[From Dan Palmer (2000.08.07.1143)]
One aspect of PCT has puzzled me for a while, and I was hoping someone could
In verbal and diagrammatic descriptions of PCT's basic unit (the control
system), there is typically a line separating the system from its environment.
The control system is said to keep a perceptual variable (internal) matching a
reference variable (internal) by protecting a controlled variable (external)
from disturbances (external). As I understand it, the line that distinguishes
the internal from the external in the case of human control systems is
equivalent with the skin of the organism. Please correct me if I am wrong
here, as I assume the above in what follows.
The thing that puzzles me is that if a system is defined as something like "a
whole consisting of elements, the interaction of which makes possible its
existence or action" (from Jarvilehto, 2000), and if some of those elements lie
outside the skin (e.g., the controlled variable), then how can those elements
be properly said to be outside the system, if we are to remain consistent with
our earlier definition of a system?
The two approaches were contrasted by Jarvilehto (2000), and also by Bateson
(1976, available at http://www.oikos.org/forgod.htm) who said "computer science
is input-output. You�ve got a box, and you�ve got this line enclosing the box,
and the science is the science of these boxes. Now, the essence of Wiener�s
cybernetics was that the science is the science of the whole circuit."
Thanks in advance,
Jarvilehto, T. (2000). The theory of the organism-environment system: IV. The
problem of mental activity and consciousness. Integrative Physiological and
Behavioral Science, 35, 35-57. Available at