Systems – abstract and concrete - recap

Copyright 2019 Graham Berrisford. One of about 100 papers on the System Theory page at Last updated 10/03/2019 10:14


The orderliness in a system

If every entity is also a system (1 for 1) the term system has no value.

A disorganised or disorderly entity is, by definition, not a system.

To be called a system, an entity must be organised or orderly in some describable and testable way.


Some say a system is a collection of parts that are related or interact.

But IBM is not well-called a system merely because it employs people who interact.

Rather, it is a system where and in so far as those interactions are organised or orderly in some way.


The primacy of behavior

The question is not so much "what is this entity?" as ''what does it do?"

Cybernetics is about systems that perform orderly behaviors.

It describes a system by typifying:

·         actors in terms of roles they play in activities

·         activities in terms of rules that actors follow

·         attributes (state variables) of the system or its parts.


Systems dynamics

Variable and rule types

<define>                         <represent>

Systems thinkers   <observe and envisage>   Orderly behaviors


Looking at IBM in different ways can reveal countless different systems.

·         a system for making its directors happy?

·         a system for making a profit for shareholders?

·         a system for making and selling products to customers?

·         a system for providing consulting services to customers?

·         a system for providing incoming to suppliers?

·         a system for employing and paying people?


And these systems may conflict with each other


Abstract and concrete systems

Systems thinkers (Ashby, Ackoff, Checkland etc.) urge us to recognise that a system is a perspective.

For some, understanding this requires making a paradigm shift as radical as is needed to understand Darwin’s evolution theory.

The temptation is to point at an animal, machine or business and say "the system is that thing there".

But a concrete thing (be it an animal, a machine or a business) may play a role countless different abstract systems.


Systems thinkers distinguish abstract systems from concrete systems.

An abstract system is a description of how some part of the word behaves, or should behave.

A concrete system features actors and activities behaving (near enough) as the abstract system .


In general

Abstract / theoretical systems

<create and use>                      <represent>

System theorists <observe & envisage>  Concrete / empirical systems


The concrete actors and activities form a system because they conform to some abstract roles and rules of particular interest to us.

The roles and rules can be described, and the conformance of a concrete system to them can be assessed.


Abstract system

A set of roles and rules (the logic or laws entities follow)

The US constitution

The stickleback mating ritual.

Concrete system

Actors playing the roles and acting according to the rules

Successive US governments

Pairs of sticklebacks.


Any part of the world that conforms (well enough) to the abstract system may be called a concrete system.


One abstract system can be realised by many concrete systems.

E.g. many US governments and many pairs of sticklebacks.

Each concrete system contains actors playing the roles, following the rules, and acting on objects or variables.


One actor may act in many systems.

E.g. any senator and congressman may play roles in many systems outside of the US government.

And any stickleback may come to play a role in the digestion system of kingfishers.


Other system concepts

Other concepts that feature in general system theory include:

·         System environment: the world outside the system of interest.

·         System boundary: a line (physical or logical) that separates a system from is environment.

·         System interface: a description of inputs and outputs that cross the system boundary.

·         System state: the current structure or variables of a system, which changes over time.



Much systems thinking (at least in cybernetics and System Dynamics) is about circularity or homeostasis.

The value of one system state variable may be shaped the value of another.

Consider how the quantity of sheep and the quantity of wolves are related in a causal loop.


A growth in the stock of


will increase the stock of


will deplete the stock of




Think of systems layered on top of each other, at different levels of abstraction.

There can be a hierarchy of process control: a control system at level N throws an exception up to a control system at level N+1, and awaits direction.

There can be a hierarchy of system definition: the rules of a system at level N are state variables that can be manipulated by a meta system at level N+1.


Further reading

·         System Dynamics

·         Social systems and networks

·         System change

·         System state change and regulation by circular causal loops