Full transcript
0:05I started this course by saying that people have made knowledge about the natural world,
0:09pretty much forever.
0:10They’ve done this by carefully observing the world and then devising tests to find
0:15out if their ideas are true.
0:16Today, we refer to a specific series of steps—coming up with a hypothesis, testing it, and drawing
0:22conclusions—as the scientific method.
0:25But, historically speaking, there is no one scientific method.
0:29There’s more than one way to make knowledge.
0:31Still, if you look at some of the great minds who helped shape today’s concept of the
0:35scientific method, a set of basic principles starts to emerge.
0:39Like rationality.
0:40Experimentation.
0:42And ruthless self-examination.
0:44For these ideas and a lot of other stuff, we have to thank three of the natural philosophers who
0:49pioneered this abstract “scientific method”: Galileo, Bacon, and Descartes.
0:54[INTRO MUSIC PLAYS}
1:03Galileo, Bacon, and Descartes are each so
1:05fascinating that they could each have their own episode.
1:08But one reason to talk about them together is that they lived at roughly the same time.
1:12A lot changed in European natural philosophy between the mid-1500s and the mid-1600s, when
1:17Newton started dropping his hits.
1:19We’ll get there later!
1:20But first, Dr. Galileo Galilei was born in Pisa in 1564.
1:24He considered becoming a priest, studied art, attended school for medicine, but then attended
1:29a lecture on geometry, and went on to study math in secret, because his dad wanted him
1:35to focus on medicine.
1:36Much to his father’s chagrin, I’m sure, Galileo became a professor of a bunch of math-related
1:41stuff at University of Pisa, a lowly, poorly paid position.
1:45In 1593, Galileo took a job as a ballistics consultant at the Arsenal of Venice, which
1:51is a heck of a title to have on your C.V.
1:54Then, starting in 1609, he built and refined telescopes, which eventually made him famous.
1:59The very first telescope was invented by Dutch spectacle-maker Hans Lippershey in Holland
2:05in 1608.
2:06But Galileo’s versions were much better.
2:07And telescopes are a good example of how scientific instruments change the nature of scientific
2:13practice.
2:14We often design experiments around how we can use our instruments—in the case of astronomy,
2:19around what we can see through a telescope.
2:21With his new telescopic success, Galileo quit his job at Pisa for a much better one at Padua,
2:26and he also took on the role of Chief Mathematician and Philosopher of Florence.
2:31I love this guy's resume!!!
2:33As he continued to research the night sky, Galileo became convinced that Copernicus was
2:38right: the earth is not the center of the universe.
2:41He also looked into Kepler’s ideas but wasn’t convinced by them.
2:44By 1611, Galileo’s name had been brought up by the Inquisition.
2:48And, of course, nobody expects that.
2:52But it seems that his vocal support of Copernicanism was creating some friction in the Florentine
2:57court.
2:58Among many others, the Grand Duchess Christina, who was basically one of his patrons, said
3:01she took issue with the idea of heliocentrism.
3:04So in 1615, he wrote to a letter to explaining that the Bible and nature did not disagree:
3:10One was God’s word to the masses—a story about how to behave and why.
3:15The other was God’s work—the physical reality that He created.
3:19So science, he said, was simply the uncovering of God’s work.
3:23Galileo was a man of faith!
3:25Unfortunately for him, Church officials didn’t like this explanation.
3:30In 1616, the Church added Copernicus’ text, De rev, to its official list of banned books.
3:34The Inquisitors deemed heliocentrism “foolish and absurd in philosophy.”
3:39This was bad news for Galileo: he was told not to uphold or defend Copernicanism.
3:43(But he may have been able to teach a heliocentric astronomy as a thought experiment.
3:49Historians aren’t sure.)
3:50But Galileo wasn’t having any of it.
3:53In 1623, Galileo published a pamphlet called the Assayer that basically said scientists
3:58should be free to do their work.
3:59Pope Urban VIII, Galileo’s personal friend, was a fan.
4:03He said that God could move the heavens in numberless ways, so the ultimate source of
4:07truth would always be faith.
4:09So sure, Galileo, you want to spend your nights staring at tiny dots of light?
4:13Knock yourself out.
4:14Urban even renamed Galileo’s next book, Dialogue on the the Two Chief World Systems
4:19of 1632.
4:21All Urban asked was for his friend to treat different astronomical systems fairly.
4:25But…
4:26Galileo picked a fight.
4:28The Dialogue made a clear argument for Copernicanism, comparing it point by point with the Aristotelian–Ptolemaic
4:34system.
4:35He brought new data to the battle: he described the phases of Venus, which appears to grow
4:39larger and smaller like earth’s moon.
4:42This phasing did not fit with a geocentric model.
4:45An even stronger argument came from the tides, whose movements seemed to prove that the earth
4:50moves.
4:51And the pope was not happy.
4:54Urban felt that Galileo had not heard his warning.
4:57All copies of the Dialogue were recalled.
4:59And in 1632, Galileo was called to Rome to speak to the Inquisition.
5:04His trial got under way in 1633, and in time, he was placed under house arrest for the rest
5:09of his life.
5:10Amazingly, Galileo didn’t give up.
5:12Humiliated, under arrest, he kept sciencing.
5:15Beyond his contributions to astronomy, physics, and the scientific method, Galileo is a rockstar
5:20thanks to his fearlessness.
5:22Galileo’s last text was also perhaps his most relevant to the idea of methods in science:
5:27His Two New Sciences of 1638 was a mathematical treatise about how bodies fall through the
5:33air, and how wooden beams break.
5:35It was also a record of the process by which he discovered these physical laws.
5:39He called for specific tests that would let experimenters confirm his laws with their
5:43own senses.
5:45This, in his words, was the mark of a “true scientist”: independent confirmation.
5:50This is an awesome norm to try to live up to!
5:53So, we shouldn’t be surprised that a lifelong nerd like Galileo would have played a critical
5:57role in developing better methods of doing science.
6:00But Francis Bacon, born in London in 1561, is more of a historical surprise.
6:05For one, he was cast out of public office for taking bribes.
6:09Two, some people for some reason think he was Shakespeare.
6:11And I mean, if you’ve ever read these two writers… there’s a clear difference.
6:16And most of Bacon’s impact on science was posthumous.
6:20We can basically boil it to down to a new approach to science, which was practical,
6:24instrumental, and supported by the state.
6:26Bacon wanted to create a whole replacement system of natural philosophy—that meant
6:31philosophy, mathematics, physics, biology, all wrapped up together.
6:34He rejected the Aristotelian way of doing science—arguing rationally using logic.
6:39Instead, he believed that natural philosophers should help improve the wellbeing of humanity
6:44through technological advances.
6:46Bacon expressed this within a Christian framework, casting Aristotle’s philosophy as a dereliction
6:52of the Christian duty of charity toward others.
6:56Improving wellbeing meant understanding and controlling the chaos of the natural.
7:00Bacon described nature as female and passive, and humanity as male and active.
7:06So, science was supposed to be a masculine activity: it allowed humans to exploit nature.
7:11Now, this metaphor has not aged well at all, and not just because it was sexist and horrible.
7:16We also now have plenty of examples of all the ways that humans simply can’t control
7:22nature.
7:23And yet this metaphor is, sadly, still very much alive.
7:25So.
7:26What did Bacon’s new system of natural philosophy look like up close?
7:29Help us out, ThoughtBubble:
7:31For Bacon, control over nature meant deriving useful arts—or technē—like gunpowder,
7:35silk, and the printing press, from basic knowledge.
7:38And how were Baconians supposed to make useful knowledge?
7:41They needed first-hand experiences.
7:44This meant testing answers to important questions, without relying on the words of long-dead
7:49Greek and Arabic philosophers.
7:52For Bacon, science also required central planning and state support.
7:56Natural philosophy should not be the domain of a few random nobles, he thought.
8:00It should be a program, or system, that worked for the public good.
8:03He outlined a vision of a utopian science bureaucracy in his book called New Atlantis,
8:09published in 1626.
8:11Bacon proposed creating a hub for intellectual work, a kind of super-university called Salomon’s
8:18House.
8:19Here, the personnel—all male, of course—would be strictly segregated into specific roles.
8:23Some would travel the world to gather facts.
8:26Others would conduct experiments to generate new facts.
8:29Yet others would extract potential facts from books—but these proto-facts would have to
8:33be tested experimentally.
8:35Further up the hierarchy, others would analyze all of the different natural facts and experimental
8:40outcomes and direct the next round of research.
8:42And at the very top were the Interpreters of Nature—three men who would take all facts
8:48and use them to produce axioms.
8:51Working along with them were “dowry men” who drew conclusions from these axioms to
8:55yield specific practical benefits.
8:56That, in a nutshell, is the scientific world according to Bacon.
9:01Thanks Thought Bubble, Now, another thinker who advocated for a practical
9:04science was René Descartes.
9:06Born in central France in 1596, Descartes lived mostly in the Netherlands.
9:10He’s known as a founding figure in mathematics and modern philosophy.
9:13So, that's not bad.
9:15In math, he’s known as the dude who bridged geometry and algebra.
9:18We call the numbered X–Y axes the plane of “Cartesian” coordinates.
9:23You can map a lot of math with this system.
9:25Now, Descartes knew what had happened to Galileo, and his publishers in France didn’t want
9:29to wind up on trial, too.
9:30So Descartes stopped publication of his own Copernican book, Le monde or The World, in
9:361633.
9:37But he did come up with a whole new cosmology, based on Copernicus, that featured a chaotic,
9:42rapidly moving ætherial fluid in which the planets and stars were suspended—instead
9:47of perfect crystalline spheres.
9:49His Discourse on Method, published in 1637, was his major contribution to the history
9:54of making knowledge.
9:55But, more than Galileo—a practicing experimentalist—or Bacon—a statesman thinking about the practical
9:59uses of natural philosophy—Descartes was a pure philosopher.
10:03He started at the very beginning with an abstract question: how we know what we know?
10:09This is question at the heart of the philosophical discipline of epistemology, which Descartes
10:14redefined.
10:15Philosophers today are still debating some of the questions Descartes raised about the
10:19origins of knowledge.
10:20Descartes wanted to replace Aristotle as the king of philosophy.
10:24And Descartes’s attack on Aristotle boiled down to two arguments: one, knowledge obtained
10:29through the senses lacks absolute certainty, because the senses often deceive us.
10:34And two, human reason can also be deceived!
10:37Logical conclusions from false premises will lead you to the wrong answers.
10:41So Descartes was like, welp, time to formulate a whole new philosophy to address these points.
10:47Ultimately, to be certain of the truth, Descartes could only count on one thing: his mind.
10:52So he described the world reductionistically, meaning using math to represent physical phenomena.
10:58Only math, which is either right or wrong, could found a total system of natural philosophy.
11:03For Descartes, the universe is composed only of things that math can describe.
11:08He thought that philosophers should be able to provide causal explanations for all observed
11:12phenomena, showing the or the mechanical principles behind the things that happen in
11:16the universe.
11:17And the tactic Descartes used for checking the validity of your own knowledge is famous
11:21and still useful today: systematic doubting.
11:24When in doubt, doubt yourself!
11:27This pairs nicely with what Bacon argued: don’t trust old books; check!
11:32When you add Galileo’s focus on independent, rational comparison of theories about natural
11:37phenomena to Bacon’s focus on experiment and social norms promoting scientific research,
11:43and then Descartes’s reminder to always ask yourself how sure you are that you know
11:48stuff, you get a kind of method or system.
11:51Was it thought of as a single philosophy at the time?
11:54Sort of.
11:55Some of the most important members of the early Royal Society, where we’ll head in
11:58a couple of episodes, pointed explicitly to Bacon as an inspiration.
12:03But this story isn’t all all about better descriptions of the Solar System.
12:07It’s also about winning wars and conquering new territory.
12:11Stay tuned.
12:12Next time—we’ll look at how the “new science” affected the healing arts and beliefs
12:16about the human form… and, yes, there will be dissections.
12:20A lot of dissections!
12:22Crash Course History of Science is filmed in the Dr. Cheryl C. Kinney studio in Missoula,
12:26Montana and it’s made with the help of all this nice people and our animation team is
12:30Thought Cafe.
12:31Crash Course is a Complexly production.
12:33If you wanna keep imagining the world complexly with us, you can check out some of our other
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