On Thu, May 08, 2014 at 12:05:24AM -0400, Richard Aiken wrote:
> Those favoring irreducible complexity have a point that a chemical
> process with ~23 steps (none of which do anything alone or in any other
> combination of each other)

They can stop right there.  Those steps *do* do something without the
full cycle.  I don't know when your text was written, so maybe it's
just obsolete rather than wilfully blind.

> Those opposing irreducible complexity say that the individual
> components of such a process could be spread through a population as
> part of other functional processes but don't give any example of
> plausible previous processes.

Again, that could just be obsolescence.  Such examples are now known.

> That lack strikes me as disingenous, since a *functional* process
> using specific components that could later form a different process
> contradicts someone's earlier point that chemical processes are
> incredibly delicately balanced - if any variable differs by the
> slightest degree, the process does not work the same or at all.

The closest I've seen anyone say that was myself, and it was in
relation to the processes of a *single* organism changing due to wide
temperature variations.  I said nothing about immutability of
processes across evolutionary timescales, nor about impossibility of
multiple processes operating in different temperature regimes.  In
fact I gave examples where processes had changed, and also examples of
organisms that do use quite different process in different conditions.

> But the opponents also say that even if these future components
> didn't spread as part of a different process, they could still get
> carried forward as non-functional junk - which is true but depends
> on the future-valuable junk being linked to Something Else that is
> selected.

No, the latter condition does not hold.  All it requires is that the
pieces not be heavily selected against.

> If not, it's prevalence would drop as per the quote above.

The quote above was giving examples of how a trait can persist for
quite some time even if it is selected against.  Traits that are
neither selected for nor against can persist for arbitrarily long time
spans.  They can be retained for longer than any one species that
carries them, via multiple mechanisms.

> There wouldn't be a million organisms carrying it around, waiting
> for the right combination of mutations to put all the pieces
> together.

That is correct, in a sense.  There would not be merely millions.

In the case of chemical mechansism evolving in bacteria, there would
likely be more like 10^31 organisms at any one time (millions of
million million million millions).  Then multiply that by the number
of generations, so tack another "million million" or so onto that.
Also note that horizontal gene transfer is more viable in bacteria
than in the much more complex organisms that came later.

- Tim