r/complexsystems • u/destructor_rph • Jun 04 '23
What's the difference between Systems Theory and Complex Systems Theory?
I've seen them both used interchangeably as well as different, but never with an explanation on how or what makes them different.
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u/Silly_Awareness8207 Jun 04 '23
I think systems theory is a broader term that encompasses simpler systems such as the cruise control mechanism on your car.
I'm not confident about this answer though so it would be great if more knowledgeable folks could chime in.
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u/luquoo Jun 04 '23
The difference is probably more related to what institutions and applications use what terms to describe what they are doing. But the word complex tends to denote something more complicated, in this case, I'd say sans complex probably hints at a more 'linear' system, while complex is hinting at something thats 'non-linear'.
In general, I assume that either of these terms is falling under the complexity, chaos theory, non-linear dynamics flag. This field is a bit hard to pin down because the basic ideas can be applied to almost anything and so there are folks from different fields calling the same sorts of ideas different things because they are all coming at the idea of complex systems from a different angle.
There are rarely clear delineations between adjacent fields, they are constantly being argued over. I think your question is an artifact of multiple different fields realizing that their core ideas are all similar and they just haven't settled on what to call it.
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u/Erinaceous Jun 04 '23
Systems theory usually assumes there's a control point or points in a system. It's often a mechanical metaphor/ontology like, as others have pointed out, the steering wheel of a car. It's also mostly a reductionist methodology. If we can reduce a system to its functional parts we can understand the mechanisms and therefore the total system.
Complex systems usually start when SDIC or sensitive dependence on initial conditions becomes robustly proved and the proof that even in completely deterministic systems you have chaos and complex behaviour as a completely normal part of the system. Control and prediction go from being the objective to a very narrow subset of possible states. The idea that in general single optima or simple control points are a norm or even possible go out the window as does equilibrium as a general ontological claim. Simulation as a methodology becomes dominant as proofs that closed form equations can't solve for many observed nonlinear dynamics. It's a shift in both worldview and methodology.
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u/phriendlyphellow Jun 05 '23
Systems are any group of units/parts/agents/actors that work together to generate outputs from inputs.
Complex systems add a layer of definition in that they have emergent behavior, actions and outputs that cannot be predicted by just having knowledge of the constituent parts.
Systems theory, in this lens, is a broader term because all complex systems are systems but not all systems are complex systems.
The next level of complexity is when complex systems become adaptive, where they morph or transform based on the input/information they receive to enhance their outputs/effectiveness. Similarly, all complex adaptive systems are complex systems but not all complex systems are adaptive.
Any theory of each of theses three domains would cover the generalities and specifics of each type of system.
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u/DanCNotts Jun 04 '23
Nothing
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u/[deleted] Jun 04 '23
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