(From Rick Marken (920805.2000))
Posting from home so here is some leader...
Avery Andrews (9208060) says:
I'm not at all happy with the way the Alife discussion is going.
Actually, it seems to me that it hasn't started yet.
Diehard PCT-ers believe that living systems have to be made out
of control systems, but nobody really *knows* this yet.
This particular die hard PCTer does NOT believe that living systems
"have to be made out of control systems". Never have believed it;
never will. What this PCTer does "believe" is that living systems
CONTROL -- it's a PHENOMENON. Try the test; you apparently have some
living systems running around your house. Push on some variables --
watch those little systems control. Right now, the only theory that we
know of that can control is CONTROL THEORY. If another theory comes
along that can account for the details of control as exhibited by
living systems better than control theory, then I'll believe that
one. I'm fanatic -- but I'm flexible.
The only
way to actually find out is for models based on this idea to be
compared with others that aren't, and this is exactly the opportunity
that Alife provides.
This is not quite true. We have shown over and over again that cause-
effect oranizations (the basis of all current non-control theory
models of behavior that I know of) cannot control. The problem is that
non-control models can often produce non-control phenomena rather
nicely. So when you compare the models (in a situation where it is
impossible to see that there is no control) it seems like a wash --
or the more detailed non-control models appear more impressive.
The only "play-off" between models that makes sense (from a PCT
point of view) is one where behavioral outcomes are produced in the
face of unpredictable (and undetectable) disturbances. I've done
such a playoff with psychological models (as has Tom Bourbon and
Bill Powers), to the total lack of interest of the community of
psychological theorists. Sometimes winning just ain't enough.
But PCT-ers will have to show up at the party
bearing goodies, rather than stand outside sneering at it.
Any sneering comes from the exasperating tendency of "non-PCTers" to
ignore the most important "goodie" that die hard PCTers have to
offer -- the phenomenon of control. Since students of living
systems seem determined to remain uninterested in trying to
figure out what the hell they are trying to explain (since they
already "know" what's to be explained -- BEHAVIOR, of course) then
it does seem that we will have to try to point out the beauty of
control theory with other "goodies". Bill Powers' "Little Man" demo,
for example, shows how computationally efficient it can be to build a
behaving system (forget that it also controls) using the principle of
control of perception. By doing so, you eliminate the need for gargantuan
computations of inverse kinematics and ridiculous assumptions about
what the system can know about the state of the environment in which
it is producing results. The roboticists will love this "goodie"
(I bet -- based on Tom Bourbon's report of the reaction to it at Aix)
but it will still take some time to show that control of perception is
not just a good technical strategy; it is also the strategy that
is used by living control systems because there is no other way to
produce consistent results in a disturbance-prone environment (ie. to
control).
What seems to me to be the most compelling criticism of Alife is that
the success of their models is judged by their producing behavior that
`merely' looks lifelike
That's the ONLY criticism; another way of saying this is " their models
don't control." (probably -- but I'd be happy to be proved wrong. Indeed,
that's what Bruce and Bill and I want to learn from the ALife dicussion;
are Alife models trying to explain control? But you say you don't
like the direction of that discussion. I can't think of a better one).
But our judgements of the
behavior of lifelike agents are not just an exiguous construction
based on our current culture, but the end result of 600 million years
or so of competitive R&D by multicellular organisms trying to fake
each other out, and so are not to be taken lightly, in my opinion.
Darn. I always have to look up the word exiguous.
A line I am thinking along goes like this: what the nervous system of
a living creature is is a continuous vector transducer whose outputs
influence its inputs. The expected behavior of such a system is a
non-viable combination of chaos and catatonia (outputs being forced to
extreme values by positive feedback effects), and the (putatively) only
way to avoid this consequence is to load the systems to the gills with
negative feedback loops. So the PCT perspective ought to improve the
design of Alife systems, and the analysis of Rlife ones (organisms).
I think this ought to be an adequate rationale for the pursuing the PCT
approach within Alife circles
I think you are putting the mechanisms before the phenomena. You
assume that living systems exhibit all kinds of behaviors that need
certain mechanisms to fix them up. I don't believe there is any evidence
that living systems normally exhibit these behaviors -- at least not nearly
as much evidence as there is that organisms control.
But why work so hard at trying to find a place for PCT in Alife?
Let's see what Alife is about and maybe it can get along just fine
without us fanatics (as Bruce Nevin correctly suggested).
Best regards
Rick (Bruce Willis) Marken
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