K. Cs.
Philosophy of Science
Lecture 1: Introduction and ancient philosophers
The main question that the course tries to answer: Is psychology a science? It is a reflection on the studies
of the past 3 years.
In the early 20th century Philosophy of Science is already starting to become its own separate discipline
within philosophy because the answer to the question “Where does knowledge come from?”
(epistemology) is answered from science so then we need to know what science is.
1.1 What is philosophy of science?
Philosophy is about thinking critically, in this case philosophy of science is a philosophical (critical)
reflection on what science is, does and generates in terms of knowledge.
- For example: Why are the claims of Stephen Hawking about black holes fall within the realm of
science and Joke Damman's (paranormal medium) claims about white ghosts does not? If you
would claim scientific status from that (something you can’t observe), you would be a
pseudoscientist. By definition, you can't see black holes, yet we say Hawkins is a real scientist.
On the other hand, don't we believe Joke Damman’s? She also sees things we cannot see. So, what
is the difference?
1.2 What is science?
When we use the word science, we usually use it in the right manner and can tell when someone uses it
wrong. We don’t make a mistake and say that e.g., someone doing the dishes is doing science. But when
we reflect and think, what makes it science? What distinguishes it from pseudoscience? We know that
science should produce knowledge. But what exactly makes something science, what are the characteristics
of science? How is an astrologer different from a physicist?
1.3 What is the importance of philosophy of science to you (as psychologists)?
Psychology nowadays has the status of being a science. Is that true?
- So first of all, you need knowledge for that: You need to know the different answers that have
been given to the question, what is science?
- In addition, you must have the skills, the ability to critically reflect on questions such as: Is
psychology a science? Is it justified to call psychology a science? If you know what science is,
you still need to be able to apply it to psychology. You must have the critical ability to reflect on
the discipline yourself. Is it right that science has a monopoly on knowledge acquisition? Can you
argue this (skill)?
- If philosophy is critical reflection and you want to critically reflect on whether psychology is a
science or not, we could ask the question: Why are we doing that? As a psychologist, it is part of
your education. Your educational institution wants you to be a good psychologist. Not just be able
to use a therapy, but they want you to be able to understand why you could or should use a
certain therapy. Therefore, knowledge and skill serve another purpose, building of character. You
want to be a good scientist that e.g., does not cheat, as to avoid another Diderick Stapel incident.
o There is a replication crisis in psychology. Psychology research usually publishes only
positive results, when the hypothesis is confirmed. But refuted hypotheses are also
interesting. Doesn't this replication crisis point to something pseudoscientific in
psychology?
Better psychologists, better scientists, better citizens
By thinking critically about what science is, and whether psychology is a science, we hope you'll gain a
better understanding of psychology as a science, making you a better psychologist. If science has a
monopoly on acquiring knowledge, why don’t we do ‘astrology for psychologists’? That is at best
pseudoscience. A method of acquiring knowledge but it is not a very good method. Thinking critically
about the scientific status of your own discipline is not so easy.
We don't just want to deliver students with knowledge and skills so they can earn a lot of money. We want
(also as a university) to understand society, to advance society. To do this, one needs to understand
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society. We must therefore remain critical of elements within science that could be pseudoscientific in the
interests of society.
Epistemology is the theory of knowledge. The ancient philosophers were already asking questions about
knowledge but not about science, as there was no science like that back then.
Philosophy of science begins with epistemology. Epistemology asks three questions:
- What is (certain) knowledge? Isn’t knowledge always certain?
- How can we justify that knowledge? (In other words, is knowledge real knowledge?)
- What is the source of knowledge?
Two positions have traditionally been adopted on these issues:
- Rationalism: true knowledge comes from the ratio, reason.
- Empiricism: real knowledge comes from sensory experience.
- Both rationalists and empiricists believe that you can have real knowledge.
They answer the question, ‘What are you sure of?’ with ‘nothing at all, I'm not even sure I know nothing
for sure’. That’s not knowledge. Therefore, this puts them in conflict with the skeptics.
Skepticism answers the knowledge question by stating ‘there is no knowledge possible’. The main figure
of this viewpoint was Socrates (Plato’s teacher), who stood at the marketplace asking ‘What do you know?
Is there something you are absolutely sure of?’. He used the so-called Socratic method, where he kept
asking ‘How do you know this?’ until it was difficult to claim certainty over a certain viewpoint. Socrates
is later convicted for atheism and having a bad influence on the younger people. The remaining question
after dealing with skepticism is whether it is indeed true that there is nothing we can actually know for
sure?
Rationalism would argue no, there is many things that we can be sure of. Since they argue that real
knowledge stems from our reason (ratio) this also brings an associated claim which is that there is innate
knowledge (nativism). Innate knowledge is something that is inborn, that you already possess. Even those
philosophers within rationalism have a different degree of radicality that they take in terms of answering
certain questions.
Plato was a radical rationalist (& defends extreme nativism). Further he believes that to learn is to
remember (anamnesis) with your ratio. This also means that there is no new knowledge, you do not really
learn anything. He says this because he believes in reincarnation. This is the belief that the soul of a
person moves from body to body and so on. This fits into his theory cause in this way he says that before
you were born, your soul was in another world. That is where the real ideas are, or the real knowledge. But
birth was a traumatic experience and you forgot everything.
- Plato distinguishes between epistème and doxa. Epistème is the knowledge of how things are.
Doxa is the opinion about how things are, it is a mere opinion that is not yet argued. He
believes that epistème is real knowledge, a justified and true belief. So, you have a belief, a
mental state that is about the world and it’s true. That means that it corresponds to the facts.
The world is actually how your mental state depicts it. It’s justified because you can explain
how you know that it’s true. A skeptic would say that you will never be able to provide a
proper justification for any belief. But then you only have doxa. If that is true, a real skeptic
should not say anything about the world.
With this distinction between epistème and doxa Plato responds to Heraclitus. Heraclitus says that if you
look at our world (the world we perceive with our senses), you notice that everything is in constant flux.
Everything is changing constantly. This is Panta rhei, everything flows. You can't step into the same river
twice according to Heraclitus, because if you step into the river, step out of it and step back in again it took
time. Within this time water has flowed through the river. So, the river is not exactly the same one that you
stepped into the first time around. This also applies to the person who steps into the river, you also
changed. If you think you have knowledge about the world we perceive with our senses, you don’t have
real knowledge because you can only have knowledge about how the things are. That means, we can only
acquire doxa if we are talking about the world we perceive with our senses. This would amount to
skepticism. Plato did not want skepticism. He lands at the conclusion that if we cannot have knowledge
about this world, then it has to be knowledge about a different world (two worlds theory).
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In this world, everything stays the same, where everything actually is. This is the world of forms, the
world of ideas. There is the idea of a chair, a river..etc. It is possible to have knowledge about them
because they do not change. Your soul belongs to this world. It is a kind of heaven, before there was
Christianity. Your soul has thus seen all the ideas. He illustrates this with the allegory of the cave
- Prisoners chained together facing a wall observe the shadow of people holding up chairs and tables,
illuminated by the fire that allows them to only perceive the objects not the people. They believe
that the shadow is the real chair. We are in a similar situation. Our souls are imprisoned in our
bodies, and we see what we believe is a real table. But the real chair and table is in the world of
forms & ideas. Plato tries to show in this way that your senses do not provide real knowledge,
about the real world (contradicting empiricism).
- What Plato implied is a universal concept, tables and chairs are universal.
Plato explains how it all works in his book, Meno. He wrote it in a dialogue format where there is a man
named Meno, who owns land and slaves. Upon talking to Socrates, he asks if one of his slaves would be
able to ‘learn by remembering’. Socrates says yes. They test this by Socrates drawing up a square in the
sand and asking the slave ‘do you know what to do to double the surface of this square?’. But this is
unacceptable, Socrates puts words in the slave’s mouth. This kind of rationalism is very extreme.
Empiricism is another view that argues against skepticism. The general claim of this view is that the
source of knowledge is the experience gained through sensory perception. Thus, they agree with the
rationalists that real knowledge is possible, they just agree on a different way of acquiring it. This is a
commonsense view compared to Plato: if you want to know what the world is like, just look at it. Comes
from the Greek word: empeira, in Latin experienta. The empiricist view also holds an associated claim. It
says that if all knowledge comes from sensory perception, there is no innate knowledge.
Empiricist is not the same as empirical. Empiricist refers to empiricism, the view that knowledge comes
from sense perception. Empirical refers to the scientific method, where one uses observable or
experimental data to draw conclusions about the world. Empirical evidence for a theory is thus the
evidence obtained through observation and experimentation. Empirical is opposed to hypothetical or
merely theoretical.
Aristotle was an empiricist. He was the student of Plato, but he was a very critical student. He rejects
Plato's two-worlds theory. He claims that there is only one world, and it can be perceived with the senses.
He only acknowledges the existence of the world as we perceive it (the changeable world). He does not
believe in the world of ideas. By observing with the senses, knowledge is acquired. This also implies a
rejection of innate ideas; the man is a tabula rasa (a blank wax tablet → in ancient Greece they wrote on a
blank wax tablet). Aristotle was the founder of the Lyceum, where he taught his students while walking
(peripateo in Greek). His student, Thomas Aquinas thus called the empiricist principle the peripatetic
principle. It says that ‘nothing is in the intellect which was not first in the senses’. Aristotle does not
formulate this principle himself. This means that Aquinas’s interpretation is mostly correct, however
Aristotle’s empiricist epistemology does have rationalist elements, it isn’t pure empiricism.
- When thinking about universal concepts (idea of the chair, table..etc.) Aristotle rejects the two
worlds theory.
- He only accepts the existence of concrete, individual things (the universal chair, the concept that
applies to all individual chairs). One does not perceive general concepts.
He solves this problem by induction. This is the notion of going from individual to general cases. When
you take a general statement such as ‘all humans are mortal’, what you perceive are just real people and
you can establish that they are mortal because you most likely know someone who has died. It is
concluding, on the basis of some (but not all) observations in which A is also B, or was followed by B, that
A is always B, or is always followed by B. The problem with it is that on the basis of observation alone,
you cannot say that a general statement like ‘all humans are mortal’ is true, only if you have observed all
cases. This is practically impossible. Therefore, this is just a correlation. Yet Aristotle did believe that this
was necessarily true. He solves this by saying induction was only a first step. A second step is needed,
you have to see through your infallible intellectual capacity of the mind (nous) that abstractions like ‘all
humans are mortal’ are necessary truths. This is intuitive induction (understanding). This is a
rationalistic element in his epistemology. When he found a general statement, he was not very critical
about it, which is understandable as he thought that he established via intuitive induction that the statement
was true.
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In the Middle Ages the Catholic Church had a lot of power. Issues relating to knowledge and reality were
resolved by either quoting the Bible or by quoting Aristotle. There was two paths to the truth: revelation
(Bible) and to use your good sense (if anyone did, it was the pagan Aristotle). Aquinas tried to unite
Christian teaching with the pagan (= born after Christ) idea of Aristotle (the Philosopher = Aristotle). An
example is that Aristotle had a theory about matter and form. Matter (such as a piece of marble) is in a
state of being, it is more than just matter. Perhaps it is a statue. Only through the form does it really
become something (think of a statue that may potentially be present in a piece of marble). The statue can
break again. This is therefore a process of creation and decay. Aquinas argues that this process of
creation and decay was put in motion by God since he created the world. Aristotle says that everything is
constantly changing, in constant flux but the movement is due to a first cause that was not itself moved by
something else but put everything in motion. This first cause is the unmoved mover, God. This view of
his is essentially what the Bible said. Hence one could not just simply disagree with Aristotle. Attacking
Aristotle implied attacking the Bible. This meant that nobody attacked Aristotle, it had some severe
consequences for acquiring knowledge. The reason why it held back progress is because of Aristotle’s
view on experiments. He did not do experiments, because he thought that they would not teach us anything
about the natural world. The reason is, he wanted to have knowledge about the natural world. He had a
classification of plants and animals (in which he classified whales as mammals), he used the method of
observation. By manipulating, let’s say by lifting a stone, we make the world go against the natural ways
of things and as such we do not learn something about the natural world. There is teleology in the natural
world, the rock wants to be at its natural place. If you want to know it’s natural place you have to observe
where it goes when moving in a natural way. The consequence of this is that in the Middle Ages both
philosophy and science came more or less to a halt. A revolution was needed where the catholic church did
not have that much power anymore.
Example questions
Plato was the founder of the first academy. What was his conception of Ideas?
[a]Ideas are in your head and are the same for everyone.
[b]Ideas are in your head and are (somewhat) different for everyone.
[c]Ideas exist independently of people and are different by culture.
[d]Ideas exist independently of people and are therefore the same for everyone.
Plato’s view that to learn actually is to remember is an example of:
[a] Empiricism, because you learn by means of experience.
[b] Empiricism, because you remember by means of experience.
[c] Rationalism, because you learn by using your reason properly.
[d] Rationalism, because you remember by using your reason properly.
Aristotle often is presented as one of the first empiricists. Which of the following claims was
something which Aristotle defended & is also in line with empiricism?
[a] Acquiring knowledge about concepts requires intuitive induction.
[b] We can acquire knowledge about the visible world by doing experiments.
[c] We know that all human beings are mortal.
[d] When someone is born, they are a tabula rasa.
Socrates, Plato and Aristotle disagreed about whether it was possible to acquire knowledge. Who of
these three philosophers would argue that it is impossible to acquire knowledge about
the river Ilisos that flows through Athens?
[a] Aristotle and Socrates would argue that it is impossible. Plato would argue that it is possible.
[b] Plato would argue that it is impossible. Socrates & Aristotle would argue that it is possible.
[c] Socrates & Plato would argue that it is impossible. Aristotle would argue that it is possible.
[d] Socrates would argue that it is impossible. Plato & Aristotle would argue that it is possible.
If it storms the clouds move really fast through the sky. Can we have knowledge of the speed of the
clouds according to Plato and Aristotle?
[a] Both think we can have knowledge about this.
[b] Both think we cannot have knowledge about this.
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