REPLY System Dynamics without Feedback (SD6491)

[SDMAIL Martin Schaffernicht]

Posted by  Martin Schaffernicht <martin at utalca.cl>

Hi Kazem,

maybe you'd find some discussion of this in
"Why has feedback systems thinking struggled to influence strategy and 
policy ..." by Kim Warren, in Systems Research and Behavioral Science; 
Jul/Aug 2004; 21, 4; pg. 331

In this article, Kim Warren argues that even without feedback, the 
interplay between in- and out-flows into and from a stock are 
dynamically complex and that feedback is not always neccesary/useful.

It is certainly true that the relationship between flows and stocks 
is "surprising" to most people; that's why there is quita an amount of 
reseach&publications about "stock-and-flow" thinking (you may refer to 
the list indicated by John Sterman in a recent reply on this list).

If there is no link from the stock to the flow, this menas you assume 
that the stock's values have no influence on what determines the flow.  
If there are good reasons to believe this, why not?  Also, such 
elementary models are useful in teaching.

Still, for anything beyond Fabian's "very thin slice of reality", Jay 
Forrester has always argued that these influences do exist.  So the 
doubt remains...

best,

Martin Schaffernicht
University of Talca (Chile)
Posted by  Martin Schaffernicht <martin at utalca.cl>
posting date  Fri, 22 Jun 2007 12:32:34 -0400