Philosophy of Science - lectures
Lecture 1
Introduction and Demarcation
What is philosophy of science?
• Philosophy of Science:
Field in philosophy that concerns questions about the foundations of
science and scientific justification
Examines assumptions about science and scientific practice
Descriptive and normative elements
• Connected with epistemology and metaphysics
• What is the value of philosophy of science?
One possible answer:
Critically examining assumptions is important for evaluating science and
scientific practice
(It is also interesting in its own right)
• Does philosophy of science make any progress?
At least by clarifying concepts, uncovering considerations for and against
positions, offering new perspectives
The logical positivists and verifiability
• Problem of demarcation: how to distinguish between science and pseudo-
science?
Importance can potentially answer why science has a certain authority
over the production of knowledge
Why is astronomy considered a science, while astrology is considered a
pseudo-science?
• Two candidates for demarcation criteria:
Verifiability (logical positivists): scientific theories need to be testable by
observation
Falsifiability (Popper): scientific theories need to entail predictions that
can be potentially false
It is both about predictions and testing them.
• Logical positivists and Popper are also of historical importance
Marks the beginning of philosophy of science
Logical positivism and verifiability
• Logical positivism is a form of empiricism: experience (not reason) is the only
source of knowledge
• Established by the Vienna Circle in Austria after WO I
• Critical of philosophers they considered to be vague (Hegel, Heidegger)
• Pro-Enlightenment values: reason, logic, no intuition or emotion involved
but is all logic
• Persecuted by the Nazis many fled to the US
• Founding of logical empiricism, a more moderate form of logical
positivism
Logical positivism
,• Central: theory of language that distinguishes between meaningful and
meaningless language
• Meaningful can be evaluated as true or false
For instance: God exists is a sentence that cannot be evaluated as true or
false, but it can be personally meaningful. So, it is not meaningful.
• Two elements:
• Analytic-synthetic distinction
• Verifiability theory of meaning
o Used as a demarcation criterion that distinguishes between science
and ‘metaphysics’
(1) Analytic-synthetic distinction
• Analytic statements: true or false because of the meaning of the concepts
involved (true or false ‘by definition’)
• A priori: No empirical experience necessary
• Example: “Bachelors are unmarried”
• Synthetic statements: true or false depending on the actual state of the world
According to logical positivists, all synthetic statements are a posteriori:
empirical experience necessary
Example: it is sunny outside
• Logical positivists: purely mathematical and logical claims are analytical (So,
Kant was wrong ;-))
(2) Verifiability theory of meaning
• Meaning of a synthetic sentence is its method of verification
• Method of verification: testable by observation
• It is sunny today = if you walk outside, and look up, you will see the sun
• Can be used to distinguish between meaningful and meaningless (synthetic)
sentences
• Meaningful sentences are verifiable: testable by observation
If you can test it by observation, and therefore it is meaningful
• Sentences do not have to be directly translatable to observations but must at
least be linked to observations
So, if you look at theories about atoms, then it needs to be linked to observations
that are testable.
• Distinction between theoretical and observational terms
• (Connection to operationalism: theoretical terms need to be measurable)
• Verifiability does not have to be possible in practice
It just needs to be somehow conceivable
• Verifiability criterion entails that following sentences are meaningless
• The Nothing itself Nothings (Heidegger): is it observable? No.
• God is omnipotent: not observable, so it is meaningless.
• Murder is wrong
• Way for logical positivists to distinguish between ‘legitimate’ and ‘illegitimate’
philosophy
• Only legitimate philosophy: logical analysis/side of analytical statement
, What do concepts mean?
• Central tasks: conceptual clarification and giving a fundament for
scientific inference
• Verifiability criterion was also used as a demarcation criterion to distinguish
between science and ‘metaphysics’
• Scientific theories must be testable by observation
• Not testable by observation pseudo-science
• Quine’s criticisms against logical positivism:
(1) Holism about testing
• Individual statements are not testable by observation in isolation
• Deriving a clear observable prediction from a statement requires
making assumptions
• Prediction turns out to be false unclear whether the statement or the
assumptions made are false
• (Godfrey-Smith: logical positivists agree with this)
(2) No clear distinction between analytic and synthetic statements
• Statements form a web of belief, where statements in the center are less
susceptible to empirical evidence than those on the outside
• However, every part can potentially be revised by empirical evidence
sometimes, the whole framework needs to be changed
Criticisms of the verifiability criterion:
• If statement A is verifiable, then statement A&B is also verifiable
• Unclear how to make the distinction between theory and observation, and how
the two are related
• Unclear what ‘testable by observation’ exactly means
• Too permissive almost every statement is meaningful
• Too restrictive almost no statement is meaningful
In short:
Logical positivists proposed a verifiability criterion to distinguish between
meaningful and meaningless synthetic sentences
• Meaningful sentences are testable by observation
• Also used as a demarcation criterion
‘Testable by observation’ is intuitive but encounters many problems when
trying to elaborate on it
Popper and falsifiability
Karl Popper
• Viennese philosopher between WO I and WO II, but not part of the Vienna
circle
• Left during rise of Nazism (to New Zealand and ultimately London)
• Concerned with the distinction between science and pseudo-science
specifically
the problem of demarcation
Popper’s demarcation criterion of choice: falsifiability
• A theory is scientific if it entails observable predictions that can be potentially
false
• The riskier the theory, the better
, Pseudo-science involves theories that can accommodate every possible
observation
• Feature of certain conspiracy theories any evidence against can be framed
as evidence in favor of the theory
Popper’s go-to examples of pseudo-science
• Psycho-analysis: any kind of behavior can be explained with the concepts of
psycho-analysis
• Marxism: regardless of whether a revolution happens, an explanation is
available
Problems with the falsifiability criterion:
• Revising theories to accommodate contradicting empirical evidence is common
in science
• (Note: Popper allows that a theory is not rejected outright when a single
prediction turns out to be false)
• Pseudo-scientific fields do seem to make falsifiable claims
Holism about testing
• Observation contradicts prediction: fault of the theory or one of the
assumptions made?
• Popper: we need to decide whether to accept the observation seems to
make falsifiability arbitrary
•In short:
• Both verifiability as falsifiability focus on observation as a mark of science
• Verifiability: scientific theories make observable prediction
• Falsifiability: scientific theories make observable predictions that can
potentially be false
• Both have problems
• According to Godfrey-Smith, both capture something central about science:
observation
• We should not ask whether theories are scientific, but whether they are
handled in a scientific way, by exposing them to observation
Alternative approaches to demarcation
• Thagard: Why Astrology is a Pseudo-Science
• Verifiability and falsifiability both fail to show why astrology is a pseudo-
science
• Verifiability: astrology makes testable predictions scientific
• Falsifiability: astrology makes predictions that can turn out to be false,
and it can be replaced by better alternatives scientific
•Both verifiability as falsifiability are criterions that focus on scientific theories
• However, the community and historical context also needs to be taken into
account
• Implicit in Kuhn and Lakatos, according to Thagard:
• Kuhn: Scientific progress characterized by periods of normal science,
with scientific revolutions in-between
• Lakatos: Only scientific fields that are progressive (solving problems
while increasing explanatory power) survive
• (More about them in the lecture about scientific progress)
• Thagard’s own criterion for pseudoscience:
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