karl popper falsifiability is the heart of science

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KARL POPPER FALSIFIABILITY IS THE HEART OF SCIENCE

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Page 1: KARL POPPER FALSIFIABILITY IS THE HEART OF SCIENCE

KARL POPPER

FALSIFIABILITY IS THE HEART OF SCIENCE

Page 2: 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”:

PS1TT1EE1PS2…

Page 3: KARL POPPER FALSIFIABILITY IS THE HEART OF SCIENCE

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.

Page 4: KARL POPPER FALSIFIABILITY IS THE HEART OF SCIENCE

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.

Page 5: KARL POPPER FALSIFIABILITY IS THE HEART OF SCIENCE

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.

Page 6: KARL POPPER FALSIFIABILITY IS THE HEART OF SCIENCE

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

Page 7: KARL POPPER FALSIFIABILITY IS THE HEART 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

Page 8: KARL POPPER FALSIFIABILITY IS THE HEART OF SCIENCE

FALSIFIABILITY 2

Falsification of scientific claim is logically valid:

T O ~ O_____Thus ~ T

T=Theory is trueO=Observation implied by theory occurs.

[Recall Salmon, invalidity of scientific confirmation: T O; O; Thus T.]

Page 9: KARL POPPER FALSIFIABILITY IS THE HEART OF SCIENCE

FALSIFIABILITY [3]

Falsifiable or not? a) Unicorns do not exist.

Assume: unicorns are not invisibleb) Unicorns exist.

c) 3 x 7 = 21 d) Hitler never once wore mismatched

socks.e) Dinosaurs once roamed the Earth

Page 10: KARL POPPER FALSIFIABILITY IS THE HEART OF SCIENCE

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 possibilitiesOR: scientific theories are constrained

by observational data

Page 11: KARL POPPER FALSIFIABILITY IS THE HEART OF SCIENCE

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?

Page 12: KARL POPPER FALSIFIABILITY IS THE HEART OF SCIENCE

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 theorybold=risky=high content

Timid: the robin will fly south in the fallBold: the robin will fly south on 26 Oct.Bolder: …26 Oct. at 1:23 p.m., SSW,…