Page 20 - DCAP601_SIMULATION_AND_MODELING

Simulation and Modelling

Notes Mechanistic systems are either open or closed, closed if their behavior is unaffected by any
external conditions or events; open if they are so affected. The universe was conceptualized
by Newton as a closed (self-contained) mechanical system, with no environment-like a
hermetically sealed clock. On the other hand, the planet Earth is seen as an open system,
one whose motion is influenced by other bodies in the solar system.

2. Animate Systems: These are conceptualized as purposeful systems whose parts have no
purposes of their own. The principal purpose of such systems is survival. A person’s lungs
have no purpose of their own; but they function to enable a person to extract oxygen from
the environment so as to survive. Animate systems are necessarily open; they must interact
with their environments in order to survive Understanding these interactions are essential
for understanding their properties and behavior.
Animate systems are living systems. “Life” has been defined in many different Ways. The
definition now most widely accepted by biologists involves the ways concept autopsies:
“The maintenance of units and wholeness, while components themselves are being
continuously or periodically disassembled and rebuilt, created and decimated, produced
and consumed.” (Zeleny, 1981, p. 5)
From this definition it follows that social and ecological systems are also alive. (Many
biologists are unhappy about this consequence of their definition of ‘life.’)
3. Social Systems: These are systems that (1) have purposes of their own,
(2) consist of parts at least some of which are animate, hence have purposes of their own,
and (3) are a part of one or more larger (containing) systems that may have purposes of
their own and that may contain other social systems. For example, a local government
viewed as a social system is part of a state government, which is also a social system, This,
in turn, is part of a national government. Social systems can be and usually are nested.
4. Ecological Systems: Such systems contain mechanistic, animate, and social systems as
parts and, therefore, containing some parts that have purposes of their own. However,
these systems as a whole are conceptualized as having no purpose of their own. Nature, of
course, is commonly taken to be an ecological system as is our environment.
Ecological systems serve the purposes of their animate and social parts, and provide necessary
inputs to these and open deterministic systems. They also provide a receptacle for their waste as
well as their useful products. Such service and support is their function. An ecological system
can be affected mechanistically by the mechanical or purposeful behavior of its parts. For example,
the purposeful use by people of fluoro-carbons as a propellant and the emissions of power
plants affect the ozone layer mechanistically.

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Caution Animate and social systems are frequently confronted with situations in which
their choices can affect their effectiveness, either positively or negatively. Such situations
are problematic. In other words, problems are situations in which a system’s choice can
make a significant difference to that system.

1.3.2 Some Reflections on Models

The use of models as a means of obtaining insight or understanding is by no means novel. One
could reasonably claim, for example, that the pivotal studies in geometry carried out by Euclid
were motivated by the desire to construct models that would assist in better understanding
important aspects of his physical environment. It could also be observed that it is rare indeed for
the construction of even the most modest of structures to be undertaken without some documented
perspective (i.e., an architectural plan or drawing) of the intended form. Such a document

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