Lecture 3: Gould and evidence as inferential

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Lecture 3

1. Kinds of evidence and reasoning at work in
   evolutionary theorizing.
2. Anticipating next readings (by A.J. Ayer and Karl
   Popper) and topic.
3. Introduction to The Minds Big Bang

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The Likelihood Principle

• O an observation or set of observations
• H a hypothesis proposed as an explanation of O
• The likelihood principle asks What is the
  likelihood of O (observations) given H
  (hypothesis)?
• P(O/H)
• NOT What is the probability of H given O?
• P(H/O)

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The Likelihood Principle

• O There is noise in the attic.
• H Gremlins are bowling in the attic.
• What is the likelihood of O given H?
• P(O/H)
• VERY HIGH!
• What is the probability of H given O?
• P(H/O)
• VERY LOW (if probable at all)!

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Paleys argument from design

• O Organisms are perfectly fit to their
  environments and their parts (e.g., eyes) are
  perfectly designed for their functions.
• H1 Organisms and their parts were produced by a
  Designer.
• H2 Organisms and their parts are the result of
  random, physical processes.
• Obviously, Paley concluded,
• P(O/H1) gtgt P(O/H2)
• The likelihood of O is much higher if H1 than if
  H2.

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Paleys reasoning updated

• O Organisms are perfectly fit to their
  environments and their parts (e.g., eyes) are
  perfect designed for their functions.
• Turns out there are many imperfections, and a
  change in environment can easily wipe out a
  population or species
• H1 All was produced by a Designer
• H2 All are the results of random, physical
  changes
• Paley could only think of two possibilities but
  now we have
• H3 Natural selection, which doesnt require
  supernatural intervention and is also not random.

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The Pandas Thumb

• O the pandas thumb (TPT) and what it actually
  is (an enlarged wrist bone)
• H1 TPT came about through natural selection the
  (blind) tinkering with available parts that gave
  those ancestors with it an advantage and, thus,
  the trait spread.
• H2 TPT was designed by perfect engineer.
• Gould
• P(O/H1) gtgt P(O/H2)

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The Pandas Thumb

• Gould P(O/H1) gtgt P(O/H2)
• What is the evidence?
• Comparative anatomy
• Both the radial sesamoid, which in its elongated
  form constitutes this false digit, and the
  relevant musculature that gives the digit its
  relative rigidness and relative flexibility, are
  common to other species, including other bears.
• The (perhaps single) genetic change producing a
  larger radial sesamoid, would given their spatial
  locations, force the change in the musculature.

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The Pandas Thumb

• Gould P(O/H1) gtgt P(O/H2)
• What is the evidence?
• Comparative anatomy
• In many other bears, the radial sesamoid is also
  somewhat enlarged.
• This is by no means a perfect thumb (it is
  neither opposable nor able to manipulate objects
  by itself).
• It is, rather, the result of tinkering with parts
  available to the pandas ancestors.

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Darwins orchids

• Non-sexual reproduction is cheaper, but sexual
  reproduction insures that an organisms progeny
  are varied (and thus will have a better chance of
  survival if conditions change).
• From the same relatively primitive petal of its
  ancestor, varieties of orchids have different
  contraptions for insuring cross-pollination
  (insuring that insects lured by their nectar are
  also coated in pollen that they will in turn pass
  on to the next female orchid they visit)

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QWERTY PHENOMENA

• Like the arrangements of the keys on a keyboard,
  QWERTY phenomena are phenomena that show signs of
  history a history of RD (research and
  development) using whats available, and limited
  or directed by contingencies and constraints
  Francis Crick called them frozen accidents
• QWERTY phenomena abound in the organic world.

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QWERTY PHENOMENA

• In our case
• wisdom teeth, the blank spot in the center of
  each of our eyes, the possibility of retinal
  detachment, our tail bone, our back problems,
  (perhaps) our appendix, relatively short
  gestational period, male nipples.
• Other cases
• blind fish in dark caves, with eyes that dont
  function, but whose ancestors had functioning
  eyes
• blind fish in dark caves, without eyes, whose
  ancestors did have eyes
• toothless species of whales in which embryos
  have teeth and lose them during natal development

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What distinguishes science from pseudo-science?
And why care?

• The emergence of the philosophy of science in the
  1920s in Europe
• The Vienna Circle
• Logical Positivism (aka Positivism or Logical
  Empiricism)
• Reacting to 2 significant developments
• The eclipsing of Newtonian physics by Special and
  General Relativity
• The growing menace of Fascism, anti-Semitism, and
  the so-called scientific theories put forward by
  Nazis

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What distinguishes science from pseudo-science?

• Logical Positivism
• Science should and must be a positive force for
  human wellbeing
• Logical Empiricism (same movement)
• Working to identify the role of logic and that of
  experience in the workings of genuine science.
• Both emphases underlie the work to identify the
  criterion (or criteria) that demarcate science
  (i.e., distinguish it from) pseudo-science and
  non-science.

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What distinguishes science from pseudo-science?

• A.J. Ayer (first reading)
• A Logical Positivist (aka Logical Empiricist)
• His target as pseudo-science (nonsense or
  without meaning) statements that cannot be
  verified by experience.
• He terms them metaphysical but as he uses it,
  the term has a different sense than that we
  discussed as philosophical metaphysics or
  ontology
• It concerns efforts to identify a reality that
  allegedly transcends our experiences.
• His criterion verifiability

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What distinguishes science from pseudo-science?

• Sir Karl Popper (second reading)
• Rejects Verifiabiliity (too many
  pseudo-scientific theories be claimed to fit
  the evidence)
• Offers Falsifiability as an alternative
  criterion
• Simply put a statement, hypothesis, or theory is
  scientific only if it is, in principle,
  falsifiable
• There are things it prohibits, which if they were
  to occur or be observed, would show the
  hypothesis or theory in question to be false.

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The Minds Big Bang

• When and how did the human brain emerge?
• A single mutation?
• Gradually?
• What kinds of evidence do scientists appeal to in
  reconstructing the event?
• The method of reverse engineering
• Drawing inferences based on what we can observe
  (by way of traits and artifacts) to historical
  episodes
• DNA analysis, paleontology, anthropology,
  archaeology

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The Minds Big Bang

• When and how did the human brain emerge?
• What kinds of evidence do scientists appeal to in
  reconstructing the event?
• Consider the evidence discussed in the film. Do
  you find some inferences more compelling than
  others? If so, why
• Cave paintings
• Tools
• Beads
• Graves