Re: action of models - indirect effects

["Dan Fiscus" <***>]

Tim,

Re: your points...

Tim Gwinn wrote:

> The quotes from Patten are enlightening, especially the second one: it runs
> contrary to a commonplace view that direct effects take precedence, and
> indirect effects have diminishing importance. This would also mean that
> stability, as well as alteration, of the biosphere would depend heavily on
> such indirect effects. Did he comment any on if (or not) the net effect of
> indirect influences tended generically toward or away from stability?

He does say in a few places that he sees the general tendency of networks
to be positive, which one could take to include stabilizing. He wrote
(in that
same chapter):

"...the kind of biological interaction observed at a proximate level may
become a qualitatively different type at a higher level of organization when
all the consequences of context are taken into account. This principle of
holism is another manifestation of hierarchical network organization...a
tendency for locally negative interactions to become globally positive
ones."
p 298.

"The present analysis supports the view of a nature dominated by "holistic
positivism" (his in italics), and organized in consequence to provide the
greatest good for the greatest number of individual lives playing out their
collective existences together...To acknowledge the good fortune for life
under network rule, I suggest that the still to be understood mechanism of
this emergence might be referred to as a kind of 'hedonic property' (his in
italics and single quotes) of ecological networks." p340.

Here we see that despite the good ideas Patten still referes to mechanisms,
even a mechanism of emergence - a new one for the oxymoron list!

> I also wonder about the role of indirect effects within an organism - it
> seems likely the same kind of concerns would arise.

Here I am reminded of a review article in Nature (vol 420, Nov. 14, 2002)
called "The Community of the Self" in which Timothy Buchman says in the
abstract "Physiology and computational biology now suggest that healthy
dynamic stability arises through combination of specific feedback
mechanisms and spontaneous properties of interconnected networks." He
means in organisms and especially humans, and the community of self
being the interaction networks of cells, organs, sub-systems, etc. He also
wrote, "It is vital to create models that embed homeostatic mechanisms into
larger networks that themselves confer robustness to perturbation and
thereby protect the community of the self."

Some other cool stuff in this article too, like a quote from a D. Noble who
speaks of the "ambiguity of causation in complex networks".

Dan