People often interpret Ashby’s Law (after W. Ross Ashby) as if the system’s internal states must have the same level of variety as its environment in order to survive, which implies that the system should be able to respond (react) to every little disturbance from the environment.
This is not completely true because, on the lowest, #regulation, level, the system blocks #variety from an (environmental) #disturbance reaching the (internal, system protected) #EssentialVariables in two ways:
1️⃣ #Passive isolation (sheltering) from most environmental disturbances, and
2️⃣ #Active reaction to (parring with) the remaining disturbance that managed to break through this passive protection.
from “Intro to #Cybernetics”
http://pespmc1.vub.ac.be/ASHBBOOK.html
Ashby’s principle of requisite #variety states, in fact, that the variety of the #controlling system must be large at least as the variety of the #controlled system .
As an external #observer can never have the full picture of the internal variety of states the controlled system can find itself in, it is obvious that, for control to be #effective, the controller must be an integral part of the same self-organized (controlled) #system.