>On Sat, 23 Nov 1996 12:54:13 -0600, Steve Clark wrote Re: irreducible
complexity:
>
>[...]
>
>SC>While I applaud Behe for producing a thought-provoking tome, I have a
problem
>>with a basic premise behind his thesis.
>>
>>My problem with the model has to do with the presupposition that evolution
>>only works by fine-tuning the function of primordial structures. That is,
>>the idea that a mouse trap evolved from a primordial structure by gradual
>>improvement of mouse catching ability. This sounds like a microevolution
>>scenario. Behe's model, however, does not seem to account for the
>>possibility that a mousetrap could evolve from something that originally did
>>not function as a mouse trap, which seems more congruent with a
>>macroevolution scenario.
>
>Actually Mike *does* deal with this:
>
>"Even if a system is irreducibly complex (and thus cannot have been
>produced directly), however, one can not definitively rule out the
>possibility of an indirect, circuitous route. As the complexity of
>an interacting system increases, though, the likelihood of such an
>indirect route drops precipitously.
What does this mean? Most people would recognize that complexity provides a
daunting challenge to evolution. Darwin recognized this in the eye. But
this is a problem for ANY model that attempts to explain the origin of
complex structures. Besides, the "indirect" route isn't a necessary
alternative to the gradual fine tuning of some functionally irreducible
structure that Behe seems to favor. If evolutionary changes are not
constrained by the requirement to gradually make a better mousetrap, then
large changes in function--to say a catapult, can be arise from relatively
small changes in structure. This is not "circuitous." In fact, significant
changes could arise quickly rather than gradually if the constraint on
function is minimized.
And as the number of unexplained
>irreducibly complex biological systems increases, our confidence that
>Darwin's criterion of failure has been met skyrockets toward the mum
>that science allows."
This is the crux of the debate. Some people cannot imagine how complexity
could arise through naturalistic means, even if there is an intelligent
force behind the process (e.g., ECism). Other people can imagine it, and
others simply say that Behe's criticism does not provide a sufficient basis
for rejecting the evolution model. My position is the latter. Simply
pointing out deficiencies in a theory is not the same thing as proposing a
counter model. That has not been done.
>His point is that *no one* has ever been able to explain even *one*
>of these complex micro-biological systems using "a macroevolution
>scenario".
Is this really his point--that no one has ever been ABLE to explain this?
Or is the point simply that there are no explanations offered? There is a
BIG difference between not offering an explanation vs trying trying to find
one, but failing. This is an important distinction that is not being made
here. From the comments on Behe's book that I have heard and read, it
appears to me that antievolutionists overinterpret this observation.
What does it mean that there are no published accounts that try to explain
the origins of complex stuctures? Has it been tried and failed? Or have no
attempts been made? If the latter, then is the question tractable to being
tested empirically? If so, how long has it been possible to test the
question? Keep in mind here, that Mike also states that our understanding
of complex molecular structures, like cilia, is much more recent that
Darwin's model of evolution.
As a counter point, one could ask how many published accounts describe
alternative, nonDarwinian ways of arriving at complex structures?
>If you believe that (say) the blood clotting cascade "evolved from a
>primordial structure by gradual improvement of" blood clotting
>ability", then why don't *you* win "instant fame" by doing it
>first, as Russ wrote:
First of all, I said that evolution by gradual refinement of a function,
such as blood clotting, is not an a priori requirement of evolution.
Second, I appreciate Mike's point that this is a hole in the evidence for
evolutionary biology. It would be nice if his point stimulated some thought
to "evolutionary molecular biology." I, however, will pass on the
challenge--it's not what I do or know.
Mike's criticism, and the discussion it has stimulated, revolves around the
philosophical concepts of probability and liklihood--they are really
different things. I plan to post something on this soon.
Steve
____________________________________________________________
Steven S. Clark, Ph.D . Phone: 608/263-9137
Associate Professor FAX: 608/263-4226
Dept. of Human Oncology and Email: ssclark@facstaff.wisc.edu
UW Comprehensive Cancer Center
CSC K4-432
600 Highland Ave.
Madison, WI 53792
Ya gotta pay yer dues if ya wanna sing the blues, and ya know it don'
come easy.
____________________________________________________________