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KARL POPPER
FALSIFIABILITY
IS THE HEART OF SCIENCE
Sir KARL POPPER 1902-1994
Hume is right: we
never get beyond
conjectures.
“Darwinian” view
of human
“knowledge”:
PS1TT1
EE1PS2…
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?
Popper’s experience in Adler’s clinic (p. 265).
Everything is consistent with, hence
corroborates or confirms his theory.
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.
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.
PROBLEM OF THE CRITERION
Observation: Marx’s, Freud’s, Adler’s,
etc., theories take no risk, but
Einstein’s is risky (= falsifiable).
So, maybe:
Falsifiability is the criterion of science
FALSIFIABILITY 1
(P’s 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
FALSIFIABILITY 2
Falsification of scientific claim is logically
valid:
TO
~ O_____
Thus ~ T
T=Theory is true
O=Observation implied by theory occurs.
[Recall Salmon, invalidity of scientific
confirmation: T  O; O; Thus T.]
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
SCIENTIFIC THEORIES
ARE PROHIBITIONS
[explanation of Popper’s item #3, p. 266]
In a state of perfect ignorance, all
things are possible so far as we can
tell.
E.g., F=ma or F=2ma or F=3ma or…
Knowledge rules out some possibilities
OR: scientific theories are constrained
by observational data
THE SCIENTIFIC ATTITUDE
[explanation of Popper’s 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?
POPPER’S “SOLUTION” OF
HUME’S PROBLEM OF INDUCTION
i) Deduction is the only logic; there is
no inductive logic.
ii) Theory of rationality: accept boldest
unfalsified falsifiable theory
bold=risky=high content
Timid: the robin will fly south in the fall
Bold: the robin will fly south on 26 Oct.
Bolder: …26 Oct. at 1:23 p.m., SSW,…