Wednesday, February 26, 2014

Design Considerations from Weinberg's "Introduction to General Systems Thinking"

For those of you bored with this topic, you will be happy to know that I am on my last post. For those of you that find this interesting, thanks for sticking with me. :-) (Also, I will suggest that you get a copy of the book and find your own insights and wisdom in it. I certainly did not cover all the details!)

Let me jump into design considerations that Weinberg highlights. These are questions that I ask myself when modeling a system/designing an ontology:
  • What notions are within and what are external to our systems? In other words, what are the boundaries of our system?
  • How might we partition or decompose our system? When we decompose, how do the parts interact?
  • In talking about "interactions", we start to talk about behavior... What is the behavior of the system and its parts? What are the system's and parts' possible states and how are they constructed or achieved?
    • What is constant (survival and stable) about the system? What changes? Are there observable causes and effects?
    • White box or black box techniques can be used to define and understand behavior. If we use black box, then we are observing and suffer the inadequacies of our observations (as pointed out in my second post on this subject). If we use white box, then we may miss behaviors that are inherent and not of our own construction. A combination of both techniques can provide good insights.
    • In understanding behavior, you have to assume that you have incomplete knowledge. This is Weinberg's Diachronic Principle: "If a line of behavior crosses itself, then either: the system is not state determined or we are viewing a projection - an incomplete view."
    • And, another, similar principle is the Synchronic Principle: "If two systems occur in the same position in the state space, at the same time, then the space is under dimensioned, that is, the view is incomplete."
  • What are the properties or qualities of our systems? How do they change as the system evolves? Are there invariant properties? In particular:
    • What properties are used for identity?
    • What is "typical" about the system?
    • What is "exceptional" (but important) about the system?
    • What properties are used to define and control the system?
  • What are we missing? (Sometimes we miss important properties or behaviors because we look at things using our "standard" approaches, notations and tools.) Can we look at a system or problem differently in order to gain new insights?
    • Weinberg highlights the need to change our methods and approaches when new problems present themselves (especially if our current ways of thinking are not working). He captures his insights in his Used Car Law, and asks "[W]hy do we continue pumping gas into certain antique ways of looking at the world, why do we sometimes expend mammoth efforts to repair them, and why do we sometimes trade them in?"
    • Another insight is Weinberg's Principle of Indeterminability: "We cannot with certainty attribute observed constraint either to system or environment." In other words, does our system have only small things in it because that is true or because we only have a net that lets in small things?
Hopefully, some of these questions will help when modeling or observing new systems. Let me know if you have other insights from Systems Thinking or just have other questions that you ask yourself when trying to understand a system or address a new problem.


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