Re: Johnson, Darwin, and transitionals

From: Chris Cogan (
Date: Sun Jan 23 2000 - 19:10:01 EST

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    > Wesley writes:
    > >I think, Chris, that you grant Johnson too much credit in his
    > >assertion that the invertebrate fossil record fails to clearly
    > >document transitional sequences. In fact, my reading leads me
    > >to almost the opposite conclusion -- the invertebrate fossil
    > >record yields a richer source of data concerning transitions
    > >than does the vertebrate record.
    > Do not lose sight of the larger picture, people. Johnson claims
    > there are no transitionals in the invertebrate fossil record. Chris
    > then uses Darwinian evolution (DE) to explain why this is expected
    > from DE. His explanations sounds reasonable and plausible. But
    > now Wesley tells us there are transitionals. Moral to the story?
    > DE is so plastic, so blob-like, and so unfalsifiable that it can even
    > be used to come up with rational explanations for states that do not
    > exist. Now....let that sink in.

    I said in my original post on the topic:

    "To determine whether Johnson had any valid point at all
    would require determination of details that he does not seem concerned to
    bother with."

    I gave an explanation that would be expected to hold *if* certain conditions
    held. I did not claim that those conditions *did* hold. What I was pointing
    out was that the fact of little or no discernible evolution over a period of
    time *by itself* would not refute evolutionary theory. Hence the "Not
    necessarily* with which I began my comments. My explanation assumed
    hypothetically the situation where there is very little environmental change
    *and* organisms are optimized for their current niches. Perhaps Mike missed
    this part of my remarks.

    If the organisms were significantly *non-*optimized for their environment,
    we would see relocation, extinction, or evolutionary change, even in an
    unchanging environment.

    And, if the environment is *not* stable, then we should expect evolutionary

    Only in the case where optimization is "complete" (within the reach of small
    genetic changes) *and* the environment puts selective pressure on organisms
    to *stay* as they are, *will* they stay the way they are.

    In fact, if it turned out that the period in question showed no evolutionary
    development *and* it was known that environmental changes were fairly
    continuous, severe, and long-lasting (i.e., lasting long enough to put
    selective "pressure" on organisms that should result in significant change),
    *THEN* we could say that something was wrong with evolutionary theory.

    Moral of the story?

    1. Evolutionary theory is more complex in the working out of its
    implications than Mike is willing to acknowledge.

    2. Try not to too closely emulate Stephen's tendency to misrepresent your
    opponent's views by ignoring context and qualifiers.

    3. Evolutionary theory is not as "plastic" as Mike would have us believe. It
    is *certainly* vastly less "plastic" in this respect than designer theory,
    which can "explain" not only what *does* or *can* happen under evolutionary
    theory, but what *can't* happen under evolutionary theory, with no
    limitations *whatsoever*! Supporters of designer theory are *hardly* the
    ones to be talking about the "plasticity" of evolutionary theory, a theory
    in which there are no *conceivable* empirical observations that could
    falsify it, because it imposes no restrictions *at all* on what the
    empirical facts must be if it is to be true.

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