Philosophy of Biology

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Natural Selection vs Intelligent Design

Paley

  • Watch maker argument
    • Designer is a more plausible explanation than randomness for the creation of complex system.

Sober

  • What's wrong with intelligent design?
    • Not testable
    • Popper's falsifiability criterion
      • Can't deal with probability statements
    • Test against one or more competing hypotheses
    • Physical theories do not make testable predictions without auxiliary propositions
    • Auxiliary propositions must be independently supported
      • No auxiliary propositions about designer's goal and abilities
    • ID always have a way out by pushing back in time to a mindless state until the big bang.
    • Observation in Popper's concept of falsifiability.
      • ID cannot make predictions.
    • Refute evolutionary cannot irreducibly complex adaptations does not imply proving of ID.
      • Evolution does not guarantee stepwise accumulation. No 1,2,3 legs horses.

Adapatation

Gould, The Spandrels of San Marco

  • Adaptation explain everything in natural selection with speculative tales
    • Fail to consider alternative to adaptive stories
    • Adaptationist programme
      • An organism is atomized into traits and these traits are explained as structures optimally designed by natural selection for their functions
      • After the failure of part-by-part optimization, interaction is acknowledged via the dictum that an organism cannot optimize each without trade-offs
      • Trivialize genetic drift, allometry and other non-adaptive evolution.
      • Common style of arguments
        • If one adaptive argument fails, try another one
        • If one adpative argument fails, assume that another must exists
        • If the the absence of a good adaptive argument in the first place, attribute failure to imperfect understanding of where an organism lives and what it does
        • Emphasize immediate utility and exclude other attributes of form
  • Spandrels of Cathedral
    • Generate for other purpose then adopted the current function.
  • Alternatives to adaptationist programme
    • No adaptation and no selection at all. Pure random factors.
    • No adaptation and no selection on the part at issue; form of the part is correlated consequence of selection elsewhere.
    • Decouple selection and adaptation
    • Adaptation and selection but no selective bias for differences among adaptations.
    • Adaptation and selection, but the adaptation is a secondary utilization of parts present for reasons of architecture, development or history
  • Evolutionary constraints
    • Phyletic constraints, no flying molluscs, no elephant size insect
    • Developmental constraints, early stage strongly restrictive of later development.

Gould, Exaptation

  • Two definitions of adaptation
    • A feature is an adaptation only if it was built by natural selection for the function it now performs
    • Feature that enhances current fitness, regardless of its historical origin
  • Aptation
    • Adaptation
      • any feature that promotes fitness and was built by selection for its current role as a function
    • Exaptation
      • operation of a useful character not built by selection for its current role as an effect
  • Significance of exaptation
    • A solution to the problem of preadaptation
    • Primary exaptations and secondary adaptations
    • The sources of exaptation

Natural selection, positive vs negative theory

Sober

  • negative theory of natural selection
    • random mutation
    • natural selection did not create the tree of life, it just determine which branches were removed and which remained

Neander

  • Cumulative selection
  • Population change

Walsh

Type vs token

Nanay

  • Scare resource

Functions

Larry Wright

Cummins