Karl Popper

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Karl Popper

• October, 10 2008

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Sir Karl Popper

• 1902-1994
• Born in Vienna.
• Left for New Zealand in 1937 (WWII).
• Moved to LSE in 1946.
• Famous encounter with Wittgenstein.

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The Demarcation Problem

• The Problem What makes science different from
  pseudoscience (and non-science)?
• Falsificationism a theory is scientific iff it
  is falsifiable.
• A theory is falsifiable iff it there are
  potential falsifiers that would refute it.
• Pseudoscience examples.

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The Demarcation Problem

• Q How (or is) this different from Positivism?

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Popper on Confirmation

• Popper is an inductive skeptic.
• Fallibilism vs. Anti-Confirmationism
• Falsification in place of Confirmation

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Poppers Scientific Method Falsification

• Take a theory.
• Deduce its observational predictions.
• Test one prediction.

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Popper on Confirmation

• Q What if one theory has passed 700 tests, and
  one theory has passed 1 test should we say that
  the first theory is more confirmed?
• Q Should we believe the first theory more than
  the second?

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Popper on Confirmation

• Q If science is only concerned with refutation,
  then what about sentences like Some Fs are Gs?
  Are they unscientific?
• Q Falsifiability of the potential falsifiers?

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Scientific Change
A. Conjecture
Scientist proposes some theory.
B. Refutation
The scientific method.
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Scientific Change
A. Conjecture
Scientist proposes some theory.
B. Refutation

• Take the theory.
• Deduce its observational predictions.
• Test one prediction.

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Scientific Change

• What kinds of conjectures?
• Bold.
• Not ad hoc.
• Considerable breadth.
• NOTE Two main ways for a theory to be better
  than its rival.

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Group or Individual?

• Economics Analogy-
• 1. Lots of irrational agents can result in a
  rational market.
• 2. Lots of agents acting self-interestedly can
  result in group altruistic behavior.