Philosophy of Science

Lecture 1

Epistemology=the theory of knowledge

EPISTEMOLOGY = THEORY OF KNOWLEGDE

• Philosophy of science began with epistemology;
• Epistemology asks three questions:
• (1) What is (certain) knowledge?
• (2) How can we justify that knowledge?
• (3) What is the source of knowledge?
• Traditionally there are two views:
• (1) rationalism: real knowledge is derived from the ratio,
reason;
• (2) empiricism: real knowledge comes from sensory
experience.

-Socrates -skepticism / asked difficult questions

-Rationalism-real knowledge stems from our reason/ there is innate knowledge , nativism ,

Plato
-to learn is to remember
• The source of knowledge is our reason;
• Plato: To learn is to remember ( = anamnèsis);
• In other words: There is no new knowledge – you do not
really learn anything (But did you know this?)
• Question: Why did he claim this?
• Plato believed in reincarnation

FORGOTTEN EVERYTHING
• Plato believed that before you were born, you had all
real knowledge (& you lost that knowledge when you
were born).

-episteme knowledge of how things are

-doxa opinion about how things are
-plato says that knowledge is a justified and true belief

PLATO RESPONDS TO HERACLITES

• Panta rhei;
• If in our world (= the world we perceive with outr senses)
everything changes constantly, then nothing is;
• And that means we can only acquire doxa, not
epistème….
• (And that would amount to skepticism)

PLATO’S ALLEGORY OF THE CAVE

• Ideas / Forms exist apart from us in a World of Ideas /
Form World;
• The soul is akin to those ideas;
• Acquiring knowledge is to remember these Ideas –
anamnèsis.

-MENO
• This is obviously unacceptable: Socrates is puts the slave
of Meno words in the mouth;
• This kind of rationalism is very extreme;

Empiricism
• General claim: Empiricists believe that the source of
knowledge is the experience gained through sensory
perception;
• This is a common sense view: If you want to know how
something is, you have to look (or listen ...).

THE TERM 'EMPIRICISM'

• The central claim thus is that you gain knowledge from
the experiences you have;
• Greek: empeira;
• Latin: experienta;
• Associated claim: If all knowledge comes from
experience via perception, there is no innate
knowledge.

EMPIRICIST #1: ARISTOTLE

• Rejected Plato's two-worlds theory: There is only one
world, and that is the one we can perceive with our
senses;
• This also implies a rejection of innate ideas: Man is a
tabula rasa (= a blank wax tablet).

ERIPATETIC PRINCIPLE
• Aristotle was the founder of the Lyceum, where he
taught while walking (peripateo in Greek);
• Hence Aquinas later called the empiricist principle
peripatetic principle: Nil est in intellectu quod non prius in
sensu fuerit (Nothing is in the intellect which was not first
in the senses).

UNIVERSAL CONCEPTS
• According to Plato the (general/universal) Idea Chair is
an entity existing in the World of Ideas;
• Aristotle rejects this;
• Aristotle accepts only the existence of concrete,
individual things (the individual chair);

INDUCTION
• ‘Aristotle called the empirical procedure by which we
move from the concrete to the universal induction (or
epagogè in Greek)[.]’ (Dooremalen, De Regt, &
Schouten, 2021, p. 40)
• Take an abstract, general statement like ‘all humans are
mortal’;
• What you perceive are just real people, and you can
establish that they are mortal.

ARISTOTLE’S SOLUTION
• Induction is therefore only a first step;
• There is need for a second step: Through our unfailing
intellectual capacity of the mind (nous) we can
understand that abstractions like ‘all humans are mortal’
are necessary truths;
• This is intuitive induction (= understanding);
• But that is a rationalistic element in his epistemology.

ARISTOTLE’S SOLUTION
• When Aristotle had found a general statement, he was
not very critical towards that statement;
• That is understandable: he though he had established
via intuitive induction that the statement was true.

THOMAS AQUINAS
• Aquinas tried to unite Christian teaching with the pagan
ideas of Aristotle (‘The Philosopher’).

AN EXAMPLE
• Aristotle had a theory about matter and form,
• Matter (such as a piece of marble) is potentially
something (a statue);
• The shape makes something that actual thing (think of a
statue that may potentially be present in a piece of
marble);
• The statue can break again;
• This is a process of creation and decay.

IDENTIFICATION WITH THE CREATING GOD

• Aquinas argued that God has put this process of
creation and decay in motion;
• Aristotle's unmoved mover (= the first cause).

• Aristotle did no experiments because he thought that

they would not teach us anything about the natural
world.

ARISTOTLE’S REASON
• Aristotle wanted to acquire knowledge about the
natural world;
• He already had a classification of plants and animals (in
which he classified whales as mammals);
• He used the method of observation;
• By manipulating (say by lifting a stone) we make the
world go against the natural ways of things and as such
we do not learn anything about the natural world.

Summary
• Traditionally there are two answers to the question where
knowledge comes from: the answer from the rationalists
and the answer from the empiricists;
• Plato’s views are very strange (seen from our
contemporary perspective) & he does not reason
properly when it is important (in Meno);
• Aristotle’s views had a big influence in the intellectual
world until the end of the Dark Ages.

Lecture 2

Francis Bacon
-argued that we should use experiments to learn about the world

The new method

-abandon epistemic prejudices
-use empirical method
-we need to use induction

Abaddon prejudices
– People have persistent epistemological biases (Bacon speaks of
idols or false conceptions);
– These stand in the way of acquiring knowledge;
– So we need to be wary not to use these prejudices.

-idols of the tribe -typical human mistakes like visual illusions /seeing a regularity when there is
none
-idols of the cave -biases because we belong to a certain group (like your generation aka
millennials )
-idols of the market place -biases because of language differences /words do not always refer to
something real and we make mistakes by thinking that they do
-idols of the theater-prejudice that we have because of authorities /because we don't listen to
scientist

Induction

• According to Bacon induction is a mix of perception and

understanding (here you can see that Bacon has a
rationalistic element in his epistemology);
• Good science uses observation and rational inference.
Bacon vs Aristotle

• Just like Aristotle, Bacon used induction;

• But Aristotle was wrong according to Bacon;
• Aristotle does not take the problem of induction seriously
enough: Bacon says you need to check whether your
general claim holds in other places (so Bacon looks for
possible refutations of the general claim).

Rene Descartes

-was a rationalist/ wanted certain knowledge /does not accept plato's theory

What are you absolutely sure of

• Descartes responds to a sceptic: Michel de Montaigne;
• For Montaigne the claim ‘I know nothing’ is already too
strong – fro you will claim to know that you know nothing;
• Hence, he made a question his slogan;
• The scale of knowledge is always balanced.

1st method Radical Doubt

-you cannot trust teachers

-you cannot trust your own senses
-a malin genie might be fooling you
-cogito ergo sum - i think, therefore i am

2nd method Clear and distinct reason

• Everything that I perceive clearly and distinctly has to be

true;
• This helps Descartes to get rid of the malin genie and to
gain knowledge about the physical world.
-believes in god and he is good and would not deceive us

Innate ideas
• Descartes believed that ideas could be innate;
• He makes a distinction between:
• (1) Innate ideas (triangle, god);
• (2) Acquired ideas (Sun);
• (3) Invented ideas (Pegasus);
• The difference with Plato is clear: Not all ideas are
innate

Optimism

• Descartes used in the beginning the method of the

skeptic (radical doubt) in order to make his opponent as
strong as possible;
• Once he discovered the Cogito, he could replace the
skeptical method by his rationalistic method (of the clear
and distinct understanding);
• Descartes is optimistic about being able to have real
knowledge.

Isaac Newton

-the world is a big machine =all natural laws like gravity

• We see, in those days, optimism about the ability to
acquire true knowledge about the world;
• The skeptic seems to be defeated.

The british empiricists

John Locke empiricism

-rejects inborn ideas
-formulates principles
-ideas
-qualities

[A] REJECTION OF INBORN IDEAS

• Empiricism cannot accept innate ideas;
• How does Locke refute the theory of innate ideas?
By showing that the alleged innate ideas do not occur in
many people;
• They are: (1) that what is, is; (2) it is impossible to be and
not to be at the same time; (3) moral principles.

• Locke: Firstly, universal principles could also be explained

otherwise;
• Locke: Secondly, they are not universal – we do not find
(1) & (2) in children and fools, and comparison of
cultures demonstrates that there are no (3) universal
moral principles;

-• Experience according to Locke: Perception and

reflection (internal perception).

Classification of ideas
-simple -one thing
-complex
-the idea of a substance

-qualities are things that leave an idea in us

-primary qualities stay on their own without being perceived
-secondary qualities exist because they are being observed/depends on you and your perception

George Berkeley
-all properties are secondary qualities
-to be is to be perceived
-the world does not disappear when you do not look at it because god is perceiving it

Idealism
-• Idealism: The philosophical (metaphysical) view that
reality essentially is mental;

David Hume

• Hume and Locke: By perceiving the world we acquire

knowledge;
• Hume formulates the 'copy principle': we have
impressions that result in ideas in our minds (analogous to
a signet ring which leaves an imprint in wax)
A problem he can not solve

We can only gain ideas from experience (Hume

is an empiricist);
• When we reasoning about the world (matters of
fact) we continuously use the idea
of ‘causality’: ‘The spark caused the explosion’,
‘The lack of dopamine induced Parkinson's
disease’, ‘the crisis caused unemployment’.

HUME’S ANALYSIS OF CAUSALITY

• Priority of event A and B: A has to occur before B (this can
be perceived);
• Contiguity of event A and B: A and B are located near
each other in time and space (this can also be
perceived);
• Necessity: event B necessarily follows event A; it could
not be otherwise / it is not a coincidence (this you
cannot perceive).
AN ATTEMPT TO SAVE KNOWLEDGE
• Hume: We can not perceive necessity, and thus
empiricists are not justified in using the idea
of 'causality';
• Hume: But we do use this concept in our
reasoning about the world;
• Hume: That's because we are so constituted
psychologically that we conclude that there is a
causal relationship whenever we perceive a
constant conjunction (that constant conjunction
is perceptible).

• This is a form of inductive reasoning and (as we have

seen) induction is an invalid form of reasoning: the
conclusion is not logically entailed by the truth of the
premises;
• Since inductive reasoning is an invalid form of reasoning,
the knowledge resulting from it is invalid;
• And so the idea of 'causation' is (again) an invalid
concept for empiricists;
• Hence, scepticism follows

Summary

• Rationalism: The associated claim that there is inborn

knowledge is untenable (even in the less extreme –
compared to Plato – version of Descartes);
• Empiricism: Some ideas that empiricists accept cannot
come from sensory experience.

WHAT ABOUT NEWTONIAN LAWS?

• We have seen that British empiricism (especially the
position of Locke) was a reaction to the rationalism of
Descartes;
• The latest version of that empiricism (the version of
Hume) shows a problem: if we are empiricists (or if
science uses induction) we can have no knowledge;
• That implies that we cannot be sure that the laws of
nature are true.
Lecture 3

Immanuel Kant

• He thought we really knew that Newton's laws were

correct;
• Then he read Hume who explained that we can never
be sure of any law;
• Kant concluded that there is indeed a problem and he
tried to save our knowledge that Newton’s laws were
true.

• Kant agrees with Hume: If we have a statement like ‘all

the candles melt in the sun’ we cannot determine
through the senses that this sentence is true;
• Kant disagrees with Hume: We can (according to Kant)
determine by a combination – a synthesis – of rationalism
and empiricism that the phrase ‘all the candles melt in
the sun’ is true.

-combines rationalism and empiricism

How does he do it ?

• We need two pairs of concepts to see how Kant makes

the synthesis;
[1] A priori & a posteriori;
[2] Analytic & synthetic.
• A priori judgment: The truth (or falsehood) of this
statement is accessible without looking at the world (‘A
brother is a man.’);
• A posteriori judgment: In order to assess the truth or
falsehood of this statement you need to investigate the
world

-analytic judgment =no new knowledge , analyze what you already know
-synthetic judgment =provides new knowledge
What does kant want to prove

• He wants to show that synthetic knowledge a priori is

possible & thus that it is a synthetic a priori judgment that
the world is causally structured;
• In this way he wants to save Newtonian laws.

• ‘Everything in nature has a cause’;

• If this indeed is true / knowledge (as Kant argues), then:
– This is something someone might learn, hence it is a synthetic
judgment;
– Hume showed that this cannot be known via the senses – so it
cannot be known a posteriori;
– Hence, if it is true, Kant has to show that it is a priori.

• He makes a distinction between the noumenal world

and the phenomenal world;
• Kant: There is no knowledge possible about the
noumenal world (the world-in-itself);
• Kant: Knowledge refers to the phenomenal world (the
world as it appears to us).

Transcendental philosophy

• Kant tries to explain what the conditions are that allow

for such knowledge (of the phenomenal world that is);
• We call this transcendental philosophy;
• Transcendental = pertaining the conditions of possibility
of knowledge;
• Here [a] the forms of sensation, and [b] the categories of
reason are of great importance.

[A] THE FORMS OF SENSATION

• The forms of sensation are space & time;
• But only time and space are not enough: We also
require the categories of reason.

[B] THE CATEGORIES OF REASON

• A collection of sensations could still be anything: We
need to put them into a category;
• One of these categories: Substance;
• If we can put something we experience in space and
time in one of these categories, only then can we have
knowledge of it.

The synthesis

• Here we clearly see that Kant proposes a synthesis of

empiricism & rationalism, and that we only can have
knowledge if the senses & reason work together.
•
‘Copernican’ turn: The world does not impose its
structure on us, but we impose it on the world (compare
Copernicus: The sun does not revolve around earth, but
earth around the sun).
-this i sa priori

• What may appear as something that does not belong to

a category of something?
• One of those categories is ‘causality’: It can not be
otherwise, according to Kant that things appear as
causes and effects to us;
• So by this he rescued the knowledge of general claims.

Problems for kant

• Kant claims that we cannot have knowledge about the
noumenal world;
• But how then is he able to claim that the things-in�themselves determine our sensations?
• He cannot do that;
• Furthermore: This would be causality, and is a category
that applies to the phenomenal world, not the
noumenal world.

• Kant thought we had knowledge (synthetic a priori), for

example, of the Newton laws;
• But then they can not turn out to be false;

• Kant believes to have real knowledge;

• His knowledge is about the phenomenal world;
• Kant sets the bar very low and the sceptic will say that
this position has not been refuted: We still do not know
(as Hume argued) that the Newtonian laws are true for
the real (the noumenal) world.

2 views

TWO VIEWS
• Assuming that it is possible to do science with respect to
human beings and their social relations, do we then:
• [a] apply the method of the natural sciences?
• [b] use a different method for these social sciences?
• Positivists defend the first view & hermeneutics the
second.

Positivism

‘Positivism’ is a term introduced by Auguste Comte;

• He wanted to solve social problems in (French) society.

• Comte: The solution of social problems lies in establishing

consensus about the foundations of society;
• A: By establishing the principles of positive thinking.
Law of 3 stadia

• Comte thought he had discovered a historical truth:

societies (and thus the 'science' in those societies)
always go through three stages:
[1] The theological, or fictional stage;
[2] The metaphysical, or abstract stage;
[3] The positive, real, or scientific stage.

[1] THEOLOGICAL STAGE

• This stage is characterized by a belief in supernatural
beings and forces;
[1.a] Animism (The attribution of spiritual life, even to material things);
[1.b] Polytheism;
[1.c] Monotheism;
• For example, life is explained by the fact that God put his
breath into humans.

[2] METAPHYSICAL STAGE

• This stage is characterized by the attributing of forces,
essences, powers to explain phenomena;
• For example, life is explained by the fact that there is a
life force in us.

[3] POSITIVE/POSITIVIST STAGE = SCIENTIFIC

STAGE
• This stage is characterized by explaining phenomena by
searching for the causal and mechanical explanations;
• We only find them through careful observation;
• Life is explained, for example, by explaining how
digesting food, metabolism, reproduction (i.e., the
different aspects of living beings) work.

Hermeneutics

• [1] Originally, it pertained to the interpretation of

mythological stories (of Homer, among others);
• [3] Around the 18th century: Hermeneutics became a
method to interpret all difficult texts;
• [4] In the 19th century: It is regarded as a scientific
method that contrasts with that of the natural sciences.

* According to hermeneutics, people are more than just

physical objects and therefore need to be approached
differently, i.e. not (only) via the scientific method of the
natural sciences.

WILHELM DILTHEY

• People fall outside the natural order of cause and effect

as we describe them in the natural sciences;
• We must therefore not try to understand humans in those
terms;
• That is not necessary either: We can do science without
that kind of laws, and then predict how people will
behave;
• That is an objective result.

THE METHOD OF VERSTEHEN

• The natural sciences want to Erklären in terms of cause
and effect (one answers the question: How?);
• The social sciences want to Verstehen in terms of reasons
(one answers the question: Why?);
• You must therefore pay attention to the individual cases:
attention must be paid to the subjective perspective.

-verstehen not a scientific method to discover facts

Criticism from hermeneutics

• Philosophers like Habermas and Gadamer point out that

you can never get rid of your own background & you
interpret others with your own ideas, so the result is
always subjective;
• If science has to be objective (which Dilthey said it
should be), then verstehen is not a scientific method

Criticism from neo positivism

• Logical Positivists also wanted an objective science &

then you can not actually say anything about the inner
life of others, because how can you check whether
what you say is actually correct?

Hempel of verstehen

• We do this from what you know interpreting others is

subjective;
• Hempel: but sometimes you will not be able to that –
because you have no knowledge about it from your
own subjective view (but you might be able to give a
good explanation – paranoia).

Summary

• Cartesian rationalism, British empiricism and Kantianism

all have their problems;
• Positivism arose, but was regarded as not sufficient for
social sciences according to hermeneutics;
• But hermeneutics is too subjective to be called a science
or scientific method.

Lecture 4

LUDWIG WITTGENSTEIN

• Wittgenstein I: Tractatus Logico-Philosophicus (1921);

• Wittgenstein was interested in the ‘higher’; • The aim of the Tractatus: Separation sense and
nonsense; • Wittgenstein defended a correspondence theory of (1) truth, and (2) meaning (=
picture theory of truth / meaning);
• Note: LW was only interested in the meaningfulness of sentences, not in philosophy of science.

• If you cannot figure out by looking at the world whether a sentence is true or false, then the
sentenced is meaningless;
• Examples of meaningless phrases: – ‘The beautiful is identical to the good.’ – ‘The soul is
immortal

• Where can we speak of? • About observable reality: Everyday / banal statements and the
empirical sciences.
• Sentences can therefore not express anything higher: we can not say anything about the
important questions of life;
• Problems are thus either (1) scientific, or (2) nonsensical;
-if one can not says something about it then be silent

Logical Positivists

= Logical empiricists; • In the 1920s in Vienna a group of thinkers was created that wanted to get
rid of incomprehensible philosophy à la Heidegger; • The group consisted of scientists and
philosophers

1929: THE LOGICAL POSITIVISTS’ PAMPHLET

• This pamphlet marks the start of philosophy of science as a separate discipline (we’ll see in a
moment why this is so).

5 key ideas

1. Rejection of meaningless statements;

2. Logic;
3. Positivism;
4. Unified science;
5. The need for a demarcation criterion.=separates science from pseudoscience

Goal 1
• They follow Wittgenstein I: Meaningful statements are scientific statements and vice versa.

*Psychologists need to be behaviorists

Goal 2 Logic

• Statements that describe reality directly are protocol sentences;

• That protocol sentences(stuff i can observe ) are connected to each other through logic;
• Hence, logic is playing an important role in the logical positivists’ philosophy of science;
• However, logic is an instrument, not a method to gain knowledge (so it is not synthetic a priori
as Kant argued)

Goals 3 Positivism
• There are two views on positivism:
• [1] The view of Auguste Comte; • [2] The view that science is the only source of real
knowledge; • [2] is part of [1];
• The Logical Positivists accepted [2], but not [1] (they disagreed with Comte on many points); •
Result: epistemology changed into philosophy of science

Goal 4 unified science

• The logical positivists believed that all scientists were working on one scientific theory about
the world;
• History, economics, sociology, psychology, physics, chemistry, etc. all belong together;

Deductive nomological model

• = Covering law model; • Greek: nomos = law;

• Model: – Premise 1: General statement = nomological statement; –
Premise 2: starting statement; – Conclusion or prediction.

● Continue from minute 47:50

Goal5 the need for a demarcation criteria

• HD: Now we can ask the question – What is science?

• The LP provide us with two (problematic) answers:
• A statement or theory is scientific if it is:
• 1. Verifiable;
• 2. Confirmable;
• Let us first look at a common sense view of science.

Demarcation criteria

Science has to be:

1. Always true
2. To be able to be checked in all cases;
3. To be able to be checked in most cases;
4. (In principle) be possibly wrong;
5. In accordance with rational thinking;
6. Objective;
7. To be able to be checked by the senses.

Criteria 1 verifiability

• A demarcation criterion = criterion that separates one

from the other;
• In this case [1] meaningful / scientific from [2]
meaningless / unscientific statements;
• Understanding a non-logical statement p means you
can specify how p can be empirically verified;
• The demarcation is empirical verifiability.

• According to the LP he experiences are neutral, so they

can serve as a foundation for science (These are raw
data; sense data);

• Consequence for philosophy: Almost everything philosophers

say is meaningless / unscientific (except epistemology &
logic);
• Consequences for the social and behavioral sciences: at first
no problem: these disciplines (including psychology) are
meaningful sciences (you can observe human behavior);

-not a good criteria

Demarcation criteria 2 confirmability

• Attempt # 2: Confirmability is sufficient to be scientific;

• Now you do not have to keep all the iron in the fire to
confirm that all iron expands when you heat it up;
• But here again a problem: Sometimes nonsense is
confirmed: horoscope (prediction that x happens or
not), readings of mediums (example: Barnum
sentences)

-not a good criteria too weak

Evaluation Logical Positivism

• Problem: There is no good demarcation;

• Problem #1 with the DN model: an induction problem;
• Problem #2 with the DN model: theory-ladenness of
perception.

• Hume: we cannot justify induction;

• The DN model needs a nomological statement;
• How do we arrive at this general statement? (Apparently
not via induction);
• ‘Solution’: formulating general claims is based on
psychological and sociological preferences.

THEORY-LADENNESS OF PERCEPTION

• Suppose someone says: ‘This is a picture

of a vase’;
• How does one establish – according to
empiricists – whether this is true?
• By looking;
• But: Without a theory one might not see
the vase.

• This would always be the case:

– Observation / perception is always theory- laden;
– The empirical data always fir more than one theory.

• The logical empiricists were attempting to find a

demarcation criterion;
• Verifiability and confirmability are both unsuitable;
• Furthermore, there are problems with the explanatory
and predictive model, and with the interpretation of the
empirical basis

Lecture 5

Karl Popper

-looks at 2 questions
1.can we save science from irrationality of induction
3.better demarcation criterion than logical positivists

-he said yes , no need for induction

Popper and logical positivism

-he was not one but he accepted that experience was important for knowledge ;he thought they
were too radical
-logics and mathematics are tools but did not provide us with new info (contrary to kant )

• Logical Positivists: First observations, then (via induction)

general laws, then (via induction) confirmation of those
laws (Context of discovery / context of justification);
• Popper: First there is a problem (why does the apple
fall?), a conjecture is postulated (a hypothesis is
generated) and then you try to refute this conjecture.

Critical rationalism

• 3.1 Falsificationism;
• 3.2 Nativism (& induction);
• 3.3 Critical rationalism;
• 3.4 Critical rationalism.

1.
• Popper:
• Marx & Freud are examples of pseudo-scientists;
• Newton & Einstein are examples of scientists;

-what is the diff between pseudo and real

-problem of demarcation

• Is truth the demarcation criterion?;

• No, a scientific theory does not have to be true;
• Old astronomical theories were false but not unscientific.
• Popper: falsifiability is the demarcation criterion.

4 properties of falsifiability
a) Human fallibility;
b) Falsifiability is the demarcation criterion;
c) Only falsifiable theories are informative;
d) Growth of knowledge is only possible via falsification
(refutation).

A.newton was wrong and was replaced by einstein

b.• Take a mini-theory that is not falsifiable (tomorrow it will

rain or not);
• This is true but it is not science;
• Truth, verifiability, confirmability fail as possible
demarcation criteria;
• The same applies to the theory of Freud: This theory is as
unscientific as ‘tomorrow it will rain or not’ is.
*first marx theory of history was falsifiable so it was scientific according to popper /his theory
was refuted so then he changed it /made the theory irrefutable so not scientific anymore

c.• Again: ‘Tomorrow it will rain, or it will not rain’;

• Is this informative?
• A prediction has to be to the point;
• Horoscope: ‘There may be problems at work.’

*• What is important is not that you only say true things, but
that you only make falsifiable claims, of which you
honestly believe that they are true.
-you always run the risk of being wrong so you need to be careful about what you say

d. What Popper calls ‘corroboration’ cannot be seen as

inductive evidence for a theory, because:
• Induction is irrational and science is rational;
• In other words scientists take a theory to be true as long
as it is not falsified;
• We can learn from our mistakes: The negative way to the
truth.

-popper claims that even unscientific claims can be meaningful / unscientific theory can lead to
scientific hypothesis
-popper thinks that the idea of inborn ideas is absurd but that each one of us has inborn reactions
Critical rationalism

• This expectation leads to dogmatic thinking;

• We are basically induction machines;
• We are usually not critical of our expectations of our
inductive intuitions;
• Hence, we are dogmatic thinkers by nature

-do not accept statements without critical thinking

-being critical is seeing if something can be classified

*Poppers warns about confirmation bias

-Poppers tries to get rid of induction y using deduction

-• Science is rational, for it uses deduction (and deduction
is a valid way of reasoning).

Problems with poppers ideas

1.pseudo sciences also make falsifiable claims

2.determining that a general statement is false based on induction

Conclusion

-falsifiability does not work as a demarcation criteria but it makes a difference between pseudo
and scientific claims
-both empiricism and rationalism have problems finding the demarcation criterion

Lecture 6

Scientific Revolutions

-Thomas Kuhn argues that we should stop looking for the demarcation criteria

Constructivism
-observations are theory laden
-we construct the facts so facts become subjective

Relativism
-constructivism implied relativism

• Constructivism (the claim that facts are dependent on

theories) thus implies relativism (truth depends on the
construction);
• And vice versa: If you state that the truth of a sentence
or theory is dependent on the construction of reality,
that obviously implies constructivism;
• Relativism & constructivism are inspired by Wittgenstein II.

Ludwig Wittgenstein again

Differences between 1 and 2

• WI: The meaning of a word depends on its reference

(Hence, no reference, no meaning; ‘meaning is
reference’);
• WII: The meaning of a word depends on its use
(‘meaning is use’);
• A word is being used in a language game (a certain
context a life form);

-language games have rules

-• A private language is a language that only one person is
able to understand;
-witt says that is not possible to have a private language

Why do some think there is a private language ?

-empiricists have an argument

• Premise 1: Meaning depends on reference;
• Hence: Psychological terms get their meaning form the
reference to subjective psychological states;
• Premise 2: Inverted spectrum.
• Conclusion: Only I know the reference of my
psychological terms (‘blue’, ‘pain’);
• Hence: Only I know the meaning of these terms;
• An empiricist could argue that all meaningful words in
the end refer to experiences.
-rules have to be public accessible because otherwise you are intelligible for yourself

CONCLUSIONS
• If rules can be changed radically, you are no longer
intelligible for yourself (diary, shopping list);
• In other words: There can be no private language;
• A language game includes more than just the language;
• Question: Was WII a relativist?
• That is not entirely clear, but ... he has influenced the real
relativists.

Thomas Kuhn

-kuhn did not want a demarcation criteria but he wanted to describe how science world
(descriptive methods instead of normative like lp and popper )

-introduces the concept of paradigm

-one example of a paradigm is newtonian mechanics

(0) PRESCIENTIFIC PERIOD

• There are activities, but these are not organized;
• There is no structure, educational system or other activity
that we could call science.

(1) NORMAL SCIENCE

• A paradigm is accepted;
• This is no lack of reflective capacities, but means that
Science is mature.
• The paradigm is never complete: There are always
anomalies;

• The physics of Aristotle was scientific: ‘Out-of-date

theories are not in principle unscientific because they
have been discarded.’ (Kuhn, 1962, pp. 2-3)
• But paradigms exclude each other (e.g. earth is center
of the universe, vs. sun is center of the universe);
• Is the transition from paradigm one to paradigm two a
gradual process or a rift?
• Kuhn: It is a rift.
(2) ABNORMAL SCIENCE
• Too many problems ➡ crisis;
• The crisis is the start of a period of abnormal science;
• How does this period end?
•1
st way: Solve all (or most) problems/puzzles and remain
in the paradigm;
•2
nd way: Via a scientific revolution.

(3) SCIENTIFIC REVOLUTION

• A crisis worsens as a new paradigm is created;
• This often occurs when someone who is aware of the
crisis comes up with a new paradigm in the ‘middle of
the night;
• A new paradigm is not compatible with the old
paradigm - it's a rival;
• In a scientific revolution scientists change to the new
paradigm.

*• Kuhn: reject a paradigm only if there is an alternative:

-• ‘The decision to reject one paradigm is always
simultaneously the decision to accept another, and the
judgment leading to that decision involves the
comparison of both paradigms with nature and with
each other.’

-paradigms can not coexist for long /no c cumulative growth of knowledge when there is a
revolution

-term revolution refers to revolutionary changes in science

-the revolution is successful if most accepts the old paradigm

INCOMMENSURABILITY
• Different paradigms generate different world views /
worlds;
• Incommensurability thesis: The different paradigms are
not rationally comparable;
• Meaning and reference of words has changed: ‘earth’
(center); ‘atom’ (indivisible).
• Kuhn: Differences of opinion make discussion impossible,
another paradigm assumes a different world: scientists
who have accepted a new paradigm also live in a new
world.

Change of world

EXPLANATION: CHANGE OF WORLD

• The theory determines what you see (theory of
perception);
• HD: That seems unproblematic;
• It may be the case that there is a rabbit that can be
seen as either a rabbit or a duck;
• Kuhn seems to go much further;

Demarcation criterion after all

• Kuhn described the development / changes in science;

• Popper looked for a norm – a demarcation criterion;
• However a norm can be found in Kuhn’s description:
science has a paradigm (Dooremalen, De Regt, &
Schouten, p. 269).

Conclusion

• Kuhn wanted to be descriptive and not prescriptive;

• However, he unintentionally came up with another
demarcation criterion.

Lecture 7

1. FEYERABEND’S EPISTEMOLOGY

• Traditions ≈ paradigms;
• In the history of science traditions follow each other, but
one is not better than the other;
• Current western science is one of the many traditions;
• Kuhn: Paradigm shift is a gestalt switch: You can not turn
back;
• Feyerabend: You can just choose a different paradigm /
tradition.

Against methods

-about the scientific method / he is pro science

-against the monopoly of knowledge acquisition

Anything goes

-• He wants a methodological anarchism;

• According to Feyerabend all methods can be sources of
knowledge: anything goes;
-if you want to understand the world you need to use all from for acquiring knowledge
-people should be free to think whatever the want

Consequences of his anarchism

• Consequence 1: Knowledge is a sea of alternatives;

• Consequence 2: There should be freedom of
methodology in education.

*• PF argues against oppression;

• PF: We did not democratically choose for science in our
educational system;
• PF wanted to separate state from education;
• PF: You are of course allowed to choose science, but
you should also be allowed to study magic or Navajo
rain dances;

Problems with relativism and constructivism

FIRST PROBLEM
• (Especially against Kuhn’s views);
• How can you know that two paradigms are
incommensurable?
• Can you do that without making that paradigm own?
• If paradigms are radically different, how can Kuhn claim
this?
SECOND PROBLEM
• The claims ‘everything is relative’ (general relativism) and
‘truth depends on the paradigm’ (Kuhn's version) or
‘truth depends on the tradition’ (Feyerabend version)
contain a contradiction:
• If everything is relative, then these statements are
relative too, but that cannot be the case, because they
are supposed to be true in general.

*• Maybe it's a good idea after all to see if we can not save
science from relativism and turn again to the project of
finding a demarcation criterion;
• That's exactly what Imre Lakatos has done.

Imre Lakatos

• Goal: To rescue the normativity of science;

• That can be done – Lakatos argues – if we change the
notion of falsificationism from (1) dogmatic, via (2)
methodological, to (3) sophisticated falsificationism.

Lakatos on popper and kuhn

• Popper and Kuhn are both right in a way, but also

wrong;
• Popper’s falsificationism clearly was not strong enough;
• Kuhn’s description of science denied progress when
science radically changes.

DOGMATIC FALSIFICATIONISM
• Before Popper there was a form of falsificationism;
• Lakatos calls dogmatic falsificationism;
• E.g. Richard B. Braithwaite.

-assumptions : • Every scientific theory is fallible;

• The empirical basis is infallible;
• Only on the basis of empirical data you can judge a
theory;
• Scientific growth is through the rejection of theory based
on (observed) facts
*• We know that the observation is theory-laden;
• So there is no infallible empirical basis;
• This makes falsification problematic

METHODOLOGICAL FALSIFICATIONISM
• This is Popper’s version of falsificationism;
• Accepts the theory-ladenness of observation;
• But it also claims that the scientists can just accept the
background theory;
• This means you can gather empirical data that conflict
with the scientific theory (≠ background theory).

*lakatos call this convenient empirical basis

*rejection because it does not fit with the accepted theoretical background

Lakatos:
• This is in accordance with Kuhn’s analysis of the history of
science;
• This is a normative alternative to Kuhn’s description of
scientific change (falsificationism is saved);

Scientific change according to lakatos

• Lakatos: There are research programs ( paradigms) RP;

• Claim #1: Scientists work with theoretical wholes;
• Claim #2: One wants to stick to a RP, at least to the hard
core of it;
• But, the RP does not exist only in succession, they coexist
and are also comparable (not incommensurable).

• The scientists from different RP’s talk to each other;

• They try to find out who is right;
• This is a rational comparison of theories, with the aim of
finding the best theory;
• Kuhn’s incommensurability thesis is incorrect;
• This gives the possibility to separate [1] degenerative RP’s (they are pseudo science )
from [2] progressive RP’s;
-we can use heuristics

Types of heuristics
-negative heuristics -what you re not allowed to do , reject the core of the research
program/implies a positive heuristics
-positive heuristics -what you're allowed to do /allowed to falsify claim in the protective belt

• Progressive RP: By adjusting the belt, the theory becomes

more complex and will have increasingly more empirical
content (e.g. medicine);

• Degenerative RP: By accumulation of ad hoc auxiliary

hypotheses, the theory is saved, but this is not the way:
this program should be abandoned if a better
alternative (more empirical content) presents itself (e.g.
sorcery.).

Demarcation between progressive and degenerative program

• (1) It predicts more, and some of these predictions are

successful;
• Progressive: Positive evidence & no refutation
-(2) has to be a real program , discover something new

Kuhn vs Lalkatos

Kuhn
-kuhn says that lakatos talks about the same concept but he just changed the name , so from
paradigm to research program but the content is the same
-kuhn also found a demarcation criteria (if there is a paradigm ) so t is more or less like lakatos

Conclusion

• Kuhn and Feyerabend are both relativists and

constructivists;
• There are severe problems with relativism &
constructivism;
• Lakatos makes an attempt to make Popper’s
falsificationism stronger and succeeds (according to
many) by accepting a set of demarcation criteria;
• Kuhn argues that this is not a normative alternative to his
views.

Lecture 8

Scientific realism vs constructive empiricism

• If you are a realist about X, you accept that X exists;

• A scientific realist says that if a successful scientific theory
holds that X exists that X exists;
• E.g.: Beliefs and electrons;
• The scientific realist is thus an anti-constructivist.

CONSTRUCTIVE EMPIRICISM
• There are proponents of constructivism;
• But these days it usually is a much more sophisticated
and less radical version than that of Kuhn and
Feyerabend;
• Bas van Fraassen’s constructive empiricism.

Realists

• In general they accept the following:

• A scientific theory informs us about (unobservable)
reality;
• There are good reasons to accept that the theory is
approximately true (and thus that the terms refer);
• Scientific progress is possible.
-the approximately true clause /they use abduction/inference to the best explanation

IBE

• X is the case;
• If A, B, C, D or E was the case, X would be expected;
• E is the most probable cause of X;
• So: We have a good reason to think that E was the case.

*most of the time we go from the best explanation to the only one

Arguments against

• The central issue in the debate is how well IBE (IOE) can
be defended;
• A theory only needs to be empirically adequate, i.e.
make successful predictions at the observable level;
• You do not have to commit to the truth of the theory
about the unobservable domains.

SECOND COUNTERARGUMENT
• What if you have a lot of explanations, of which you
argue to the best of them, but did not come up with the
explanation that was the actual explanation;
• Then you have an inference to the best of a bad lot.

Pragmatism vs skepticism

THE SCEPTIC
• Sceptics claim we cannot ever give any justification for a
belief & thus knowledge is impossible;
• Science uses general claims & these indeed cannot be
justified (the problem of induction);
• So: We want knowledge in the sense of justified & true
beliefs, but we cannot ever get that.

PRAGMATISM
• A pragmatist couples knowledge – or better beliefs – to
actions;
• If someone acts, you can see what his beliefs are;
• The clearly is criticizing the traditional view that
knowledge is always certain knowledge (like we saw in
Descartes’ epistemology).

-peirce does not think that descartes actually had doubts

-• He made a distinction between [1] paper doubt & [2]
living doubt;(real doubt )
• Cartesian doubt is paper doubt.
-descartes had paper doubts because he wrote everything down

-living doubt feels uncomfortable , you didn't know what to believe so you do not know what to
do
-you want to get rid of the irritation of the feeling so you can act out
-you want to fixate your beliefs

Tenacity
-make sure you do not get into the situation of living doubt
-but this is basically impossible

Authority
-you assume the authorities in the groups have knowledge about the world
-but there are always other people doubting why we believe what we believe

A priori method

• You look (because of problem with [b]) for those truths

which are indisputable and then take it from there;
• But do we not differ in which claims we believe to be a
priori true?
• Thus, according to Peirce this method is analogous to
the development of taste – it is subjective;
• This is of course the method of Descartes.

Method of science
• The scientific method provides knowledge that is
independent of my taste and applies to everyone;
• There is a realistic assumption behind this idea (but who
doubts seriously that the world exists?): There is a world
that exists independently of us and we can gain
knowledge about this world.

Epistemology naturalized

-Quine is an empiricist and naturalist

-he says that it is impossible to find a foundation to justify all of our believes
-we should look at science to learn about science
-we do not want to justify science but instead know how people acquire knowledge

*• Epistemology is no longer something of philosophy, but

belongs to psychology according to Quine;
• And thus epistemology belongs to science.

• Hume: Argues that there is no certain knowledge (of

causal relations), but that we are psychologically so
constituted that we conclude to causal relations;
• Bacon: Show that typical human idols may stand in the
way of knowledge.

Part 2 of the course

Lecture 1

Critical thinking

• Rational thinking
• Assess the reliability of our beliefs by reflecting on how these beliefs were
formed.

-the goal of critical thinking is to lead to reliable conclusions and distinguish reliable from
unreliable
-not spontaneous , has to be learned

3 rules of thumb
1.demand external support for beliefs
2.occam's razor -the most parsimonious explanation is the best
3.we should be aware of a number of cognitive pitfalls / illusions -they are systematic ,
permanent and universal

*base rate fallacy -prior probability in the population

*availability bias
*anchoring
*framing -when presented with the same information , people can take different decisions based
on how it is framed
*allais paradox
*hindsight bias

Summary

•What is critical thinking?

• Rational and autonomous thinking
•What are the three rules of thumb of critical thinking?
• Demand external (not psychological) support for beliefs.
• Apply Occam’s razor: choose the most economical / parsimonious
explanation.
• Beware of cognitive illusions.

Lecture 2

The evolution of irrationality

-the base of our thinking apparatus is evolution by natural selection

● Random genetic variation

● Heredity
● Selection
*can sometimes lead to suboptimal design
*system 1 and system 2 of thinking

The fallibility of system 1

1.heuristics
2.error management -making more mistakes to avoid costly mistakes
3.mismatch - system 1 is outdated
Sources of irrationality

1.the social environment /system 1 and self deception

*.system 2 also leads us to astray /the argumentative theory of reason /confirmation bias and
overconfidence bias (francis bacon talked about this )
2.Emotion -driving factor of action /affect heuristic / ingroup -outgroup heuristics

Lecture 3

Irrationality in action

● Superstitions -craving causal relations -consequence of error management because of

natural selection making sure we do not miss anything in our environment to protect us
● Seeing order in randomness and randomness in order
● We often misinterpret causal relations

Conspiracy theories

• Causal reasoning errors: A leads to B, C wants B, so C must be

responsible for A.
• Confirmation bias
•Ingroup – outgroup bias
• Built-in immunization strategy: hard criticism is seen as confirmation.
Ways to debunk
-occam's razor

Pseudo sciences
-• Lack a self-critical dynamic.
• Popper’s demarcation criterion: ‘Falsifiability’ distinguishes science
from pseudo-science.
-aristotle already distinguished between real and made up science
-pseudo sciences do not make claims that could be tested and maybe read to their debunking
-the chance of a theory of being wrong is what makes it falsifiability
• Built-in vagueness: e.g. not specific what the outcome of a (successful) therapy
should be

Pseudo scientific healthcare

• Therapy experience is unreliable

• Placebo-effect
• Confirmation bias
• Spontaneous healing

-tradition is unreliable
-randomized double blind trials with control groups

Cognitive science of religion

•Hyperactive agency detection

•Intuitive dualisme
•An innate preference for teleo-functional explanations (in terms of
purposes).
•Ingroup – outgroup bias

Summary

• Which biases lead to:

• Superstition?
• Hyperactive pattern detection, confirmation bias
• Conspiracy theories?
• Causal reasoning errors, confirmation bias, ingroup-outgroup bias, lack of
self-criticism
• Pseudo-sciences?
• Lack of self-criticism, confirmation bias
• Religion?
• Hyperactive agency detection, intuitive dualism, preference for teleo-functional
explanations, ingroup-outgroup bias

Lecture 4

How to protect against reasoning errors

3 sources of reasoning errors

•Intuitions
• Emotions
• Confirmation bias – overconfidence bias

Intuition
•Genetically anchored reasoning processes
• Ecological rationality: Gigerenzer(intuition is right sometimes because it is based on responses
we are used to in our environment ) responds to Kahneman
• Check the context
• Beware of cognitive pitfalls due to error management
-system 1 can be very accurate

•Acquired automatic reasoning processes

• Examples:
• Chick sexing
• (Art) experts
-when you first drive a car everything goes to system 2 but once you practice it moves to system
2
-is the intuition innate or acquired /if innate then it is applied in an ecologically valid way

Emotions

• Emotions can lead to irrationality by:

• Determining which beliefs we do and don’t take on board (ingroup – outgroup
bias).
• Determining which beliefs we refuse to discard in the face of
counter-evidence.

*cognitive dissonance reduction -leon festinger and the clarion believers

System 2 bias protection

• The confirmation bias

1. Play devil’s advocate in your own thinking.
2. Surround yourselves with people who think differently.
3. Use the ‘wisdom of the crowd’.

What makes humans specials

-the extended mind hypothesis (we use external elements to guide our thinking )
Three cognitive levers
•Other minds
• Cognitive artifacts
•Instruments
Summary

•How to protect against reasoning errors coming from:

• Intuitions
• Check their origin
• Innate intuitions: only reliable in an ecologically valid context
• Acquired intuitions: usually reliable
• Emotions
• Be careful not to engage in irrational cognitive dissonance reduction!
• Confirmation bias - Overconfidence bias
• Be aware of these biases!
• Play devil's advocate in your own thinking
• Surround yourself with people who think differently

Lecture 5

The importance of critical thinking

Illusions i the financial world

-overconfidence
*hyper active pattern detection
-chance blindness

• Singer’s escalator effect of reason on morality

• Expanding the moral circle
• Questioning moral intuitions / aversions
-people start expanding their moral circles when they start thinking about morality

-moral intuitions are modeled by natural selection

-critical thinking was influenced during the ancient greeks
-then flourished again during the renaissance and illumination period

Summary

•What is the impact of irrationality on the world?

• Positive illusions (overconfidence) can lead to war and financial crises.
• Religion can lead to group conflict and is a brake on moral progress.
•What leads to moral progress?
• Critical, rational thinking.
•Why?
• According to Singer, by reflecting on norms and practices we tend to expand
our moral circle and rid ourselves of unfounded intuitive aversions.

Lecture 6

The scientific method and the demarcation criteria

• The empirical sciences comprise natural and human sciences.

• Natural sciences are: physics, chemistry, biology, etc.
• Human sciences are: history, psychology, economics, sociology, anthropology,
etc.
-natural sciences aim to explain while the human ones aim to understand
-only natural sciences can make precise predictions

•Interaction with the study object in the social sciences: Hacking’s

“looping effect”.

* cognitive artifacts protect against intuitive reasoning errors

•Against the bandwagon effect: rivaling research groups

• The importance of universal standards for epistemic success: logical validity,
coherence, simplicity, etc.

Popper falsifiability

• Verification is too strong, confirmation is too weak.(find something that confirm your theory
which one thing is not enough )
•Against which reasoning error does this criterion protect?
• The confirmation bias!
-we can never prove something with certainty so verification too strong
-science is a matter of probability not certainty

Criticism

•In practice scientists do not always discard a theory in the light of

contradicting information and they shouldn’t.
• The discovery of Neptune
• Pseudo-sciences (sometimes) also make falsifiable claims.

Feyerabend’s epistemological anarchism

•Against a demarcation criterion
•‘Anything goes’!

Postmodern constructivism
Sokal’s hoax
•‘Transgressing the boundaries: Towards a transformative
hermeneutics of quantum gravity’.
• Sokal’s paper containing nothing but relativistic, deep sounding
nonsense got through peer-review and was published.

Conclusion: striving for an equilibrium

• Science should not be too restrictive, but it shouldn’t be too inclusive
either, otherwise there are:
• No universal standards
• No reliable base to build upon

Summary

•What do all (good) sciences have in common?

• They are self-correcting.
•Why?
• Cognitive artifacts protect against intuitive reasoning errors.
• Framework and context protect against reasoning errors of system 2 and
against emotional distortion.
•What is the importance of a demarcation criterion?
• Universal standards for good science ensure that scientists can criticize (and
improve) each other's work.
• Scientific progress requires a reliable basis on which to build.