Thursday, May 26, 2022

Systems thinking

"Life was simple before World War II. After that, we had systems"
Rear Admiral Grace Hopper, USN
Matthew Squair, a systems safety expert, has this to say about that (*):
  • From the Gesalt (**) school comes the [systems] view that the whole is often greater than the sum of the parts, i.e. there exists properties that emerge from parts aggregated together .... [which is a telltale sign of a 'system of parts']

  • From the cybernetic (**) school comes the view that systems can be understood by studying, in the abstract, control and communication between the parts that effects causal feedback loops and interactions with the environment [The 'blackbox' view of systems is a cybernetic concept]

In other words, there is more than one way to look at or perceive a system. For those that have given this some thought in the past, or have worked with or in system engineering, that there is more than one point of view of what we would call a system is not new news, but multiple views is a key concept when thinking about systems. 

But nonetheless, the I've found these ideas seem to be most common:
  • There is the hierarchical view of a system as a collection of subsystems that all combine in some way to make a system. In the hierarchical view, the system is parsed into major subsystems according to their similar position in a hierarchy, which, in turn, these subsystems are further reduced to lesser subsystems until there is no meaningful reduction to be made.

  • The proposition for breaking apart a system in order to understand it, to scope and specify it, and to be able to actually construct it is generally called reducing the system to its constituent parts, summarized as reductionism.

    And, the 'science' or 'art' of reductionism is no small matter. Some truly awful reductions have been made in my experience that harmfully impact the understanding and the means to implement the system successfully.

    The risk inherent in reductionism is that the focus is continuously narrowed until the 'big picture' fades way into the background; all sense of synergy and emergent properties that give rise to the 'sum is greater than the parts' is lost. 

  • There is the black box view of a system which is about boundaries, boundary conditions, and means to interface with the system for providing input, obtaining output, effecting control, and processing telemetry or feedback to establish stability and predictability of performance.

    The question is begged: is there a 'white box' view? Yes, such is the internal detail known to 'insiders', but not necessary to those system 'users' and controllers that stand outside the black box.

    Reductionism plays a lesser role; the main utility of reductionism is to decide or allocate functions and performance requirements to the black box, thereby setting boundaries for what is in the box and what is not.

    The great advantage of the black box view, apart from a clear understanding for boundaries, is that interfaces become the focus: how to stimulate the system; how to control it; how to measure it; how to use it's outcomes; and how to repair-by-replacement. In turn, these give rise to widely recognized standards for size, weight, connectors, and other physical attributes, as well as standards for intangibles like software objects and APIs.

    (*) "Critical Uncertainties; the theory and practice of system safety" Matthew Squair, Review Copy, April 2022

    (**) Gesalt is a term of art taken from German meaning that the attributes of the whole are not deducible from analysis of the parts in isolation. First used in psychology to understand behaviors.

    Cybernetics is “the science of control and communications in the animal and machine.” The core concept of cybernetics is circular causality or feedback—where the observed outcomes of actions are taken as inputs for further action in ways that support the pursuit and maintenance of particular conditions, or their disruption.

    Norbert Weiner, American mathematician, is credited with defining cybernetics in systems terms.


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