Systems Theory

A system's state is the collection of properties it holds at any given moment. Its environment includes any external properties that can influence it — closed systems have no environment by definition.

Events and Static Systems

An event occurs whenever a system's properties change. A static system never experiences events; a homeostatic system, by contrast, has dynamic properties that continuously work to maintain a constant state — a thermostat is the classic example.

Reactions, Responses, and Acts

Not all events are equal. A reaction is deterministically caused by an external stimulus — press a light switch and the bulb turns on, no cooperation from the bulb required. A response requires the system to co-produce the outcome alongside a stimulus: a doorbell only chimes if someone presses it AND the bell is ready to ring. An act is an internally generated event with no external trigger at all — you suddenly decide to start reading, or a background script launches a cleanup job at midnight.

The key distinction: when studying behaviour we care about consequences; when studying reactions, responses, and acts we care about antecedents. Behaviour is the event that leads into one of those three categories — the chime of a doorbell, or the person walking up to press it.

Goal-Seeking Systems

A goal-seeking system can respond differently to different events in order to reach a specific target — navigating a maze is a simple example. When you combine a system with a goal you get a process.

A multi-goal-seeking system can pursue different goals depending on context: you behave differently when hungry than when tired. A purposive system selects the means toward something but stops short of acting — like drawing up a study plan and never opening a book. Add actual execution and you have a purposeful system.

Goals, Objectives, and Ideals

A goal is a specific target reachable in a single step from the current state. An objective is a larger outcome that requires a sequence of goals to achieve. An ideal is an ultimate state that can never be fully reached but can be approached indefinitely. A system that continuously sets new goals and objectives to move closer to its ideal is called an ideal-seeking system.

Variety: More or Less

Combining systems can either expand or constrain the total range of possible behaviours. A variety-increasing combination lets the joined system do more than either part could alone — one unit closes the windows when it gets cold, another turns on the heater if the room stays cold, so together they can act in sequence. A variety-decreasing combination does the opposite: two people who agree to study only on weeknights have collectively narrowed their options compared to what each could do individually.

Adaptation

Systems adapt to change along two axes: the source of the change (other vs. self) and the target of the modification (environment vs. self).

Other-other adaptation: reacting to an external change by modifying the environment — turning on the air conditioning when a room gets too warm. Other-self adaptation: reacting to an external change by modifying yourself — moving to a cooler room instead. Self-other adaptation: reacting to an internal change by modifying the environment — turning up the heat when you feel cold. Self-self adaptation: reacting to an internal change by modifying yourself — taking medication to suppress the chills.

Learning

To learn is to increase efficiency in the pursuit of a goal under unchanging conditions — doing the same thing better over time, without the situation itself needing to change.