History and Philosophy of Science:

HISTORY AND 
PHILOSOPHY OF SCIENCE
Appunti di Elisa Belotti
Università degli Studi di Bergamo
Facoltà di Scienze della Comunicazione
Corso di laurea in Filosofia e Storia delle Scienze Naturali e Umane
Esame di History of Science
Docente: Robert Iliffe
Anno accademico - 2019/2020History and philosophy of science
Professor Robert Iliffe
The course goes from Aristotle, Medieval, than WWII, passing through Scientific 
Revolution and a great variability of items such as natural philosophy, astronomy, some 
chemistry and biology and he will enfasize the role of instruments which are really 
important in science. 
Let's start with the Aristotle and Plato and their legacy with european philosophy, let's 
contrast their philosophies → mathematical, rational and metaphisical as Plato and 
empirical with Aristotle. 
Plato's basic: teacher of Aristotle and student of Socrates and then foundend Athens 
Academy. The early dialogues concern life and teaching and than the later works concern 
utopian such as the Timaeus → key idea was forms or ideas and perfect exemplars of 
characteristics such as beauty, truth, virtue and justice. As humans, we're able to perceive 
these dimly, since we're in the “Cave” and we're not allowed to go out of it! 
Plato influenced by the numerical philosophy of Pitagoras → Plato is interested towards 
arithemtic, plane, solid geometry, astronomy and harmonics (which is music making 
pleasing sounds, both in theorical and practical sides)  which aim at what is eternal, after 
this one person should study philosophy. 
One of the main claim was that math is both beautiful and useful for training the mind a 
necessity for the education of the soldier-philosophers who were guardians of the Republic. 
His most important student was of course Aristotle, born in Stagira, and sent to Athens to 
study under Plato but than founded the Lyceum in 335 a.C, they deal with what we called 
scientific knowledge but their completly different approach is truly fascinating. 
When Plato died, he came back to Macedonia and became the teacher of Alexander the 
Great but then returned to Athens but founded the Lyceum where he composed works on 
astonishing variety of subject, physics and logic, poetry. The variability of his interest is 
truly massive but fondumental for our science. 
Plato's philosophy was an ispiration for persons such as Galileo, Newton and Huygens but 
at his time he was critized because he thought that this world is unflaw, the thought that 
there's a perfect, with perfect ideas of geometry etc, for Aristole this is the world of potential
and realization → a seed will and try to become a big tree! This is the world where things 
born and than die! Aristotle's basically work is natural history and his works were carried by
his studend through the Cristanity and Medieval time. 
Human beings were not incorrect about the perspeption of the world, human sense are good 
enough to describe the world as it really is → the world is as we see it basically but this will 
be overturned in Scientific Revolution of course! 
There is a true distiction between  the world and its nature and what human beings create 
starting from the world, but this will be resume and overturned by S Revolution as well. 
Aristotle's forms are something than can not be different from its material structure, it's what
makes a thing what it is → the substion form of human beings is soul and this is essential, 
but there are also something that it's not, and these are things called “accidental” forms. 
There's a geocentric cosmos with the Earth in the centre of this universe, and there's a huge 
1difference between thing below  the Moon, the world of change, of death, what's on top of 
Moon is the place of perfection and immortality and this is the cosmos of the Christian text, 
particularly the Old Testament which is literally undersood as a geocentric cosmos. 
The living world is in motion (kinesis) and the objects are in “potetial” and “actuality” 
which means that the world is in a continuos work in progress → things seeking to fulfil 
their potential by various means: a human being can realize his potential when he or she is a
the “polis” because he is a politic creature! 
The notion of causes operated through the four elements which are always in motion and by 
their mix, they create things → in this world things tended to move towards their elements 
such as rocks fall toward Earth because they're composed most by the element of the Earth. 
The cosmos, moreover, has in its centre the Earth and it's finite and full, Moon, Sun and the 
other planets revolved in invisible “cristalline” celestial spheres and this will be the 
astronomy till the beginning of Scientific Revolution. 
In his physic the vacuum was impossible and there are not things such as the atoms since 
this would imply a vacuum, so he explains phenomena such as motion, light and sound in 
terms of aethere, in which everything moves. 
In the mid of the Eighth century CE a major translation process took place in Baghdad and 
the Avicenna and Averroes composed major workes based on Aristotle's consideration of th 
world. 
In the 12
th
 and 13
th
 century, when universities apperead, translation of aristotelians's text nd 
islamic commentaries in finally Latin together with a growing confidence of the Christian 
world. 
Medieval universities witnessed tension between the high regar for Aristotle and a more 
suspicious attitude held by Augustinian scholars in Theology departments, so Aristotelism 
was condemned in the late 13
th
 century by the Archbishoph of Paris, Tempier, for the 
eternalism which denied the specificity of God's creature, its astrological determins, its 
strong link between form and substance and its excessivitvely high regard of human reason. 
The imagine by Raphael of Aristotle and Plato!
Despite criticisms, Aristoteliansim vied with the Platonic superior to mathematical and 
became the main philosophy, since the beginning of the Neo Platonism. 
Aristotelian natural philosophy was generally held to superior to math, which merely 
describe the external, measureable characteristics of things. However, many internal 
contradiction and empirical problems apperead within the Aristotelian system. 
This lecture will be on the Copernican Revolution. As said before, within Aristotelian 
system contained inconsistences and problems, and as the result of this we see a major 
arising from the italian schools of the Neo Platonism, especially with Giordano Bruno and 
many others who propose a new natural philosophy. In 1572 and in 1604 there were two 
supernovae which were events of great frightening, since someone thought that were signs 
of the end of the world, but they demonstrate the imperfection of the cosmos cause they 
show new bodies in the sky! In the seventeenth century it became accectable to use 
scientific instruments, artificial devices, new tools elaborated by scientices such as Decartes,
Bacon, and Galileo himself etc and experiment an the use of math  to investigate Nature, 
that create the mechanic philosophy as a respons to the aristotelism → understand Nature 
better by placing instruments and tool between you and Nature itself. 
Medieval astronomy stands for the geocentric universe basend on Claudius Ptolemy with his
Almagest, and his Ptolemaic system existed uneasily side by side Aristotle's doctrine of 
homocentric spheres, so it's a very different system → ptolemiac system is unclear. 
2As part of the undergraduate quadrivium, students learnes by basic astronomy but more 
serious students would study the Almagesto itself and its complecated commentary. 
The Ptolemaic system in really complex but was supposed to account for the visible motion 
of sun and planets → it includes the apparently non-circular motion of planets and the so 
called “retrograde” motion, to explain this one, planets were held to move on epycicle that 
revolved around points on a “carrying” or “deferent” circle and to explain apparent non-
circular motion planets were held to move with a consiste angular velocity around a point 
that lay on the other side the centre of the planetary orbit BUT how these things related to 
the reality, it's an open question. 
Imagine of retrograde Mars! 
What it means retrograde motion in physical sense or it's just a way to explain what we cans
see, just a tool? 
Nicolaus Copernicus was a polish and a brilliant astronomer and his jobs was about to 
calculated in a detailed way the day of Easter at the beginnig of his career, so the astronomy 
now was correlate to the role of Church → people'd to becoma an astronomer to become a 
university teacher or to have a role, a carrer along the Church, not for astronomy's sake. 
Copernicus during the years of his study, matured the idea that the Ptolemaic system was 
wrong and in a number of works, he argued that Earth was a planet with 3 different motions 
and not at the centre of the univers! In De Revolutionibus he argued these notion and that jis
system was simpler of that of his predecessors but only 10 people before 1600 agreed that 
the Copernican theory was probable or true, the 2 most important were Kepler and Galileo. 
Copernican explanation of the retrograde motion: it's just an illusion caused by the the speed
and the relative position of the planet! No real retrograde motion, so you don't need 
epyclices! 
At this point, for the predecessors of Copernicus, Earth was not just the simple center of a 
mathematical system, used only to calculate position or so, but it was considerate the real 
center of the univers! This change is not just a about the special transition from a place to 
another, but it also concerns the position of human beings in the univers. 
De Revolutionibus has a particular preface which was written by Osiander and that claimed 
that Copernicus' system was only a technical device for making better prediction of 
heavenly motions, so it means that it claimed to be only a mathematical device and not a 
real consideration of the univers, a real description, but Copernicus himself was not in a 
position to defend or other his book because he received the first copy while he was in his 
death bed. What Osiander was saying was that Copernicus was not so arrogant to introduce 
a new view of the univers, but only a mathematical device to calculate more easily the 
Easter day and so. 
There are many problems with heliocentrism in the 16
th
 century, first of all that it disobeyed 
Aristotelian dictum that each body had only one proper motion ad it conflicted with 
common sens and daily experience of the sun rising and was in conflict with Scripture → 
Joshua 10:12-13 - “Sun stand thou still at Gibeon”. 
But the problem that Copernicus was a real Copernican! So he did not intend his 
masterpiece like only a mathematical device, but as a real description of the univers, that it 
was true! 
Copernicus' text creates a barrier between of proficient astronomers and regular people and 
he provided a new kind of hybrid professional identity → the mathematically proficient 
natural philosopher and this innovation of the natural philosopher became persons in 
Galileo, Kepler and Newton himself. He showed that innovations in astronomy and natural 
philosophy were more likely to take place outside universities. 
3The discovery by Brahe and Maestlin → a comet of 1577 lay outside sphere of the moon 
and these findings created the opportunity about an infinite univers! 
In 1572, Brahe made studies of the new star which provided to be a distant phenomenon and
not sublunary but he remained a profound anti-Copernican, mostly for religious reasons and 
devised his own “geoheliocentric” system known as the tychonic system → the Sun 
revolves around the Earth with its own subsystem. 
His “Nova Stella” was the nova, a super bright new star that appeared in the sky and the 
disapperead in a month → a super  scary event for people of the 16
th
 century: they 
interpretate this nova as a sign of destruction and bad events. 
Johannes Kepler, a protestan student that became quickly a copernican and found his new 
astronomy in 1609 with Astronomia Nova , the greates year for astronomy, and he was an 
“hybrid” between an astronomer and a natural philosopher! 
Kepler did not believe that Copernicus was not a copernican himself but was convinced that 
it was true due to mathematical reasons and argued thatbiblical geocentric passages could be
explained away by appeal to “accomodation”, so people do not have to read the Bible in an 
literally way but it's written in a way to be understood by everyone, expecially by the most 
ignorant people: he was saying that professional astronomer can tell theologics how to do 
their job! Kepler also worked on Somnium that explained the copernican system through a 
dream trip to the Moon, a protoscience fiction! 
There is a polihydral forms that compose the universe in a perfect, harmonic way! 
His work is extremely important and in 1601, in Prague, he inherited the astonishingly 
accurate measeruments of the Martian orbit made by Tycho and noticed that his data showed
that the orbit was not circular, so to fit these data he determinated that the orbit had to be an 
ellipse, generalizing this form to all the known planets and this became the first law 
published with the second law, with respect to either of the two foci of their elliptical orbit, 
planets sweep out equals areas in equals times,  in Astronomia Nova in 1609. 
He thought that the univers had to be created to conform the perfection of the Holy Trinity, 
the Sun the Father, the Earth Jesus and the space between Sun and the planets was the holy 
spirit → refearing to this imagine, he believed that the Sun was a giant magnet that swept 
around the planets but there was also something musical concerning about the heavens and 
each planet has its own music, its own song  and the great Harmonices Mundi, contains the 
third law about the squares and his describe the harmony in the world, it's a book about the 
music, it'a about the Pythagorean thought that there's harmony in the cosmos → Kepler was 
someone who belived in astrology as Galileo and believed that the planets sang their own 
songs. 
Yes he is a brilliant creator the modern astronomy but he himself lived in a very different 
time and his context was something other our one. 
Galilean Science → there many different ways of doing science and during Scientific 
Revolution there many approaches of doing science, there's not only one. 
Born in Pisa in 1564 and he trained in a medical degree but soon became interested in math 
and his talent got him a position as the major mathematician at the University in Padoa, he 
wanted to change the world with his ambitious and wanted to destroy the aristotilian physics
and science and to replace it with his own thought. 
Early in his carrer in Padoa became a copernican but durung this period was still difficult to 
be one of them but he demonstrated that the aristelism was incoherent and inconsistent. 
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