Not unexpectedly, Jim Bell disagreed with my point, but he did not really
address the central issue on which my point is based. Rather he offered a
rather specious criticism of one of my illustrations. If you just had Jim's
response to my critique of irreducible complexity to go on, you would think
that I only provided some speculative "sound bite" rather than asked whether
a central a priori assumption of Behe's model was necessary.
Jim wrote:
>Sure, one can imagine (and I use that term advisedly) virtually anything. But
>at some point it becomes so fabulistic (e.g., Glenn Morton's motorcycle) that
>it strains credulity past the breaking point. This is why Phil Johnson dubs
>much of evolutionary thinking "just-so stories." As in the Kipling fable of
>how the leopard got its spots, one can "imagine" anything for an explanation.
>But scientific evidence is another matter.
>
>The imaginary tool I find evolutionists waving like a magic wand is the one
>Steve uses above, viz.: "Suppose a primordial structure provided an early
>selective advantage..."
A "just-so" story is much different than an illustration, Jim. The former
invokes some plausible scenario as a factual explanation of something.
Kipling's story of how the leopard got his spots fits this definition. On
the other hand, an illustration is less ambitious and simply provides a way
in which to help the reader understand an abstract point. Illustrations do
not need to be factua, and some are in fact obviously fabulistic. My
criticism of irreducible complexity does not rely on any just-so story. In
fact, my criticism can be made without invoking any illustrations.
Therefore, if you wish to take issue with my point, Jim, then address it
directly rather than pick on an irrelevant and tangential issue.
Using Behe's illustration here, I restate my point that a mousetrap could
"evolve" without first functioning to catch a mouse. A subtle change in a
primordial structure, say a catapult, results in astructure with a
completely different function, a mousetrap. Thus, the complaint from
irreducible complexity that a mousetrap minus any of its parts is not a
mousetrap, represents a normative statement rather than any law of
antievolution. Irreducible complexity is not necessarily relevant to the
evolution of complex systems.
At 01:23 PM 11/25/96 EST, Jim wrote:
>Steve Clark writes:
>
><<Suppose a primordial structure provided an early selective advantage because
>it increased the surface area of the cell and facilitated nutrient uptake?
>This primordial structure would not need all of the components of a cilia
>which seems to take care of the problem of irreducible complexity of cilia.
>
>The point of this exercise is that the concept of irreducible complexity
>has an a priori constraint of functional similarity between
>proto-structures and "final" structures that I am not sure is reasonable.
>In other words, it seems that by irreducible complexity, Behe
>means that complex structures are FUNCTIONALLY irreducible. If we ignore
>the functional constraint, is Behe's view of evolution still reasonable?>>
JB
>Yes. Behe discusses this point, and on pg. 40 says: "Even if a system is
>irreducibly complex (and thus cannot have been produced directly), however,
>one cannot definitively rule out the possibility of an indirect, circuitous
>route."
So, Behe answers my question. There is no reason to assume, a priori,
FUNCTIONAL irreducibility. The thing that "one cannot definitively rule
out" is called evolution.
"Such an appeal to brute luck can never be
>refuted. Yet it is an empty argument....Luck is metaphysical speculation;
>scientific explanations invoke causes."
Is luck involved in evolution? Well, most of the reflectorites seem willing
to accept the notion of microevolution which posits selection as a driving
mechanism. Behe might call this luck, but it is really much more than
simple metaphysical speculation. For instance, even microevolution due to
artificial (intelligent) selection, such as in pigeon breeding, entails
"luck" for the selected pigeons, but this represents a reality that cannot
be dismissed by misleading rhetorical labels, like "metaphysical." If
Behe's criticism doesn't apply to microevolution, why should it apply to
macroevolution which is supposed to also be driven by selection?
Cheers,
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
"...a university is a collection of disparate academic entrepreneurs united
only by a common grievance over parking." Clark Kerr, former Chancellor
of the Univ. of California
_____________________________________________________________