Does feedback need to involve levels
Posted: Fri Apr 02, 1999 4:58 pm
Khalid Saeed wrote:
> A feedback loop must,
> however, have at least one stock in its circular path that decouples flows,
> creates integration and delays.
This is unquestionably true for any system dynamics (SD) feedback loop.
But: IMHO also "non-SD feedback loops" do exist. Let me give an example
from Paul Watzlawicks classic "Pragmatics of Human Communication":
A couple might have the following problem: She always criticises her
husband, because he keeps off her. He keeps off her, because she always
criticises him.
This is unquestionably a reinforcing feedback loop, which actually is
not so seldom among couples - says Watzlawick. Now, where are the
"stocks" and the "flows" in this loop? Of course this situation can be
modeled using the stock-and-flow technology - that is not my point. My
point is that this feedback loop does exist without any stocks and
flows "creating" the dynamic structure. Watzlawick had most probably no
idea about stocks and flows; nevertheless he was able to identify and
describe that feedback loop as a feedback loop.
Another, even more compelling argument for the existence of non-SD
feedback loops is George P. Richardsons great book "Feedback Thought",
which gives a fascinating overview over the emergence of the
feedback concept (and thus feedback loops) in different fields.
Reading that book makes clear that most of the feedback thought originally
was _not_ based on the stock-flow-technology.
This doesnt diminish the power of the SD approach a a very versatile and
mighty tool for describing and analyzing feedback structures; I just think
it is fair to acknowledge that we have feedback concepts beyond SD, too.
Guenther Ossimitz
--
Dr. Guenther OSSIMITZ
University of Klagenfurt
A-9020 Klagenfurt, Univ.str. 65 Austria/Europe
mail: ossimitz@bigfoot.com
home: http://go.just.to/ossimitz
> A feedback loop must,
> however, have at least one stock in its circular path that decouples flows,
> creates integration and delays.
This is unquestionably true for any system dynamics (SD) feedback loop.
But: IMHO also "non-SD feedback loops" do exist. Let me give an example
from Paul Watzlawicks classic "Pragmatics of Human Communication":
A couple might have the following problem: She always criticises her
husband, because he keeps off her. He keeps off her, because she always
criticises him.
This is unquestionably a reinforcing feedback loop, which actually is
not so seldom among couples - says Watzlawick. Now, where are the
"stocks" and the "flows" in this loop? Of course this situation can be
modeled using the stock-and-flow technology - that is not my point. My
point is that this feedback loop does exist without any stocks and
flows "creating" the dynamic structure. Watzlawick had most probably no
idea about stocks and flows; nevertheless he was able to identify and
describe that feedback loop as a feedback loop.
Another, even more compelling argument for the existence of non-SD
feedback loops is George P. Richardsons great book "Feedback Thought",
which gives a fascinating overview over the emergence of the
feedback concept (and thus feedback loops) in different fields.
Reading that book makes clear that most of the feedback thought originally
was _not_ based on the stock-flow-technology.
This doesnt diminish the power of the SD approach a a very versatile and
mighty tool for describing and analyzing feedback structures; I just think
it is fair to acknowledge that we have feedback concepts beyond SD, too.
Guenther Ossimitz
--
Dr. Guenther OSSIMITZ
University of Klagenfurt
A-9020 Klagenfurt, Univ.str. 65 Austria/Europe
mail: ossimitz@bigfoot.com
home: http://go.just.to/ossimitz