So Why on earth would anyone study
history and philosophy of science?
What's the point? I'm goint to tell you the
story of the 17 year old Hakob.
Not this one. This one - a 17-year-old Hakob.
When I was 17, I was a bright kid
and I knew my science... I thought I
knew my science. If somebody asked me:
"Hakob, what do you know about the history of science?
You know your physics, chemistry, and so on.
But what do you know about the
history of science?"
What I would tell back then was pretty
much along the lines what every
high school kid - probably every talented high
school kid - would say in response.
This is basically what you find in popular
science literature,
or you find in science textbooks, or even in
professional science accounts.
This is what I call "Popular Science Mythology"
and this is the story of the 17 year old
Hakob, which I think many of you will share:
Sightly after the Big Bang,
there were these weird guys called ancient Greeks.
These ancient Greeks, they were
very very bright guys because they tried
to understand the universe, how the world
works and what things are made of and
so on and so forth. But the trouble was,
they got all of it wrong. For instance,
I knew back then
Plato would say that every object is made
of tiny tiny triangles.
Aristotle believed that the Earth was in the center
of the universe.
And this guy here - Hippocrates -  would teach that the 
human body is made of four bodily fluids
- whatever those bodily fluids are! And finally, that guy 
over there, Democritus, he actually believed
that education is basically for the
unfortunate - this is one step from saying
that ignorance is bliss. So basically these
guys got everything wrong.
So it's really not surprising that back then there
was no science whatsoever.
What was there in abundance? Tons of religion!
The funny thing was that you could actually
choose your religion. You could decide to
pray to Greek gods or to your Egyptian
gods. Or if you were so inclined you could
even choose to pray to the Gods
of the Seven - Old Gods, New Gods. You could
even choose to pray to the Lord of Light
for the night is dark and full of terrors.
But this whole fun ended when Christians came along.
They provided a religion that was supposed to be good
for everyone - you know: one size fits them all.
And the whole fun ended... 
They would teach you that God made everything:
the Universe, mankind and all the living things.
For a very long time, there was no science but just 
religion, until some heros of science appeared.
Among those heroes there was this guy: Galileo Galilei. 
He was the first brave enough
to say everything he thought about the
dogmatism any the ignorance of the churchmen.
Well, quite naturally they didn't
understand him and they decided to
punish him. What they did - they tortured him,
they imprisoned him and he found himself
in a situation when he knew all the
right answers. It's just that the right answers
were not available. He was like that.
Right? He knew the right answer. It's just
the right answer was not available.
So what do you do?
(Student) "Call a friend!" (Hakob) Exactly! Luckily he 
had friends and with the help of his friends
like Copernicus and Newton, he managed
to liberate science from religion. Hurrah!
And that's where the real science began in the
17th century. They created the so-called
"scientific method" and with the help of
the scientific method they proved
newer and newer theories and they discovered more and 
more facts. So that brought us to the
contemporary science. In the contemporary science
what have we? We have experiments,
observations but none of the metaphysical
nonsense about Gods and religion and
all sorts of things. Just experiments and observations. 
Nowadays scientists believe
that God does not exist. And finally it
is because of the scientific method that
science is a rational activity.
It's the scientific method that allows us to
demarcate proper science from
pseudo-science.
In a nutshell, my friends, this is what any
educated high school kid thinks about science.
This is pretty much the popular
mythology of science - abundant everywhere.
Watch science documentaries,  read popular
science literature,
open science textbooks - this is what you get.
Well, probably if you skip the Lord of Light part.
Everything else you pretty much get in abundance.
Now this is a story. But let's now try
to be philosophers here and try to
extract the basic myths on which this story is based.
And this this is exactly
what I'm going to do now.
Myth #1: "Science was created in the
17th century and there was no
science before that." This is the #1 myth.
Myth #2: "Galileo was a martyr of
science - basically, he was tortured and he
was punished and he was treated unjustly."
This is the #2 myth.
"The Scientific Revolution
liberated science from religion."
This is the #3 myth.
Myth #4: "The contemporary science believes that
God does not exist."
Myth #5: "Contemporary science is all about
observations and experiments and it has
nothing to do with metaphysical stuff,
stuff that we cannot observe and that we
cannot measure -  it's all about
observations." This is myth #5.
Myth #6: "Science proves things."
Myth #7: "The method of science is universal and
unchangeable, meaning that the way we do
science nowadays is the same as we used
to do it 200 years ago and it's
exactly the same as going to be
300 years from now  - it's unchangeable."
Myth #8: "Science is a rational enterprise
because it's universal method."
Myth #9: "Each succeeding theory
encompasses more and more true facts."
And finally myth #10: "There is a
strict demarcation line between science
and pseudoscience." These are the ten myths.
If you pay attention,
five of these myths are historical and five
of them are philosophical.
My question is: "Does any of these hold water?
Does it make sense? Is any of this true?"
Now that I told you that these are myths, you might be
inclined to say: "Well, no, no, I never
believed in these. It's only you Hakob."
But let's be honest here: how many of you
- before my telling you that these were myths -
would subscribe to something like this,
give or take?
How many of you? (Students raise their hands)
I'm glad to see many brave people here.
Very good! Now the thing is this question
here cannot not have an answer unless you
study history and philosophy of science.
That's why you need history and
philosophy of science: to avoid ignorance
when you get people  - very educated people
such as famous scientists - saying things right as far 
as science is concerned but
once they get to the history of science
or philosophy of science and they talk
about these things and you say, you cannot be
this uneducated, can you?
What we are doing here: we're fighting against basic 
ignorance. I'm going to skip philosophy for now.
I'm going to start with history.
What do we mean by "history of science"?
I will give you two options here:
Option #1: biographies of great
scientists - intellectual biographies of
guys like Copernicus, Galileo,
Newton, Einstein. This is one thing.
On the other hand, we also come across histories
of scientific institutions.
What are those institutions? You can have
universities: Bologna, Paris, Oxford,
Cambridge, the University of Toronto (why not?).
Or it could be other institutions like
European Organization for Nuclear
Research (CERN) and you can have the
history of The Royal Society and you can have the
history of the German Academy and so on and so forth.
So you have two options.
Which one of these you think we're going to study?
Biographies of individual
scientists or scientific institutions?
Which of the two? So how many of you
think that its intellectual biographies
of individual scientists that we're
going to focus on? How many?
Alright, quite a few! How many of you think that
we're going to focus on scientific institutions?
Even more!
Well, I'm sorry to disappoint you.
The right answer is neither, because there's
a third option. And the third option is
scientific theories. That's what we're
interested in: people, institutions, papers,
journals, articles, magazines - it's all
science to be sure, but the real essence of
science is its product, its outcome, its theories!
That's what it's all about.
It's not about just putting people
together, having conferences. That's not
real science. Real science is the outcome.
And the outcome is the theories and that's
the interesting part. So basically what
we are interested  are changes in the
mosaic of accepted theories.
So what is this thing, the mosaic? I'm going to give
you the outline of a contemporary mosaic.
If I asked you: What is it that we accept
nowadays? What theories do we accept as the
best available descriptions of reality?
What is it that we teach our
students?  We will probably say,
"Well, couple of physical theories: quantum physics,
general relativity, cosmology, Big Bang, and stuff..."
What else? Some chemistry, 
genetics, biology, and neurophysiology.
I'm going to miss some of the sciences. So I have to
apologize. There wouldn't be enough room
if I portrayed each and every one.
And then some social sciences too:
psychology, sociology, economics, history ...
right? And mathematics. Basically what we have
here is a mosaic of different scientific
theories. These are the theories that we
have nowadays are believed to provide the best
available description of the world.
Some of these theories belong to natural sciences
because their objects are
physical reality, chemical reality
biological phenomena, so they are natural sciences.
Even human body -  human anatomy - the study of
human body would be a natural science.
Then you get to social sciences and social
sciences would include everything
that has to do with human beings and creations of
the human mind.
In addition,  you have formal sciences. Formal sciences 
are basically logic and mathematics.
These are the sciences that deal with
formal objects, numbers, so on and so forth.
So we have natural sciences, social sciences, and
formal sciences. I'm going to give you a
few definitions now. So what's a theory?
This here is a sign of definition.
Theories are basically any set of propositions.
It can be comprised of thousands of
different propositions, like when we say
Newtonian physics, classical physics, thousands
and thousands of propositions.
Or, in extreme cases, it could be comprised of
one proposition, such as when we say “the theory of flat earth" which only says the earth is flat.
Or, "the theory of spherical earth" which
basically says that the earth is a spheroid.
So at one extreme you can have a theory
comprised of one proposition or you can
have very complex theories made out of
thousands of propositions these are all
theories for us, OK?
Now you have many accepted theories. 
Put   them together - what do you get?
You get a scientific mosaic.
That's the definition of scientific mosaic: a set of all accepted theories.
By the way, are there any computer programmers here?
Or any future computer programmers?
Do you know your UML (Unified Modeling Language)?
So this sign here shows that a scientific mosaic
is made of theories. It means "consists of". 
That's the sign. Is it clear, this relation?
Very good! And finally this brings us to the concept of scientific change.
This sign here is the sign
that we use the concept of scientific mosaic
to define the concept of
scientific change.
What is scientific change? It's any transition in the mosaic. Whenever you switch from one theory
to the next, you have an instance of scientific change. I'm going to give you a few examples.
It's a historical fact that the
scientific mosaic was not always like this.
We are going to take a timeline: 100 years ago,
200, 300, and 400 years ago, and so on.
Now if we went back 250 years ago to the middle of the 18th century,
and if I asked you, say, "Go and check
what educated people of that time period
would study in their universities -  
I'm not talking about the laymen
- not interested in vox populi which is not always vox Dei -
we are interested in the opinion of the educated people, people like you!
If you were born in the 18th century and
if you were to go to the best
universities of the time, let's say
Paris or Bologna or Oxford or
Cambridge, whichever, what is it that you
would study back then?
So this is what comprises the scientific mosaic of the time.
You understand? It's not the opinion
of the laymen. It's the opinion of
the educated people, the scientific community. Back then we wouldn't recognize anything
- or just probably recognize some things.
Here we zoom in and you'll probably recognize calculus which is still part of our
contemporary mosaic. But pretty much everything else is different.
In the middle of that mosaic, you have
the Newtonian physics here which we
still use but we no longer accept. I'm
going to explain it later - we use it but
we don't believe it's the best available
description of reality because we have
quantum physics, general relativity...
What else do you have?
You have phlogiston theory of combustion, which is the idea that pretty much everything that has a
capacity to combust, to burn, it's because
there is this internal substance,
the internal principle called "phlogiston" that makes 
things combustible. Then let's have a look at
this thing here. This is a theory of
preformation. This is the idea that
human beings are created as fully formed
organisms with limbs and everything.
Even in a male semen, it's fully formed. You see here? 
It's basically in this position.
That's what the theory says. So this was the
theory that human beings are preformed
and the only thing that happens to them
is that they grow in size. You know, just like
tiny pieces, you put them in a microwave
and they grow in size. Pay attention to this tile here:
theology, the study of God, was part of the
scientific curriculum. You would say
"Well, wait a second, this is religion,
right? This is not real science!"
Nowadays, yes!
Nowadays, if you say "well, you know what, I
have this interesting idea of a
project I want to apply to a grant
agency because I have a way of studying
attributes of the Creator. In particular,
I want to tackle the question as to how
many angels are there." You think you're
going to get a grant? Chances are you are not
going to get anything. We have a theology
department these days,
but pay attention: nowadays when we say theology, it's
not exactly the same theology back then.
There are two different meanings to the word "theology".
One is theology proper, which is the study of
God and His attributes in His words
and so on and so forth.
This is the classical sense. And the
second sense is what we nowadays often
call religious studies, the study of
different religions, different
religious attitudes, history of religion - that 
scientific discipline,
theology in that sense, is still part of the
scientific mosaic. It's part of
historical disciplines: part of history, part of cultural studies.
That's what it is. But the theology proper: the belief 
that God exists and belief that
God is the Creator of the universe, is no
longer part of the mosaic, but it used to be,
In the 18th century they believed
that the earth is spherical
and they believed that the God created the earth. 
It was on the same level.
It was not like he was a scientist here and he went
home and he was a religious person. No!
It was part of the same thing: they believed
that the God exists as much as
they believed the laws of Newtonian physics.
It was the same for them, so it shouldn't
come as a surprise that guys like Descartes or Newton and 
all of the 18th century -
they all believed in God (with some exceptions
obviously). But the accepted view,
what you study if you went to Paris
University or Oxford or anywhere, you would
study theology. It would be part of the
curriculum. Now, let's zoom out.
500 years ago, this is the late medieval
period - here, I promise that you won't
recognize anything or maybe only this
thing here, the Pythagoras's Theorem.
You will recognize that! But everything else is absolutely different.
In the center you have
the Aristotelian theory of
four elements - I'm going to explain that shortly. 
Then you have geocentric cosmology
with earth in the center of the universe. 
Please pay attention to the next tile:
this is astrology! "Wow, wait a second, 
astrology was part of scientific mosaic?" Yes,  it was!
It was part of the scientific mosaic. In fact,
if you were going to become a physician,
in the 15th century or 16th century or even in
the 17th century, you were supposed to
know your astrology. Again, I'm not
talking about the laymen. I'm talking about
the best minds of the time. 
Isn't this shocking?
Astrology was part of the scientific curriculum. 
So, what have we here? It's safe to say
that the scientific mosaic changes throughout time.
I'm going to give you only one example -
I'm going to move all these things and
let's take a very simple case:
a falling apple. And the question here is: 
what's going on in here? Why does it fall down?
A very simple question. You would be
surprised to find out that even this
very basic phenomenon has received many
different explanations throughout the
history of science. I'm gonna give you the
Newtonian, the Aristotelian,
and the contemporary Einstein explanations.
I'm going to start with
a basic textbook example: 
Newton's physics which is not difficult.
We zoom in and we have Isaac Newton himself,
You say: "Well, it's very simple.
everyone who knows the foundations of my theory
will tell you what's going on here.
You have two objects: the earth and the apple. 
The earth has a certain mass and the apple has certain mass.
We know from the law gravity that two
objects with mass must attract each other.
Very straightforward! The force of
gravity pulls them together. This is what happens.
Simple? You all know this. Well, if Aristotle was alive, 
he would say "well this doesn't
make any sense to me. This is not what's going on. 
In fact, what's going on is something
completely different. And this is the
Aristotelian view on the subject.
He'd say, "first and foremost, you have to
appreciate that the universe is made out
of two distinct regions - two completely 
distinct regions in the universe.
The earth is in the center of the universe, -
says Aristotle, - and all planets
revolve around the earth. So you have two
regions: you have the celestial region
here and everything in the celestial
region is made out of the so-called
quintessence or the fifth element.The element of ether. 
And it's in the nature of this
element to revolve around the center of
the universe." This is the way they
explained why planets move in circles 
 - because they're made out of
the fifth element: the quintessence. When you
get to the terrestrial region here,
everything in this region - the earth, 
the air around us,
all the way until the sphere of the moon, 
that would be the so-called sub-lunar
region or terrestrial region - everything
in this region is made out of four
elements: earth, water, air and fire. 
And if we zoom in this region, two of these
elements, earth and water, were thought to
be heavy. The two other elements,
air and fire, are light. That difference is 
essential because they believe that
everything made out of heavy elements
has a natural tendency to descend
towards the center of the universe. That
was the basic principle of their physics.
when you drop heavy things, they will go down 
 well, because
they have a natural tendency to descend
towards the center of the universe.
For light elements the situation is the
opposite. Everything made out of air and
fire has a natural tendency to ascend
towards the periphery of the sub-lunar region.
So basically when you fire a match, 
  the fire goes up. Why?
Because it has natural tendency to ascend.
 If you drop a stone into water,
why does it go down? Well, because earth is heavier
than water and therefore things are made
of earth shall penetrate through things
made of water and therefore they go
all the way down. Very straightforward. So if
you take this then you can explain
what you see around us. In particular this
explains why the earth must necessarily
be in the center of the universe: because
if your basic physics tells you that
everything made of earth collects in
the center of the universe
then where else could the earth be? 
 So  you don't get a choice here. You can't accept
the Aristotelian physics and think "maybe
we'll abandon geocentrism
and accept some heliocentrism (the Sun in the center)." 
You can't have it!
You can't have it both ways!
OK? So, the first layer is that of Earth,
 then comes the layer of water,
then comes the layer of air, then comes
 of fire. If you apply this phyics to
our basic case of a falling apple, how would 
 Aristotle explain? It's very straightforward.
The very fact that the apples goes down
tells us that it's made of heavy
elements. It's some sort of combination
of
earth and water, right? That's what it
indicates. And as a heavy object,
it must descend towards the center of the universe.
 This is very straightforward.
This is what going on. There is no gravity. The only 
thing that the apple must know is the position of
the center of the universe. That's the
only thing that everything in the
universe knows. Where is the center of the
universe? There it is! So I have to go there.
That's it. So for an Aristotelian
guy, the whole Newtonian idea of
everything in the universe attracting
each other would be ridiculous.
Now for the same phenomenon you have two
explanations: the Aristotelian explanation is
that the apple as the heavy object descends
towards the center of the universe
and the Newtonian explanation is that the
earth and the apple  attract each other
because of the gravity. Two different
explanations: the first one accepted
all the way until the early 18th century ...all 
 the way until the late 17th century
and the early 18th century. This is what was
accepted. Then for the next 200 years
the accepted view was that of
Newton, all the way until the 1920s.
And the contemporary view? 
 It was suggested by this guy. He is remembered for
theory of general relativity.
 Einstein would say, let's take a fragment of space.
The arrows here and the lines indicate
the light rays.
This particular fragment of space will be
flat because there are no objects
therefore light rays travel in straight
lines, as you can see. Now the question
here is, says Einstein, if we have a massive
object, let's say, a star.
- let's say our own star, the Sun - 
 what would happen to the fabric of space?
Einstein says if you have a star like the Sun, 
  it would curve the space around it -
in reality space-time - I'm gonna keep it
simple for now - it would curve the space
around it so that everything including
the light rays would bend when traveling
in the vicinity of this object. This is
something new. This is something
unpredicted by Newton. This was the new
prediction of Einstein's theory.
So this is very similar to when you have
a suspended bed sheet.
And you put a ball - let's say a basketball - 
in the center of it. What will happen
to the bed sheet? It gets curved slightly. 
 Well, it depends on how suspended it is
but it gets curved and you have a ball here
 let's say a basketball and you take a small
ball - let's say a tennis ball - and put that
in the vicinity of that bigger ball.
What's going to happen to the tennis ball?
 It's going to seem like there is an
attraction between the two as if there's
a gravity that attracts the tennis ball
to the basketball, right? That's what's
going to happen. What would happen if we
have an even heavier object, 
 a more massive object, like a black hole.
In the case of a black hole,
the curvature of space will be such that
nothing will be able to escape.
This light ray here would be able to escape
the curvature but here nothing would
help it. Now if we apply this theory to
our fundamental case of a falling apple,
Einstein would say that well it's very simple:
the space around the earth is curved due to
the Earth's mass. The curvature is not
great you can't compare the curvature
produced by the Sun
or, God forbit, the black hole, but there is some curvature. 
So what happens with the Apple? Same thing
that happens to the tennis ball:
seemingly attracted by the basketball.
The same thing! So there is no gravity and there's no
such thing as two things pulling each other.
There's no such thing. 
 It's is an inertial motion in a curved space.
Just like tennis ball. OK? 
 (Student) "No offense to Einstein, but to me
the theory seems to be most circular because 
 the example you are giving relies on
gravity to understand so the rolling ball 
  is pushing down, right? (Hakob) Very good!
Any response to this? You understand the point Miriam is making?
 So the point is
that basically that the metaphorical example that I brought up
with a suspended bed sheet itself relies
on the concept of gravity.
Anyone wants to reply?
(Student) "I completely agree. From my
understanding it's just a really
simplified example to help people
understand the super complex theory of
relativity and curved space-time but
you're absolutely right it does rely on
Newtonian gravity to help you understand Einstein's relativity."
(Hakob) Very good! That's 
exactly the case. Now I hope you
understand that that silly example that
I brought up. I didn't come up with it.
It's a common example to help people
to imagine a curvature of space-time
which is not an easy thing to imagine.
And the problem with all those examples are
that many of them rely on classical notions -
notions of classical physics like gravity 
 and it was very good of you to point it out.
Now what I want you to get from 
  long story is not so much about
theories themselves but to appreciate the fact
that for the same phenomenon you can get
more than one explanation and these
explanations are not some random
explanations - these are the theories that
have actually been accepted at different
times of the history. I'm not talking
about some rubbish explanations
somebody came up with. No these are the things
that people were studying at the universities.
And our theory has only been accepted for
about 90-odd years - compared
with the Aristotelian physics that has been accepted 
for almost 20000 years and the Newtonian
theory that has been accepted for more than 200 years. 
I'm not asking you to accept these
theories. There is a reason why we no longer
accept these theories. But we have to
appreciate here is that there is
scientific change, that science changes
through time. Is this clear? Very good. This brings
us to two fundamental questions of
the history of science.
If you're a historian then it becomes
your task to pick a date and for that date
you have to be able to reconstruct
the mosaic of the time. Let's say you're
interested in the second decade of the
16th century (1510s)
and you are interested in particular in the Oxford
scientific community. So what you do as a
historian? Delve into archives and it
becomes your task to unearth
and to reconstruct what people back then
thought about the World,
thought about the universe. Isn't this
fascinating? This is what historians do.
The second question which immediately
follows the first question: OK, you know
what happened here and you know what
happened there. What about
the transitions? You have the snapshots: you 
 know the mosaic around 1510 and you know
the mosaic around 1520. What about the
transition? Why is it and how do
scientific mosaics change through time. 
 So two questions, and basically
this is the history of science.
Any questions so far? (Student) "Was alchemy 
 ever part of the scientific mosaic?"
(Hakob) A very good question! We
are going to talk about alchemy in lecture 6
when we deal with science and
pseudoscience. The short answer is
not as far as I know, no! It was
considered a proper scientific enterprise
and was considered something worth pursuing
but so far as I know there was never a
point when alchemy or any alchemical
theory has been part of the scientific mosaic.
 It was never part of the official
curriculum but then again the idea that
you can take some basic metals
and transform them into more noble metals
like gold for instance,
this idea was considered quite
viable and there's a reason why.
It follows the Aristotelian physics of the time.
 Now what does philosophy of science
has to do with all this? We have
historians and historians study
history of science. What do we need 
 philosophy of science for? What's the point?
You know what they say about philosophy? 
 I was told - this is an old joke
but I didn't know about it - don't look at
anything in the physics lab, don't taste
anything in a chemistry lab, don't smell
anything in a biology lab, don't touch
anything in a medical lab, but most
important of all never listen to
anything that tell you in the philosophy department.
And there I am, I ended up teaching
philosophy of science.
Now, why philosophy of science?
If you ask my opinion of these two
sister disciplines: history of science
and philosophy of science -
it is true of course that history of science
is very interesting and it's really
fascinating - you study different ideas and
different time periods. It's very
interesting. But without actually tried
to unearth the mechanism of scientific
change, without trying to understand why
things changed the way they change,
it's interesting but not so much at least not for me.
You see I have a theoretician's mind.
I want to understand how things work.
Whatever I'll look into, I really try to
understand not just what happens but also
why it happens. I try to understand the 
 underlying mechanism and for this you need
philosophy, philosophy of science. Question 1: We know
that scientific theories change. We've seen one example:
transitions from Aristotle to Newton to Einstein.
You could take any scientific discipline, 
 let's say, take astronomy,
the same thing will happen.
Transitions from geocentric astronomy 
 to the Kepler's astronomy
and then contemporary cosmology and
astronomy. You can take any field you want
and you have a case of scientific change.
Now the question is: does everything in the
mosaic change or are there things that
are immune to change? Are there such things that,
once in the mosaic, are staying in the
mosaic for ever. Or are we in a position
to say that everything is changeable?
 So this is the first question.
Another way of putting this is:  
 Can we know anything for certain?
Or, same question: Is there such a thing as absolute knowledge? 
This is the question number one.
What I'm asking you to do is not to ask you 
 to come up with an answer on the spot.
What I'm asking you to do is appreciate the question.
Question 2: We have different
theories, so how do we evaluate these theories?
How do we accept something
theories and reject some other theories?
In other words, what is the method 
 of theory evaluation?
What criteria should any
theory satisfy in order to be accepted
in the mosaic? This is a philosophical
question. For instance, nowadays we accept
general relativity. Why relativity and
why not the Aristotelian physics?
Certainly there must be a reason for
that. So what is the reason?
Understand? Very good! Question 3:  
 scientific change. Theories change.
Is there any logic in the change? What's 
the mechanism of scientific change?
Why do we abandon some theories and accept some
other theories? Is this because we just get tired?
Just like it happens in fashion? 
 You know when you buy
yourself  new clothes not necessarily
because you didn't like the old ones but
because you just need something new, 
 not necessarily better. Scientifc change:
Is it similar to changes in fashion? 
 or is it something deeper? You understand?
Is there a logic ? What's the 
 mechanism of scientific change?
That's the question. Question 4:
scientific progress. After all these 
 changes and after all these
transitions in the mosaic, we've seen
many cases where theories accepted
for centuries or millennia were eventually
abandoned. Take the cases like
Galenic physiology - this is a theory that human
body is made out of four bodily fluids -
this theory actually stayed in a mosaic
for about 2000 years and yet
it's no longer accepted. Another theory 
  is classical geocentric astronomy
This one had been accepted for more than 2000 years 
 but it was rejected. If it is a case
that even time-honored theories
eventually become rejected, and
we know this from the history of science, 
 is there such a thing as scientific progress?
Are we moving towards anything? 
 Are we getting any better? You understand
the problem here? You can't say well our theories, 
as opposed to theories of the past,
are the true theories. 
 This would be very presumptuous.
Even the best of our theories have been accepted for
no more than 100 years so that
would be very presumptuous of us to say
"Well, no, now we know for sure; those guys
were mistaken." History shows that a
theory accepted for two thousand years
was eventually abandoned. Are we going to
take the risk and say "we know for sure"? 
 So the question here is
Is such a thing as scientific progress? 
 That's the question!
The 5th and the final philosophical question
that we're going to talk about in this course
concerns the difference between science and pseudo-science.
If you look at the history of the scientific mosaic, 
you would come across many theories that were once
part of the mosaic and nowadays not only
rejected but also considered
unscientific. There are theories that are
rejected nowadays but still considered
scientific. Let's say, Newtonian physics:
we no longer accept it but if you ask
anyone: it's a proper scientific theory - 
 no longer accepted but still scientific!
But then again we have theories like astrology: when we rejected
the classical astrology, we didn't replace
it with some new astrology.
We just rejected the whole discipline. And now we
consider astrology as pseudoscience.
It's an interesting thing and my
friends here know that I'm very much
interested in the business of using astrology 
 because it's fun. You say, "Oh I know, you are typical
Sagittarius, Greg!" We do those things
because it's fun but when it comes to
distributing PhD degrees, we say "No, you can't be a PhD in astrology."
That's impossible these days. So, is there any other case of a
theory accepted for a very long time and then nowadays
considered unscientific? Theology!
Theology was part of the scientific mosaic 
 but nowadays no longer!
The question is: Is there such a thing as a
clear cut line between science and pseudoscience?
Is there such a thing as demarcation criteria?
There you have it: five philosophical questions regarding science: 
 Is there absolute knowledge?
How do we evaluate competing theories? 
What is the mechanism of scientific change?
Is there such a thing as scientific progress?
What is the difference between science and pseudoscience?
Five philosophical questions. Any questions about these questions?
(Student) "How does something change from 
pseudoscience to accepted science?"
(Hakob) He asked the question, how do some theories
change from pseudoscience to science
and the other way around too I guess?
It would be a very good example of a
philosophical question. To understand
that you need to answer the question 3: 
 what's the mechanism of scientific change?
Is there any logic in these things?
 You see, if you ask philosophers,
you are not going to come across one single unified
answer because unfortunately nowadays we
don't really have a commonly accepted
theory of scientific change.
But we are getting there. In  lecture 4 your going
to study one such theory that presumably
explains why and how we switch from one
theory to another? Why and  how it happens
that the theory that was considered
 "scientific" for thousands of years ends up
in a trash bin. We have to wait for that! 
 Any other question?
Very good! So next time we are going to start
with the first question.
This is the question of absolute knowledge: 
 Can we know anything for certain?
Any other questions? 
 Is this fine? (Students) "Yes!"
(Jokingly) Do you think you could tolerate me
for more than one week? I was very glad
to see you all and I hope to see you all
next week. Have fun!
