[From Bruce Abbott (950918.1425 EST)]
Bill Powers (950918.1130 MDT)]
Hans Blom (950918)
There is a tendency among control engineers -- and not them only --
to reify control, as in sayings like "control is a fact". No,
control isn't a THING. It is a way of looking at things. A
perspective, very useful sometimes, confusing maybe at other times.
The AS IF aspect of control should always be kept in mind, I think.
. . .
The control-system MODEL is a proposal about how the observed phenomenon
might be brought about by the internal organization of the behaving
system. If we believe that such an internal organization really exists,
we are reifying the model (accepting it as physically real). We then
interpret behavior AS IF this model really existed as a physical
organization inside the organism.
The problem in 1979, as I have come to understand it, is that researchers in
the field (including both physiologists and psychologists) reified the
standard block diagram of the control model, found evidence that
contradicted that particular reified model, and concluded that "the" control
model was incorrect. They did not seem to realize that the models they
proposed in its place often reduce to the same block diagram. Take Bolles
for example. His proposal: a mechanism that limits with increasing
opposition the further upward (or downward) excursion of a quantity. This
mechanism employs negative feedback, can be viewed as type of one-way
control system and, more importantly, behaves according to the same
mathematical rules governing all such closed-loop, negative feedback
systems. Bolles "demonstrated" the absurdity of the control-system analysis
in living organisms by arguing (with supporting examples) that most if not
all "homeostatic" quantities are not regulated by a classical control
system, but rather, by a "different" mechanism which reduces on closer
inspection to the same block diagram.
Regards,
Bruce