Long ago, some philosophers worked very hard
to separate myths from what they actually 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. If you'd like to keep Crash Course free for
everyone, forever, you can support the series at Patreon, a crowdfunding platform that allows
you to support the content you love. Thank you to all of our patrons for making
Crash Course possible with their continued support.
