Every book I’ve read on systems pretty much opens with exactly this point. It is merely the questions you want to ask, or otherwise your scope of meaningful control, that determines what is a suitable definition (or delineation) of “the system of inquiry.”
If that seems confusing, circular, or unsatisfactory, consider reading the work of the Pragmatists for the eye-opening revelation that this is what your brain is doing 100% of the time to 100% of your sensory input in order to make any sense of anything whatsoever.
Your perception is intrinsically linked to what you can do with that perceptual data. You separate a system from its components the same way you separate a rock from dirt, one piece of dirt from another, or soil from a tree: you do it based on what’s useful to you in the moment.
If that seems confusing, circular, or unsatisfactory, consider reading the work of the Pragmatists for the eye-opening revelation that this is what your brain is doing 100% of the time to 100% of your sensory input in order to make any sense of anything whatsoever.
Your perception is intrinsically linked to what you can do with that perceptual data. You separate a system from its components the same way you separate a rock from dirt, one piece of dirt from another, or soil from a tree: you do it based on what’s useful to you in the moment.