Lecture 2 - The scientific revolution Flashcards
How do we see history of science during the middle ages? Why is that a problem?
The middle ages are portrayed as a low point in a history of science
- lot of poverty, plague, the church influencing science and being strict on what should the focus be on (not lot of science happening)
- it’s a very eurocentric view since science was happening in other places
What scientifically significant was happening in the middle east? Who were the main people?
In the Middle East science flourishes
- Scholar Ibn Al-Haytham → infleuntial in optics - found out that we see things because that the light falls on the object that we are looking at and that reflects back to the eye
- Ibn Sina → father of medicine, book of medicine that became influential in Europe as well
- Both did important work in mathematics, physics and medicine
- Until the 13th century, Aristotle was not really part of philosophy in Europe (his writings were translated to Arabic in the middle east and then brought back to us)
- Through the Middle East, Christian scholars gradually began to study Aristotle (had to write it on animal skills and translate it to latin)
- Augustine of Hippo
What did Augustine of Hippo develop?
The Algerian Augustine of Hippo develops an early theory of learning → more empiristic view
- “When grown-ups named some object and at the same time turned towards it, I perceived this, and I grasped that the thing was signified by the sound they uttered, since they meant to point it out.” (Confessions, 1.8)
What did Augustine of Hippo establish about consciousness?
- Develops an early theory of the unconscious mind:
- “what if memory itself loses any thing… Where in the end do we search, but in memory itself?…What we have completely forgotten, we cannot even look for… It is therefore the case that our mind encompasses more than it knows of itself at any moment.”
- Also indentifies the problem of other minds: how do we know others have consciousness?
↪ we can only assume - problem for empiricists because you cannot directly observe it - later suggested a solution with analogy that if we see that we have consciousness, we assume that others have the same (the argument from analogy)
↪ still not solved
What is the name of Augustine’s book?
On the Trinity - it’s one of the first works in philosophy of mind
- discusses the argument from analogy
Who invented the ‘zero’ and where?
In India, Brahmagupta, mathematician and astronomer, invents the number “0”
- This results in a positional number system in which the position of a number indicates whether it’s a multiple of ten’s or hundred’s and the possibility of negative numbers
- Revolutionizes calculation, and enters Europe through the Middle East
Despite the low rate of scientific developement happening in Europe during the middle ages, what significant was indeed happening?
- Increasing traffic between europe and the east brought greek classics as well as commentaries and other works from Arab scholars
- When the work of Aristotle is rediscovered, scholars in Europe work hard to teach and preserve it
- Translating greek and arabic scientific texts to latin
- In addition, scholars build on Aristotle’s work to expand knowledge and use the empirical method
- Monastic and cathedral schools, with the center of education being the study of the Bible, precede ‘universities’
What is the scientific revolution?
Name given to a series of discoveries in the seventeenth century, involving Galilei, Descartes and Newton, that enhanced the status of science in society
What were the medieval worldviews in Europe?
- Church has a big influence
- Some common views influenced by the church:
↪ the earth is 6000 years old
↪ humans are not animals (humans and the earth are special)
↪ the sun revolves around the earth
↪ heaven and hell are real
↪ thinking happens in the immaterial mind
↪ the end of times is near - The ancients knew all; with Aristotle and the Bible you have nearly all knowledge
- Scholars mostly preserve rather than generate knowledge
What was the system of the universe believe in at the time of Medieval Europe?
Ptolemy’s system (i.e. geocentric model): all celestial bodies orbit around the earth (picture 1)
- Aristotle started to propse the system and Ptolemy perfected it
- Most of the time, the planets move gradually through the stars from West to East
- Sometimes, the planets’ path amongst the stars appears to stop and go backwards from east to west = retrograde motion explained by epicycles (small cycles made by the wandering stars in addition to their main orbit around the Earth)
↪ Epicycles made the model be closer to reality but it resulted in a complex mathematical model
Now epicycles are of course debunked, we see the planets from different angle everytime since we are rotating around the sun at a smaller orbit than mars for example
What is a Copernicus’ alternative to Ptolemy’s system?
He developed an alternative model for the solar system called heliocentric model (not concieved by him for the first time but by Aristarchus of Samos, ca. 300 B.C. but at that time the model was not taken seriously)
- In this model, the sun is in the middle and the planets rotate in perfect circles around the sun (now we know it should be ellipses)
- He describes this model in 1514, but publishes it only in 1543
Why didn’t Copernicus publish his model earlier?
Two debated reasons:
1. Scared of the church
2. The evidence was not yet so strong
What were the objections against Copernicus’ alternative model?
- The model does not describe the data very well (because of the circles instead of ellipses) and is as complex as the Ptolemy’s: so what do we gain?
- Why aren’t we thrown into space if the earth is indeed orbiting the sun? (107,200 km/h !!)
- Why isn’t the moon also orbiting the sun? (the earth was the only planet with a moon)
- Why does a stone you throw from a tower fall right down?
What was the role of Galileo Galilei?
He is trying to show with thought experiments that the objections against Copernicus’ alternative don’t hold
- he writes a book in italian (language of people)
- Does it in a not very tactical way: a conversation between three figures: 1. mediator, 2. Sophiaty who represents the view of Copernicus and he is very intelligent, 3. Simplicio (means simple mind) who represents the view of the Church
- The conversation goes back and forth between the views of those two figures and Galileo defends the view of Copernicus
How did Galileo refute the objection why don’t we feel the earth move in such a high speed?
Used a metaphor of a ship (Galileo’s ship)
- You are in the cabin of a boat which is moving, and there are flies flying around, you are able to throw a ball and catch it… and if the boat is going in a uniform motion regardless of the speed, you wouldn’t notice anything because everything within the ship (the air as well) is moving in the same speed
↪ So as long as the earth moves in a uniform motion, we wouldn’t notice anything
- (picture 2) He also did an experiment where he climbed on the mast and threw a ball and it feel straight down since the ball is pulled by two forces: gravity and the force of the moving boat
↪ From a bystender’s perspective it looks like the ball is moving in a parabola but the person on the boat, throwing the ball, doesn’t see that
What did Galileo’s experiment on falling objects inspired?
Inspiration for relativity theory of Einstein - the movement of the falling objects is relative to where you are (in the boat it seems like it’s falling straight down, but if you’re outside of the boat, it will look like a parabola = movement is relative just as Einstein will show that time is relative)
The mathematical description as a parabola was inspiration for Newton
What is Galileo’s famous quote about other philosophers?
“I have been twice as good a philosopher as those others because they, in saying what is the opposite of the effect, have also added the lie of their having seen this by experiment; and I have made the experiment – before which, physical reasoning had persuaded me that the effect must turn out as it indeed does.” - Galileo, 1624
How does Galileo compare to Aristotle?
Aristotle believed in observations but not in experiments
- Recognizing the value of experiment is a big step forward
- Galileo is credited with the insight that artificial conditions provide insight into the natural world
- An important theme in psychology; see e.g. discussions on ecological validity
What else did Galileo Galilei do which revolutionised science?
- Galileo learns that Christiaan Huygens has built a telescope
- He manages to get a building plan and builds one within a week (!)
- Galileo will be the first to point a telescope at the sky
What did Galileo discover with his telescope?
- Venus has phases (just like the moon) and thus must orbit the sun
- Jupiter has moons
- There are mountains on the moon
↪ Aristotle thought the moon to be a perfect smooth disc - Galileo proved him wrong which also showed that there is still a lot of knowledge to be discovered rather than to be retrieved from antiquity (made him unpopular since Aristotle was regarded as ‘the all-knowing’)
What was the problem Galileo faced when he introduced his telescope to the world?
The idea that you see something better with an instrument than with your eyes is revolutionary and is viewed with suspicion
- So Galileo went to a collegue Cesare Cremonini, Professor in Aristotelian philosophy at the University of Padua but he refused to look through the telescope at all cost!
- Galileo’s response in picture 3 (read it, it’s quite funny)
