More%20mental%20gymnastics

1
Lecture 8

1. More mental gymnastics
2. Tales from the history of science
3. Poppers solution to the problem of induction
4. Which of two possible conclusions about
   scientific reasoning is Popper actually arguing
   for?
5. Is either argument successful?

2

• On a distant island, there are 3 kinds of humans
  Knights, Knaves, and Normals.
• Knights always tell the truth. Knaves always lie.
  Normals sometimes lie and sometimes tell the
  truth.
• Detectives investigating a crime questioned 3
  inhabitants, A, B, and C of the island. They knew
  one of them had committed the crime, but not
  which one.
• They also knew that the criminal was a Knight,
  and that the other two they questioned were not.
• The investigators made a transcript of the
  statements made by each of the 3 inhabitants.
• Using logic, did they identify A, B, or C as the
  guilty person?

3

• On a distant island, there are 3 kinds of humans
  Knights, Knaves, and Normals.
• A I am innocent
• B That is true.
• C B is not a normal.
• Which one is the Knight and, therefore, the
  criminal?
• Identify the possible solutions.
• Identify the fact list.
• Evaluate the possible solutions given the fact
  list (which includes what each said) and solve
  the puzzle

4

• A I am innocent.
• If A is the Knight,
• B That is true.
• If B is lying,
• C B is not normal.
• If C is lying,

5
Popper Falsificationism

• From falsifiability as the criterion that
  distinguishes science from pseudo-science to
  falsificationism as a model of scientific
  method/reasoning.
• A rejection of all forms of inductivism (both
  narrow and Hempels sophisticated version).
• There is no principle of induction that will
  justify induction or an inductivist account of
  scientific method/reasoning
• Like Hempel, Popper emphasizes that there is no
  logic of discovery, but only a logic of
  justification (testing)
• But, unlike Hempel, Popper argues that the logic
  involved in the context of justification or
  testing is deductive and specifically the logic
  of falsification.

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Part 2

• Tales from the history of science

7
Cases of planetary misbehavior

• A physicist of the Newtonian era took Newtons
  law of gravitation, N, the accepted initial
  conditions, C, and calculated the predicted path
  of the planet, Uranus. But the planet deviated
  from the calculated path.
• Did our Newtonian physicist consider, that once
  established, the deviation of Uranus from its
  predicated path refutes the law, N?

8

• Well, yes, a few did.
• But more proposed that there was another, yet
  undiscovered planet whose gravitational pull
  explained the deviation in Uranus predicted
  path. Using Newtonian theory, they predicted
  where the planet would be, its mass, etc.
• Was this prediction Ad hoc? How might we be able
  to decide if it was?
• In this case, when they trained telescopes to the
  predicted region of the sky, they discovered the
  planet Neptune and claimed a victory for
  Newtonian theory!
• Because Neptunes predicted path also deviated
  from what was predicted, they proposed another
  planet and discovered Pluto!

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Cases of planetary misbehavior
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Uh, oh! What to do about the peacocks tail?

• As Darwin understood things, Natural Selection
  cannot select a trait that is disadvantageous
  to its bearer that compromises its survival
• So what to do with all the ornaments that
  (predominantly) male members of various species
  are endowed?
• The Peacocks tail
• Antlers
• Bright colors

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Uh, oh! What to do about the peacocks tail?

• It seemed that many such traits were not benign
  but actually put those so endowed at a distinct
  disadvantage
• Its very hard for a peacock to take off, fly
  easily, and land
• Young males with antlers often crash into trees,
  each other, buildings, and so forth
• Bright colors seem to make an organism an easier
  target for prey
• Apparent counter-examples to or falsifiers of
  evolution by Natural Selection!

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Uh, oh! What to do about the peacocks tail?
13
Uh, oh! What to do about the peacocks tail?
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Poppers Falsificationism

• One problem facing the Aristotelian and Ptolemaic
  model of astronomy (geocentrism) was its
  complicatedness (or what todays physicists might
  describe as its inelegance).
• Because it assumed that planets move in a
  uniform, circular motion and at a uniform speed,
  it had to contend with (among other observations)
  the apparent retrograde motion of some planets.
  Mars, for example, seems at times of the year to
  stop and go in reverse for awhile before resuming
  its regular circular motion

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Poppers Falsificationism

• But, although this was seen as a major flaw with
  the geocentric model, the Copernican model, also
  had to include epicycles to make it compatible
  with apparent retrograde motion of planets
  albeit, somewhat less.
• It was not until Kepler recognized that the
  planets orbits are elliptical that astronomers
  no longer needed epicycles.

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Poppers Falsificationism

• To address the problem, astronomers added
  epicycles to planetary orbits
• Smaller (but still circular!) orbits compatible
  with apparent retrograde motion
• As the story goes, the Copernican hypothesis was
  much simpler and superior.

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Poppers Falsificationism

• The moral if the need for epicycles was taken to
  be a reason to reject the geocentric model, it
  was not solved (initially) by the Copernican
  model but scientists accepted the latter anyway.

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Part 3

• Poppers solution to
• The problem of induction

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Poppers explication and defense of
falsificationism

1. Reiterate (in contemporary terms) why inductive
   reasoning cannot be justified.
2. To justify it would require a principle of
   induction, itself known a priori or being the
   conclusion of a sound argument. We do not and
   cannot have either.
3. Even a probabilistic understanding of inductive
   reasoning would require its own principle of
   induction, and suffers from the same problems.
4. So if (as Hume claimed) it might turn out that
   psychologists report scientists (and the rest of
   us) use induction, this is not itself an
   epistemological issue.

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Poppers explication and defense of
falsificationism

• Reject psychologism
• The question of how an idea (hypothesis) occurs
  to a person may be of interest to psychologists,
  but not to those interested in the logical
  analysis of scientific reasoning (i.e., in the
  epistemology of science).
• The former is concerned with description the
  latter concerned with questions of justification
  or validity i.e., is normative rather than
  descriptive
• Reiterate the discovery/justification
  distinction However a scientist arrives at a
  hypothesis, all that philosophy of science
  (epistemology) is concerned with is whether the
  hypothesis is justified.

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• Provide an alternative to inductivist accounts of
  scientific reasoning and, in particular, a
  deductivist account of the testing of hypotheses.
• Make use of the fact that while the logic of
  confirmation involves a deductively invalid
  argument form, and is beset by the (old?) problem
  of induction, the logic of falsification involves
  a deductively valid argument form and avoids the
  problem of induction altogether.
• If H, then I
• Not I
• --------------
• Not H

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Poppers Falsificationism

• The tests any proposed hypothesis is (or should
  be?) subjected to
• Internal consistency does it include any logical
  contradictions/inconsistencies?
• Is it actually scientific, i.e., falsifiable?
• External consistency is it consistent with
  relevant theories that are currently accepted?
• How does it fare when it is tested?
• So long as a theory avoids being falsified, we
  say it is corroborated (weaker than confirmed).
• There is no inductive reasoning involved here!

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Poppers Falsificationism

• Stages in scientific reasoning (as it is or as it
  should be?)
• Bold conjectures they go out on a limb, prohibit
  the occurrence of some set of phenomena (events,
  objects, and so forth).
• Rigorous efforts to falsify the hypothesis by
  subjecting it to tests.
• Falsification (or corroboration). If the first,
  rejection of the hypotheses and search for and
• The emergence of a new bold conjecture proceed
  to steps 2, 3 and 4

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Poppers Falsificationism

• Questions
• If we reject psychologism (the study of how
  scientists actually think and reason), is
  Falsificationism itself an empirical account of
  how they do or an account of how, ideally, they
  should reason?
• If the former, is it in fact how scientists
  proceed do they rigorously attempt to falsify
  the hypotheses they propose?
• If it isnt how scientists actually proceed, what
  is the justification for the claim that they
  should proceed this way?