What we discovered last time is that there is
actually proof in science but only
in a very limited number of cases. It's only in formal science when you actually get proof.
If you look at anything beyond formal sciences - if you focus on
social sciences or natural sciences,
all knowlege is fallible.
At this point you should be clear that why they are fallible - you have to think about three reasons:
the problem of sensation, the problem of
induction, and the problem of theory-ladenness.
That shall be enough to convince anyone that all knowledge in empirical sciences.
All theories in empirical sciences are fallible
yet we believe
that some theories are better than others.
Basically that's the reason why
why we don't teach Aristotelian physics.
If you go to the Department of Physics,
you're not going to study any Aristotelian
physics or any Cartesian physics, God forbid.
We do teach Aristotelian physics and
Cartesian physics but only
in the Department of History and Philosophy of Science
and only out of historical curiosity
but we don't present those theories as the best
available descriptions of reality.
A question immediately arises:
why do we prefer currently accepted theories?
What makes one theory better than another?
In other words, how do we decide
which theories should be accepted?
This is our question today. But before we get
to that, we have to clarify
what acceptance is. I'm going to give you three
definitions and I want you to understand
the difference between the three
definitions. The first one is "acceptance":
a theory is said to be accepted if it is
considered the best available
description of its object. Now what's object?
An object could be something physical: a falling
apple or a revolving planet. The object
could be something social:
a group of people,
individual human beings, social
institutions like government,
or it could be formal like a number or
logical relations. In any case you have some
objects that a theory tries to describe.
A theory is said to be accepted if we believe that
it is the best available description of its
respective object. Is that clear? Very good.
Now this should be differentiated from "use".
A theory is said to be used when
there is a practical application for it
regardless of whether it's accepted or
not accepted. I'm going to explain this later.
In the final category of "pursuit",
a theory may or may not be accepted and they may or
may not be any particular use for the theory
but you may find a theory worthy
of further elaboration. You may have this
idea: "You know what, I have to say, I have this
vague idea that I know is not the best
in the market - it's  just a vague idea - I know
that there's not much use for it at the moment
but I think it's something worthy
of further elaboration. We have to work
in that direction."
Essentially every scientific endeavor
starts from that when you have this vague
idea. Think of Einstein around 1900 when
he had that idea of the curved space-time
and all those sorts of things. There was
no theory to speak of at the moment,
not much a theory but this guiding idea
so in those cases when we believe that
a theory and an idea is worthy of further
elaboration, we say that the theory is "pursued".
I'm going to give you some examples..
Take a timeline:  200 years ago,
400 years ago; accepted theories,
used theories and pursuits. Let's start
from the contemporary state of affairs.
If I asked you: which theories,
which physical theories you think best
describe the physical world? What would
you say? Well, general relativity and quantum physics.
That's what you would say.
These two theories provide us with the best
available descriptions of physical processes.
But if I asked you which theory
do we use in any sort of
technological applications?  OK,
sometimes we use some general relativity,
0.00001% of all projects maybe we use some general relativity.
We also use some quantum physics. Do we
have any engineers here? Which theory do we use
to build a bridge? Do you really use
general relativity or quantum physics?
In 99% of all practical applications we
still use the good old Newtonian physics
elaborated by several generations of
physicists despite the fact that
we no longer believe that that theory provides the best available description of reality.
We don't believe that there is empty space. 
We don't believe that things
affect each other at a distance and that
there is a force of gravity.
We do not accept the theory but it's very useful because its calculations are easy and
simple compared to calculations based on
general activity and quantum physics.
In theory you could do everything with
quantum physics and general relativity.
We could do those things but it would be enormously complicated and that's the reason why we
still use the old classical physics
despite the fact that we do not accept it -
we do not believe is the best available
description but it's useful.
It's a useful calculating tool. So as an engineer if your task is to build a bridge, you are going to
stick to classical physics unless it's a
trans-cosmic bridge in which case
you'll probably have to take into
account some general relativity
effects but other than that you are going to
stick to your classical physics. Now if I ask you
which theories you think most physicists
pursue these days? What are they
working on and elaborating? You may
say Superstring theory, one version or another.
And in the 90s a theory was created
which is called "M theory" which allegedly
unites many different theories in this field.
I'm going to explain this later on,
but essentially this theory is widely
pursued because we believe that
there is a chance that this might be
the next big thing in physics although
we do not accept it -
- not at the moment - we do not believe it is
the best available description of reality.
You see the difference?
Accepted theories, used theories
and pursued theories. Sometimes
they coincide.
If you had a time machine, if you went
back to the early 19th century, accepted
theory, used theory, and pursued theory
were all the same - all Newtonian physics.
It was the theory they taught in the
universitys, the theory they used in
practical applications, and the theory they
try to elaborate. But cases such as this
one are far and few between. In most cases you get a situation which is very
similar to what we have nowadays:
400 years ago you have your
Aristotelian-Medieval natural philosophy
and Aristotelian-Medieval cosmology
but if your task was to
calculate the future position
of a certain planet, let's say Venus -  you
couldn't really use any of these theories
because these theories didn't have any
serious calculating capacity. The theory
that they used was this one:
Ptolemeic astronomy. That's what they used. Another theory they used was Copernicus's Astronomy.
You understand that they believed that the
Earth was the center of the universe
and yet the Copernican astronomy, which was only about 50 years old at that time, proved very
useful when calculating positions of
planets and in fact some of the
astronomers used both of these theories at
the same time. You see? That's possible.
And finally when it came to pursued
theories they pursued obviously
versions of Copernican theories: Galileo, Kepler and many others and Tychonic Astronomy.
A bunch of different astronomical ideas!
The whole market of astronomers was full of different theories, different ideas.
So there you have it:
difference between acceptance, use, and pursuit.
Now a few things before we move on.
I'm not going to talk about pursuit because
it's very difficult to say from the
outside which idea is worthy of further
elaboration and which idea is not. You never
know what's going to work and what is not.
I'm not going to talk about that.
I'm not going to talk about use because from a practical standpoint what you have is basically
an accumulation of tools in your toolbox.
Think of it as a tool box: if you're an
an engineer you don't really care which theories are accepted and which theories are not.
The way you see science is basically you
have a huge tool box of different theories.
You have your hammers, you have your cutters, your screwdrivers, whatever.  When a new
theory arrives on the market, you would not
necessarily discard your previous tools.
You can have a new hammer or screwdriver to use it together with the previous one.
So this is the engineer's approach when you don't care about acceptance and
you care about use. This is true not just in
physical engineering but also true in
social engineering or in any sort of
engineering. If you want to open an
astrology boutique, you don't really care
which astrology is accepted or not.
What do you care is whether they bring
money. That's what you care about.
That's the whole point. So I'm not
going to talk about use.
Acceptance, however, is something very special.
You cannot accept two incompatible
theories at the same time. You can use
them at the same time. You can pursue
different incompatible theories at the
same time. But when it comes to
acceptance, you have to choose.
You can't believe that the earth is both flat and spherical. It is impossible. You have to choose.
So the question is: how do we
decide which theory is the best
available description of its object? This is
the question. We have couple of
theories and we have some evidence.
In order to decide which of the two theories
is better,
clearly this is not enough. What we also
need is a list of rules or criteria to tell us
that this theory is better than that
theory, given the evidence. That's
what we call the scientific method.
We need a method of appraisal to tell us
which theory is better,
given the available evidence.
That's what the method is: it tells you which competing theory you have to choose
if you take that evidence.
So this is your definition of method:
a set of requirements, criteria, rules, standards, and so forth for employment in theory
assessment, valuation, appraisal,
comparisons. These are all synonyms.
In literature you may come across a
formulation that says
a set of criteria for theory reevaluation, or a
set of rules for theory reappraisal, a set of
standards for theory comparison.
It can be any pair of them.
Don't get confused. They all refer to the method.
They are the same thing, OK? Some examples:
here's one "Accept theories that are more simple" - whatever makes them simple.
This will be an example of a method.
Alternatively, "Accept theories that
provide confirmed novel predictions", or
"Accept theories that solve more problems",
or "Accept theories that more precise and
accurate." All these are examples of methods.
I'm not saying this is what we
actually employed in theory assessment.
OK? That may or may not be the case.
We don't know at this stage. But these are
some examples of methods which we may employ.
Let's zoom out. So this is what method is:
a set of criteria for theory evaluation.
Two more clarifications before we move on.
First, methods should not be confused
with methodologies. When we say
methodology we mean something
openly formulated, something explicitly
stated. Basically, methodology is a set of
explicit requirements of theory assessment.
That's what scientists say the real
science should be about.
Method is a different thing.
Method basically is your implicit
expectations. Here you have methodology:
these are the rules openly prescribed by
the community as the correct way of
doing science, and method: those are your
actual and implicit expectations, your gut
feelings if you will. Think of a movie review.
Let's say you watch a movie and you say
"Well, it was a waste of time." You certainly
have some implicit expectations as to
what a decent movie should be like,
otherwise you wouldn't be able to say that.
So you have some implicit
expectations. That would be that set of
implicit expectations whether
you know about them or not.
it would be your method of movie assessment.
And then I ask you:
"Can you write down your  criteria?"
How you ended up saying that the movie
was a waste of time?
Then you sit down and try to explicate
your implicit expectations. You try to
come up with a list of requirements and
then the thing is your openly formulated
requirements that may or may not be the same
as your actual expectations. Very often
we have no idea how we evaluate things.
Think about finding a proper partner.
If people ask me: "Hakob, how do you
evaluate those things?" Well, you know, I can
try really hard and sit down and come up
with a huge list of requirements:
you should be funny, clever,
you know, all sorts of things,
but then once in awhile I end up liking
a girl nothing like that. People
who know me, they know it!
And you know from your own experiences,
the person could be nothing like that. The bottom
line is, you may or may not have an openly stated
methodology but you do have a method.
You see the difference here? You may or may
not be aware of what it is that guides
you in your choices. That would be a
methodology. But you do have a method:
your implicit and tacit expectations which
allow you to choose between competing
girlfriends or competing theories.
This is what scientists say
they should be doing: that's methodology.
And this here,
method, is what scientists actually do.
Albert Einstein once said, very famously,
"If you really want to understand
what science is all about,
don't listen to what scientists say they
do but look at what they actually do."
Basically what he was asking us to do is
not to focus on methodology but focus on
the method - on the actual the
expectations and they are never on the
surface. They're very difficult
to unearth but that's what
we have to try to understand. It's not
the methodology that does the job.
It's the method that does the job.
Clear? All agree? Very good!
Another thing that we have to keep separate
from method is research techniques.
In literature, in popular literature and
science literature, when they say method
they mean two things: they mean first and
foremost, a set of requirements for
employment iin theory assessment,
that's true. But in addition to that,
very often you also come across
method as a set of procedures for theory construction.
In philosophy we distinguish between
the two. It's one thing how we arrive at a
theory,  how we generate an idea.
That's one thing. Its another thing
how we assess that idea. For instance, I'm
trying to come up with a solution to
a given problem and then I say
"Well I've heard that brainstorming is a
good technique.
Let's sit down in a group and brainstorm."
That would be a research technique.
The product of that brainstorming may
or may not be correct.
How do we know that is correct? Well,
you have to apply certain methods to
evaluate whether they're correct or not.
So philosophically speaking we're not
really interested in research techniques.
We are not interested how people come up
with ideas. You could see it in your
dreams. You could have downloaded it from
somewhere,
stolen it from somewhere. Maybe some
aliens told you about that. It doesn't make
any difference.
Scientifically where the theory comes
from? Who cares? It's interesting if you
study you know intellectual biographies
of different scientists. That might be
very interesting but we don't really
care. It doesn't make a theory any more true.
Does it? So we are going to put research
techniques aside. We are not going to talk about that.
So it's all about method. This
brings us to a problem: if there were a
fixed set of rules employed by the
scientific community in theory
assessment then we would be in a
position to say that our current
theories are better than the
theories of the past and the whole
process of scientific change will be
governed by this fixed and universal
scientific method. So theories would
change but the method would remain.
You see? The whole process will be rational
if there only were a universal
unchangeable scientific method - if we
only have that. The question is:
is there such a thing as an unchangeable
method of Science? Suppose there is,
suppose for the sake of argument that
there is. The question is: what is that
method? What are the requirements of that
unchangeable scientific method?
So let's try to explicate those requirements.
You understand that those requirements are not
going to be on the surface.
We have to study specific
transitions in the mosaic and try to
understand why was it that this
particular theory became accepted
instead of that theory? And only that
would give us some ideas about what the
actual expectations of the community were?
Are you following?
This is what we are going to do. Let's take a
basic example, a very very straightforward
example: the law of free fall. The law here 
says that distance traveled by a falling
object is proportional to the square of
the time traveled. Now what would it take
for this theory to become accepted? What
do you think? What should we do? Any ideas?
How do we test? (Student) "I would assume that 
you have to do some sort of experiment."
(Hakob) You have to see whether it fits the data,
right? You have to actually go out there
observe and see whether it fits the theory.
Very straightforward. This is what we are
going to do. We are going to take a falling object,
then we are going to try to deduce specific
predictions from this equation
like that - this is the time the distance travel
OK? This is going to be our prediction for
every tenth of a second and then we have
to try and see whether that actually
holds, whether it actually fits the
actual data, and we see that it does.
This will be enough. This will be
sufficient to convince us that the
equation is correct. The general idea is
very straightforward: whether it fits the
data. Now, unfortunately not everything is
this simple. In many cases we know that
precision and accuracy are not
enough. Very often we expect something
more than just precision and accuracy.
We expect the so-called confirmed novel
predictions or predictions of things
which are hitherto unobserved:
something that nobody has ever observed
before. I'm going to give you a historical
example. We are going to go back all
the way to the 17th century, the late
17th century. what's the year?
1687. This is the year when Isaac Newton
created his theory. That's not the year when
it became accepted. This is the year when
the theory was created. So this is the
theory and the theory has a bunch of
laws: First Law, Second Law, Third Law, Law of
Gravity, all Newton's laws. What
happened is that it became very clear
from the outset that this theory is
very very precise when it comes to
the exploration of the whole bunch of
phenomena.
Terrestrial, phenomenon, celestial phenomena ...
It was very precise and very accurate.
More accurate than any other theories,
any of the available theories on the
market. So in terms of precision and
accuracy, there was nothing like it and
this was clear from the outset. Everybody
appreciated it. And yet, it took about
half a century before this theory became
accepted. Now the question is: why is that?
Why would it take another half a century
for the theory to become accepted?
Well, because the community was expecting
confirmed novel predictions, predictions of
things which were not yet observed. Luckily,
the theory made such a prediction.
The theory predicted that if you take our
planet, the earth - this will be the
polar diameter and this will be the
equatorial diameter. And the theory says
that the earth is oblate: slightly
flattened towards the poles. Basically
oval in shape if you want,
slightly flattened towards the poles.
This type of spheroid is called oblate.
This is what the theory predicted. And it took the
scientific community about 50 years to
actually confirm that. Now why would
they bother with this? Why would they
actually try to confirm this?
Well, that's because the accepted theory
at the time was one created by Rene
Descartes, the Cartesian theory. And according
to that theory, the
Earth was supposed to be lemon shape,
or "prolate": slightly elongated towards the
poles. This was the accepted view back
then, and it took the scientific
community huge efforts,
huge determination, two very expensive
expeditions were sent to different parts of
the globe to measure the length of one
degree of arc. That's how they discovered
the actual shape of the Earth.
You measure the difference between any two
degrees. First you measure the distance
between any two degrees around the
equator and then somewhere up north and
if the two numbers are the same then
there is a perfect sphere; if the number
grows, as you move northward, and it shows
that your sphere is oblate, that is
flattened towards the poles. And if the number
decreases then it's an indication that
it's prolate. That's basically the idea.
In the 1730's, there were two expeditions which
were sent to confirm this. One was sent
to Lapland - that's contemporary Sweden,
Finland, up north. And the other one was
sent to Peru.
Well actually contemporary Ecuador which back
then was Peru. Why Ecuador? Spanish
speakers know that it means equator: because
we have to get as close to the equator as
possible. That's the reason. Anyways,
the theory became accepted on the
Continent only after the confirmation of
this novel prediction. You would say, "Well,
why is that? Why is it that in some cases
precision and accuracy are sufficient
while in other cases precision and
accuracy are not enough? Why is that?"
Scientists seem to be behaving
differently in different cases but why
is that?  I think the answer has to do
with the concept of accepted ontology.
What is ontology? Ontology is basically
the set of views about entities and
interactions that populate the world. So if I
say that I believe that the world is
populated by quarks, leptons, and bosons, 
that would be an ontological
statement. The contemporary science, for
instance, has its own ontology.
The science of the past had its own on ontology.
I believe that our attitude towards a
theory depends on whether that theory
tries to convince us that there is a new
ontological element. It depends on
whether the theory tries to modify the
accepted ontology. If a theory, let's say,
introduces a new particle or a new force,
or a new interaction, we say "no no no no no -
precision and accuracy is not sufficient.
You have to do better than that." If, on
the other hand, the theory just tries to
come up with an equation that creates a
link between any two known quantities,
they would say, "Yeah, just show us that it's
precise and accurate." I think what we
have in mind is something along those lines.
I'm going to give you a nice flow chart. So the
question is: Does a new theory try to
modify the accepted ontology. If it does
not, mere precision and accuracy are
sufficient.
Just go out there, do as many experiments
as you can, make sure that the
predictions of the theory fit the
available data and then you are fine.
Your theory will become accepted - just like
the Law of Free Fall. But if you try to
convince us that there are new forces,
new particles and super strings, whatever,
if you try to convince us that our
ontology is not correct, that we have to
change something in our ontology, then
well we will require some more
extraordinary evidence. This is basically
what Carl Sagan had in mind when he
said, "Extraordinary hypotheses require
extraordinary evidence". This is basically the issue.
I'm going to give you a few
examples. First: precision and accuracy.
We are going to go all the way back to the late
18th century: 1785, this is the year when
French physicist Charles-Augustin de Coulomb 
formulated his famous law of electrostatic force.
This is the law: it says you have two
point charges, q1 and q2.
r is the distance between them.
Opposite charges attract each other.
Like charges repel each other. The law
says that the force of attraction or
repulsion between the two point charges
is proportional to the product of
magnitudes, meaning q1 and q2
and inversely proportional to the square of
the distance between them.
It's very similar to Newton's law of gravity
as you can see. In form it's very similar.
Of course the ideas are different.
We have two point charges. We have a distance. 
This is the equation. Look at this.
This law didn't introduce any new entities.
It didn't introduce any new interactions.
People knew about point charges. People
knew about the fact that they attract
each other, repel each other. They knew
about it. What was missing was
an equation that would show us the
relation between a force and a charge
and the distance. We didn't have that
equation and he provided us with it.
He wasn't trying to convince us that our
accepted ontology was incorrect.
He was trying just to come up with some
equation that connects things that we
already know. And that's what he did. This is 
the reason why the theory became accepted.
without
any confirmed novel predictions. The moment
it became obvious that the theory
provides predictions are accurate and
precise, it became accepted. All right?
Now let's consider another example. 1810, this
is 25 years later. At the time
the accepted theory of light was the
so-called corpuscular theory of light.
This is the theory: it was
believed at the time that light is made
of tiny particles -
corpuscles. And it follows that 
the corpuscles of light travel
in straight lines with a finite velocity
because they're made of particles
therefore this should be subject to the
same laws just like any other particle.
They should travel in straight lines unless
they are affected by an obstacle,
let's say a mirror or something. Other than that,
they should travel in straight lines.
Let's take a basic setup with a source of light, 
with a wall and we have a disk in the center.
Since light particles travel in straight
lines, no light corpuscle ends up in
the shadowed region. It's very straightforward
because since light is composed of tiny
particles, therefore some of the
particles will be blocked by the disc,
other particles will continue traveling
in straight lines essentially. As a result,
you would get a uniform shadow.
This was the accepted belief at the time.
Now, 1819, this is the year
when another Frenchman, Augustin-Jean Fresnel
proposed his wave theory of light.
This was a completely different theory.
Unlike the accepted theory, it tries to
convince us that the light is a wave.
It's a wave that spreads in a universally
present media, ether. So this is similar
to water waves when you drop a stone
and it propagates. It is very similar to
the idea of water waves. And it follows 
that the light waves can diffract and
interfere when they meet obstacles.
Again, similar to water waves. Some water waves,
and there's an obstacle in front of me. What
happens as light reached the obstacle,
it is bent behind the obstacle. This is what
happens with light as well according to
Fresnel. This was his new theory.
So if we take the same setup. When the
light waves reach the edges of the
disc, according to this theory, some waves
would continue the same direction.
But there will be others which would diffract. 
As a result of this, you would have
to get a very tiny bright spot in the
central the shadow. This was the novel
prediction of the theory. Something never
observed before. And what do you know?
The prediction was confirmed the same year
by Francois Arago and the theory
became accepted. Let's take a
contemporary case. If I ask you what's
the theory that we nowadays accept when
it comes to fundamental particles and
forces, you say, "Well, it's the Standard Model
of quantum physics. Everybody knows that!"
You have quarks, you have leptons, you have 
bosons. This is basically your zoo of
particles. Fermions here
(quarks and leptons) -  they make up ordinary
matter: everything around you.
Here are the so-called Gauge bosons. They are
the ones that transmit forces:
strong force, weak force. And this is the
recently discovered Higgs boson which is
the one responsible for giving other
particles mass. But if it comes to pursued
theories, let's see what it's all about,
Superstring theories. What is Superstring
theory? I'm not going to explain the theory
but the basic idea is that all known
particles, quarks, leptons and bosons are effects of
vibrations of the so-called
supersymmetric strings or superstrings in
11 dimensional space. So don't think of
this as strings on your guitar.
That's not what this theory says. It says that other 
spaces here - of course the space that we
inhabit appears to be three-dimensional.
We all know that - XYZ. But in reality,
the theory says, the world is 
11-dimensional. So two particles which are
very far removed from each other in the
three-dimensional space may turn out to
be part of the same Superstring in an 
11-dimensional space.
They may turn out to be
connected.  If this turns out to
be the case, it would explain such
phenomena as quantum nonlocality.
You've ever heard of that? When you have
a particle here and a particle very far
removed from this one, and then you do
something on this particle, and the other
particle changes over there. According to
our theories well that must exist but
then we don't really understand how it's
possible. If this theory were correct,
that phenomenon would be explained because it
would turn out that those particles
which were seemingly far from each other - 
in reality they are connected through
other dimensions. It's a crazy idea. We do
not accept this idea for now.
But we pursue the idea. So what it says that all
these particles here are results of
vibrations of the Superstring so
basically it explains the known particles
and forces by postulated the existence
of Superstrings. This is what the theory does.
Now Superstrings are a new entity.
It's a new ontological entity.
What would it take us to accept this
theory? What should be done to make sure
that the theory becomes accepted?
Would mere precision and accuracy be enough? 
From the outside, this theory is very
precise and accurate. It's so constructed
so that it reproduces each and every
prediction of quantum physics. So in terms of
accuracy and precision, it's as
accurate and as precise as the accepted theory.
And yet we do not accept it.
Why is that? (Student) "We need representative 
evidence that these Superstrings
do really exist." (Hakob) Very good! So
basically the theory postulates a new
ontological entity. We are not going
to allow any theory that is merely precise to
change our ontology. We are not going to be 
convinced. Give you another example: suppose
we come up with a physical theory
which postulate the existence of
tiny little angels, tiny, tiny, very tiny,
within quarks let's say! I believe that
there are these tiny angels. And the theory
is created in such a way that it
reproduces each and every prediction of
our accepted theory. In terms of
precision and accuracy, for the
sake of argument, in terms of precision
and accuracy my theory of tiny angels is as
precise as the accepted physical theory.
Would you accept it? You'd say, "No, Hakob, come on!
If you postulate the existence of
ontological entities you really have to
try very hard to convince the community.
Mere accuracy and precision are not going to
be enough." Why is that? Well, because we
know that everyone can be smart after
the fact. Specifically, especially when
you know how to reproduce the
predictions of a previous theory.
You just take the equations of a previous
theory - you may or may not even change those -
but you can postulate some other 
ontological entity in such a way that the
same set of predictions is produced.
Everyone may be smart after the fact.
So in order to avoid possible problems here, 
what we do -  we say, "Well, you know what?
if you want to convince us of this,
you have to try
very hard! You have to try and show that there
are things that you predict but we never
expected!" And it's the absence of confirmed 
novel predictions that is the reason -
not one of the reasons but the very reason - 
why physicists nowadays merely pursue the
theory but they do not accept it.
There is a decent chance that
it'll take us decades or even maybe even
centuries to test this theory. So at the
moment the theory is not accepted.
It is merely pursued. Is it clear? 
(Student) "Because it probably
will take us so long, so why is this
being pursued at all?"
(Hakob) Your question is: if we're not sure 
what is going to be accepted, why we
would pursue those things? I think the
answer is very clear: because we want to
understand how the world is. (Student) "How do we
determine it's more important than other pursuits?"
(Hakob) It's a question that I
don't think has a reasonable answer.
It's a question that anyone who 
works for a grant agency
faces sooner or later.
You have all these different
applications. You wander by this guy
named Albert Einstein
and he proposes that he might develop a
theory in which space-time actually
curves. Are you going to fund that? Difficult!
Difficult! It's always a risk. It's very
difficult to say from the outside what was
going to become of an idea.
I don't believe the you have to actually limit the
development of certain ideas, but you
have to be brave enough and understand
you taken a risk that may or may not pay off.
Right? Let's sum it up here. So basically
this is what we have. In some cases we
seem to be satisfied by mere accuracy
and precision. In other cases we seem to
require confirmed novel predictions. 
Together, if I zoom out, and put it here,
this would be what we nowadays called
hypothetico-deductive method.
It basically says that you are allowed to
hypothesize and it is OK to hypothesize
about the internal structure of the
world. It's totally fine. This is what science
is all about. Provided that
some of the novel predictions of the
theory are actually confirmed. This is
basically the idea. Propose the hypothesis
and test it. If your hypothesis
is such that tries to modify the
accepted ontology then you have to come
up with confirmed novel predictions. If not
then mere accuracy and precision would suffice.
This is what we call hypothetico-
deductive method. I think it's safe
to say that nowadays this is what actual
working scientists have in mind when
they evaluate competing theories. My
question is: is this method unchangeable?
Is this method trans-historical and fixed?
This is the question again: if we suppose
for the sake of argument that this is
the method of contemporary science?
Is this method unchangeable? Is this a
fixed method of science?
The answer is "No, it isn't!" 
I'm going to show you examples
from history of science. First we are going to
go all the way back to the early 17th century.
This is a time of Galileo. If we observed
or we had a chance to observe what the
scientists back then were expecting
from theories, we would see that their
expectations had nothing to do
whatsoever with our hypothetico-
deductive method. Then, a proposition
or a theory was acceptable if one of two
conditions was met: if it grasps the
nature of a thing through intuition - 
I'll explain it - or it followed
deductively from intuitive
propositions. So basically back then
if you wanted to convince your peers of the
scientific community, you'd have to show
that the theory that you have is intuitively
true, meaning it is based on
common sense that any educated person in
the field will say, "Of course, we know that!"
So this idea of intuition based on
experience should not be confused with
the contemporary idea of intuition like,
"You know, I have this gut feeling." No,
that's not what they were referring to.
What they had in mind is that if you
want to understand the nature of bees
then you don't go and ask your favorite
barber, you have to go and find a
beekeeper - a person who has experience
with that type of things, bees in this case, 
and ask that person what is it
that constitutes the nature of things?
And if you're experienced with bees,
the story goes, you are in a position to
say what their nature is. Maybe the
answer would be "to produce honey". 
Similarly if you want to understand
what the nature of human beings is, you
don't go and ask  - but maybe you may go
and ask your favorite barber -  he may
know a thing or two about the nature of
human beings - but probably your first
choice, according to the Aristotelians
would be to go and ask a professional
philosopher, a person who is experienced
enough about human beings.
They had some weird understanding with 
what philosophers do, really!
Anyways, this is the idea. As a result of
that, you would have to have an
axiomatic, deductive system in which your
fundamental axioms will be grasped
intuitively by an experienced person and
the rest of your system would be deduced
from axioms. So if you lived in the early
17th century and you had this grand idea
of the earth being not in the center of
the universe but being one of the
planets revolving around the Sun, how would
you ever convince your peers that this
idea really makes sense?
By confirmed novel predictions? Let's see
if it works. 1543, this is the year when
Copernicus proposed his theory.
According to the theory,
if we zoom in here in this region of the
Sun, the Earth, and Venus. Now we have a
picture from the perspective of the earth.
This is Venus. Since Venus, according to
this theory, revolves not around the Earth
but around the Sun, we must be able to
observe from observers on the Earth
the full set of phases of Venus.
You see? The full set of phases from crescent,
first quarter, so on, and so forth all the way
to New Venus. Full set of phases! 
And this was one novel
prediction of Copernicus theory. Why was
it a novel prediction? Because the theory
accepted back then predicted something
completely different.
The theory that was accepted at a time,
Ptolemaic theory or something along the line
of Ptolemaic theory did believe
that everything revolves around the
Earth but when you observe the motion of
celestial bodies - the planets -  
they appeared to be moving not in
perfect circles but something like that,
you see.  They sometimes retrograde.
If you are the Earth and I'm the planet.
I go forward.
Most of the time. But sometimes I stop
and go backwards a little bit like a
little turn and then I go forward again. So
most of the time I go forward but
sometimes I retrograde. So how would
you explain this sort of motion with
circles?  Ptolemy had an ingenious
idea. He says, "Well, you know what, you don't
have to explain that. In order to
reproduce that motion we have to
hypothesize that every planet revolves
a small circle and I'm going to call
that epicycle. You have an epicycle for every
planet and this epicycle here
moves along a larger circle called the
deferent and the deferent itself
revolves around the Earth. So you put all
the motions together -
the revolution of the epicycle and the
revolution of the different,
you put them together and this is what you get.
Have a look! You see: ingenious! 
Absolutely false but ingenious!
That was what they believed is the case. And the
interesting thing about this theory is that
it actually allowed you to predict future
positions every planet with utmost
precision, at least for that time period. 
Now in this theory, if you consider the
motion of Venus -  this will
be Venus's epicycle and this will be
Venus's deferent - you would never be in a
position to observe the full set of
Venus's phase. So people back then
believe that at best you could see it
half-lit. This will be the first quarter.
And after that you would have
crescent again and then you would get a
new Venus. You would never have a
full Venus, OK? And then it would be
another crescent, another quarter,
another crescent and another new Venus. 
So at best you can only see half-lit.
Make sense, right? Because it revolves around
the earth according to the theory.
So what happened? Around 1610, Galileo actually
managed to confirm Copernican predictions.
He managed to confirm that "Yes, you
actually see the full set of phases!" So if
it were nowadays you would say  
"Well, now you have it!"
A confirmed prediction. Theory must be accepted, 
right? We have that intuition nowadays.
But back then it wasn't accepted. Why is that? 
Of you ask Galileo, he would say "I told you
those guys were just stupid,
irrevocably stupid! You know, the clergy
of the time. But his opponents would say
"No! The reason is that nobody cares about
confirmed novel predictions. The requirements
of our methods
are different. What we expect is
intuitive truth and your theory is
anything but intuitive. You really, really
honestly believe that this whole thing
revolves around anything? Why is it that
nobody feels anything? Why would even
God bother to create such a thing? But you
know the main reason why they didn't
believe in a revolving and a rotating Earth.
The main reason being their physicics. You
remember the Aristotelian physics. If you
accept that physics, the Earth which
is a combination of element Earth 
and element Water, must necessarily be in
the center of the universe. So for them it
wasn't just a random choice. It was
something that followed from their
physics. And there you have
Galileo who tried to convince everyone that the whole
thing revolves and did it in a wrong way
and that's the reason why nobody was
convinced. The middle of the century, 1644,
this is the year when Rene Descartes
proposed his theory. This was the theory
that actually managed to convince the
community of the time. It is with this
theory that heliocentrism - the idea of
Sun being in the center -
became accepted. Not before that. 
Descartes was a smart guy. He knew the
rules of the game. He knew that there's
no way to convince the Aristotelian
community unless you make sure that your
theory appears intuitively true.
What you have to do? You have to play the
game the way the rules tell you to play.
OK? Galileo didn't understand that. That's
why he failed. Descartes understood that and
there are passages in Descartes when he
made this clear. He says, "Well, I'm not
doing anything different from what you
Aristotelians tell me to do. I'm just
trying to build a system which is
intuitively true. And in order to make
sure that my system is even truer than
that of Aristotle's, I'm going to start from
scratch. I'm going to erase everything
and only accept those things which are
absolutely true, which are beyond any
reasonable doubt." You see what he's
trying to do? He is trying to create a
system that would convince the
Aristotelian community? I'm going to only
give you one fragment of the theory.
Let's take a material object.
What are the qualities, says Descartes, that every
material object must necessarily have?
Well, we have five candidates, says Descartes.
We have a colour, sound, taste, smell,
and shape. We have five candidates.
These are the properties a material 
object normally have. Which of
the properties are indispensable? Can
you think of a material object that
doesn't have colour, for instance? Can you
or can you not? Can you think of something
material yet colorless and transparent?
Clearly you can do that.
Therefore colour is not indispensable. You
can think of material things like air.
Air occupies space, right? It's material and yet
it doesn't have color, therefore this is not
an indispensable quality of matter. 
So this is not a fundamental property.
Therefore it must go. Can you think of
objects that don't make any sound?
Clearly you can do that.
Therefore sound is also not
indispensable. The same applies to taste.
There are objects that don't have any taste.
Smell is the same thing. Not everything
smells and thank goodness that not
everything smells. When it comes to
shape. Descartes says you 
cannot possibly conceive of a
material object that does not occupy
some space. It could be a fixed limited
space just like the remote control - not
that they had any remote controls back then -
but you get the idea. Or it could be
some fuzzy space like air but there
must be some space. So if you happen to
come across a material object that does
not occupying space, well, it's not much
of a material object, is it?
If it's material, it must occupy some space - could
be very tiny space, you know very very
very tiny or it can be a huge space but there
must be some space. And if it doesn't occupy
space it's not material. So you cannot possible 
think of something material that doesn't occupy
space, says Descartes. Makes sense? And this
brings to his fundamental principle of
"matter is extension": the 
fundamental property of matter is
extension - the capacity to occupy space.
Once you accept this, several interesting
conclusions follow. For one, says Descartes.
material objects are composed of
bits of interacting matter. Really, think
about it, if the only thing a material 
object can do is to occupy
some space, everything in
the universe is composed of just things
that occupy space, just a tautology
in a sense. Only small tiny bits which
can only interact with each other and
how they interact? Only by actual contact.
Think of billiard balls. How can one billiard 
ball affect another one? Just by
touching,  just by actual contact. This
is Descartes's fundamental idea.
The only way one bit of matter can interact
with another bit of matter is not that the
distance. It is not by somehow affecting the
other one at a distance. There is no such
thing. Only by actual contact. So the
whole world is a mechanism. The whole
world is like a clockwork with levers, 
springs, and clocks, and what have you.
This is the idea of the mechanistic
universe. The interesting thing about
this whole theory was basically an
attempt to convince the community of the time.
You see how he arrived at that? No
experiments and observations, just pure
intuition, and the rest is just deduction.
He says, "Now you Aristotelians, look at this!
Isn't this intuitively true? Of course it
is intuitive true. We just arrived at
it together. I'm just playing your game,
the game that you want me to play, and
this is intuitively true." And again this
is an essential difference, difference
from Galileo if you think about it. On the
Continent Descartes's theory became
accepted at the turn of the century.
This is the basic point: it was accepted
not because it has confirmed novel
predictions, nor was because it was precise and
accurate, but because it was intuitively true.
Let's sum it up: Is here an unchangeable 
method of science? Unchangeable meaning fixed and
trans-historical. If you say "Yes", this
will bring you to the so-called static
method thesis: the idea that the method of
science is unchangeable. If you say "No",
then you arrive at the dynamic method thesis
which says that method of science
changes through time.
OK? If I asked you what are the arguments
against static method thesis? What would
you say? Now I have told you the whole thing. 
(Student) "We know that methods used in
the past have changed over time so
that's kind of evidence that it does change."
(Hakob) "Exactly! Very good! Historical 
record is your argument. We know from the
history of science
that Aristotelian method had nothing to do
with the hypothetico-deductive method,
and there was a transition from one to
the other. We are going to study that transition
next time. But essentially we can all
agree that the historical record shows that
there is no such thing as a static method. 
The method of science changes throughout time.
A little bit of history for you. If we went all the
way back to the ancient Greeks,
Aristotle was one among
many many other scientists and
philosophers who believed that there are
certain fixed rules for conducting
science. He believed that there is a
fixed way of doing science. 2000 years
after Aristotle, Isaac Newton also
believed that there is a certain set of
rules for conducting science. In his
programmatic work,
Mathematical Principles of Natural Philosophy, he proposed
foundations of classical physics. There is a chapter
when he outlines the list of rules which
he believed what are the rules of science.
They had nothing to do with the actual
expectations of the community of the
time, to be sure, but the essential point is
that he believed that the rules are
fixed and that there is scientific method,
a fixed scientific method. Even all the way
to 50 years ago, Karl Popper, he also
believed that there is an unchangeable
method of science. And they all disagreed
as to what that actually unchangeable
method of Sciences is. If you asked Aristotle,
Newton, and Popper to try to explicate
that method, you would see a whole
bunch of different opinions. Aristotle would 
say that the actual method of science is
intuitions and deductions. Newton would
say it's about inductions from phenomenon.
Popper would say it's all about
falsification. Forget about those things!
What you have to understand is that
for the most part of the history of
human knowledge, the idea of static
method was taken for granted.
People believe that theories change, yes,
but something remains unchangeable.
That's what they believed. This guy - 
anyone know who this guy may be?
This guy who wrote the famous treatise called
Against Method. Paul Feyerabend! Bingo!
There is no unchangeable method of
science - he said it among many others.
Thomas Kuhn was another one who said that.
And nowadays it is commonly accepted
that there is no such thing as a fixed
unchangeable method of science.
Methods change. So until the 1970s
it was believed that theories
are evaluated by this fixed scientific
method. Therefore only
scientific theories change
while the method remains unchangeable.
And philosophers like their
philosophical jargon and they would say
in this case that the method is
"transcendent", meaning that it's not part of
the process of scientific change, that it's
beyond the process and it remains there
unchanged. OK? So this was what they
believed to be the case and nowadays we
believe that there is no such thing.
As a result, we accept that methods are not
something external to the mosaic.
They are part of the mosaic. They are here...
They are part of the process of
scientific change. Therefore we have
to redefine the concept of scientific mosaic.
This was our original definition: 
a set of accepted theories.
We have to redefine it: a set of accepted theories
and employed methods. Makes sense?
Therefore, what undergoes scientific
change is not only theories but also methods.
Next time I'm going to show you
many examples of changes in methods.
But at this point we have to appreciate 
that not only theories change
but also methods change. And this brings
us to what is probably the most
important question in the contemporary
philosophy of science.
If there are no fixed methods,
does it mean that the whole process of
scientific change is irrational?
Another way of putting it,
why do we employ the hypothetico-
deductive method and not, say,
Aristotelian-Medieval method? Is this
choice arbitrary?  Is there
a certain logic that governs transitions
from one method to the next? You see
the dilemma? If it turns out that the choices 
are completely random - you can
choose your methods of evaluation and I can
choose my methods of evaluation, then we end
up in what philosophers called absolute
relativism. Your theory is better by your
own standards and my theory is better by my
own standards. I can have my own
scientific community and you can have your
own scientific community and we all live
happily ever after. That would be a grant
agency's nightmare. And not just a grant agency,
it's a educators' nightmare if you think about it. 
I'm here to teach
accepted theories - well not me, you know, I'm a 
philosopher and I can teach anything, but if you
go to a science department, those guys would
really be in trouble. So this is the
question we are going to talk next time: 
what is the mechanism of scientific change?
We know how theories change - when they meet the
requirements of the method of the time.
Very well! But how do the methods change?
This question remains open. Any questions?
(Student) "So you look at how the method changes,
and the next time we are going to see how 
the fundamental ideas about how
the method changes - but what if that idea changes?" 
(Hakob) The question is
very straightforward: we discovered that the
method is changeable once we believe
that it wasn't but now we discover that it
is changeable. Now we are going to try
and come up with some kind of a
mechanism that would explain how methods
change. Then your question is what if it
turns out one day that that mechanism
itself is also changeable. Is there a guarantee
that this will occur to us?
No, there's no guarantee.
But does it mean that we have to
stop searching for something
unchangeable? Again we have to subscribe
to the idea of the process might as well
be endless, but it doesn't mean that we have
to just give up? After all it's fun
and it pays off mortgages! Very good! Any
other questions? Thank you very much!
Have fun!
