Plato and Aristotle: Crash Course History of Science #3

Plato and Aristotle: Crash Course History of Science #3

Pop quiz: are you a Platonist or an Aristotelian? An idealist or an empiricist? Do you think up neat rules to describe the
universe and then try to fit data into your theory? Or do you observe the world and draw conclusions
from what you see? Do you trust math, or your senses? Before you decide, let’s take a trip to
urban Athens circa 399 BCE… [Intro Music] Last week, we met the Presocratics: despite having by any reasonable standard invented
science in Europe, these thinkers are lumped together today as simply “not Socrates.” So who was this smarty pants? Socrates didn’t have a single, clearly formulated
natural philosophy. He didn’t even study nature! He studied politics and morality and prided
himself on not claiming to know things. But Socrates did two important things: he
asked a lot of questions, which influenced how philosophers went about teaching their
ideas. And he inspired the two rockstars of classical
Greek philosophy. Socrates held that knowledge comes from asking
questions. So many questions! His name is attached to the Socratic method—in
which you constantly ask questions so that students can steadily break down a big problem
into smaller parts, parts they can test hypotheses against. It’s okay if they realize that a hypothesis
is wrong: in fact, it’s good! It means they’re moving away from falsehood. The Socratic method is an example of negative
hypothesis elimination, or proving that something is wrong to narrow down the possibilities
of what might be right. But Socrates’s biggest legacy might be his
student, Plato, and his student’s student, Aristotle. Both were inspired by Socrates’s methods,
but they arrived at some very different conclusions about the world. We know a lot about Socrates thanks to his students. Chiefly Plato founded a physical school called
the Academy to train Athenians in how to think like Socrates. Plato wrote down dialogues between Socrates
and other thinkers including Parmenides: he was the Eleatic philosopher who believed that
nothing really changes, and thus we can’t trust our senses. This had a big impact on Plato. Whose best known works include Republic, in
which Socrates defines justice and argues for rule by philosopher-king instead of democracy, and Timaeus, in which Socrates talks about the nature of the universe. Plato had a big impact on thinking about thinking. Today, we still use Plato’s name for a place
of philosophical learning, “Academy,” to describe the concept of higher education
in general. At the original Academy, Plato emphasized
training in how to think properly. Over the door of the Academy was inscribed
the dictum, “Let no one enter here who is ignorant of geometry.” Plato based his own philosophy on geometrical
laws. He taught a Pythagoras-inspired idealism,
or a theory of nature based on perfect abstractions—rules, of which real-world stuff could only ever
be imperfect examples. So Plato had to fit his observations to his
theory. That idealism is one of the reasons people
think of Plato as more of a philosopher than a scientist. Plato built on the work of the Presocratic
schools. But he developed a more complete way of looking
at the natural world than they did. And his students took off in search of solutions,
even as they changed his underlying theory. The only Greek who wrote more philosophy than
Plato was Plato’s own star student and rival, Aristotle. Compared to Plato’s idealistic abstractions, Aristotle’s philosophy makes more common
sense. His ideas are based on empirical evidence:
he observed the world and then came up with a theory that explained it. This order of operations is at the heart of
modern scientific practices. Aristotle was from Macedonia, in the north
of Greece. But he studied at Plato’s Academy in Athens
for twenty years, until Plato died. Afterward, Aristotle took a lucrative gig:
King Philip II of Macedonia hired him as tutor to his son, Alexander. And, you know this particular Alexander: he decided
to conquer the entire earth. Before age thirty, he ruthlessly conquered
much of Asia, Africa, and Europe, ruling over more area than anybody until Genghis Khan. Aristotle’s influence on Alexander
“the Great” reminds us that science is always social. From the very beginning, scientists have served
bad, heartless dudes. Aristotle, a man who literally wrote the book
Ethics, pushed his most famous pupil to invade Persia, kill “barbarians,” and become
a brutal warlord. After Alexander died young, Aristotle went
back to Athens to start his own school, the Lyceum. The Lyceum was pretty different from Plato’s
Academy. Because Aristotle liked plants and liked to
walk and talk, his school wasn’t in a building, but a grove of trees outside the city. And his school was called the Peripatetic,
meaning “walkie” and thus informal—not like the Academy. It was during the Lyceum years that Aristotle
probably wrote many of his most famous works, including Metaphysics, On the Heavens, On
the Soul—which is actually an amazing book of proto-biology-meets-psychology—and his
school’s highly influential set of textbooks on natural philosophy, called Physics. How did Aristotle answer our big questions about physics, such as “what was stuff?” And “where are we?” He posited a complete system, joining the
elements and the heavens. This became the basis for European thought
about the physical world for two thousand years! Let’s compare Aristotle’s system to his
mentor Plato’s in this week’s ThoughtBubble. For Plato, the cosmos was perfect. It had perfect rules that could be studied. And all cosmic stuff was made up of atoms
that were perfect geometric “platonic solids”, each creating one element: tetrahedrons
of fire, cubes of earth, octahedrons of air, icosahedrons of water, and dodecahedrons as
the shape of the whole universe… Like a giant celestial set of D&D dice! Plato’s theory of the heavens stated that
the wandering stars—that is, the planets—followed a path of uniform circular motion. You see, the wandering stars must move in perfect circles,
since the cosmos is orderly. Ah, but
this one is moving backwards! Plato’s students could see that Mars, for
one, seemed to jump backwards, showing retrograde motion. Plato didn’t really have an explanation. European astronomers would spend the next
two thousand years meticulously trying to solve this problem. They’d end up learning a lot in the process. How did Aristotle build on Plato’s system?
Aristotle’s cosmology was abstract, too, but attempted to make sense of observations
about the world. He crossed those same four elements, plus
a new anti-void one called æther, with four physical sensations: hot and cold, dry and
wet, and used these to explain everything: Earth was the heaviest element, so it was
the center of the cosmos. Water was lighter than earth so the oceans
rested on top of the earth. So far so good. Air’s natural state is above water. That also checks out! Fire sat on top of air, which is a little
weird… but it does go up, I guess? And way out beyond these four terrestrial
spheres—out past the Moon—spun the stars, acting according to their nature as ætherial,
or perfect-circle-moving, objects. And nowhere, anywhere in this theory, was
a void. Nature abhors a vacuum! In Aristotle’s cosmos, all of the elements
were actively trying to get back to their natural states. Why did flames rise? They were just trying to get back to the fiery
celestial realm above the air. Thanks Thought Bubble. From the Presocratics to Plato to Aristotle,
we’ve ended up with a bunch of spheres inside of spheres, each with a natural tendency. This confirmed the average Bronze Age farmer’s
experience… and ours. The earth seems to stand still. Water sits on earth. Air isn’t very heavy. Aristotle recognized that elements didn’t
always exist in their pure forms. A tree, for example, was a combination of
earth, water, and air: roots go down into the earth, and branches up into the air. His theory also worked for comparisons. Why does a book fall faster than a piece of
paper? Because it has more earth in it. Aristotle could even explain natural phenomenon. Why does rain fall from the sky to the ground? Why do volcanoes shoot fire up? Obviously this isn’t how I think gravity
works, but it’s a way of explaining it that made sense to the Ancient Greeks. Where Plato saw a world of ideal shapes, Aristotle
had a theory that acknowledged that we’re all kind of a hot mess. Things are naturally jumbled up, but always
trying to get back to their essential place. [Living things]
Aristotle also loved looking at living things. And he looked closely. He noticed, for example, that the octopus
can change color—which is awesome—and that male octopi have a special arm called
a “hectocotylus”—which is… something you should Google. Because it’s weird and gross but also kind
of awesome. And it wasn’t confirmed by scientists until
the 1800s! Aristotle thus trusted that knowledge proceeded
from the experience of the senses. In works such as History of Animals, among
others, he wrote down observations like these about all kinds of organisms. He also tried to classify the world in an
orderly system, giving rise to taxonomy. When he attempted to answer the question “what
is life,” the taxonomy he created relied on a system of souls. Plants have a vegetative soul, responsible
for reproduction and growth. Animals have a vegetative and a sensitive
or animal soul, responsible for mobility and sensation. And humans—and only humans—have a vegetative,
a sensitive, and a rational soul, capable of thought and reflection. This led Aristotle to further theorize that
all things can be placed on a line from simplest-slash-least-soulful to highest-slash-most-soulful. On one end, he placed plants, then worms,
and so on. These low animals bore their offspring cold,
dry, and in thick eggs. The higher animals made warm and wet babies. So of course, at the other end of the line,
Aristotle placed men. Meaning not “humans,” but dudes: according
to him, cold maternal blood produced inferior humans, AKA girls, while hot paternal semen
produced boys. Aristotle was… maybe not someone we’d
want to elect as our philosopher-king today? But Aristotle’s system of classification
again seemed to confirm his classical and medieval readers’ daily experiences. His proto-biological ideas stuck around in
various forms until Darwin, getting lumped under the heading of the Great Chain of Being—that
all creatures on earth stand somewhere on a ladder of perfection up toward God. You may have already guessed that this concept
has been particularly troublesome when it comes to scientific racism. But that’s a story for later. The creepier effects of some his ideas aside, Aristotle had an answer for everything. For the most part, these were based in observation
and conformed to common sense. His answers were able to explain how the world
worked… most of the time. And not only did Aristotle come up with a
complete theory of everything, he wrote it down. He was a prolific author, and a significant
percentage of his texts have survived thanks to our Arabian scholars. Then again, Plato’s transcendental ideas
about the cosmos—even if wrong in their particulars—inspired centuries of scholars
to think about the universe as having underlying laws, ones that hold regardless of what our
senses can show us. So are you a Platonist or an Aristotelian? Or, taking a page from Socrates, is that a
trick question!? Next time—we’ll follow Alexander the Maybe-Not-So-Great
to India to witness the rise of the Maurya dynasty, set the earth spinning on its axis,
and found a science of life! Crash Course History of Science is filmed
in the Dr. Cheryl C. Kinney studio in Missoula, Montana and it’s made with the help of all
this nice people and our animation team is Thought Cafe. Crash Course is a Complexly production. If you wanna keep imagining the world complexly
with us, you can check out some of our other channels like Scishow, Nature League, and
The Financial Diet. And, if you’d like to keep Crash Course
free for everybody, forever, you can support the series at Patreon; a crowdfunding platform
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Crash Course possible with their continued support.

local_offerevent_note September 27, 2019

account_box Matthew Anderson


4 thoughts on “Plato and Aristotle: Crash Course History of Science #3”

  • Plato and Aristotle came up so many question's about socrates . According to Plato ' let no one enter here who is ignorant of geometry. Plato made a history of science , a very long story that show's different shape's , figure's and number of size's . Plato no exact explaination , how the earth work's , for him the earth world work's start by earth followed by water which is the support and the air who given us life and also the fire above them all , which is given also the hottest of World . But , Plato's work nad studies has no proper explaination. For Aristotle he really look and observe closely . He discovered that the Earth , works throught plants , animals and humans. Aristotle believe that our senses can show us .

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