Week 5
Chapter 7: Critical Rationalism: Science on Piles, Above a Swamp
7.1: Introduction
• Karl Popper was the first of a long line of critics of positivism
• He was a philosopher from Vienna
• Obituaries hailed him as the most important thinker
• He swung the pendulum back from empiricism to rationalism (critical rationalism)
7.2 Popper and the Weiner Kreis
• The circle would not admit him member
- He heavily criticised Wittgenstein for being a dogmatist
• Logic of Scientific Discovery - critique of positivism
- Book called the Trojan horse; popper disagreed with positivists and his conceptions of science were so
different they soon led to the Circle’s collapse.
- He agreed on the importance of logic and mathematics and appreciated empirical testing but he
believed there was also a rational aspect to knowledge and science
- For Popper theory come before, not after, observation
7.3 The Crucial Year, 1919
7.3.1 Popper’s clash with Marxism
• He quit high school because he believed his teachers couldn’t teach him anything new: went directly to
University
• He became marxist for a couple of months until violent protest killed multiple innocent people and he
realised that:
1. Humans are liable to make mistakes and there is no denying that human beings are fallible
creatures (he made a mistake by joining the Marxist group)
2. There is a major difference between dogmatic theories like the Marxist theory of history and
critical thinking (Marxist theory was always right and not built on critical thinking ->
pseudoscience)
7.3.2 Popper meets Alfred Adler
• Popper came up with cases where Adler’s theory (Adlerian psychoanalysis) was not true and compared
them to the theory
• Adler was able to explain these cases by adding another statement to the theory that essentially led to every
single case being true
• The statements had a ring of logic in them that made them always true
• Similar to: “tomorrow it will or will not rain”
• Poppers problem with such theories is that we can never know if they are right since we do not know if
they are wrong (due to the structure)
• The experiences with Marxism and Adler’s psychology led him to question the scientific value of theories
that are able to explain every possible observation
• —> Believed Marxism and Adlerian psychoanalysis were much like astrology in the sense that they could
explain everything; they have unlimited explanatory power (everything explained them)
- Popper believed that was not a strength but a sign of profoundly unscientific character of such
theories
7.3.3 Popper and the bending of light
• Showed Popper how real science is conducted
• Revolution in Science - Newtonian Ideas Overthrown: refereed to a meeting that Popper Ould later call the
‘falsification’ of Newtonian physics
• Newton believed light of starts would bend (0.”84) as it passes alongside an enormous mass like the sun
• Einsteins calculations doubled the value of gravitational bending
• Before the observation we already knew which observations would prove Newton or Einstein right
• Looking for falsifying elements in theories (only ones that can be falsified are true)
• Arthur Eddington designed a test to decide between Newtons’ and Einstein theories (Einstein was correct)
• Eddington's experiment proved that even an important old theory could be falsified
• The theories of Newton and Einstein were bold and risky: could be tested and refuted in a crucial test
(eclipse observation)
7.4 From verification via confirmation to falsification
,• Popper also struggled with drawing a line between science and non science
• If we adopt the logical positivists criterion of verification the implication is that some of the best scientific
achievements no longer deserve to be called scientific
• Many theories turned out not to be true yet still must be considered scientific
• A lot say science is inductive however there is a fundamental problem with induction
• As Hume said induction cannot be logically justified
- Impossible to take the leap from the limited amount of observations one has obtained in the past to a
universal claim that applies to each and every observation in past, present and future
- Example: impossible to verify the claim “all swans are white”, in order to establish its truth or falsity
on would have to check each and every swan for its whiteness (even those dead and still unborn) no
matter how many swans you examine you cannot state the the next one will not be black, or even
purple.
- It follows from Hume that the core statements about science cannot be verified
- No law can be verified because it is impossible to check each and every instance that falls under the law
• Schlick’s response: Theories are not absolute truth but an instrument to predict ex. “all metals heat when
expanded” has no truth value but is a statement used to generate the prediction that this particular piece of
iron will expand when heated
• Carnap’s response: attempt to increase a statements degree of confirmation: a theory must be in
agreement with established facts
- He believed we would have to reject everything if we had to state with certainty that something can
be verified
- Science characterised as increasing confirmation
- With every white swan we spot the degree of confirmation of the theory increases
- Verifiability replaced by confirmability
Popper’s response to Carnap
• The boundary between science and non science is not clear
• Empiricist solutions don’t work good enough
- Verification too strong: Verification meant to confirm through empirical evidence (factual and formal
statements)
- logical positivists believed in phenomenalism where statements where 100% verifiable but subjective
(correspondence: experience = reality)
- Confirmation too weak: related to logical positivists physicalism where they believed statements to be
true but not certain if they were highly coherent (many people agreed), they were objective but not
verifiable
• High confirmation leaves too much room for pseudoscientific and non-scientific statement to count as
science e.g.
- Tomorrow it either rains or not
- There exists an omnipresent and omniscient personal spirit (the arch-metaphysical assertion)
- They are virtual tautologies
- —> such statements are always right (high degree of confirmation)
Criterion of demarcation: distinguishing between science and non science
Popper’s solution: falsificationism
7.5 Falsificationism
Falsibialiity is an adequate criterion of demarcation
• Theories are science as long as they are falsifiable: we know the conditions under which they would be
falsified. We look for cases in which the statement is not true, if we do not find any the theory can be
accepted temporarily, this temporary acceptation is called corroboration
• If a theory fails to make predictions that might conceivably be wrong (as do the arch-metaphysical
assertions, the Marxist theory of history and Adler’s individual psychology) it is not a scientific theory
Characteristics of Popper’s falsificationism
1. Real sciences are falsifiable, pseudosciences lack this potential of being wrong
• Statements such as ‘it will or it will not rain tommorow’ are useless because they are always true
• Horoscopes are similar to tautological weather forecasts
2. Popper’s falscificationism acknowledges that humans are fallible creatures
- We do not know, we can only guess
- History shows every theory can turn out to be wrong, like Aristotle’s or Newtons’
- Negative road to truth: Popper believes the only way in which our knowledge can grow is by trying to
locate, remove and correct our mistakes (by trying to find instances in which our theories are not true)
3. Only theories that are falsifiable are informative
, - The weather statement does not inform us about anything
- Human beings are error prone and our biological make up prevents us from ever attaining certainty
- Statements such as: you might be sick next week also do not inform us about anything, they are not
falsifiable because they just state something might or might not happen
- Important to remember Popper had no issue with the meaning of statements, he just used falsification as a
demarcation criteria but that did not mean that statements or theories had no meaning, they simply were
not scientific, same as the arch-metaphysical statement we considered earlier is unscientific but not
meaningless
Popper: states theories can start as myths:
- Myths or pseudoscience can be very meaningful (in society only), however it needs to be transformed into
science in order to be called a theory -> falsification demarcation
- Example: evolution theory is based on myth of Empedocles of Agrigentum (plants and humans were once
one)
4. Only through falsification can scientific knowledge grow (through conjectures and refutations,
trial and error, deduction instead of induction)
• Unlike induction, deduction is logically valid
• Example of induction: swan a, swan b and swan n is white therefore all swans are white
• Popper believed we cannot accept it because we cannot exhaust the possibilities of where a swan could
be a different colour
• Example of deduction: all As and B, B. All men are mortal, then the next individual A. The president of the
US with be B. Mortal
• If the premises are true the conclusion must be true
• We can assume all swans are white and reach a conclusion that the next swan will also be white
• A true scientist will working on falsifying their theory
• We must come up with risky predictions from our theoretical guesses concerning the nature of reality
• These conjectural theories must be put to test under serve circumstances
• Observing another white swan will not teach us anything yet observing as for all we know the next one
might be purple but observing the first black swan teaches us that not all swans are white.
Poppers criticism of Freud’s Oedipus complex and Adler’s Inferiority Complex
• Adler inferiority complex theory: man saves kid because he does something no one else dares or lets it
drown to also do something no one else does (theory cannot be falsified)
• Oedipus complex: all boys want to sleep with their mothers and kill their fathers and all that don’t admit
are in denial)
- Both scenarios (both the boy that admits to this and the one that denies it) will confirm the theory, there
is not case in which the theory is false
• All use immunisation tools: changing your theory so it become right when new information comes up
- Their formulation makes them always right
- They adjust the theory after observations
- Their theory explains everything
- That cannot be scientific according to Popper
7.6 Critical Rationalism
• He believed science should come from the mind -> we have to think in order to reach further truths about
the world; observations can prove those thoughts
• Like Kant Popper was dissatisfied with Humes psychological solution to the induction problem in terms of
custom, habit and association: the fact that we believe in laws is the results of having experience certain
events being ‘constantly conjoined’ with other events
• Hume believed only in senses for valid knowledge and Popper for cooperations of senses and reasoning
capacities (agreed with Kant)
• Popper also agrees that we do not see the world as it is an sich but only through theories (Kant)
• He believed our mind is not a tabula rasa but did not believe the view associated with rationalism that we
have innate knowledge, more inborn reactions and responses (expectations) -> newborns expect to be fed
and protected or that goslings believe the first thing they see is their mother (in nature it is true but in case
of Lorenz goslings followed him)
• These expectations are a priori, they are not in any way inductively based on observations
• We are born with instinctive theories that allow us to find regularity in the world
• Although Popper agrees with Kant on innate instincts he criticises him for his absolutism: the innate
knowledge should not be understood as valid a priori and can often fail to be fulfilled (not certain)
because humans are fallible and thus make mistakes
Chapter 7: Critical Rationalism: Science on Piles, Above a Swamp
7.1: Introduction
• Karl Popper was the first of a long line of critics of positivism
• He was a philosopher from Vienna
• Obituaries hailed him as the most important thinker
• He swung the pendulum back from empiricism to rationalism (critical rationalism)
7.2 Popper and the Weiner Kreis
• The circle would not admit him member
- He heavily criticised Wittgenstein for being a dogmatist
• Logic of Scientific Discovery - critique of positivism
- Book called the Trojan horse; popper disagreed with positivists and his conceptions of science were so
different they soon led to the Circle’s collapse.
- He agreed on the importance of logic and mathematics and appreciated empirical testing but he
believed there was also a rational aspect to knowledge and science
- For Popper theory come before, not after, observation
7.3 The Crucial Year, 1919
7.3.1 Popper’s clash with Marxism
• He quit high school because he believed his teachers couldn’t teach him anything new: went directly to
University
• He became marxist for a couple of months until violent protest killed multiple innocent people and he
realised that:
1. Humans are liable to make mistakes and there is no denying that human beings are fallible
creatures (he made a mistake by joining the Marxist group)
2. There is a major difference between dogmatic theories like the Marxist theory of history and
critical thinking (Marxist theory was always right and not built on critical thinking ->
pseudoscience)
7.3.2 Popper meets Alfred Adler
• Popper came up with cases where Adler’s theory (Adlerian psychoanalysis) was not true and compared
them to the theory
• Adler was able to explain these cases by adding another statement to the theory that essentially led to every
single case being true
• The statements had a ring of logic in them that made them always true
• Similar to: “tomorrow it will or will not rain”
• Poppers problem with such theories is that we can never know if they are right since we do not know if
they are wrong (due to the structure)
• The experiences with Marxism and Adler’s psychology led him to question the scientific value of theories
that are able to explain every possible observation
• —> Believed Marxism and Adlerian psychoanalysis were much like astrology in the sense that they could
explain everything; they have unlimited explanatory power (everything explained them)
- Popper believed that was not a strength but a sign of profoundly unscientific character of such
theories
7.3.3 Popper and the bending of light
• Showed Popper how real science is conducted
• Revolution in Science - Newtonian Ideas Overthrown: refereed to a meeting that Popper Ould later call the
‘falsification’ of Newtonian physics
• Newton believed light of starts would bend (0.”84) as it passes alongside an enormous mass like the sun
• Einsteins calculations doubled the value of gravitational bending
• Before the observation we already knew which observations would prove Newton or Einstein right
• Looking for falsifying elements in theories (only ones that can be falsified are true)
• Arthur Eddington designed a test to decide between Newtons’ and Einstein theories (Einstein was correct)
• Eddington's experiment proved that even an important old theory could be falsified
• The theories of Newton and Einstein were bold and risky: could be tested and refuted in a crucial test
(eclipse observation)
7.4 From verification via confirmation to falsification
,• Popper also struggled with drawing a line between science and non science
• If we adopt the logical positivists criterion of verification the implication is that some of the best scientific
achievements no longer deserve to be called scientific
• Many theories turned out not to be true yet still must be considered scientific
• A lot say science is inductive however there is a fundamental problem with induction
• As Hume said induction cannot be logically justified
- Impossible to take the leap from the limited amount of observations one has obtained in the past to a
universal claim that applies to each and every observation in past, present and future
- Example: impossible to verify the claim “all swans are white”, in order to establish its truth or falsity
on would have to check each and every swan for its whiteness (even those dead and still unborn) no
matter how many swans you examine you cannot state the the next one will not be black, or even
purple.
- It follows from Hume that the core statements about science cannot be verified
- No law can be verified because it is impossible to check each and every instance that falls under the law
• Schlick’s response: Theories are not absolute truth but an instrument to predict ex. “all metals heat when
expanded” has no truth value but is a statement used to generate the prediction that this particular piece of
iron will expand when heated
• Carnap’s response: attempt to increase a statements degree of confirmation: a theory must be in
agreement with established facts
- He believed we would have to reject everything if we had to state with certainty that something can
be verified
- Science characterised as increasing confirmation
- With every white swan we spot the degree of confirmation of the theory increases
- Verifiability replaced by confirmability
Popper’s response to Carnap
• The boundary between science and non science is not clear
• Empiricist solutions don’t work good enough
- Verification too strong: Verification meant to confirm through empirical evidence (factual and formal
statements)
- logical positivists believed in phenomenalism where statements where 100% verifiable but subjective
(correspondence: experience = reality)
- Confirmation too weak: related to logical positivists physicalism where they believed statements to be
true but not certain if they were highly coherent (many people agreed), they were objective but not
verifiable
• High confirmation leaves too much room for pseudoscientific and non-scientific statement to count as
science e.g.
- Tomorrow it either rains or not
- There exists an omnipresent and omniscient personal spirit (the arch-metaphysical assertion)
- They are virtual tautologies
- —> such statements are always right (high degree of confirmation)
Criterion of demarcation: distinguishing between science and non science
Popper’s solution: falsificationism
7.5 Falsificationism
Falsibialiity is an adequate criterion of demarcation
• Theories are science as long as they are falsifiable: we know the conditions under which they would be
falsified. We look for cases in which the statement is not true, if we do not find any the theory can be
accepted temporarily, this temporary acceptation is called corroboration
• If a theory fails to make predictions that might conceivably be wrong (as do the arch-metaphysical
assertions, the Marxist theory of history and Adler’s individual psychology) it is not a scientific theory
Characteristics of Popper’s falsificationism
1. Real sciences are falsifiable, pseudosciences lack this potential of being wrong
• Statements such as ‘it will or it will not rain tommorow’ are useless because they are always true
• Horoscopes are similar to tautological weather forecasts
2. Popper’s falscificationism acknowledges that humans are fallible creatures
- We do not know, we can only guess
- History shows every theory can turn out to be wrong, like Aristotle’s or Newtons’
- Negative road to truth: Popper believes the only way in which our knowledge can grow is by trying to
locate, remove and correct our mistakes (by trying to find instances in which our theories are not true)
3. Only theories that are falsifiable are informative
, - The weather statement does not inform us about anything
- Human beings are error prone and our biological make up prevents us from ever attaining certainty
- Statements such as: you might be sick next week also do not inform us about anything, they are not
falsifiable because they just state something might or might not happen
- Important to remember Popper had no issue with the meaning of statements, he just used falsification as a
demarcation criteria but that did not mean that statements or theories had no meaning, they simply were
not scientific, same as the arch-metaphysical statement we considered earlier is unscientific but not
meaningless
Popper: states theories can start as myths:
- Myths or pseudoscience can be very meaningful (in society only), however it needs to be transformed into
science in order to be called a theory -> falsification demarcation
- Example: evolution theory is based on myth of Empedocles of Agrigentum (plants and humans were once
one)
4. Only through falsification can scientific knowledge grow (through conjectures and refutations,
trial and error, deduction instead of induction)
• Unlike induction, deduction is logically valid
• Example of induction: swan a, swan b and swan n is white therefore all swans are white
• Popper believed we cannot accept it because we cannot exhaust the possibilities of where a swan could
be a different colour
• Example of deduction: all As and B, B. All men are mortal, then the next individual A. The president of the
US with be B. Mortal
• If the premises are true the conclusion must be true
• We can assume all swans are white and reach a conclusion that the next swan will also be white
• A true scientist will working on falsifying their theory
• We must come up with risky predictions from our theoretical guesses concerning the nature of reality
• These conjectural theories must be put to test under serve circumstances
• Observing another white swan will not teach us anything yet observing as for all we know the next one
might be purple but observing the first black swan teaches us that not all swans are white.
Poppers criticism of Freud’s Oedipus complex and Adler’s Inferiority Complex
• Adler inferiority complex theory: man saves kid because he does something no one else dares or lets it
drown to also do something no one else does (theory cannot be falsified)
• Oedipus complex: all boys want to sleep with their mothers and kill their fathers and all that don’t admit
are in denial)
- Both scenarios (both the boy that admits to this and the one that denies it) will confirm the theory, there
is not case in which the theory is false
• All use immunisation tools: changing your theory so it become right when new information comes up
- Their formulation makes them always right
- They adjust the theory after observations
- Their theory explains everything
- That cannot be scientific according to Popper
7.6 Critical Rationalism
• He believed science should come from the mind -> we have to think in order to reach further truths about
the world; observations can prove those thoughts
• Like Kant Popper was dissatisfied with Humes psychological solution to the induction problem in terms of
custom, habit and association: the fact that we believe in laws is the results of having experience certain
events being ‘constantly conjoined’ with other events
• Hume believed only in senses for valid knowledge and Popper for cooperations of senses and reasoning
capacities (agreed with Kant)
• Popper also agrees that we do not see the world as it is an sich but only through theories (Kant)
• He believed our mind is not a tabula rasa but did not believe the view associated with rationalism that we
have innate knowledge, more inborn reactions and responses (expectations) -> newborns expect to be fed
and protected or that goslings believe the first thing they see is their mother (in nature it is true but in case
of Lorenz goslings followed him)
• These expectations are a priori, they are not in any way inductively based on observations
• We are born with instinctive theories that allow us to find regularity in the world
• Although Popper agrees with Kant on innate instincts he criticises him for his absolutism: the innate
knowledge should not be understood as valid a priori and can often fail to be fulfilled (not certain)
because humans are fallible and thus make mistakes
