"Guy Hoelzer"  wrote in message
news:cf0iaq$1nf6$1{at}darwin.ediacara.org...
> in article cev3s2$17fm$1{at}darwin.ediacara.org, Perplexed in Peoria at
> jimmenegay{at}sbcglobal.net wrote on 8/5/04 10:10 PM:
>
> > "Anthony Cerrato"  wrote in message
> > news:cetl73$lte$1{at}darwin.ediacara.org...
> >> "Perplexed in Peoria"
 wrote in
> >> message news:ceru6h$48v$1{at}darwin.ediacara.org...
> >>> It seems that your slime beast is "autopoietic".
> >>> In fact, this word was invented with specifically
> >>> this issue in mind. It is an attempt to characterize
> >>> "life" as something different than reproduction or
> >>> replication.
> >>
> >> Yes indeed! That is a perfect word, if a little awkward in
> >> common conversational use--but an autopoietic system
> >> is exactly what I meant--any dissipative structure, i.e.,
> >> non-equilibrium dynamic system, perfectly mimics life, be it
> >> a chemical clock reaction, or Jupiter's Great Red Spot! It
> >> seems appropriate for a more general definition of life,
> >> including non-replicating life. Thanks,
> >
> > Careful!  An autopoietic system and a dissipative structure
> > are not necessarily the same thing.
>
> Hmm.  This is true in a trivial (IMHO) sense.  The radiator in your
> car is a dissipative structure that is not an autopoietic system.

Hmmm.  Your definition of a dissipative structure is broader than
mine.  Although a radiator has structure and dissipates, I would
have never have thought to call it a dissipative structure sensu
Prigogine.  It is not self-organizing.

> On the other hand,
> it is a functional part of the SYSTEM of the car's engine, which necessarily
> includes homeostatic mechanisms.  Would you agree that all autopoietic
> systems are also dissipative structural systems?

Certainly not by my definition of a dissipative structure!  Though
I might agree that all real world natural autopoietic systems will
include one or more dissipative structures among their components.
However, this does not follow from the definition of an autopoietic
system.  It just happens to be true of all known autopoietic systems.

To my mind a dissipative structure arises spontaneously when there is
a thermodynamic flux sufficient to maintain it.  Therefore, I think
that a dissipative structure has to be simple.  You can disrupt a
dissipative structure by perturbing it internally, but when the
perturbing force is removed, the structure will simply reform as long
as the environment still supplies the fluxes.

By contrast, an autopoietic system can be "killed" by an internal
perturbation.  If the processes of self-maintenance are halted, and
the structure that supports them is disrupted, there is no automatic
bootstrap mechanism to get them running again.

> > I'm not sure that
> > Maturana and Varella intended "autopoietic" to include
> > such simple systems as Prigogine's dissipative structures.
>
> Can you specify what it is that Benard cells or a BZ reaction lack that
> exclude them from your list of "autopoietic" systems?

Well, the main things missing seem to be a notion of component parts,
plus the boundary of a dissipative structure is far too nebulous
and/or externally imposed.

Here is a checklist of features that must be present for a system to
be called autopoietic:
http://www.enolagaia.com/Checklist.html
I think you will agree that M&V did not intend to include Benard and
BZ systems under their umbrella.

> > Dissipative structures tend to be less homeostatic than
> > autopoietic systems.
>
> This does not make sense to me as I view all autopoietic systems as a subset
> of all dissipative structures.  Perhaps your response to my question above
> will help to clarify your meaning here for me.

> > While DSs maintain their existence
> > over a range of environments, they do not necessarily
> > maintain their form.  Nonetheless, the definition of
> > "autopoietic" could conceivably be stretched to include them.
>
> I guess I am pushing the stretch here in your view.  Why do you think that
> structural plasticity is inconsistent with the notion of autopoietic
> systems?  In my view, it is an essential aspect of autopoiesis.

Well, it appears that you are right that structural plasticity (the system
changes its structure in response to changes in the environment) is
permitted to an extent greater than I had thought.  So my
homeostasis distinction is not a valid distinction.  But I think that
you are wrong to suggest that structural plasticity is an essential aspect
of the definition of autopoiesis.  It is better classified as a central
aspect of the *theory* of autopoiesis - a crucial feature to the interesting
applications of autopoiesis to the theory of cognition.

Furthermore, when I said that an autopoietic system maintains its form,
I was thinking of the size and shape of the boundary and other aspects
of gross spatial structure.  I did not have in mind the subtle internal
structural changes that accompany learning.  Those kinds of changes seem
to be the ones that are most frequently referred to as plasticity.

For example, add some lactose to the environment of an autopoietic E coli.
There is a "structural change" in that various chemicals are created that
switch the lactose operand on.  But the cell morphology does not change.
Now add some lactose to a Benard or BZ system and the change in viscosity
will change the size of the Benard cells, while the added sugar fuel may
change the period of the BZ "chemical clock".  That is not only a
structural
change - it is morphological.
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