Basic System Theory

From CasGroup

Jump to: navigation, search

Topics and Subjects

Evolution Self-Organization Feedback General Principles

System Theory is the interdisciplinary study of the abstract organization of systems. It is a field related to Cybernetics, Catastrophe Theory and Chaos theory which studies the properties and principles systems as a whole. Cybernetics pioneer W. Ross Ashby has proposed a number of theorems about systems in general, but they do not say much. Some of the basic principles are mentioned in the table above: from the left to right the most fundamental (evolution), the most interesting (self-organization), the most important (feedback) and the most general (complexity). Many of these principles are well-known from physics, biology, mathematics, computer science and engineering.

Basic Principles
Natural Selection
Red Queen Effect
Swarm Intelligence
Self-Organized Criticality
Butterfly Effect
Control Loop
Lever Point
Frozen Accidents
Path Dependence
Complexity, Simplicity
Edge of Chaos
edit this box


The most fundamental and basic principle in nature is certainly evolution by natural selection. The only thing that has not changed in the last 14 billion years since the universe exist is the principle that it is subject to evolution. The forms of evolution and evolutionary systems vary - from cosmic evolution of galaxies and atoms to cultural evolution of cultures and languages - but evolution itself remains unchanged. Many living things and life-forms appear to organize themselves, but they are also subject to evolution. It is doubtful if self-organization is really an essential ingredient of any living organism. If there is any essential ingredient controlling natural organisms it is self-replication, self-(re)production (autopoiesis) and evolution. Organisms are selfish, they are subject to evolution, they are born, they die and they reproduce themselves constantly, which allows them to adapt to different environmental conditions. They try to outmatch and surpass each other, which leads to co-evolution, arms races and the red queen effect.


The most interesting, fascinating and frustrating principles in nature are certainly emergence and self-organization. Emergence is associated with the observation that a system is more than the sum of its parts. In some systems, fascinating patterns and interesting behaviors can appear. Yet common sense says that things do not appear suddenly out of nowhere without reason (contrary to the principle of emergence), and that things do not organize themselves (contrary to the principle of self-organization). Everybody knows that these concepts do not belong to everyday occurrences. And yet some examples exist. This unusual occurrence is the reason why emergence and self-organization are interesting and fascinating. They are interesting and fascinating because they don't happen normally in everyday life. They are of great interest, because they are rare. They are possible, but they are the EXCEPTION, not the RULE. If they occur, then they can be found mostly at borders, boundaries and margins. At the edge or margin of something, in the concept of emergence usually at the border between microscopic or macroscopic regions, in the concept of self-organization mostly at the boundary between system and environment. This is not surprising, because in the broader sense, the emergence of something is always possible at a clear border or boundary. Nicholas Humphrey begins his book "A History of the Mind" with the words "Everything that is interesting in nature happens at the boundaries: the surface of the earth, the membrane of a cell, the moment of catastrophe, the start and finish of a life". Although they are interesting, many of the concepts related to self-organization have to be treated with care. There are many buzzwords among them, and some describe only very special phenomena. There is certainly no comprehensive theory of autopoiesis or theory of non-equilibrium systems.


The most important principle in system theory and control is feedback. The study of cybernetics was (or is) mostly based on regulatory feedback. Negative feedback is very useful, because it allows us to control and to stabilize a black-box system without knowing how it works in detail. Positive feedback can lead to rapid amplification of differences in form of butterfly effects, path dependence and frozen accidents. These principles are very important because they characterize events and processes which have a strong and lasting effect on the development of a system.


The most general principles apply to many systems: complexity, context, code, edge of chaos or organization. For example, nearly all systems can be considered as complex or organized, only the degree varies. Every system is also embedded in an environment, situated in some context, and usually based on some form of code. There are also a few general laws and theorems about system theory that have been proposed by Cybernetics pioneer W. Ross Ashby, for example the "The Law of Requisite Variety" and the "Conant-Ashby Theorem", but it is controversial if they are general principles or not.

Personal tools