Over at casa de Dembski,
DaveScot tries to debunk a debunking of an ID argument. It goes
something like this:
Michael Behe: The bacterial flagellum is irreducibly
complex, that is, all of its components need to be in place before
it’ll work. It can’t have evolved by gradual addition and improvement,
because none of the subparts do anything until they’re all put
Nick Matzke: Ah, but the Type Three Secretory System (TTSS), a
sort of bacterial syringe, is made up of proteins that look an awful
lot like ones used in the flagellum. That is, you can build
something useful using just some of the parts requied for a
flagellum, and that gives natural selection something to work with.
For instance, the flagellum could have evolved by adding parts to a TTSS.
Ah, but I have here a paper about a species of bacterium that started
out with a flagellum, but lost most of its parts through natural
selection, leaving only the parts needed to construct a TTSS.
To which I reply below the fold.
This is a red herring: Behe’s original claim that the flagellum is
irreducibly complex (IC) and therefore could not have evolved
rests on the assumption that natural selection cannot select
for any subset of its components, since none of them do anything
Matzke effectively demolished that assumption by showing that at least
one subset of the flagellum’s parts—specifically, those used for
building the TTSS—are useful, and therefore natural selection
could have provided those parts as something to build upon to make a
DaveScot’s paper, then, doesn’t demolish Matzke’s argument. At best,
it weakens it a tiny bit (if we assume that the TTSS is the only
possible useful subassembly of the flagellum; this seems dubious,
because in nature, there’s very rarely just one of anything; if one
subassembly is useful, it seems likely that another is, as well).
Behe: Evolution of the flagellum could not have
Matzke: Yes it could. For instance, TTSS.
DaveScot: But that’s not how it did happen.
Or try a different argument with the same structure:
Behe: Mormons could not have walked from New York to
Utah in the 19th century. It’s simply too far. So they must have been
Matzke: Actually, they could have walked from New York to Iowa,
and from Iowa to Utah. You’ll concede that neither one of those trips
is too far to walk.
DaveScot: Ah, but historical evidence shows that that’s not the
route they took.
Just in passing, I wouldn’t mind seeing a diagram of this argument,
since I’m refuting DaveScot’s refutation of Matzke’s refutation of