of this week's ThoughtBubble:

Democritus held that everything is made of

atoms.

Indestructible, uncreated, always in motion, and infinite in number.

And they came in all kinds of shapes and sizes.

In his focus on matter, Democritus was a materialist like the Milesians.

He is even credited with holding a bottle of air underwater to show that air is made

of stuff—thus giving rise to experiment as a way to illustrate a theory.

Still, Democritus had a lot to prove.

He would ask “What is air?”

And people would be like, “Nothing.”

And that's when he'd say “That's where you're wrong.”

Most famously, Democritus argued against other theorists—Parmenides and Zeno—using something

that we call the void hypothesis.

Democritus was like, “Everything is made of little indivisible bits stuff, I call them

atoms.”

Then Zeno is all, “But, Democritus my friend, what is between two atoms?”

Then Democritus says, “Nothing, between atoms there is only a void.”

And then Zeno replies, "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?"

And then, presumably, Zeno dropped the 450 BCE equivalent of a mic and the crowd went

wild.

Thanks Thought Bubble, This was rational debate, and this particular

debate would go on for centuries.

But, more importantly, the structure of the dialogue...the celebration of rational debate

as almost a sporting event for these nerds was a new and valuable way to analyze our

universe.

This debate is just one example of how the presocratics elevated being curious about

the world into natural philosophy.

It's important to remember that the natural philosophers of ancient Greece lived in a

very different world, both physically and socially, from that of Jeopardy! and GitHub.

But the way that this group of thinkers framed problems about stuff, change, nothingness,

mathematical elegance, perception, truth, and the cosmos has echoed across the centuries.

Next time—we'll watch Plato and Aristotle duke it out over idealism and empiricism.

It's gonna be a throw-down for the ages!

Crash Course History of Science is filmed in the Dr. Cheryl C. Kinney Studio in Missoula,

MT and It's made with the help of all of these nice people.

Our animation team is Thought Cafe and Crash Course is made using Adobe Creative Cloud.

Crash Course is a Complexly production.

If you want to keep imagining the world complexly with us, check out some of our other channels

like The Financial Diet, SciShow Space, and Mental Floss.

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Thank you to all of our patrons for making Crash Course possible with their continued

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