Have you ever taken any history of
science courses before? Anything related
to philosophy of science? What normally
happens in those courses is: when they teach you
the 17th century, most of the time
they focus not on the Aristotelian worldview,
instead they focus on a whole bunch of
different philosophical views and
theories that were available on the
market. They talk about Galileo, they
talk about Boyle, they talk about Gassendi,
they talk about many different
directions which were pursued in that
century. But what's interesting from our
standpoint is that none of those views was
actually accepted. The accepted theories all
the way until the end of the century
remained in the good old Aristotelian-Medieval
worldview. Why did it remain accepted
until the end of the century? What was
wrong with those suggestions? By the 
Second Law we know that if something
doesn't become accepted, there's only one
reason for that: because it doesn't
satisfy the requirements of the time.
Cartesian natural philosophy and
theories that came with it became
accepted only towards the end of the
century. And the chief author of that
system is Descartes who realized that the
only way you can convince the community
is not by making experiments - that's not
going to help you - but actually
satisfying the requirements of that
community. Now Descartes realized that in
order to convince the community, he has to
show that his theory is intuitively true.
How do you do that? Let's have a look. This 
worldview was accepted for a very short period
of time. Actually for about forty years
and primarily if not only on the
continent. In England it was accepted for 
a very short period of time in Cambridge.
Other than that it was mostly
accepted on the continent: France,
Netherlands, Sweden. In the center of this
mosaic you have Cartesian natural
philosophy and physics. So you have optics,
mechanistic physiology, geology (study of
Earth), cosmology - all mechanistic!
Geology is still part of the mosaic.
Metaphysics - I'm going to explain that.
Mathematics is a Cartesian space.
Mechanistic biology. And finally we have
hypothetico-deductive method. Let's
start with the metaphysics. Here he is,
carrying a sword. One Swedish princess who
was very fond of Descartes' teaching
invited Descartes to Sweden to teach her
philosophy and science and all sorts of
things. But the particular thing about
her schedule was that she was so busy she
could only study at 5 a.m. in the
morning. So Descartes had to wake up at
four in the morning. He didn't survive.
He didn't survive two months. This is what 
Descartes says: we have an external world.
We have the mind. We have things as they
exist in reality and we have our
experiences of things and this here
would be theories about things.
Descartes says that if you want to convince someone that what you say is intuitively true,
the first thing you need to do you is
to erase, delete, remove, reject
everything you thought you knew!
Everything! You have to make sure that
you only accept what is true. And in
order to do that you start by doubting
everything. Since we are looking for a
clean sheet, we are erasing all the
knowledge. First thing, we erase all our
theories. And then I doubt my experience.
I doubt the existence of the external world,
even my own existence. I have to start
by doubting everything. Otherwise how do I
know what I accepted is actually the case?
I might be accepting something without
necessary foundation. So let's erase and
only accept those things which are true. Let's see where he goes with this. We erased
everything. Everything is clean. And then
he says: "But even when I doubt everything, one thing
becomes certain immediately. What is it? It is the fact that I doubt. Can we all agree that?
You cannot doubt without doubt. It
would be very difficult to do.
At the moment you realize you doubt you also understand that you think because doubt
is just a way of thinking, isn't it?
It's just one way of thinking. "I doubt,
therefore I think." But in order to be
able to doubt and think, should I not least
exist? It would be very inconvenient to do
the thinking without existing, 
if not impossible.
It follows that "I exist". Now this proves that my mind exists - that thing that does the thinking!
But it doesn't really say anything about my body or the external world, right?
This might be an illusion. We don't know at this stage and we decided
to doubt everything. So what do you do? Descartes
says that after I prove my own existence,
it becomes obvious to me that God, 
the ultimately perfect being, also exists.
Well, how can you ever prove anything like this?
Sorry to disappoint you: I'm not going to
give you the answer. I cannot give you the
answer because the answer is going to be your
DIY assignment for this week's tutorial.
It is a very peculiar argument: how on earth
can you arrive from something like I exist
to God exists? That's exactly what
Descartes argues. At this point I want you to
accept for the sake of argument that he
has proven this. But why would anyone
bother to prove that God exists? Why would
he need this? There's an old saying which
says that it had never occurred to
anyone to doubt the existence of God
until the likes of Descartes 
who undertook to prove it.
So why would he bother? You see he needs
God to prove the existence of the
external world. Without God you cannot
prove this. And this argument is very
interesting. He says this: 
As a supremely perfect being, God
is all good. He is what we 
call "benevolence", meaning
he doesn't do any evil as a supremely
perfect being because if he does
something bad he wouldn't be perfect. He
would be malicious, therefor a perfect
being is all good by definition. Everyone
agrees? So the moment that you accept the
existence of this being, you also have to
accept that he's all good because this
is what's implicit in the definition of
this being. The the moment you accept this, you
also realize that everything that you
perceive clearly and distinctly must be
true. Why is that? Because if it so
happens that what I perceive clearly and
distinctly is not really true, it would
mean that God is a demon - he's a
deceiver but we know that his all good,
therefore he couldn't have possibly allowed
such a huge deception to take place,
therefore - Descartes says - the moment that 
you realize that a certain idea is very
clear, very distinct, you can be
absolutely sure it is true. Let's see
where he goes with this. He says: I perceive
clearly and distinctly that my
sensations are caused by external objects.
Now when you sense there are several options
here.
One option is that the source of your
sensation is your own mind, but this clearly
cannot be the case because if I'm the source of
my perceptions, it means that I can
control them but I certainly cannot
control my perceptions, can I? It's not
really up to me to decide whether I
perceive red apple or green apple or
blue apple. I do not control these things,
therefore I'm not the source of my
perceptions, are you following? Therefore 
the source of my perception should be
something external and this is how I
come to appreciate that I perceive
clearly and distinctly that it is the
external world affects my sensations.
At this stage I don't know whether my
sensations match the world - maybe
something completely different out there!
But one thing I know at this stage for
sure is that the source of perceptions
is from the outside, and since you
perceive clearly and distinctly that
your sensations are caused by external
objects,  this cannot merely
be products of your imagination or
otherwise God would be deceiving you
which is impossible because he's not a
deceiver and therefore the material
world exists independently of my mind.
Let's recap the argument to see the
logical connections. Now he starts from
this the idea of God's benevolence: God
is a supremely perfect being; God is so
good - this follows from the definition of
God; it follows from this that clear
distinct ideas are true. Everything that I
perceive clearly and distinctly is in
fact true. On the other hand I perceive
very clearly that the mind-independent
material world actually exists. You have a
clear and distinct perception of the
existence of the external world and you
have a guarantee given by the creator
himself that whatever you perceive clearly
and distinctly must actually be the case.
You put those two together and you
arrive at the conclusion of matter or
the external mind-independent material world
actually exists! What do you think about the argument?
(Student) "Is there any similarity
between the statement that clear ideas
are true and the Aristotelian-Medieval
belief in intuitive truth?“ (Hakob) That's a
very good point! Descartes knew
the rules of the game. He knew that the only
way to convince the community is by
showing that your theories are
intuitively true and when he was devising
his own method he put everything in
such a way so that the Aristotelian
community would be convinced. That was his
major target. So this clear and distinct
idea is nothing else but a way to
satisfy the requirements of the
Aristotelian community. This is what you are
looking for - you are looking for intuitive truth!
I'm going to give you one that is beyond
any question. So I'm going to be more
Aristotelian than Aristotle himself. This was
basically the idea and he succeeded!
He showed that his theory is
more intuitively true than Aristotle's
theory itself!
Let's see how! This is the proof of the
existence of the external world. Now you
have two substances: you have 
mind and you have the material world.
The question is what are the
indispensable properties, the essential
properties of mind and essential
properties of matter. What are the
properties without which you cannot
possibly conceive mind? Is there a quality
which if you take away from mind it is no
longer mind ... the quality that every mind
should necessarily have, otherwise it's
not really mind. It's the capacity of thinking.
You cannot possibly conceive of a mind
that is not capable of thinking anything.
If you have come across one, it's not much
of a mind. Mind is thought. The principal
attribute of mind is thought -  by
"principal attribute" he means essential
indispensable properties, properties that you
cannot take away from that substance.
What about the indispensable properties of 
matter. We've covered this: it is the capacity to
occupy space. It can be fuzzy shape,
it can be some fixed shape, but
extension is required: you cannot be
material if you don't have extension.
the material objects are very different 
but they have one thing in common:
their capacity to occupy space therefore
matter is extension, the principal
attribute of matter is extension! 
Descartes would say that
these statements are intuitively true, we
have arrived at them without any
experiment, just think of these things,
and these things become obvious.
Whether they are or aren't is a different issue. 
We can all appreciate one thing that this
appears very intuitive indeed! 
Now let's zoom out.
Several interesting consequences follow
from this. The first one is the idea of dualism,
the idea that there are two
substances. I'm going to explain this in
detail, one by one. The next one is the
idea of mechanicism, the idea that
material objects are composed of bits of
interactive matter. And finally, if you
ask the question how can two bits of
matter affect each other, you arrive at
the idea of action by contact, that
everything happens only by contact.
Now let's start with mechanicism. This is
the idea that material objects are
composed of bits of interactive matter.
This is essentially the idea. And as such
it came to replace Aristotelian idea of
hylomorphism. This is the one I'm going
to explain. In the Aristotelian worldview
this was accepted. This is the idea that
every compound, everything essentially
can be decomposed into its form and
matter. Let's take Aristotle and a
typical compound - a human being: Socrates.
If you analyze his body,
you can say that it is a compound of the
four bodily fluids, right? The four humors. 
But this is not the whole story
for Aristotle. If you only have the four
bodily fluids, is this enough to make a
human being? Not really. What's missing is
the soul which makes a living thing
alive, which organizes the fluids in such
a way that they produce a working human
organism. This is the idea. This is the
matter of the body before the fluids and
this is the form of the body and
everything in the universe is
combinations of matter and form except
for the God which is a different story.
If you look now at each of the fluids, for i
nstance blood, it is the same story:
blood is a compound of the four
elements predominantly element air but
also some other elements, some water and
mixture of other elements. But this is not
enough. You also need a formal 
organizing principle that makes a thing.
The same applies to the elements.
If you take the element of air, it is the same
picture! It is also composed of matter
and form. Zoom in here, you get some primary
matter - we don't really know what the
matter is - but it must be composed of
some sort of matter - but this is not
enough. It has to have an organizing
principle. In the case of air, it is the substantial
form of airness imposed on it, so this
was the idea of hylomorphism. "Hylo" is Greek for
matter and "morph" is Greek for form.
We have morphology in linguistics, the 
study of forms. So hylomorphism is the idea
that every compound can be analytically
decomposed. It doesn't mean that you can
have a separate form and a separate matter.
You can never have that. It is impossible
to have matter without form, according to
Aristotle. So you can only analytically
decompose. Every compound can be
analytically decomposed to its form and
matter. If you ask Descartes, he would say that
this is complete and utter nonsense. Why
is this nonsense? Because you see this talk of
form gives the impression of explanation but
it doesn't explain anything. In reality
the moment you realize that the only
attribute of matter is extension, there
are no such things as forms. The only
thing that we do have is bits of matter
interacting with each other therefore we
realize that these forms are utterly
fictitious, so they must go. In
reality what you have is the body here is
essentially a complex hydraulic
machine - think of it as a machine -
operating purely mechanistically. So if
you zoom in specific organ in this case,
the eyes and any other organ is nothing but a system
of valves, pulleys, pipes and pumps.
And essentially every effect in the bodies
produced by the collisions of moving
particles that compose the body.
This is your purely mechanistic picture. 
Think of it as a clockwork universe,
a universe in which everything is just a
machine. It's a very complex machine but
it's just the machine. There is
nothing more. There are no organizing
forms. There are no organizing principles.
It's just combination in
collisions of tiny bits of matter.
Now this is the idea of action by contact.
Action by contact came to replace
the Aristotelian idea of final cause. We
have to start from Aristotle again.
If you ask Aristotelians, they say the
universe is full of goals, full of
purposes.
Everything that exists exists for a certain
goal, certain end, certain purpose. It's not
a meaningless universe. Everything that
exists has a certain goal. If you take
let's say the reproduction of animals.
Why do animals reproduce? The answer is
they reproduce because that's their
intrinsic goals, that's their purposes, OK?
That's their aim. The aim of animals is to
reproduce. Why does an apple tree grow?
Because growing is the intrinsic goal of an Apple tree
dictated by the substantial form. Why does
the statute exist? It exists because it serves
certain purpose. What's the purpose? It's
not intrinsic this time. It's extrinsic.
It's something external, for the sake of
beauty. That's why it exists. Human beings? What's
the purpose of the existence of human beings?
It must be dictated by our form,
our indispensable quality, which is our
capacity of thinking. Therefore the goal
of human existence would be to fulfill
your capacity of thinking to its fullest,
to develop and to exercise your capacity
of thinking to the fullest.
This will be your Aristotelian purpose.
Why do we exist? To think and
exercise are thinking to its utmost
degree. Everything in the world, according
to this type of thinking, exists for a
certain goal. This, for Descartes, what
would you say to this whole world? 
It just doesn't make any sense.
Talk of goals, aims and purposes doesn't
make any sense if we recall that matter
has only one principal, one attribution, 
which is extension! There is nothing in
extension that it says that 
things must have any goal.
Things happen not for a certain
goal but because things touch each other,
contact each other. Everything happens
because of pushes and collisions so this
whole idea of teleology is utter
nonsense. Change can only be brought
about by actual contact thus here
everything that happens here must have a
purely mechanical explanation. We can be
a very complex explanation but
essentially is just a clockwork, very
complex but it's a clockwork. It's a
mechanism. You don't need any
purposes. How do you explain the workings
of a clock? You can say it shows the
right time because it was created to do that.
Yeah ... but is this is a sloppy explanation,
isn't it? The real mechanistic explanation
would be to say according to the
laws of mechanics of this clock here has
this spring attached to it then this
lever here and this escapement here and
then they move the whole thing in such
a way that assures the right time. That
will be the mechanical explanation and
that's the only type of explanation that
Descartes would accept. Same applies to the
animal kingdom, to inanimate matter and to
the whole universe. If you think of bits
of interacting matter, they can all
collide with each other and there are no
other capacities, no goals. If you accept this,
you also accept the basic principle of
the Cartesian physiology, the idea that
changes in organisms are caused by
collisions of material particles like
that. If you take the phenomenon of
vision for instance - these are by the way
actual drawings from Descartes - light
rays here from external objects
impress subtle particles into the eye, so
it's purely mechanistic:
particles arriving at the eye and
pushing then the image from the eyes is
transmitted to the brain, again purely
mechanistically. There is no mystery here.
It's all like in a clockwork. Similarly
the human heart is just a hydraulic pump
that pushes the blood into the arteries,
effectively all reflexes in the body are
produced by the motion of material parts.
If you accept this, then you also accept
that changes in organism are explicable in
purely physical terms. Here are a few
drawings from the same time period.
This is in particular an attempt to explain
flight in geometric terms.
Here is another one and here's another one.
The idea was all sciences including
sciences of animals, zoology,
can be geometrical, can be
mathematical. Now dualism. This is the
third idea. What's dualism? Dualism is 
the belief that there are two
independent substances, two types of
things that can exist on their own:
extended substance which we call
matter and thinking substance which we
call mind. This idea came to replace
the Aristotelian idea of pluralism.
Pluralism is the idea that there are many
many different types of substances not
really reducible to one another: they're
very distinct. If you ask Aristotle,
he will say that the world is full of different types
of thing. A thing is characterized by
its substantial form. It is made of
some matter but it's also characterized
by a certain substantial form, the
quality that makes it what it is and the
quality that organizes it. Now what is
the substantial form of a mountain?
It's the quality of mountainness,
if there is such a thing.
Substantial quality of an apple tree 
is its capacity to grow apples.
Fair enough?
The substantial quality of a lion cub
is that it can grow into a mature lion.
And finally the quality of a human 
being is his capacity of reason.
So there are as many substances as there
are types of things! Every individual
type of thing, humans, animals, and every
individual type of thing is characterized
by a certain form that separates it 
from other things. If you compare
the mountain to any apple tree, two
different substances for Aristotle, these
only share some kind of matter that must
be made of a similar combination of
elements - must be some earth and some
water probably also some air.
So from the
point of view of the elements, they might
be very similar. But what makes them very
different is the substantial forms, the
respective substantial forms. So no
matter how you rearrange the matter of
the mountain it will never be capable of
bearing fruits. This is the 
Aristotelian idea. Why is that?
Not because they are made of different
stuff. Sometimes you have two different
things made of similar stuff but they do
different things because they are
organized differently. If you ask Descartes 
he would say the Aristotelians multiply
substances without any reason. You don't
needs thousands and thousands of
different substances. You actually don't
need them. In reality, you only need two types of
things. What are other types of things?
Things are material that occupy
space. All material things are nothing
but systems of moving particles. And the
only attribute they have is a capacity
to occupy space. So all material things
are essentially different arrangements
of the same extended substance, which is
matter. Mind, according to Descartes,
is a different substance. The mind is different
because it's not made of particles. It's
not made of material stuff. It's
immaterial. Its primary attribute,
thought, cannot be explicated in terms of
shape, size, emotional, or material particles.
Human beings therefore are the only
creatures in the universe who are citizens
of two different worlds - the world of
matter and the ideal world, the world of mind. 
Ideal comes from the noun idea, meaning "thought".
Ideal here doesn't mean "perfect" in this 
case. it just means having to do with ideas.
Descartes believed there are other creatures 
who have only minds but do not bodies. So what
would be those creatures? Any ideas?
Angels and the Creator himself: they have
minds but they don't have bodies.
On the other hand, there are things that 
are purely material. This includes even
animals. You see, animals would be pure mechanisms.
(Student) "Why didn't he think animals
have minds?" (Hakob) Because he believed that
there is no capacity of thinking really
but all based on reflexes and as
far as reflexes are concerned even the
human body as far as reflexes are concerned
is pure mechanism, just like he was
trying to explain vision: you don't need
any capacity of thinking to do any seeing,
right? Similarly animals only have
sensation but they don't have any capacity 
of thinking. In particular they don't have
self-awareness, they cannot create theories, 
they don't have language. They have only
some animal signals and stuff but there's
no capacity of thinking and as long as
there's no capacity of thinking, there's
no mind. What is it that characterizes
mind? It's the capacity of thinking. In a Cartesian
universe only human beings are citizens
of two worlds. Everything else is either pure
mind or pure matter. This is your idea of
dualism. There are two substances, the
extended substance and thinking
substance and we are the only 
creatures that have both.
(Student) "How can mind interact 
 with physical matter to change it?"
(Hakob rephrases) The question is how can something
that is not extended, something that's
just pure mind, affect something that is
material? If everything is material, if
it's only neurons, it's possible to
explain that. Matters affect one another!
But if one is completely different 
from other, how can they ever
interact. That's the question, right? They
couldn't really find an answer.
There are a whole bunch of different hypotheses 
but none of them really worked but it didn't really
stop them from appreciating that there
are two different types of things.
Let's sum it up. We have dualism, we have 
action by contact, and we have mechanicism.
They are some of the fundamental principles
of Cartesian mosaic. Now tell me which
principle of the Aristotelian-Medieval 
mosaic dualism came to replace?
Pluralism! Action by contact 
came to replace the idea of teleology,
the idea that everything has a
goal and things can change because they
have a goal, that animals
reproduce because of their goals.
In the Cartesian worldview, this sort of 
explanation is no longer acceptable.
You cannot say it's their goals. You must explain
the mechanism. It really pays off to have
lots of former girlfriends so you can tell about 
all of them without repeating. This is a
completely different one. So the
discussion came to the point when I was
explaining Cartesian worldview - it was that
boring - and she said it wasn't very much
of a romantic was ... it doesn't really strike me as 
romantic. How so? How could you deduce anything like that
from this? What's the connection? 
She said that in his world view
everything happens by actual contact, 
right? It's is only touching and you
know it's only contact! So I say "Ah 
... that's what you mean! OK."
What's the opposite of mechanicism? 
Hylomorphism: there is form and
there is matter.
This is what we have. Any questions so
far? (Student) "So where does an explanation of
gravity fit into this this?
(Hakob) It's a natural question and
I like you asked the question. You can say, all
right I understand as far as things like
billiard tables are concerned, we can explain
everything as a result of actual 
contact. So for mechanical things
like clockwork, this makes sense. But what
about those phenomena which seemingly
involve action at a distance, like when
you have a magnet that attracts another
magnet or iron or something? What
happens that doesn't seem to be anything
in between? The same applies to gravity.
When you let this go you really believe
that there is something in between that
does the pushing. So how do you explain
gravity by actual contact? You understand
that this is an interesting question so
any mechanistic worldview faces the
challenge. The moment you say everything
in the universe happens just like in a
clockwork then immediately you have to
face this question: what about gravity?
what about a magnet? It's essentially the
phenomenon that seemingly imply actions
of two things at a distance without any
actual mediators. Now we have 
Cartesian physics and cosmology.
Matter is extension and 
it follows that particular
objects can interact only by actual
contact. If the only quality the material
things have is the capacity to occupy
some space and how can one extended
thing affect another extended thing? It
cannot send signals because it doesn't
have that capacity and even if it sends
signals those signals should be material.
They should occupy some space. So the
only way that two bits of matter can
affect each other is by actually touching
each other. Now if you accept this idea,
then it follows from that every part of
matter maintains its state unless a
collision with another part changes to
state. So think of a typical billiard
ball, what can happen 
if nothing whatsoever
affects that ball? It is
going to maintain its state.
Nothing whatsoever can happen to it.
So the only time that it can change its state is
when it's affected by something else so
this would be Descartes' First Law.
The Second Law would be "every part of matter
regarded by itself tends to continue
moving only along straight lines." Why
straight? Because Descartes had shown that
the motion in a straight line and a state
of rest are essentially the same thing.
There is no acceleration.
Something is moving at a constant
velocity in this direction, how can it
ever change its velocity? Something should
affect it, otherwise it is going to maintain its
states of motion along a straight line
forever!
Well, it is true that in our universe
it never happens and there are reasons why
nothing really moving in straight lines
because the world is full of things and
they affect each other but by itself the
tendency of a thing is to move along straight lines
because that's the most simple of all
motions. So these are his laws.
Here is a question for you: can there be absolutely
empty space in such a universe?
By absolutely empty space we mean
space devoid of matter, space that
has no matter whatsoever. What do you think?
(Student) "I don't think there can be because matter
by definition must take up space so if
there is space there it must contain the
matter." (Hakob) You are very close to the actual
reason, very close! Now Descartes says
there can be no empty space. You cannot
have space without matter. Descartes's
explanation is that space is not a
separate substance. It's just a property.
What is space? Space extension is the
attribute of matter so if miraculously you
remove all the material things from the
world you would remove space itself.
Space is not something that exists on
its own. Space is just that extension
and there is as much space as there are
material things. Yes, he did believe that
the universe is extended indefinitely,
that there are no boundaries, but he also
believed that you only have space where
you have material things.
Space is not a substance. There
are only two substances out there:
material substance and the thinking
substance. What is space? It's not a substance.
It's an attribute of a substance. It's a
property. It's the capacity to occupy
space, the extension itself! That's why
you cannot have space without matter.
It's almost the same as to have redness
without anything actually being red.
You cannot have just redness floating here.
You should be attached to something.
You can have a red shirt, red hat, red
cup but you cannot just have "red".
Red what? Red is a quality and attribute. It has
to be attached to certain substance. Make sense?
So think of space as a quality, as 
an attribute.  as a property. It cannot
be free-floating. It should be attached
to something, So it can be no empty
space The name for this is plenism, from
Latin "plenum" meaning "full".
Another name for this is Horror vacui,
"nature abhors vacuum". What is
vacuum? Vacuum is the empty space. 
There can never be empty space
according to this worldview. Nature does
everything possible to prevent of that.
Now we know for a fact motion exists:
things move. Next question for you is how
can anything move in a universe that is
full of things? He did believe that there
is no empty space. Space here is full of
tiny particles of air. The cosmic space
is filled with tiny particles that
occupy the cosmic space. They might be
visible or invisible - that's a different
issue - but it's all full of particles.
So how can anything possibly move
in a space that is full? If a space
is empty, if this is empty, the next
step here, this is no longer empty. This is
empty. But what happens if this is full.
How can anything move despite the fact
that every bit of matter taken by itself
tends to move along the straight lines?
In reality, since the world is full of
things, the actual motion is always
circular, always involve some sort of 
displacement. It can be an immediate
displacement like that or it could be 
I'm stepping here, this goes here, that
goes there, that goes there, and this
comes here so there is going to be a huge circle.
There must be some sort of a circular 
displacement, circularity of motion!
All motion is circling. It is an
interchange of positions. Remember this!
Now let's try to explain gravity. How
would you explain gravity in this
universe?
Let's take this. The Sun rotates
around its own axis. This rotation,
says Descartes, create a vortex of particles
around the Sun, just like in a whirlpool
OK? Gradually, he says, that matter within the
solar vortex forms
itself into a set of stratified bands,
each lodging a planet. Some of the planets
also rotate around their own axis and
this individual rotation creates smaller
vorteces, such as terrestrial vortex and Jupiter vortex.
So it's all one whirlpool within
another whirlpool within another whirlpool.
It's all whirlpools. Let's zoom in here: 
the Earth, the moon. The Earth's rotation
creates a vortex of particles around 
the Earth. The moon here
revolves around the Earth because it is
in the Earth's vortex, not because
there is any sort of gravity. There is no
such thing. It just revolves because it's
being carried by the Earth's vortex. Now
since the earth rotates on its axis,
there is a centrifugal force that draws
all terrestrial matter away from the
rotating earth. This is easy to understand. 
Let's say you're not terrestrial,
the natural tendency is away from the center.
Why is that? Because every object has a
natural tendency to move along straight
lines
and when you are revolving in a
circle, your natural tendency is not
revolving in a circle but to go away from
the center of the rotation, basic
mechanics here. What would happen if the
space beyond the Earth's vortex were empty?
You have a natural centrifugal force
because of this rotation. What would
happen if the space beyond the world
were empty?
Can you guess? What would happen? 
(Student) "The moon would just fly off."
(Hakob) Not just the moon, everything 
if the space beyond the Earth is empty,
all terrestrial matters and everything
within the terrestrial vortex  would soon
disperse. But it doesn't because
the outer space here is not empty!
In fact it is full of particles revolving in
the solar vortex. We are part of a
greater vortex, right? So this space is
never empty. This results in a very
interesting effect. As a result, 
the finer particles - those gases
condensed at the periphery of the terrestrial 
vortex and because there is no more space
to go -  they condense there. Now think of
this little terrestrial vortex as a pot.
When you make yourself oatmeal - have you tried?
It's very good for you!
First thing you do is to fill it with water
and then you put some salt in it and it melts
very quickly. But before it does when you
mix it, have you noticed what happens?
It gathers in the center, just before it
melts. The particles of salt gathering in
the center. Why would they do that?
There is a centrifugal force, right?
They have to gather towards the periphery. 
But they gather in the center. Why?
There is an explanation for that.
The explanation is those particles that are
small and swift, they gather towards the periphery.
But since space is limited they create
an inward pressure. They pushe more
rough bits of matter that were solid
towards the center of the world.
Think of it this way: you
have a rough bit of matter and a swift
one and even a swiftest one. Everyone of
these three have a natural tendency to go
towards the periphery. That's the
centrifugal force forces them to do.
But there is only that much space that
only one of them can be there so what
happens to the other ones? There is no
more space and we are pushed back to the
center. This is what happens here. 
This inward pressure is gravity.
This brings us to the Cartesian concept of gravity.
Gravity, says Descartes, is the
inward pressure caused by the
condensation of finer matter at the
periphery of a vortex. Similar
mechanism applies to the solar system and
similar mechanism applies to any
vortex. Brilliant, right? It's false, 
but brilliant!  (Student)
"If that was the case, why would the moon be on the
outside rather than like near the earth?"
(Hakob) Descartes' explanation is very 
straightforward: because it's in a state of
equilibrium. It's already there and once you're
there you have two tendencies: one is the
inward pressure that has to supposedly
push you towards the Earth and the other
one is the natural tendency to go
along a straight line and in the case of
moon and all the satellites,
all the planets and all the smaller
planets you have an equilibrium, you have a balance
of two forces. Make sense? Can you appreciate
the beauty of this? In my opinion this is
one of the most brilliant ideas 
in the history of science.
False but brilliant: they don't have
anything to do with each other. Most of
the ideas that we accept these days are
going to be considered not as true as
the ones of the future. We understand 
that. In 500 years from now we
must be in a position to appreciate the
beauty of Einstein's theory, just like we
appreciate the beauty of Descartes's theory.
Isn't it beautiful and ingenious?
Something that seemingly cannot possibly
have a mechanistic explanation but here
he gave a mechanistic explanation. So the 
mechanistic concept of gravity allowed to explain a
whole bunch of phenomena, terrestrial and
celestial. In particular it allowed to
explain the revolution of planets around
their Suns and satellites around the
planets. Here you see different vortices. 
This would be the solar vortex.
This would be
another vortex of another star. It also
allowed to explain that motion of the
moon in the Earth's vortex and the tides.
Tides were explains in a mechanistic
fashion. Also the transition of comets
from one vortex to another vortex.
You see this light blue line here: it's a
path of a comet. So back then they
believed that comets pass from vortex
to vortex. Essentially they are
wanderers from one vortex to another. They
didn't think they were coming back!
What about magnets? It explains gravity but
there's one more thing to explain, right?
This here is an original drawing by
Descartes himself. It is twisted, OK?
(A) here is your South Pole and (B) is
North Pole and here you have 
round lodestones (I), (K) and (L).
All of these are lodestones. So this is I
think along the lines of what he would
do if he had PowerPoint or Photo-shop
and other things - he would probably go
for something like this. So this is your
North Pole and this is your South Pole and
a bunch of lodestones here. Now
according to Descartes the Earth is fitted
with parallel threaded pores that form long passages
oriented north and south. Very very tiny
pores invisible to the naked eye but
that's what we have, Descartes 
says, tiny helical
(corkscrew shaped) 
particles circulating from and to
this thread of pores in two directions.
Here you see these other particles go
this way and that way.
Lodestones are also fitted with parallel threaded 
pores. That's what makes them lodestones.
If we zoom in here, these are your
helical particle. An object that is
magnetically neutral would have pores in
all different directions but the moment
you have pores parallel to one another
then you get something that is no longer
magnetically neutral. A magnet can affect
that object. While reaching the lodestone,
these particles cause it to turn
in the direction so that threaded
pores are aligned with circulating
streams. The moment these particles reach
the lodestone, they become aligned in a
direction of the motion of the particles.
So in this particular case it will be north.
This explains the orientation
of the compass towards north and south.
And in general these helical particles
pass through the tiny pores or the
lodestone or a piece of iron and 
cause magnetic effects and this becomes
very technical when he explains how 
it was possible for a magnet to attract
another magnet or to repel another
magnet. He gets very technical here and assumes
the motion of two different types of
course of particles and two different
directions and then in some cases some
of the pores should be in such a way that
they only accept particles moving in
this direction and not the ones that are in
this direction ... anyways it is very
complex although the basic idea I think is clear.
So you have a space for these spiral-like
particles and they penetrate through
everything that is not magnetic neutral
and they create a magnetic effect so
this is your Cartesian magnetism:
magnetism is a result of the circulation
of tiny helical particles through
parallel threaded pores and through space
around magnets. This is your magnet. 
I know we are getting a bit technical here but
the explanation of the presentation of
Cartesian worldview wouldn't be complete
without this, OK? If there are no
questions then we are going to move on to the
hypothetico-deductive methods. You know
a thing or two about this method already.
The idea that a hypothesis 
introduces unobserved entities is
acceptable only if it provides 
novel predictions and it is based on two
principles: the principle of complexity
and the principle of Post hoc explanation,
as by the Third Law. This was
only one aspect of the method of the time.
I'm going to give you two more in
contrast with the Aristotelian method.
Let's start with the Aristotelian no-
experiments methods. You remember this.
We covered this last time. According to the
Aristotelian scientists if a theory
about the nature of a thing
relies in any way on experiments, 
it is unacceptable.
The nature is
to be studied in observation only. Why is
that? Why are experiments beyond
natural? Experiments are unnatural
because that's what experiments are. They
involved artificial set-ups. Experiments
are not natural. We understand that and they
are unnatural because there is a strict
distinction between things natural and
thhings artificial. This is the key belief that
leads to this method. It's only when you
believe that natural things one thing
and artificial things is another thing,
it's only when you believe in this
clear-cut distinction between the two,
you exclude all the experimentation and
this is what the Aristotelians accepted.
They believed in a clear-cut distinction
between natural things and artificial
things. In other words between things
with their inner source of change
and things that have an external source of
change, that are created artificially.
For Descartes this distinction would make
no sense whatsoever. Why? You understand
the Cartesian worldview now. You have
let's say an artificial thing and a
natural thing. Why are there no
difference? In what way they are not
different for Descartes? (Student) "All matters are 
just extensions so should all be the same in principle."
(Hakob) Exactly. All matter is just the
combination of particles. Everything!
Artificial or natural doesn't matter.
It doesn't make any difference whatsoever.
They are subject to the same laws. Their
behavior is explained by the same set of
laws, artificial or natural, just like we
would have it nowadays. We don't
distinguish between things natural and
artificial. The motion of planets is
explained by the same set of laws which
we use to explain the motion of the
clock so by the theory rejection theorem, 
once Descartes's theory became accepted,
this proposition has to go and it is
replaced by an idea that all things obey
the same laws. There is no strict
distinction between natural and
artificial. Both natural and
artificial things are essentially
systems of moving particles. And there is
no distinction. There is no qualitative
distinction. Therefore when studying the
world the artificial set of experiments
is not an obstacle and therefore you
arrived at the experimental method that
it is ok to rely both on the results of
observations and results of experiment.
This acceptance of Cartesian
worldview doesn't create experimentation.
The whole idea of experiments. It was all
over the place. But this one, 
this particular move, it
legitimized experimentation; after that
it was OK to accept the results of
experiments just as it was OK to accept
the results of observations. You could no
longer say that you study that bird in
the cage so you cannot accept the result.
You can no longer say that. Behaviour in
the cage would be as indicative is
behaviour outside of a cage because it is
a behaviour that needs to be started.
It can tell you something about the bird. 
There is no limitation any more. You can
experiment as much as you want
Now it is commonly believed especially by philosophers 
that Descartes doesn't have anything to do with
experimentation. It is true that he
used pure intuition and deduction to
arrive at the foundations of this system. He
said "well, yes. when it comes to such
principles 'matter is extension' and the
existence of the human mind and existence
of God and all those sort of things you
don't need experiments to prove those".
But when it came to specific
explanations of specific phenomena, let's
say gravity or magnetism, he realized
that there is not a single chance that
you can deduce those explanations from
the fundamental principles. So what do
you do? You can no longer have absolute
knowledge about those things. These are not
deducible. The same gravity can be
explained in ten thousand different ways.
So he appreciated that this is where you
have to hypothesize. This is where you
have to suggest a hypothesis and test
that hypothesis in experiments and
observations. When it came to the nitty-
gritty of things, to specific
explanations of things, he realized that
you cannot have intuitive truth. You
must hypothesize and you must test your
hypothesis with experiment. Yes,
fundamental principles is a different
matter but they are already established.
You already have them. It's already been
proven that mind exists. It's already
been proven that God exists, that
the material world exists before
everything else. For actual explanations,
why is it that this particular clockwork
or why is it that this particular animal
reproduces or anything really, you need to
hypothesize. There is no other way. Makes sense?
Very good. Now let's move on to the
next important ingredient of the
Aristotelian method which was the idea
that if the theory about certain
qualitative change employs some
mathematics, it is unacceptable.
This is the so-called Nonmathematical Method.
This restriction was part of the
Aristotelian-Medieval mosaic and by the Third Law it
follows from the accepted theories of
the time, in particular the idea that
mathematics is inapplicable to instances
of qualitative change. Why is that? Why
did they believe that mathematics is not
really applicable to such things such as 
metamorphosis of a caterpillar to
butterfly? (Student) "Because there is a strict
distinction between qualitative and
quantitative phenomenon". (Hakob) Exactly. Because 
they believed in a strict distinction between
qualitative and quantitative. This is
what they believed. They believed that
there is qualitative change, the acquisition
of a new quality, and there is a change
that concerns numbers, shapes, the
quantitative changes and these are
essentially different. If you are Descartes, 
can you hold on to this view?
Can you still accept it? Why yes and why not? 
(Student) "I think because if matters were made of
one thing then there's no duality
between quality and quantity." (Hakob) Exactly!
According to Descartes this distinction
makes no sense whatsoever.
Descartes says that all instances of qualitative
change in material things are essentially
quantitative. Why? Because it's 
only extension and everything that
is extended by definition are subject of
geometry, isn't it? This thing here is
different combinations of material
particles. Yes, very complex ones ... maybe
such that we will never be able to know
with utmost precision and yet
essentially what matters here
is that these are only combinations of
different particles and as such they are
amenable to mathematical explanation,
they are quantifiable because they're just
extension. That's how we arrived at this
conclusion: mathematics has a universal
application. It is applicable to all
types of change including the so-called
qualitative changes. In this world you
don't really have a purely qualitative
change. Everything that appears to be an
instance of acquisition of new quality is
essentially movement and rearrangement
of particles and as such must be
explicable mathematically - might be very
difficult. We grant that and he understood
it might be a task that thousands of
generations of human scientists wouldn't
be able to accomplish but it is in
principle explicable mathematically.
Therefore theories concerning
qualitative changes are allowed to
employ mathematical tools just like any
theory really. Any theories are allowed
to employ mathematical tools. Mathematics
is no longer confined to the domain of
quantitative change. It can be applied to
all sorts of change. Let's sum it up.
You have Aristotelians and you 
 Cartesians. Pluralism here and dualism here.
Teleology here and action by contact here. 
Hylomorphism here,
the idea that everything is a
combination of natural forms. And here
you have mechanicism, everything is
just bits of interactive matter. Let's
move on to the methods: the Aristotelian
intuitive truth and now you have the
hypothetico-deductive or novel predictions
essentially. Then when they had No
Experiments and you have experiments and
when they applied mathematics to
limited number of phenomena and here 
you have universal application of
mathematics. So you see what Descartes did? 
He removed many of the boundaries.
No experiments, no mathematics, and this
essentially opened the doors to the science
as we nowadays know it. So in terms of
the method, hypothetico-deductive
method, experimental method, mathematical
method were all very similar to what we
have nowadays. Very good! Next time, 
the Newtonian worldview. Thank you very much!
