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### General System Principles in this Toolkit

Twenty-one general system principles were mentioned in this toolkit. This is nothing like a complete list of system principles. (I argued toward the end of the toolkit that such a list could be neverending.) Here they are in order of presentation.

On the page: What is a System?

The principle of system definition: Anything perceivable or conceivable is a system.

On the page: Hierarchical Structure

The principle of decomposability: All complex systems are hierarchical in structure, composed of successively smaller subsystems. Each system, in turn, participates as a component in successively larger systems.

On the page: Efficiency of Modular Construction

The principle of modular construction: Complex systems are built more efficiently when constructed out of larger rather than smaller components.

On the page: Top-Down vs Bottom-Up Processing

The principle of top-down and bottom-up processing: Complex systems produce optimal outcomes through interaction of top-down and bottom-up processing.

On the page: Networks

The principle of network representation: Any system can be represented schematically by a diagram of nodes and relationships.

The principle of incomplete represen­tation ("All knowledge is schematic.") Network representation, including representation in the brain, never includes all the detail of real world systems, but it can include accurate and useful information.

The principle of multiple consistent mappings: Different maps of the same territory may highlight different things, but if all the maps are accurate, none will contradict the others.

On the page: Open Systems

The principle of open systems: Systems can maintain order and increase complexity only by consuming energy.

The principle of dynamic equilibrium: Stability (equilibrium) is maintained in an open system by consuming energy to counteract changes.

On the page: Equifinality

The principle of equifinality: Equilibrium can be approached from many different starting points. A variety of paths can lead to the same stable endpoint.

On the page: Negative Feedback

The principle of deviation-reducing (negative) feedback: All goal-directed activity, whether directed toward restoring an equilibrium or reaching a target in the future, depends on negative (deviation-reducing) feedback.

On the page: Positive Feedback

The principle of positive (deviation-amplifying) feedback: Positive feedback is a change or disturbance in a system that amplifies itself until limited or interrupted.

On the page: Rhythmic Behavior in Systems

The principle of oscillation: Oscillations occur when opposing forces take turns influencing a system.

On the page: Synchronization

The principle of synchronization: Synchronization occurs when system compo­nents showing rhythmic activity influence each other, resulting in simultaneous activity of many different units.

The principle of pacemaking: If individual units in an oscillating system can influence each other, the fastest unit will drive the rhythm of the oscillation and establish a dominant frequency.

On the page: Growth Processes

Principle of the S curve of growth: Systems grow through positive feedback until resources become limited, producing an S curve of growth.

On the page: Saltatory Processes

The principle of saltation or punctuated equilibrium: A system moving between two stable states will appear to jump if the intermediate states are unstable.

On the page: Creativity: Variation with Selective Retention

The principle of variation with selective retention: Creativity, the production of novel adaptive forms, requires generating variations by combining available building blocks, then selecting and reproducing adaptive outcomes.

The principle of opportunism: Complex systems are assembled most efficiently by using pre-existing parts or modules. This process may transform the meaning or function of parts included in a new system.

On the page: Truth and Non-Trivial Prediction

The principle of non-trivial prediction: Scientific theories or models are tested by using them to generate non-trivial (surprising or unusually precise) predictions.

The principle of convergent validation: A model supported by multiple independent sources of evidence is provisionally true.

Write to Dr. Dewey at psywww@gmail.com.

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