Is there a "theory of system dynamics."

[jforestr@MIT.EDU (Jay W. Forrest]

Recent communications from Mukherjee (SD0788), Rodrigues (SD0784, SD0789,
SD0792), and from others have raised the question of a theory of system
dynamics.

I see system dynamics as a profession similar to engineering or medicine.
System dynamics is devoted to designing policies to create systems with
better performance. Medicine attempts to create a better functioning
patient. Engineering seeks a better automobile or bridge.

One does not think in terms of a unified theory of engineering or of
medicine. Such professional practices are based on fragments of underlying
theory (physics, metallurgy, biology), which use such theory as there is
along with experience, art, invention, and internship under a more seasoned
professional, to create improvement in the world.

One comment speaks of "there is no theory of SD... as in... physics." But
knowing the several "laws" of physics does not make a successful physicist.
There are no ten rules or laws that one can follow to win a Nobel Prize in
physics. All professions rest on some underlying concepts but good
practice goes far beyond that for which there are orderly theories.

Jay W. Forrester
Professor of Management, Emeritus
and Senior Lecturer, Sloan School
Massachusetts Institute of Technology
Room E60-389
Cambridge, MA 02139
tel: 617-253-1571
fax: 617-252-1998

email: jforestr@mit.edu

[Bruce Hannon]

I could not agree more with the statement below by Professor Forrester.
Daniel Dennett (Darwins Dangerous Idea) speaks of biological evolution as
an engineering-like process. The making of law for a civilized society seems
to proceed in much the same way. It humbles us to think of ourselves as
dynamically myopic, with changing goals, but it is realistic. It is even
more humbling (and more realistic) to take the stance that
this is the way it will always be, and develop the process as an art.


Bruce Hannon, Jubilee Professor
b-hannon@uiuc.edu
Liberal Arts and Sciences
Geog/NCSA
220 Davenport Hall, MC 150
University of Illinois
Urbana, IL 61801
http://www.gis.uiuc.edu
217 333-0348 office
217 244 1785 fax

[hamersma.maarten@columbus.co.za]

Prof Forrester wrote:

>I see system dynamics as a profession similar to engineering or medicine.
>System dynamics is devoted to designing policies to create systems with
>better performance. Medicine attempts to create a better functioning
>patient. Engineering seeks a better automobile or bridge.
>

Now this makes sense. The "objective function" of each project that
an engineer/doctor tackles, is determined by a need of a business, society
or patient, which manifests as a "problem" (Peter Checkland) that requires
solution or improvement. The correct use of the "fragments of underlying theory"
is what makes good practice.

Regards everyone
Maarten Hamersma Phone: +27 (0)13 247 2235
Systems Engineer Fax: +27 (0)13 246 1108
Columbus Stainless, South Africa
hamersma.maarten@columbus.co.za