Subject: System Objective

Posted by Gallaher Ed on 9/4/2006
In Reply To:System Objective Posted by Ah Kau LIM on 9/4/2006

Message:

No, a ‘system’ cannot be assumed to have only one objective.

A ‘system’ includes a set of interacting elements, but there is no requirement that these elements are acting together to accomplish a single goal.

Our front yard is on a typical urban cul de sac just south of Portland; the back yard faces Summer Creek. When the beaver builds a dam we have a pond, extending upstream about 1/4 mile. We see Canada ducks, blue heron, mallards, wood ducks, belted kingfisher, and the occasional river otter. (coyote, mink (once), raccoon, ‘possum, skunk, and dozens of other bird species . . . ) The pond also attracts nutria (real pests), and in large numbers their aggressive behavior can cause the beaver to leave. If the beaver leaves, the dam deteriorates over a year or two and the pond reverts to a creek and we see different varieties of flora and fauna. This cycle has repeated itself 4-5 times over the past 20 years.

A variety of ‘goals’ and [stakeholders] are described below:

Is the ‘goal’ to have more [beaver], and a stable pond? Or more [nutria]? ([We] say no, but the nutria disagree.) Is the ‘goal’ to provide ‘waterfront property’ for [homeowners], who then lobby the [city council] to establish a permanent dam whenever the beaver leaves? Is the ‘goal’ to maintain the environment for [endangered trout and steelhead]? [Oregon Dept of Fish and Wildlife] and the [Army Corps of Engineers] will not approve a dam. [FEMA] is also concerned about wetland storage capacity, and the effects on upstream and downstream flooding. The [Park Dept.] would like to install a series of trails along the creeks (not in [my] backyard . . . !)

Is this a ‘natural’ system? Or a ‘political’ system? What were the ‘objectives’ of this ‘system’ 300 years ago, with very little human influence? What were the ‘objectives’ 200 years ago, when trappers saw an ‘unlimited’ supply of furs?

When engineers conceive of, and create a new ‘system’ (ie. air conditioner; automobile), it may (?) be possible to state a single objective. But ‘natural system’ simply are!

When studying systems that ‘are’, our task is to limit the focus of our inquiry to gain insights into system behavior. The ‘art’ comes in asking the right questions, and formulating thoughtful simulations.

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Wikipedia: Occam's razor states that the explanation of any phenomenon should make as few assumptions as possible, eliminating, or "shaving off", those that make no difference in the observable predictions of the explanatory hypothesis or theory. In short, when given two equally valid explanations for a phenomenon, one should embrace the less complicated formulation. The principle is often expressed in Latin as the lex parsimoniae (law of succinctness):

entia non sunt multiplicanda praeter necessitatem,

which translates to:

entities should not be multiplied beyond necessity.
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We want the model to be as simple as possible. In our case, however, an examination of ‘raccoon populations’ would be unrealistic if it did not include the City Council . . .

Ed Gallaher