KARL POPPER

1
KARL POPPER

• FALSIFIABILITY
• IS THE HEART OF SCIENCE

2
Sir KARL POPPER 1902-1994

• Hume is right we
• never get beyond
• conjectures.
• Darwinian view
• of human
• knowledge
• PS1?TT1?
• EE1?PS2?

3
PROBLEM OF THE CRITERION (264, theme of whole
essay)

• Problem what distinguishes science from
  non-science or pseudo-science?
• Lots of theories in political science (e.g.,
  Marx, Spengler, Nazism), psychoanalysis (Freud,
  Adler, Jung), claim to be scientific.
• ARE THEY?
• Poppers experience in Adlers clinic (p. 265).
• Everything is consistent with, hence
• corroborates or confirms his theory.

4
NONSCIENTIFIC THEORY

• Marx, Spengler, Hitler, Freud, Adler
• Everything confirms their theories,
  nothing falsifies them.
• N.B. not just every actual thing, but
  every conceivable thing.
• NON-SCIENCE IS UNFALSIFIABLE.

5
SCIENTIFIC THEORY

• Newton, Einstein most conceivable things falsify
  their theories
• N.B. though no actual thing does
• Example A body has to fall (orbit, etc.) with a
  precise acceleration (velocity, etc), or else
  theory is false.
• N.B. though in fact theory is not
• falsified.

6
PROBLEM OF THE CRITERION

• Observation Marxs, Freuds, Adlers, etc.,
  theories take no risk, but Einsteins is risky
  ( falsifiable).
• So, maybe
• Falsifiability is the criterion of science

7
FALSIFIABILITY 1 (Ps summary of numbered list,
p. 266)

• Popper accepts above solution
• Falsifiability is the criterion of science
• Falsifiability DEF the logical possibility of
  being proven false by observation DEF can
  conceive of such proof without self-contradiction

8
FALSIFIABILITY 2

• Falsification of scientific claim is logically
  valid
• T ? O
• O_____
• Thus T
• TTheory is true
• OObservation implied by theory occurs.
• Recall Salmon, invalidity of scientific
  confirmation T ? O O Thus T.

9
FALSIFIABILITY 3

• Falsifiable or not?
• a) Unicorns do not exist.
• Assume unicorns are not invisible
• b) Unicorns exist.
• c) 3 x 7 21
• d) Hitler never once wore mismatched socks.
• e) Dinosaurs once roamed the Earth

10
SCIENTIFIC THEORIES ARE PROHIBITIONS

• explanation of Poppers item 3, p. 266
• In a state of perfect ignorance, all things are
  possible so far as we can tell.
• E.g., Fma or F2ma or F3ma or
• Knowledge rules out some possibilities
• OR scientific theories are constrained
• by observational data

11
THE SCIENTIFIC ATTITUDE

• explanation of Poppers item 5, p. 266
• Genuine test is defined in terms of attempts to
  falsify.
• Theories can be protected from the evidence by
  qualifications, promises, etc.
• E.g. Is the theory of global warming
• falsified by the years of cooling?

12
POPPERS SOLUTION OF HUMES PROBLEM OF
INDUCTION

• i) Deduction is the only logic there is no
  inductive logic.
• ii) Theory of rationality accept boldest
  unfalsified falsifiable theory
• boldriskyhigh content
• Timid the robin will fly south in the fall
• Bold the robin will fly south on 26 Oct.
• Bolder 26 Oct. at 123 p.m., SSW,