Re: [asa] Behe Responds To Ken Miller - Edge of Evolution

> David C. said: Co-option falsifies IC (irreducible complexity) because it
> provides a
> way to assemble the complex system step by step.
>
> Not so. In itself, cooption shows only that some components of a putatively
> IC system could possibly have been borrowed from some other system. It does
> not, in itself, show how the entire system could have been assembled
> step-by-step such that there is some utility in the system at each step.

Not all steps actually must have utility-as long as they do not have
significantly negative influence they can exist and persist.

Each step of the way could involve co-option, so co-option provides a
potential way to assemble every step. IC tends to assume that the
current function was the original one.

Cf. the question I raised previously in this context-what's the
probability of someone inventing the automobile, given a starting
point culturally and intellectually similar to early modern humans?
If you want the Cro-Magnon think tank to be inspired by a lump of iron
ore and a tar pit to come out with plans for a 52 DeSoto, you will
assign a low probability. If you think that over time, individuals
are likely to discover the wheel, its application to transportation,
how to make an engine, and how to put those together to produce some
sort of self-propelled vehicle, not necessarily looking much like
anything current automakers have selected beyong the basic constraints
of physics, then your probability estimate will be much higher.

Well back in the ASA list archives was a post noting that the Krebs
cycle is present basically in two halves (one "half" has a component
not fully integrated but closely associated) in some bacteria.
They're both in the same cell; putting it all together is not much of
a stretch for evolution yet IC claims it's impossible.

Of course, for any given situation one must investigate possible
co-option steps along the way, and in many cases the evidence is
probably long lost. However, complex biochemical systems function
through a series of steps. Each step thus does something and is
potentially useful-the apparent difficulty of IC only arises when one
assumes that the present function is the original goal. "One still
has to show how the incomplete IC system would function as it coopts
parts" falls into this error-it doesn't yet have its final function as
it co-opts parts.

There are other stepwise ways to a more complex end besides co-option
(such as serial addition of steps or gene duplication foloowed by
division of function).

Also, there is the question of exactly what is being argued.
Absolutely ruling out IC is probably impossible, but absolutely ruling
out non-IC is probably impossible too. I would assert that co-option,
among other things, shows that IC is not a solid basis to claim proof
of a designer. I would not assert that IC does not pose a challenge
for evolutionary explanations; however, it is a challenge that has
been met in several examples.

-- 
Dr. David Campbell
425 Scientific Collections
University of Alabama
"I think of my happy condition, surrounded by acres of clams"
To unsubscribe, send a message to majordomo@calvin.edu with
"unsubscribe asa" (no quotes) as the body of the message.