3. Boundary and Environment
Source: ebook ch. 6 (“Boundaries & Environment”).
Having built a model of a system’s internal workings (elements, function — see
02-system-fundamentals.md), this chapter turns outward: how a
system relates to what lies beyond it.
System boundary
The system boundary demarcates a limit to the system’s internal components and processes. Internal to its boundary, the system has a degree of integrity — its parts are working together — and this integrity gives the system a degree of autonomy.
Take a tree: every part (bark, leaves, trunk) has been “designed” in some way to function as part of the entire system, serving some function with respect to the whole. Through this integration, the tree is able to function independently from other systems in its environment. Leaves depend on the trunk and the rest of the tree, but are independent of the leaves and trunks of other trees — the tree as an entirety has a degree of autonomy.
A system’s boundary is where the nexus of relations that let it function as an integrated, autonomous whole reaches its limit. Beyond that point, the system loses its autonomy and has to interact with other systems and its environment.
This generalizes past the merely physical. A nation’s border is only a meaningful boundary insofar as public functions are integrated within it as an entirety, letting the nation act autonomously with respect to other nations. If a region shares its cultural heritage with a neighboring country rather than its own, this reduces the internal integrity of the parent nation, its autonomy to act as an entirety, and thus the degree of definition to its own boundary. Boundaries may have a physical dimension but can’t always be defined in purely physical terms — to achieve the generality systems theory aims for, boundaries need to be understood in this more abstract language of integrity and autonomy.
Autonomy is not the same as agency. Autonomy is independence — a system’s capacity to
function without being governed by other systems. Agency is the further, distinct capacity to
make choices directed at an internal goal or value. A thermostat’s control loop (see
06-dynamics-feedback-homeostasis.md) gives it a kind of
autonomy without anything worth calling agency; an animal pursuing a goal has both.
Autopoiesis vs. allopoiesis
A system’s boundary and integrity can be maintained in two structurally different ways:
- Autopoietic systems continuously reproduce and maintain their own components and organization from within, preserving their identity despite total turnover of the matter that makes them up — a living cell replaces essentially all of its molecules over its lifetime, and an institution persists through the recurring choices of individuals who are themselves eventually replaced. Autopoiesis (Maturana & Varela) is what gives an open system (see below) a stable identity despite constant material exchange with its environment.
- Allopoietic systems are produced by something other than themselves, according to a pattern imposed from outside — a factory produces tractors, not more factories.
Most engineered systems are allopoietic; most living and social systems are autopoietic — which is part of why the latter are so much harder to fully close off, redesign from outside, or replace piece by piece without disrupting their identity.
Open, closed, and isolated systems
| Type | Definition | Consequence |
|---|---|---|
| Open | Interfaces and interacts with its environment: receives inputs, delivers outputs, across a permeable boundary that may exchange materials, energy, information, or ideas. | High rate of input/output makes open systems dynamic — constantly changing, responsive to their environment. |
| Closed | Resists incorporating new inputs; more strongly defined by the static properties of the boundary itself. | By not adopting inputs, a closed system ceases to properly serve a function within its environment — it may be deemed unnecessary by its parent environment and risks atrophy. |
| Isolated | More restrictive than closed: does not interact with its surroundings in any way. | Largely a theoretical limit case — the universe as an entirety might be an example, though whether such a construct can really exist is debatable. |
“A system is closed if no material enters or leaves it; it is open if there is import and export and, therefore, change of the components. Living systems are open systems, maintaining themselves in exchange of materials with environment, and in continuous building up and breaking down of their components.” — Ludwig von Bertalanffy
Examples:
- Open: a hospital — continuously admitting new patients and discharging others, receiving medical supplies and removing old ones, hiring and retiring personnel.
- Closed: a boat on the sea, specifically designed not to take in water from the ocean environment it’s part of; or a group of teenage friends in a public park, engrossed in their own internal cultural dynamics, capable of only very limited input from their broader environment.
Environment
All systems have a boundary and operate within an environment. The environment is the sum total of other systems and input/output resources that the system interacts with during its operation — everything outside the system’s boundary that provides its inputs and receives its outputs.
A system’s environment is relative to its functioning:
- A biological system requiring natural resources operates within the natural environment.
- A business requiring economic resources operates within a given market environment.
- The political system of a nation operates within the international political environment.
This relativity matters: “environment” is not a single universal backdrop, but whatever context is defined by what a given system needs to draw on and discharge into in order to function.
A permeable boundary only lets exchange actually succeed if both sides share a protocol — a specific channel, medium, and set of rules that makes an input intelligible on receipt (two people conversing need a shared language; two computers need a shared network protocol). A boundary’s permeability is necessary but not sufficient for functioning exchange with the environment; the protocol is what makes the exchange legible on both ends.