[Martin Taylor 931007 19:30]
In introducing PCT to a control engineer in our Human Factors division
yesterday, I came across a relationship that I am not aware of having
been discussed (but I haven't read all of LCS 1 and 2, so, like emotion,
it may be there). I call it "mutuality."
In "The Selfish Gene" Dawkins uses the image of the chromosome as a team
of agents, each of which does something that benefits the reproductive
success of the others, though not directly of itself. Genes that have
this kind of complementarity tend to be found nearby on a chromosome
because chromosomes can break and reconnect differently, reducing the
chances that distant genes will, over long time scales, be passed together.
Likewise (not from Dawkins) if there are two cells, each of which produces
as a side effect of its own operation a substance that enhances the operation
of the other, the bi-cell will survive better than either alone, if they find
a way of sticking together physically, and of reproducing in tandem.
I propose that it is very likely that evolutionarily early control systems
may have joined in such mutual arrangements, and that evolved control systems
continue to do so. Here's the argument.
A single ECS (A) controls its perception in the presence of disturbances to
its CEV (CEV-A). It can neither predict nor directly observe these
disturbances, except as fluctuations in the value of CEV-A. Any ECS has
limits on the speed with which it can compensate for the disturbances, and
the range of disturbance force that it can counter.
Consider a second ECS (B), which has as its CEV-B some part of the variable
that disturbs CEV-A. ECS-B has no perception of ECS-A or CEV-A. It simply
controls CEV-B. But as a consequence of that control, the disturbance
to CEV-A is reduced, easing the control by ECS-A of its own perception.
Now suppose that CEV-A is part of the variable that disturbs CEV-B. Now
ECS-B has an easier job of control, which directly eases control exercised
by A. Each ECS in this figure-8 loop has a multiplicative effect on the
apparent gain of the other.
Here's a picture:
> >
> ref-A | ref-B
----------O--------- ---------O----------
> > > >
PIF-A OUT-A PIF-B OUT-B
> > > >
=======^====================V======^===================V=======
> > > >
<-----CEV-A<-------- <------CEV-B-------
> > > >
V DIST-A<-------------------V DIST-B
> ^
----------------------------------| This loop in the
environment is unperceived
by either ECS
In the diagram, DIST-A and DIST-B are supposed to be influenced by, but not
identical to CEV-B and CEV-A respectively. The effect of each control
system is to smooth the disturbance on the other, purely as a side-effect
of its own perceptual control.
If the necessary (and I think not uncommon) environmental conditions hold,
ECS-A and -B become symbiotes. It is advantageous for them to stay together.
Organisms that evolve so that they do will be more stable than those in which
the symbiotes are separated.
The mutuality connection need not, of course, be restricted to pairs of
ECSs. Any situation in the environment in which there is a cycle of
influences among variables that disturb controlled perceptions is enough
to enhance the stability of all affected control loops. But bilateral
mutuality (it's not cooperation) seems most likely to occur in a random
environment.
A consequence of this thought is that mutuality is likely to be quite
common within any evolved control hierarchy. There will be many ECSs
for which a biologist might say "the purpose of this structure is to
assist that structure," where a PCT analyst might initially say that
the second structure is not perceptible to the first, and that the control
exercised by the first is for its own selfish purposes. Not being able
to perceive the second structure or its CEV, the first could not control
for helping it. But evolutionary reorganization will have "controlled"
for the mutuality.
Do I see a model here for social structures, perhaps?
Here today, gone tomorrow.
Martin