Tim Ikeda wrote:
> "Irreducibly complexity" is a distinct term (IC) although Mike does
> use "complexity" by itself and in the colloquial sense elsewhere
> in his book. Thus IC and "complexity" are separate things. Or
> to put it better, IC refers to mostly one type of thing while
> "complexity" means lot of things in Behe's book.
Actually, Behe uses the term IC to mean TWO types of things.
(IC-1) Systems that must have all the parts in order to function at all.
(IC-2) Systems whose parts could not of been produced "evolutionarily."
The problem is --- and this is the biggest problem I have with Behe's
arguments --- those two classes of systems are NOT identical! Behe uses
them equivalently, but they simply are not equivalent, nor is one a subset
of the other. It is demonstrably true that various computer programs,
using a variety of different strategies, can "evolve" systems which must
have all their parts in order to function. For a variety of computer
programs (and also for mousetraps) there are IC-1 systems which can,
in fact, self-assemble.
Now, Behe is explicitly uninterested in these computer programs. He is
concerned with biochemistry.
Is IC-1 a subset of IC-2 when restricted to biochemical systems? I
think I know of at least one set of counter-examples. Some heteromeric
ion channels fall into IC-1, but appear to have evolved from homomeric
channels (simpler systems which are not IC-1) via gene duplication and
mutation. Admittedly, heteromeric ion channels are a particularly
simple example of IC-1. As Behe has pointed out, he doesn't need to prove
that *every* little biochemical example of IC-1 falls into IC-2. He only
needs to show IC-2 for *some* biochemical systems.
Perhaps Behe can re-define IC-1 to set the "complexity threshold"
higher and thereby exclude such "simple" examples as heteromeric ion
channels. But this creates a new problem. If you're going to argue
whether a particular biochemical system in a particular organism could
(or could not) have evolved, you really need to know the gene sequences
and genome locations of every element of that system, plus all of the
closely-related sequences in the genome, plus all the homologous sequences
in related organisms (both those organisms with that biochemical system,
and those organisms without it). Until we have these comprehensive data
sets, arguments about whether or not a particular system could (or could
not) have evolved are necessarily hand-wavy.
Behe dismisses all hand-wavy hypotheses about the evolution of various
complex biochemical systems. But without the genomic data necessary
to propose detailed hypotheses, all Behe can do is off hand-wavy arguments
*against* their evolution. Should Behe's hand-wavy arguments be as readily
dismissed as he dismisses the hand-wavy arguments of his opponents? At
this point, it becomes a bickering match over who has the "burden of
proof." Whose hand-wavy argument trumps the other's?
Since the two definitions of IC are not equivalent in general, and
probably aren't equivalent when restricted to biochemistry, what we
really need is specific and *comprehensive* genome data.
Loren Haarsma