PART 1: Hans Dooremalen
Lecture 1: Introduction and Ancient Philosophers
Philosophy of science: the philosophical, critical reflection on what science is, does and how it
generates knowledge
What is science? - we have an idea but no clear answer, we need knowledge and skills to
answer
Is psychology a science?
Epistemology: where knowledge comes from (rationalism vs empiricism)
= theory of knowledge
Philosophy of science began with epistemology
Asks 3 question:
- What is certain knowledge?
- How can we justify that knowledge?
- What is the source of knowledge?
Traditionally there are 2 views:
1. Rationalism: real knowledge is derived from the ratio, reason
2. Empiricism: real knowledge comes from sensory experience
Real knowledge is possible
Ancient Greek philosophers:
Skepticism: claim we cannot have any knowledge at all - “perhaps the conclusion must be that
we do not know anything at all, and never will”
- Socrates: main skeptic, convicted to death for atheism and having a bad influence on
young people in Athens
Rationalism: real knowledge comes from our reason (ratio)
- Associated claim: there is innate knowledge (nativism)
Plato: most radical rationalism, “to learn is to remember” → anamnesis
- There is no new knowledge - you do not really learn anything
- Plato believed in reincarnation: that before you were born, you had all real knowledge
and you lost that knowledge when you were born, because birth was traumatic - you
don’t have immediate access to that knowledge but you use ratio to access it and
remember what you already knew
Episteme vs doxa:
- Epistéme: knowledge of how the things are
- Doxa: opinion about how the things are
- Plato: knowledge = justified and true belief
- Correspondence theory of truth: a sentence is true if it corresponds to the facts and
depicts the world the way the world is
Plato responds to Heraclites with this idea with episteme and doxa
- Agrees that we learn through observing
1
,Panta rhei: everything is in a constant flux, everything changes constantly → we can only
acquire doxa and not epistéme (this amounts to skepticism)
- You can never step into the same river twice, because both you and the river change
But Plato did not want skepticism, he thought knowledge is possible
Plato’s allegory of the cave: ideas / forms exist apart from us in a world of ideas / world of
forms
- The soul is akin to those ideas
- Acquiring knowledge is to remember these ideas (your soul has seen all these ideas /
forms but you forgot them when you were born) - > anamnesis
- Prisoners only observe the shadows of the chairs and table, and they believe these
shadows are the real tables
- We are in the same situation - we believe that what we perceive is the real world, but
there actually is another world that is the real world
- Explains how this works is in his book “Meno”: Meno is a land owner, Socrates says to
Meno “to learn is to remember your ideas” and he says “so one of my slaves will also be
able to do that”, Socrates draws a square in the sand and asks the slave to double the
surface of the square, the slave draws 4 times the square and Socrates draws this and
the slave says he now remembers
This is unacceptable: Socrates puts words in the mouth of Meno’s slave
- This kind of rationalism is very extreme
- Descartes had a weaker version (lecture 2)
Empiricism: the source of knowledge is the experience gained through sensory perception
- Common sense view: if you want to know how something is, you have to look
- Greek: empeira → not like scientific “empirical”
- Latin: experienta
- Associated claim: if all knowledge comes from experience via perception, there is no
innate knowledge
Empiricist ≠ empirical
- Empiricist = opposite of rational
- Empirical = scientific method, which uses observations of experimental data to infer
conclusions about the world
- Empirical evidence is evidence that is gained through observations of
experiments → the opposite of purely hypothetical
2
,Aristotle: empiricist
- Rejected Plato’s two-worlds theory: there is only one world and that is the one we can
perceive with our senses
- Implies a rejection of innate ideas: man is a tabula rasa (blank wax tablet)
Peripatetic principle: Aristotle was the founder if the Lyceum, where he thought while walking
(peripateo in greek)
- Hence Aquinas later called the empiricist principle peripatetic principle: “Nothing is in the
intellect which was not first in the senses”
Is Aquinas’ interpretation of Aristotle correct?
- They key to Aristotle’s epistemology is indeed sensory perception, so we can rightly call
Aristotle an empiricist
- But he does have some rationalist elements in his empiricist epistemology (so he is not
a pure empiricist)
Universal concepts:
- According to Plato the (general / universal) idea “chair” is an entity existing in the world
of ideas
- Aristotle rejects this: he accepts only the existence of concrete, individual things (the
individual chair)
- How then do we arrive at a universal, abstract concept (thus the concept “chair” that
applies to all individual chairs)?
Induction: Aristotle called the empirical procedure by which we move from the concrete to
the universal induction
- Take an abstract, general statements like “all humans are mortal”
- What you perceive are just real people (individuals), and you can establish that they are
mortal
- Induction is concluding - based on observation of some cases (but not all) in which A
was also B or was followed by B - that A is always B or is always followed by B
(generalization) → constant conjunction
Problem with induction: on the basis of observation alone one can not tell that the abstract
general proposition “all humans are mortal” is true - it’s just a correlation, you cannot check if
every single human being is mortal
- Yet Aristotle believed that “all humans are mortal” was necessarily true
Aristotle’s solution: induction is therefore only the 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
- When Aristotle had found a general statement, he was not very critical towards that
statement
- That is understandable: he thought he had established via intuitive induction that the
statement was true
3
, Aristotle’s role in the late middle ages
- In the middle ages, the Catholic Church had a lot of power
- Issues relating to knowledge and reality were solved either by quoting the Bible or by
quoting Aristotle
- 2 paths to the truth: 1. Revelation and 2. To use your good sense (and if anyone did, that
was surely the pegan Aristotle)
Thomas Aquinas: tried to unite Christian teaching with the pagan ideas of Aristotle (“The
Philosopher”)
Example: Aristotle had a theory about matter and form
- Matter (as piece of marble) is potentially something (a statue)
- The shape makes something that actual thing (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 in the causal chain of event): there has to be
something that was not itself moved by something else
- Christian God is the unmoved mover
Implication of the coupling of Aristotle to the Bible:
- One could not just simply disagree with Aristotle
- For what Aristotle has said was the truth that was in the Bible → attacking Aristotle
meant attacking the Bible (this meant severe consequences on the development of
knowledge)
Aristotle’s views on experiments:
- In modern science we perform experiments to learn about the natural world
- Aristotle did no experiments because he thought that they would not teach us anything
about the natural world
Aristotle’s reason:
- He wanted to acquire knowledge about the natural world
- He already had a classification of plants and animals (classified whales as mammals)
- He used the method of observation → wait and see what happens in the world if
you don’t touch it
- By manipulating (lifting a rock) we make the world go against the natural ways of things
and as such we do not learn anything about the natural world
- If you manipulate, it is not natural → it is dangerous to do experiments
Consequence: in the middle ages both philosophy and science (no difference back then) came
more or less to a halt
4
Lecture 1: Introduction and Ancient Philosophers
Philosophy of science: the philosophical, critical reflection on what science is, does and how it
generates knowledge
What is science? - we have an idea but no clear answer, we need knowledge and skills to
answer
Is psychology a science?
Epistemology: where knowledge comes from (rationalism vs empiricism)
= theory of knowledge
Philosophy of science began with epistemology
Asks 3 question:
- What is certain knowledge?
- How can we justify that knowledge?
- What is the source of knowledge?
Traditionally there are 2 views:
1. Rationalism: real knowledge is derived from the ratio, reason
2. Empiricism: real knowledge comes from sensory experience
Real knowledge is possible
Ancient Greek philosophers:
Skepticism: claim we cannot have any knowledge at all - “perhaps the conclusion must be that
we do not know anything at all, and never will”
- Socrates: main skeptic, convicted to death for atheism and having a bad influence on
young people in Athens
Rationalism: real knowledge comes from our reason (ratio)
- Associated claim: there is innate knowledge (nativism)
Plato: most radical rationalism, “to learn is to remember” → anamnesis
- There is no new knowledge - you do not really learn anything
- Plato believed in reincarnation: that before you were born, you had all real knowledge
and you lost that knowledge when you were born, because birth was traumatic - you
don’t have immediate access to that knowledge but you use ratio to access it and
remember what you already knew
Episteme vs doxa:
- Epistéme: knowledge of how the things are
- Doxa: opinion about how the things are
- Plato: knowledge = justified and true belief
- Correspondence theory of truth: a sentence is true if it corresponds to the facts and
depicts the world the way the world is
Plato responds to Heraclites with this idea with episteme and doxa
- Agrees that we learn through observing
1
,Panta rhei: everything is in a constant flux, everything changes constantly → we can only
acquire doxa and not epistéme (this amounts to skepticism)
- You can never step into the same river twice, because both you and the river change
But Plato did not want skepticism, he thought knowledge is possible
Plato’s allegory of the cave: ideas / forms exist apart from us in a world of ideas / world of
forms
- The soul is akin to those ideas
- Acquiring knowledge is to remember these ideas (your soul has seen all these ideas /
forms but you forgot them when you were born) - > anamnesis
- Prisoners only observe the shadows of the chairs and table, and they believe these
shadows are the real tables
- We are in the same situation - we believe that what we perceive is the real world, but
there actually is another world that is the real world
- Explains how this works is in his book “Meno”: Meno is a land owner, Socrates says to
Meno “to learn is to remember your ideas” and he says “so one of my slaves will also be
able to do that”, Socrates draws a square in the sand and asks the slave to double the
surface of the square, the slave draws 4 times the square and Socrates draws this and
the slave says he now remembers
This is unacceptable: Socrates puts words in the mouth of Meno’s slave
- This kind of rationalism is very extreme
- Descartes had a weaker version (lecture 2)
Empiricism: the source of knowledge is the experience gained through sensory perception
- Common sense view: if you want to know how something is, you have to look
- Greek: empeira → not like scientific “empirical”
- Latin: experienta
- Associated claim: if all knowledge comes from experience via perception, there is no
innate knowledge
Empiricist ≠ empirical
- Empiricist = opposite of rational
- Empirical = scientific method, which uses observations of experimental data to infer
conclusions about the world
- Empirical evidence is evidence that is gained through observations of
experiments → the opposite of purely hypothetical
2
,Aristotle: empiricist
- Rejected Plato’s two-worlds theory: there is only one world and that is the one we can
perceive with our senses
- Implies a rejection of innate ideas: man is a tabula rasa (blank wax tablet)
Peripatetic principle: Aristotle was the founder if the Lyceum, where he thought while walking
(peripateo in greek)
- Hence Aquinas later called the empiricist principle peripatetic principle: “Nothing is in the
intellect which was not first in the senses”
Is Aquinas’ interpretation of Aristotle correct?
- They key to Aristotle’s epistemology is indeed sensory perception, so we can rightly call
Aristotle an empiricist
- But he does have some rationalist elements in his empiricist epistemology (so he is not
a pure empiricist)
Universal concepts:
- According to Plato the (general / universal) idea “chair” is an entity existing in the world
of ideas
- Aristotle rejects this: he accepts only the existence of concrete, individual things (the
individual chair)
- How then do we arrive at a universal, abstract concept (thus the concept “chair” that
applies to all individual chairs)?
Induction: Aristotle called the empirical procedure by which we move from the concrete to
the universal induction
- Take an abstract, general statements like “all humans are mortal”
- What you perceive are just real people (individuals), and you can establish that they are
mortal
- Induction is concluding - based on observation of some cases (but not all) in which A
was also B or was followed by B - that A is always B or is always followed by B
(generalization) → constant conjunction
Problem with induction: on the basis of observation alone one can not tell that the abstract
general proposition “all humans are mortal” is true - it’s just a correlation, you cannot check if
every single human being is mortal
- Yet Aristotle believed that “all humans are mortal” was necessarily true
Aristotle’s solution: induction is therefore only the 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
- When Aristotle had found a general statement, he was not very critical towards that
statement
- That is understandable: he thought he had established via intuitive induction that the
statement was true
3
, Aristotle’s role in the late middle ages
- In the middle ages, the Catholic Church had a lot of power
- Issues relating to knowledge and reality were solved either by quoting the Bible or by
quoting Aristotle
- 2 paths to the truth: 1. Revelation and 2. To use your good sense (and if anyone did, that
was surely the pegan Aristotle)
Thomas Aquinas: tried to unite Christian teaching with the pagan ideas of Aristotle (“The
Philosopher”)
Example: Aristotle had a theory about matter and form
- Matter (as piece of marble) is potentially something (a statue)
- The shape makes something that actual thing (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 in the causal chain of event): there has to be
something that was not itself moved by something else
- Christian God is the unmoved mover
Implication of the coupling of Aristotle to the Bible:
- One could not just simply disagree with Aristotle
- For what Aristotle has said was the truth that was in the Bible → attacking Aristotle
meant attacking the Bible (this meant severe consequences on the development of
knowledge)
Aristotle’s views on experiments:
- In modern science we perform experiments to learn about the natural world
- Aristotle did no experiments because he thought that they would not teach us anything
about the natural world
Aristotle’s reason:
- He wanted to acquire knowledge about the natural world
- He already had a classification of plants and animals (classified whales as mammals)
- He used the method of observation → wait and see what happens in the world if
you don’t touch it
- By manipulating (lifting a rock) we make the world go against the natural ways of things
and as such we do not learn anything about the natural world
- If you manipulate, it is not natural → it is dangerous to do experiments
Consequence: in the middle ages both philosophy and science (no difference back then) came
more or less to a halt
4
