Re: [asa] RE: (irreducible complexity and evolution) design and the nature of science (was: Re: [asa] Re: Gingerich on TE and ID)

From: Iain Strachan <>
Date: Tue Jun 16 2009 - 14:16:20 EDT


I must admit I find it hard to digest your rather lengthy responses and be
sure I've not missed something, so I'll try and respond to what I see as the
main point and try to be brief. I don't have the time to read the large
number of lengthy essays that get posted on ASA listserv - if I did there
would be nothing else that got done during the day!

On Tue, Jun 16, 2009 at 2:16 PM, Cameron Wybrow <>wrote:

> Iain:
> We are still not connecting. You write as if I offered this sentence --
> "To disprove the claim that the flagellum is irreducibly complex, one would
> need to rip out a part of the flagellum and have it still function *as a
> flagellum* (not as a Type III secretory system)."
> as the basis of an argument that, if the flagellum evolved via Darwinian
> means, it had to have evolved from a series of less effective flagella, and
> that as this is impossible, the flagellum could not have evolved by
> Darwinian means. But this was not what I had in mind when I wrote the
> sentence. It was intended only to show that your previous remarks (about
> the possibility of co-opting existing proteins) had not disproved the
> irreducible complexity of the flagellum, and in fact were based on a
> misunderstanding of Behe's use of the term "irreducible complexity". That
> is, *even if it is true* that the flagellum evolved from some earlier
> system (which could have been the Type III secretory system, or something
> else) by making use of ready-made sets of proteins, it does not follow that
> the flagellum, as we have it now, is not irreducibly complex.

> As I said to Bernie, the question "Is this system irreducibly complex?" is
> distinct from the question "Could this irreducibly complex system have
> evolved via Darwinian means?" The notion of "irreducible complexity" is not
> by definition connected with the notion of "unevolvability" (in the way that
> the notion "having no legs" is by definition connected with the notion
> "unable to walk"). IC may have *implications* for evolutionary speculations
> of certain kinds -- Darwinian speculations -- but those implications aren't
> part of the definition.

> ***"Irreducible complexity" is an "engineering" description of the
> functioning of a system, not a statement about lack of evolvability. ***

I'll focus on this sentence as it seems to be the kernel of where we
disagree. I think the argument from irreducible complexity is at least a
statement that leads to the belief that something couldn't evolve. It's
what convinced me when I read DBB, and had me believing that Intelligent
Design was a viable proposition for a while, until I found the idea of
change of function, when the whole thing collapsed (fortunately I didn't pin
my faith on it, so that's still intact).

Here's what Wikipedia <>says about

Behe is best known for his argument for irreducible
a concept that asserts that some structures are too
complex<>at the biochemical level
to be adequately explained as a result of
evolutionary mechanisms and thus are the result of intelligent

That certainly states that the implication of irreducible complexity is that
evolutionary mechanisms are inadequate to explain complex structures, ie
they are not evolvable.

OK, one might say that Wikipedia is written by a lot of godless liberals and
is biased. So let's see what the right wing and creationist friendly
<>has to say about Behe:

He argues that molecular
such as the bacterial flagellum <> are
irreducibly complex <>. Such
machines require all of their parts to function, Behe says, and so could not
have come into being through an unguided process. He considers this evidence
that the flagellum must have been designed.

Well, that looks pretty much the same as the Wikipedia entry, with a little
more detail.

Thus the commonly accepted implication of Irreducible Complexity is that
unguided evolutionary processes can't account for something and that this is
evidence for intelligent design.

If you want to say that the definition of Irreducible Complexity doesn't
exclude change of function, then it's useless for the purpose of drawing the
conclusion of design. If all the bits were present and being used happily
for something else before forming the flagellum, then that's a whole lot
more plausible than if a few dozen absolutely useless pieces of equipment
occurred by chance before they came together as a flagellum. In the first
case, evolution is plausible and there is no need to draw a design
inference, but in the second case, evolution is implausible.

Miller's example (and all the other information we have of proteins in the
flagellum having other uses) tend one towards the first case.

Which brings me back to my main point. If irreducible complexity only
applies to the function of given system and not other systems that might
have evolved earlier, then the only response has to be a big "So what?"



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Received on Tue Jun 16 14:16:55 2009

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