Comments on Ken Miller's Reply to My Essays
 

                                           Michael J. Behe
                                          Discovery Institute
                                           January 8, 2001
 

Kenneth Miller, Brown University Professor of Biology and author of
Finding Darwin's God, has posted a response to my essays.
http://biocrs.biomed.brown.edu/Darwin/DI/Design.html Overall I'm satisfied
with his reply because, although he continues to defend his position, from
the substance of his writing I think it should be plain to most
open-minded readers that he is struggling to fend off examples that weigh
heavily against Darwinism. So, for the most part, I am content to let the
exchange end here. I simply urge all who are interested to read my essays
as well as his response and come to their own conclusions. I do, however,
want to make a few additional comments, in just two areas, to keep the
issues in focus.

On the "acid test"

Professor Miller claims that the careful work of University of Rochester
biologist Professor Barry Hall is an experimental demonstration of the
ability of Darwinian evolution to produce an irreducibly complex
biochemical system. (Barry Hall himself never made such a claim.) I
disagree. The fact that the artificial chemical inducer IPTG was added to
the lactose-utilizing system effectively mitigated its irreducibility,
turning the system into one that could be improved a step at a time. In
his recent essay Miller wrote:

"Does Barry Hall's ebg system fit the definition of irreducible
complexity? Absolutely. The three parts of the evolved system are: (1) A
lactose-sensitive ebg repressor protein that controls expression of the
galactosidase enzyme; (2) The ebg galactosidase enzyme; (3) The enzyme
reaction that induces the lac permease. Unless all three are in place, the
system does not function, which is, of course, the key element of an
irreducibly complex system."

Miller's claim is incorrect because in the presence of IPTG the three
features he lists are not all needed. In the presence of IPTG, the "enzyme
reaction that induces the lac permease" is not required because IPTG
itself induces the lac permease. Thus in the presence of IPTG the system
is not irreducibly complex. And, as I wrote in my original essay, Barry
Hall clearly noted that in the absence of IPTG--when the system actually
is irreducibly complex--no viable mutants have been found in his 25 years
of investigation.

The inclusion of IPTG was the result of the decision of an intelligent
agent (Barry Hall) to deliberately alleviate the irreducibility of the
system. In the absence of that intelligent action, Darwinian processes
alone were ineffective. That is exactly what intelligent design theorists
would expect.

Miller also writes, "the ebg gene is actually only 34% homologous to the
gene whose activity it replaces (meaning that about 2/3 of the protein is
quite different from the galactosidase gene whose function it replaces)".
Yet he knows as well as I do that 34% general sequence homology makes it
virtually certain that the three-dimensional structures of the two enzymes
are essentially identical. And since the active sites (the business end)
of the enzymes are much more similar (they are identical in 13 of 15
residues), the ebg enzyme is pretty much a spare copy of the lac enzyme.
Thus it seems to me that the taking over of lac galactosidase function by
ebg hardly even rises to the level of microevolution.

What is actually surprising--even to a design theorist such as myself--is
Barry Hall's finding that no enzyme other than ebg could fill in for the
missing lac galactosidase. I would have expected otherwise. Perhaps even
changes we would consider to be "microevolution" are often times beyond
the reach of Darwinian processes. Perhaps even I give natural selection
too much credit.

On the mousetrap example

Professor Miller writes, "MacDonald's drawings address Behe's contention
that 'all components have to be in place before any mice are caught.' They
don't, of course, because there is more than one way to construct a
mousetrap from mechanical parts."

But they do--all of the parts of my mousetrap do indeed have to be in
place for it to function. I noted clearly in my book, and in my mousetrap
essay on this website, that I am very much aware "there is more than one
way to construct a mousetrap from mechanical parts." Nonetheless, if you
just take away pieces from the trap I pictured--and don't manipulate it
further--the trap doesn't work. What Miller actually means is that if you
take away some components and then go on to, say, twist a couple of metal
pieces in just the right way and add a few staples in the correct
positions, you can construct a new kind of working trap, which may
superficially resemble the starting trap. That, however, is intelligent
design. Neither Miller nor anyone else has shown that the mousetrap I
pictured in my book can be constructed by a series of small changes, one
at a time, as Darwinian evolution would have to do. The important
take-home lesson is that even things that look superficially similar, such
as the series of traps Miller showed, may not be able to be transformed
into each other through a Darwinian process.

Towards the end of his essay Miller writes, "If simpler versions of this
mechanical device [the mousetrap--mjb] can be shown to work, then simpler
versions of biochemical machines could work as well . . . and this means
that complex biochemical machines could indeed have had functional
precursors."

However, consider the general statement, "System A looks like system B but
cannot be transformed into system B by a series of small, Darwinian-like
steps." Miller explicitly agrees that is true for the mousetrap series.(1)
Yet in the statement above he seems to think that the very fact it is true
for mousetraps somehow shows it is not true for biochemical systems.

That reasoning isn't completely backwards, but it's pretty close. If the
simpler mousetraps can't be transformed into the
similar-looking-but-more-complex ones by something analogous to a
Darwinian process--which, again, Miller freely admits in his essay--then
the mousetrap series gives us no reason to think that postulated simpler
biochemical systems could have been transformed by natural selection into
the complex systems we see today. On the contrary, the mousetrap series
gives us a prima facie case to think they couldn't.

Endnote

(1) In his essay Miller wrote the following:

"Behe argues that MacDonald's four simpler mousetraps do not present a
good model of a 'Darwinian process.' Even the simplest mousetrap, Behe
argues, requires 'the involvement of intelligence,' and the 'involvement
of intelligence at any point in a scenario is fatal.'

"I agree. And if I or MacDonald or any one else had presented the simpler
mousetraps as examples of an evolutionary transition, Behe would be
right."
 

Oryginal: http://www.discovery.org/crsc/CRSCrecentArticles.php3?id=579