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An Introduction to System Thinking. Contents. What is a system? System Stability Things in Common Change and Growth Putting the Pieces Together Complex Systems. What is a System?. Use “system” in everyday sense A collection of parts which interact with each other to function as a whole

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an introduction to system thinking

An Introduction to System Thinking

Session 3 - System Thinking

contents
Contents
  • What is a system?
  • System Stability
  • Things in Common
  • Change and Growth
  • Putting the Pieces Together
  • Complex Systems

Session 3 - System Thinking

what is a system
What is a System?
  • Use “system” in everyday sense
  • A collection of parts which interact with each other to function as a whole
  • A “heap” is not a system
  • “Heaps” are not essentially change by adding or subtracting from the “heap”
  • A system can be part of larger systems
    • subsystems form a hierarchy

Session 3 - System Thinking

hierarchical system
Particle

Atom

Molecule

Cell Nucleus

Brain Cell

Brain

Nervous System

Individual

Local community

State

Nation

World Civilization

World Ecosystem

Planet Earth

Solar System

Galaxy

Universe

Hierarchical System

Session 3 - System Thinking

systems and stability
Systems and Stability
  • If start at different point, still same results -- why?
  • A system of smaller units is more stable
    • Protons & neutrons - smallest natural particles
    • Large atoms unstable - uranium

Session 3 - System Thinking

systems and stability continued
Systems and Stability (continued)
  • Holds true for maximum size of animals
    • Whales and dinosaurs
  • A group of 5 versus 5000
  • A large group is a mob unless higher levels of system organizations are created

Session 3 - System Thinking

systems and stability continued7
Systems and Stability (continued)
  • Even if gigantic low-level systems were possible, a series of higher level systems would be easier
    • Millions of possible molecules
    • 92 atoms
    • 3 particles - protons, neutrons, electrons

Session 3 - System Thinking

systems and stability continued8
Systems and Stability (continued)
  • System definition key word - interact
  • One part has effect on system - system has effect on one part
    • Circular relationship or loop
  • Example - bicycle and rider
    • A two part system
    • Combined, can do things individual can not
    • Constant small adjustment for “errors”

Session 3 - System Thinking

systems and stability9
Systems and Stability

“Input”

Brain

Muscles

Bicycle

“Output”

Information

Session 3 - System Thinking

systems and stability10
Systems and Stability

Feedback loop

Provides Stability

Cancels out slight changes

“Negative” feedback loop

Negative feed back loops

Occur by the thousands

Are in our everyday life

Session 3 - System Thinking

stability
Stability

Negative feedback loops are everywhere

The thermostat

Body temperature

Float valves

Thirst

Inventories

Group membership

Predator and prey

Session 3 - System Thinking

stability12
Stability

Systems can

“Aim” at a fixed “target”

“Track” a moving “target”

Tracking systems

Get feedback on how far it is from where it should be

Uses the feedback to reduce the difference

Session 3 - System Thinking

stability13
Stability

Tracking systems

Set-back thermostat

Radar-controlled anti-aircraft guns

Satellite docking systems

Sun tracking solar collectors

Driving a car

Riding a bicycle

Session 3 - System Thinking

stability14
Stability

Tracking systems

Human/Mechanical

Person starts system going

Guides with series of corrections

System works so fast and so smoothly in some cases - hard to believe there is time for negative feedback to work

Common in natural and social systems

Sunflower

Politicians

Companies

Session 3 - System Thinking

things in common
Things in Common

Self-stabilizing systems make an active response to change

Bicycle

An active response to change requires the use of energy

Wind generator

Session 3 - System Thinking

active systems
Active Systems

Almost all living systems are active in sense that they continue to function and use energy even when dormant

Must stay active when at rest or die

Session 3 - System Thinking

active systems17
Active Systems

General rule

The more complex a system - the more energy spent on maintenance

Holds for social systems

Isolated peasant community vs a modern community

Session 3 - System Thinking

things in common18
Things in Common

System limitations

Amount and kind of change

“Exposure”

“Heat Stroke”

Many negative feedback systems stable over wide range, but fail abruptly when pushed beyond its limits

Session 3 - System Thinking

things in common19
Things in Common

Loose systems

Negative feedback does not prevent change

Negative feedback responds to change and keeps it under control

The result is a characteristic wobble - “sloppy”

Session 3 - System Thinking

things in common20
Things in Common

Reaction times

Every negative feedback system has time limits

Reaction time is most important

The minimum amount of time necessary for one complete circuit

If too slow, fast change can damage system

Session 3 - System Thinking

things in common21
Anticipation

Sometimes can’t afford the delay

Systems cope - react to warnings

Need ability to interpret warnings

Inadequate reaction time due to responding to problems rather than warnings

Things in Common

Session 3 - System Thinking

things in common22
Counter-intuitive systems

Behavior contrary to common sense

Predator - prey

High blood pressure

Rent control

The “obvious” solution doesn’t work

negative feedback loops fight direct intervention

Change the way pieces interact

Don’t try to “out-muscle” the system

Things in Common

Session 3 - System Thinking

things in common23
Hidden systems

Hard to predict how system will react

Feedback loops needed are not in sight

African village

1929 tariff on imports

Things in Common

Session 3 - System Thinking

things in common24
Vulnerable systems

Even the most stubborn system is vulnerable to interference with information flow

Slight breeze and bicycle

Can be used to advantage to change way system acts

Things in Common

Session 3 - System Thinking

change and growth
How?

Negative feedback loop breakdown

system becomes unstable and breaks down

A different kind of feedback - positive

Change and Growth

Session 3 - System Thinking

change and growth26
Negative feedback works to cancel out change

Positive feedback works to cause more change

Sound amplifier - “squawk”

Interest on money

Living things

Knowledge

Power

Change and Growth

Session 3 - System Thinking

putting things together
Plus and minus

The organization of every complex system is built out of the same two elements - positive and negative loops

Can apply knowledge about one system to another

Putting Things Together

Session 3 - System Thinking

putting things together28
Simple system - one of each type of loop

Population growth

Multiple loops

Add factors that could affect the loops

Putting Things Together

Session 3 - System Thinking

complex systems
Characteristics

Self-stabilizing

Goal-seeking

Program-following

Self re-programming

Anticipatory

Environment modifying

Self-replication

Self-maintaining and repairing

Self-reorganizing

Self-programming

Complex Systems

Session 3 - System Thinking

complex systems30
Problems of complexity

The tragedy of the Commons

Cost of information

Rule of thumb

Make each decision at the lowest possible level, but be ready to shift the control of the situation to a higher level if a serious problem occurs

The distortion of feedback

Loss of predictability (due to flexibility)

Complex Systems

Session 3 - System Thinking