1. Standard memberHalitose
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    15 Sep '05 18:54
    Evolution: The supposed change in the genetic composition of a population during successive generations, as a result of natural selection acting on the genetic variation among individuals, and resulting in the development of new species.

    What are its requirements? Is it statistically possible?
  2. Donationbbarr
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    15 Sep '05 19:02
    Originally posted by Halitose
    Evolution: The supposed change in the genetic composition of a population during successive generations, as a result of natural selection acting on the genetic variation among individuals, and resulting in the development of new species.

    What are its requirements? Is it statistically possible?
    I'm sorry, what precisely are you asking? Presumably, evolution requires all sorts of things (e.g., a source of genetic mutation, preservation of at least some genetic mutations in offspring, various selection pressures, etc.). Of course evolution is statistically possible, after all, anything that in fact occurs has a probability of 1.
  3. Standard memberHalitose
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    15 Sep '05 19:10
    Originally posted by bbarr
    I'm sorry, what precisely are you asking? Presumably, evolution requires all sorts of things (e.g., a source of genetic mutation, preservation of at least some genetic mutations in offspring, various selection pressures, etc.). Of course evolution is statistically possible, after all, anything that in fact occurs has a probability of 1.
    I'm sorry, what precisely are you asking? Presumably, evolution requires all sorts of things (e.g., a source of genetic mutation, preservation of at least some genetic mutations in offspring, various selection pressures, etc.).

    Yes, exactly the requirements I'm looking for.

    Of course evolution is statistically possible, after all, anything that in fact occurs has a probability of 1.

    Is it statistically possible for evolution (with all the requirement) to form a new species.
  4. Donationbbarr
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    15 Sep '05 19:141 edit
    Originally posted by Halitose
    I'm sorry, what precisely are you asking? Presumably, evolution requires all sorts of things (e.g., a source of genetic mutation, preservation of at least some genetic mutations in offspring, various selection pressures, etc.).

    Yes, exactly the requirements I'm looking for.

    Of course evolution is statistically possible, after all, anythi

    Is it statistically possible for evolution (with all the requirement) to form a new species.
    When you use the term 'species', are you employing the Biological Species Concept. Or, rather, are you using 'species' to refer to some nebulous notion of a natural kind?
  5. Not Kansas
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    15 Sep '05 19:16
    You forget the sun has been pouring free energy on the Earth for billions of years, making it all happen.
  6. Standard memberHalitose
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    15 Sep '05 19:17
    Originally posted by bbarr
    When you use the term 'species', are you employing the Biological Species Concept. Or, rather, are you using 'species' to refer to some nebulous notion of a natural kind?
    Species in the Biological sense is good for me.
  7. Standard memberHalitose
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    15 Sep '05 19:18
    Originally posted by KneverKnight
    You forget the sun has been pouring free energy on the Earth for billions of years, making it all happen.
    Yes. But I'm more interested in examining mutations as I'm sure most would agree they are the mechanism behind evolution.
  8. Donationbbarr
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    15 Sep '05 19:21
    Originally posted by Halitose
    Species in the Biological sense is good for me.
    O.K. Then, 'yes', speciation is statistically possible. That is, the probability of speciation having happend is greater than 0. Of course, any process that is nomologically possible will have a probability greater than 0.
  9. Standard memberHalitose
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    15 Sep '05 19:281 edit
    Originally posted by bbarr
    O.K. Then, 'yes', speciation is statistically possible. That is, the probability of speciation having happend is greater than 0. Of course, any process that is nomologically possible will have a probability greater than 0.
    Okay. Isn't there a point above 0 where something is statistically considered unreasonable. Lke it is statistically possible that I might win the lottery with one ticket, but unreasonable that I would win it 20 times running.
  10. Standard memberDoctorScribbles
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    15 Sep '05 19:323 edits
    Originally posted by Halitose
    Okay. Isn't there a point above 0 where something is statistically considered unreasonable.
    Only in a relative or Bayesian sense. That is, in the face of two possible explanatory stochastic processes which could have produced the observed outcome, under one of which the event occurs with probability .99, while it occurs with probability .01 under the other, in the absence of further information, it is unreasonable to conclude that the latter produced it while rejecting that the former produced it.

    In an absolute sense, what is unreasonable is to find that a statistically unlikely but possible event cannot or did not happen. If such a finding were reasonable, then possibility would be a useless notion.
  11. Donationbbarr
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    15 Sep '05 19:421 edit
    Originally posted by Halitose
    Okay. Isn't there a point above 0 where something is statistically considered unreasonable. Lke it is statistically possible that I might win the lottery with one ticket, but unreasonable that I would win it 20 times running.
    Yes, as Herr Doctor points out above. There are notorious problems with setting Bayesian prior probabilities, however. Anyway, how would you go about demarcating the logical space of probabilities germane to the question of evolution? You need to do this before you can draw any inferences concerning the likelihood that evolution has resulted in speciation.

    EDIT: Telerion is an authority on these matters. Hopefully he will contribute to this discussion...
  12. Standard memberHalitose
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    15 Sep '05 19:42
    Originally posted by DoctorScribbles
    Only in a relative or Bayesian sense. That is, in the face of two possible explanatory stochastic processes which could have produced the observed outcome, under one of which the event occurs with probability .99, while it occurs with probability .01 under the other, in the absence of further information, it is unreasonable to conclude that the latt ...[text shortened]... did not happen. If such a finding were reasonable, then possibility would be a useless notion.
    Wouldn't one chance in ten thousand trillion trillion trillion be considered impossible?
  13. Standard memberDoctorScribbles
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    15 Sep '05 19:45
    Originally posted by Halitose
    Wouldn't one chance in ten thousand trillion trillion trillion be considered impossible?
    No. 0 chances in ten thousand trillion trillion trillion would be considered impossible. That's just what impossible means in such discrete problems.

    In the same way that (ten thousand trillion trillion trillion minus one) chances out of ten thousand trillion trillion trillion is not considered to be a certainty.
  14. Donationbbarr
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    15 Sep '05 19:46
    Originally posted by Halitose
    Wouldn't one chance in ten thousand trillion trillion trillion be considered impossible?
    This question doesn't make any sense. Given a lottery with those odds, there will still be a winner. Prior to the lottery drawing, the proposition that any particular player will win will be massively improbable, but since there will be a winner of the lottery, the proposition that no particular player will win is false.
  15. Standard memberHalitose
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    15 Sep '05 19:47
    Originally posted by bbarr
    Yes, as Herr Doctor points out above. There are notorious problems with setting Bayesian prior probabilities, however. Anyway, how would you go about demarcating the logical space of probabilities germane to the question of evolution? You need to do this before you can draw any inferences concerning the likelihood that evolution has resulted in speciation. ...[text shortened]... Telerion is an authority on these matters. Hopefully he will contribute to this discussion...
    Okay. Here's my proposed framework in order to calculate the odds of mutation creating a new species.

    1. What is the chance of getting a mutation.
    2. What fraction of the mutations have a selective advantage.
    3. How many replications there are in each step of the chain of selection.
    4. How many of those steps there have to be to achieve a new species.
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