Lecture 1
What is philosophy of science?
= this philosophical (critical) reflection on what science is, does, and how it generates knowledge
Why philosophy of science for psychologists?
Psychology is a science
o Knowledge – why?
o Skills
Is psychology a science?
Is it justified that science has the monopoly on acquiring knowledge?
o Character
Building of character
Better psychologists, better scientists, better citizens
Understanding society advancing society
Epistemology
= theory of knowledge
Philosophy of science began with epistemology
Epistemology asks three questions
o What is knowledge
o How can we justify that knowledge
o What is the source of knowledge
Traditionally there are two views
o Rationalism = real knowledge is derive from the ratio, reason
o Empiricism = real knowledge comes from sensory experience
Is it possible to have real knowledge?
Rationalism and empiricism say yes
What are we certain of?
Skepticism
Socrates in the market square
Ask difficult questions
o Always question about if you really know something no
Skepticism = perhaps the conclusion must even bet that we do not know anything at all and
never will
Socrates is convicted
Rationalism
General claim: real knowledge stems from our reason (= ration)
Associated claim: there is innate knowledge (= nativism)
Different views on rationalism
o Plato, Descartes etc.
Plato
The source of knowledge is our reason
To learn is to remember (= anamnesis)
, There is no new knowledge – you do not learn anything
Why did he claim this?
o Reincarnation
o Plato believed that before you were born, you had all real knowledge and you lost
that knowledge when you were born
Using your ratio to recall the knowledge
Plato made distinction: Episteme vs doxa
o Episteme = knowledge of how the things are
o Doxa = opinion about how the things are
Plato: knowledge = justified and true belief
o Justification – You can explain how you know it is true
Plato responds to Heraclitus
o Panta rhei = everything is a constant flux
o If in our world (= the world we perceive with our senses) everything changes
constantly, then nothing is
o And that means we can only acquire doxa, not episteme
o And that would amount to skepticism but Plato did not want that
Plato’s allegory of the cave
o Ideas/forms exist apart from us in a world of ideas/forms
o Those ideas do not change
o The soul is akin to those ideas
o Acquiring knowledge is to remember these ideas – anamnesis
Meno – book
o How do you double the surface of this square? Asking Meno the slave
o First Meno 4 doubles the surface
o Zeus (Plato) then makes another square which is double the surface and Meno say
now I remember how to double the surface - anamnesis
o This is obviously unacceptable: Socrates puts the slave of Meno words in the mouth
o This kind of rationalism is very extreme
o Descartes had a weaker version
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
The general 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
There is a difference between empiricist and empirical
o ‘empiricist’ refers to empiricism, the opposite of rationalist
o ‘empirical’ refers to scientific method, which uses observational of experimental data
to infer conclusion about the world
Empirical evidence is gained through observations or experiments
Empirical is the opposite of purely hypothetical
,Aristotle
Rejected Plato’s two-world theory – there is only one world and that is the one we can
perceive with our sense
This also implies a rejection of innate ideas: man is a tabula rosa (= a blank wax tablet)
Peripatetic principle
o Aristotle is the founder of the lyceum, where he taught while walking
o 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
The key to Aristotle’s epistemology is indeed sensory perception
In this sense we can rightly call Aristotle an empiricist
But he does have some rationalist elements in his ‘empiricist’ epistemology
Universal concepts
o According to Plato the general idea chair is an entity existing in the world of ideas
o Aristotle rejects this
o Aristotle accepts only the existence of concrete, individual things (the individual
chair)
o How then do we arrive at a universal, abstract concept (thus the concept ‘chair’ that
applies to all individual chairs)?
Induction
o Aristotle called the empirical procedure by which we move from the concrete to the
universal induction
o Take an abstract, general statement like ‘all humans are mortal’
o What you perceive are just real people, and you can establish that they are mortal
o Induction is concluding based on observation of some cases (but not all)
o Problem
Are you sure that all humans are mortal?
No: on the basis of observation alone one cannot tell that the abstract
general proposition ‘all humans are mortal’ is true – it’s just a correlation
Yet Aristotle did believe that ‘all humans are mortal’ was necessarily true
Aristotle’s solution
o Induction is therefore only a first step
o 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
o This is intuitive induction (= understanding)
o But that is a rationalistic element in his epistemology
o When Aristotle had found a general statement, he was not very critical towards that
statement
o That is understandable: he thought he had established via intuitive induction that the
statement was true
The role of Aristotle in the late middle ages
In the middle ages, the catholic church had a lot of power
Issues relating to knowledge and reality were resolved either by quoting the bible or by
quoting Aristotle
Two paths to the truth
o Revelation
o To use your good sense (and if anyone did, that was surely the pagan Aristotle)
Thomas Aquinas
o Aquinas tried to unite Christian teaching with the pagan ideas of Aristotle
, o Example:
Aristotle had a theory about matter and form
Matter is potentially something
The shape makes something that actual thing
This is a process of creation and decay
o Aquinas argued that god has put this process of creation and decay in motion
o Aristotle’s unmoved mover (= the first cause)
implication of the coupling of Aristotle to the bible
o one could not just simply disagree with Aristotle
o for what Aristotle had said was the truth that was in the bible
o so attacking Aristotle implied attacking the Bible
experiments
o in modern science we perform experiments to learn about the natural world
o Aristotle did no experiments because he thought that they would not teach us
anything about the natural world
Why did Aristotle hold these views?
o Aristotle wanted to acquire knowledge about the natural world
o He already had a classification of plant and animals
o He used the method of observation
o By manipulation we make the world go against the natural ways of things and as such
we do not learn anything about the natural world
In the middle ages both philosophy and science (there was no difference back then) came
more or less to a halt
Lecture 2
Francis Bacon’s new method
Bacon had no problem with questioning the Aristotelian worldview
Against Aristotle, Bacon argued that we should use experiments to learn about the natural
world
The new method
o We need to abandon our epistemic 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
It involves the following idols
Idols of the tribe
o Prejudices we have as humans
o We tend to make typical human mistakes
o Bacon
Seeing order and regularity where there is none
The search for confirmation and ignoring refutations
of what you believe
We see the sun go down (but that is not what
happens)
Sailors that trust in the power of prayer
Idols of the cave
o Prejudices that we have because we belong to a particular
group
What is philosophy of science?
= this philosophical (critical) reflection on what science is, does, and how it generates knowledge
Why philosophy of science for psychologists?
Psychology is a science
o Knowledge – why?
o Skills
Is psychology a science?
Is it justified that science has the monopoly on acquiring knowledge?
o Character
Building of character
Better psychologists, better scientists, better citizens
Understanding society advancing society
Epistemology
= theory of knowledge
Philosophy of science began with epistemology
Epistemology asks three questions
o What is knowledge
o How can we justify that knowledge
o What is the source of knowledge
Traditionally there are two views
o Rationalism = real knowledge is derive from the ratio, reason
o Empiricism = real knowledge comes from sensory experience
Is it possible to have real knowledge?
Rationalism and empiricism say yes
What are we certain of?
Skepticism
Socrates in the market square
Ask difficult questions
o Always question about if you really know something no
Skepticism = perhaps the conclusion must even bet that we do not know anything at all and
never will
Socrates is convicted
Rationalism
General claim: real knowledge stems from our reason (= ration)
Associated claim: there is innate knowledge (= nativism)
Different views on rationalism
o Plato, Descartes etc.
Plato
The source of knowledge is our reason
To learn is to remember (= anamnesis)
, There is no new knowledge – you do not learn anything
Why did he claim this?
o Reincarnation
o Plato believed that before you were born, you had all real knowledge and you lost
that knowledge when you were born
Using your ratio to recall the knowledge
Plato made distinction: Episteme vs doxa
o Episteme = knowledge of how the things are
o Doxa = opinion about how the things are
Plato: knowledge = justified and true belief
o Justification – You can explain how you know it is true
Plato responds to Heraclitus
o Panta rhei = everything is a constant flux
o If in our world (= the world we perceive with our senses) everything changes
constantly, then nothing is
o And that means we can only acquire doxa, not episteme
o And that would amount to skepticism but Plato did not want that
Plato’s allegory of the cave
o Ideas/forms exist apart from us in a world of ideas/forms
o Those ideas do not change
o The soul is akin to those ideas
o Acquiring knowledge is to remember these ideas – anamnesis
Meno – book
o How do you double the surface of this square? Asking Meno the slave
o First Meno 4 doubles the surface
o Zeus (Plato) then makes another square which is double the surface and Meno say
now I remember how to double the surface - anamnesis
o This is obviously unacceptable: Socrates puts the slave of Meno words in the mouth
o This kind of rationalism is very extreme
o Descartes had a weaker version
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
The general 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
There is a difference between empiricist and empirical
o ‘empiricist’ refers to empiricism, the opposite of rationalist
o ‘empirical’ refers to scientific method, which uses observational of experimental data
to infer conclusion about the world
Empirical evidence is gained through observations or experiments
Empirical is the opposite of purely hypothetical
,Aristotle
Rejected Plato’s two-world theory – there is only one world and that is the one we can
perceive with our sense
This also implies a rejection of innate ideas: man is a tabula rosa (= a blank wax tablet)
Peripatetic principle
o Aristotle is the founder of the lyceum, where he taught while walking
o 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
The key to Aristotle’s epistemology is indeed sensory perception
In this sense we can rightly call Aristotle an empiricist
But he does have some rationalist elements in his ‘empiricist’ epistemology
Universal concepts
o According to Plato the general idea chair is an entity existing in the world of ideas
o Aristotle rejects this
o Aristotle accepts only the existence of concrete, individual things (the individual
chair)
o How then do we arrive at a universal, abstract concept (thus the concept ‘chair’ that
applies to all individual chairs)?
Induction
o Aristotle called the empirical procedure by which we move from the concrete to the
universal induction
o Take an abstract, general statement like ‘all humans are mortal’
o What you perceive are just real people, and you can establish that they are mortal
o Induction is concluding based on observation of some cases (but not all)
o Problem
Are you sure that all humans are mortal?
No: on the basis of observation alone one cannot tell that the abstract
general proposition ‘all humans are mortal’ is true – it’s just a correlation
Yet Aristotle did believe that ‘all humans are mortal’ was necessarily true
Aristotle’s solution
o Induction is therefore only a first step
o 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
o This is intuitive induction (= understanding)
o But that is a rationalistic element in his epistemology
o When Aristotle had found a general statement, he was not very critical towards that
statement
o That is understandable: he thought he had established via intuitive induction that the
statement was true
The role of Aristotle in the late middle ages
In the middle ages, the catholic church had a lot of power
Issues relating to knowledge and reality were resolved either by quoting the bible or by
quoting Aristotle
Two paths to the truth
o Revelation
o To use your good sense (and if anyone did, that was surely the pagan Aristotle)
Thomas Aquinas
o Aquinas tried to unite Christian teaching with the pagan ideas of Aristotle
, o Example:
Aristotle had a theory about matter and form
Matter is potentially something
The shape makes something that actual thing
This is a process of creation and decay
o Aquinas argued that god has put this process of creation and decay in motion
o Aristotle’s unmoved mover (= the first cause)
implication of the coupling of Aristotle to the bible
o one could not just simply disagree with Aristotle
o for what Aristotle had said was the truth that was in the bible
o so attacking Aristotle implied attacking the Bible
experiments
o in modern science we perform experiments to learn about the natural world
o Aristotle did no experiments because he thought that they would not teach us
anything about the natural world
Why did Aristotle hold these views?
o Aristotle wanted to acquire knowledge about the natural world
o He already had a classification of plant and animals
o He used the method of observation
o By manipulation we make the world go against the natural ways of things and as such
we do not learn anything about the natural world
In the middle ages both philosophy and science (there was no difference back then) came
more or less to a halt
Lecture 2
Francis Bacon’s new method
Bacon had no problem with questioning the Aristotelian worldview
Against Aristotle, Bacon argued that we should use experiments to learn about the natural
world
The new method
o We need to abandon our epistemic 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
It involves the following idols
Idols of the tribe
o Prejudices we have as humans
o We tend to make typical human mistakes
o Bacon
Seeing order and regularity where there is none
The search for confirmation and ignoring refutations
of what you believe
We see the sun go down (but that is not what
happens)
Sailors that trust in the power of prayer
Idols of the cave
o Prejudices that we have because we belong to a particular
group
