From: Terry M. Gray (grayt@lamar.colostate.edu)
Date: Sat Aug 31 2002 - 11:43:19 EDT
Howard (and list),
Two thumbs up! Highly recommended reading.
There's hardly anything I can quibble with here (except for maybe
your classification of naturalisms, but that's a side issue IMO, but
see a bit below).
If I may take the liberty to underscore a couple of points....
1. You point out the difficulty in calculating the probability of
these designed items occuring by "the chance mechanism." I have never
been convinced that these calculations are any more than stabs in the
dark (or built on completely fallacious assumptions). Sometimes they
remind me of the Drake equation for extra-terrestrial intelligence
that Carl Sagan used to promote. I have the same problem with some of
the cosmological fine-tuning arguments. But correctly calculating the
very low probability is *essential* to the ID enterprise. So the
whole idea is built on a calculation that we don't (or even can't)
know the answer to.
2. You also discuss the possible functional precursor to the
flagellum in the type III secretory apparatus. (To be fair it must be
recognized that the secretory apparatus may have evolved from the
flagellum rather than vice-versa, but the jury is still out on this
last i heard.) But, as you point out, the mere possibility of a
functional precursor undoes the probability calculation based on the
flagellum being a "discrete combinatorial object". If there is a
functional precursor on the way to being a irreducibly complex thing
then the probability calculation fails. This is the argument from
pre-adaptation or exaptation that I and other critics have made
against Mike Behe's argument now for about 10 years (and is what
Dawkins' *Climbing Mount Improbable* is all about).
I see this faulty probability calculation most commonly used in
creationist and ID circles in the calculation of probabilities for
functional proteins. They calculate 1/20 to the nth power where n is
the chain length. Sometimes, more subtly, they change the 1/20 to
5/20 or 10/20 or 19/20 for a given position depending on that
positions tolerance to amino acid substitutions as suggested by
sequence comparisons or mutagenesis experiments. But I and many other
have no doubt that this calculation is wrong because that's not the
way function proteins came into existence. The fluidity of the genome
(lateral gene transfer, exon-shuffling, gene duplication, chromosome
duplication, etc.) has severe consequences for that type calculation.
Also, our ignorance of minimal structure to produce minimal function
is a big unknown (because most well-studied biological systems have
been fine-tuned to produce near-optimal structure for the now
selected for specific function). Finally, such calculations seem to
suggest a mechanism of protein assembly (random assembly of amino
acids into a chain) that doesn't seem right if there is any kind of
templating or reproduction of sequence (either in the modern sense or
in some more esoteric version as speculated by some origin of life
researchers).
I always wonder what's the motivation here. Why are we so keen to
speculate on the probabilities to meet the "specified complexity"
criterion? Why "give up" the search or the hard thinking about
options (the broad outline of the answers, though certainly not the
detailed answers, are there--the critics of ID have been pointing
them out as long as the arguments have been made)?
I do think that in answering these questions Howard's discussion of
flavors of "naturalism" come into play. Phil Johnson once called our
"theistic evolutionist" claims vacuous because they looked no
different than full-blown (maximal) naturalism. While I'm not totally
comfortable with the terms "naturalistic theism" and "minimal
naturalism" or the way they are defined in Howard's paper or Howard's
aversion to "coercive supernatual intervention", I am comfortable
with a version of God's action in the world that can be described
without reference to God's direct action (or injection of
information). The scholastic (?) doctrine of concurrence as part of
the doctrine of providence sees God's action as neither coercive nor
interventionist. It fully gives account to the character of the
creature to behave according to its God-given abilities. As such, it
can be described in terms of those creaturely capacities without
reference to the enabling and concurring and providential work of God
(this by the way is how we normally do science, history,
jurisprudence, etc.).
Thanks, Howard, for you work on this.
TG
>Various persons on this list have expressed an interest in Bill Dembski's
>latest book, No Free Lunch. For a variety of reasons I decided to give this
>book a thorough read and to evaluate both its rhetorical strategy and its
>scientifically-relevant claims. The resulting review essay is now posted on
>the AAAS web site at:
>
>www.aaas.org/spp/dser/evolution/perspectives/vantillecoli.pdf
>
>To whet the appetite of ASA listserve members, here is the title and
>abstract info:
>
>
>
>E. COLI AT THE NO FREE LUNCHROOM
>Bacterial Flagella and Dembski's Case for Intelligent Design
>
>by
>Howard J. Van Till
>Professor of Physics and Astronomy Emeritus
>Calvin College, Grand Rapids, MI 49546
>
>Draft 7/22/02, as submitted for posting on the AAAS website, DoSER section.
>
>
>ABSTRACT: The Intelligent Design movement argues that it can point to
>specific biological systems that exhibit what ID's chief theorist William A.
>Dembski calls "specified complexity." Furthermore, Dembski claims to have
>demonstrated that natural causation is unable to generate this specified
>complexity and that the assembling of these biological systems must,
>therefore, have required the aid of a non-natural action called "intelligent
>design." In his book, No Free Lunch, Dembski presents the bacterial
>flagellum as the premier example of a biological system that, because he
>judges it to be both complex and specified, must have been actualized by the
>form-conferring action of an unembodied intelligent agent. However, a
>critical examination of Dembski's case reveals that, 1) it is built on
>unorthodox and inconsistently applied definitions of both "complex" and
>"specified," 2) it employs a concept of the flagellum's assembly that is
>radically out of touch with contemporary genetics and developmental biology
>and 3) it fails to demonstrate that the flagellum is either "complex" or
>"specified" in the manner required to make his case. If the bacterial
>flagellum is supposed to demonstrate ID, then ID is a failure.
-- _________________ Terry M. Gray, Ph.D., Computer Support Scientist Chemistry Department, Colorado State University Fort Collins, Colorado 80523 grayt@lamar.colostate.edu http://www.chm.colostate.edu/~grayt/ phone: 970-491-7003 fax: 970-491-1801
This archive was generated by hypermail 2.1.4 : Sat Aug 31 2002 - 11:44:46 EDT