Laudan, Demystifying Underdetermination

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Laudan, Demystifying Underdetermination

• November 3, 2008

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Underdetermination

• Egalitarian UD
• The inductive methods of scientific theory choice
  rationally allow us to choose any theory in light
  of whatever evidence we have.
•  
• Non-Uniqueness UD
• The inductive methods of scientific theory choice
  rationally allow us to choose more than one
  theory in light of whatever evidence.

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Goodman

• Straight Rule of Induction If you get a lot of
  successful instances of a hypotheses, suppose
  that you will continue to get successful
  instances.

Observe 500 emeralds that appear to be
green.
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Goodman

• Straight Rule of Induction If you get a lot of
  successful instances of a hypotheses, suppose
  that you will continue to get successful
  instances.

Observe 500 emeralds that appear to be
green. Straight Rule allows T1 All emeralds
are green. T2 All emeralds are grue. T3 All
emeroses are grue. etc.
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Goodman

• Straight Rule of Induction If you get a lot of
  successful instances of a hypotheses, suppose
  that you will continue to get successful
  instances.

Observe 500 emeralds that appear to be
green. Straight Rule allows T1 All emeralds
are green. T2 All emeralds are grue. T3 All
emeroses are grue. etc. Straight Rule
prohibits T4 All emeralds are red.
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Kuhn
Laudans Claim Kuhn argues for Egalitarian UD.
According to Kuhn the methods of science are
inadequate ever to indicate that any theory is
better than any rival, regardless of the
available evidence.

• Some Shared Standards
• prefer consistent theories,
• prefer theories that correctly make surprising
  predictions,
• 3. prefer theories that have been tested
  against diverse phenomena, rather than similar
  phenomena.

Q Is Kuhns claim Egalitarian in this sense?
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Kuhn

• Possible Egalitarian UD
• The inductive methods of scientific theory choice
  rationally allow us to choose any possible theory
  in light of whatever evidence we have.
• Actual Egalitarian UD
• The inductive methods of scientific theory choice
  rationally allow us to choose any seriously
  proposed theory in light of whatever evidence we
  have.

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Bulging Earth

• Newtonian mechanics The earth will have a
  greater diameter from equator to equator than
  from pole to pole.
• Cartesian mechanicsThe earth is a perfect
  sphere so the diameters will be equal.

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Bulging Earth
The Methodological Rule when two rival theories,
T1 and T2, make conflicting predictions that can
be tested in a manner that presupposes neither T1
nor T2, then one should accept whichever theory
makes the correct prediction and reject its rival.
Laudan That complex of rules and evidence
determined the choice between the two systems of
mechanics, for anyone who accepted the rule(s) in
question. (342)
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Two Tempting Underdetermination Arguments
(1) If nonuniqueness UD is true, then the
adoption of theories is due to extra-scientific
causes. (2) Nonuniqueness UD is
true.--------------------------------------------
--------------------------- (3) Thus, the
adoption of theories is due to extra-scientific
causes.
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Two Tempting Underdetermination Arguments
(1) Sometimes scientists change their theoretical
beliefs with no change in the evidence. (2)
Sometimes scientists maintain their theoretical
beliefs in the face of changing, and problematic
evidence.----------------------------------------
-------------------------------- (3) Thus,
reasonable scientists are free to believe what
they like, independent of evidence.
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Laudans Parody
(1) Sometimes surgery is not required to cure
gall stones. (2) Sometimes gall stones are not
cured, despite surgery. -------------------------
---------------------------------------------- (3)
Thus, surgery is never the required treatment
for gall stones.
(Sometimes evidence is not required to change
theoretical beliefs.)
(Sometimes theoretical beliefs are maintained,
despite problematic evidence.)
(Thus, evidence is never the required way to
change theoretical beliefs.)