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- Date: Sat, 15 Aug 1992 09:02:04 -0600
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- From: "William T. Powers" <POWERS_W%FLC@VAXF.COLORADO.EDU>
- Subject: Amplification: organism vs environment
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-
- [From Bill Powers (920815.0930)]
-
- Martin Taylor (920815) --
-
- Rick Marken says:
- >>The short
- >>answer is "because the organism amplifies, the environment dampens".
-
- and Martin replies
-
- >Not always true, and certainly not true of that part of the environment
- >that contains control systems. Not true in sensitive parts of the
- >environment that don't (e.g. bifurcation points, such as things >balanced
- on table edges). Sufficiently often true that it is a >beguiling temptation
- to take it as truth.
-
- When control systems come in contact, that's a rather special case.
- Generally they avoid doing so in a way that pits their outputs directly
- against each other. The reason is that they're BOTH high-gain systems. This
- doesn't negate Rick's statement. The non-controlling environment is not, in
- general, a high-gain system.
-
- The rest of the environment contains so few instances of significant
- amplification that they're pretty unusual. It's hard to think of a case in
- which the gain of a human controller isn't higher than that of the
- environment by a wide margin. When a car moves along the crown of a
- cambered road, the car is unstable about a knife-edge line along the crown;
- its path bifurcates. But a human driver has no problem keeping the car
- centered on the crown within a small range. The book teetering on the edge
- of the table is easily kept from falling by a person who lays a finger
- lightly on it. Even ten-year-olds have no problem with balancing a
- broomstick on end. To find instances of significant amplification in the
- physical world, you have to talk about explosions and things that snap from
- one state to another faster than a human control system can control them
- between states. There aren't just a heck of a lot of such phenomena. Most
- of those that do occur are man-made (like explosions and switches).
-
- As to the mirror diagram, it is an epistemological tool. This diagram could
- be expanded to show the hypothetical world of physical reality between the
- two mirroring hierarchies. When we analyze control processes, that is
- essentially what we do: we apply physical analysis to our experiences and
- attribute them to physical properties of the world between the systems.
- That's the only practical thing to do. The mirror diagram itself exists
- only in the perception of the beholder; it's an hypothesis about the
- relationship between two control hierarchies, as envisioned by one of them.
- To continue this process of abstraction is to head for a state of mute
- contemplation. I think we have to admit that it's all hypothetical, and try
- to formulate our hypotheses in the way that's most tractable both for
- theorizing and for experimenting. My formulation puts a physical world
- running by physical laws between the organisms which are control systems
- running by closed-loop laws. That seems to work passably well. And in that
- formulation, Rick's comment is right nearly all of the time, if you
- understand "environment" to mean the milieu between control systems.
- ----------------------------------------------------------------------
- Best,
-
- Bill P.
-