> 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.
Chris
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
change.
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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