System thinking - Engineering for Society

Everything should be in there lol

A system (Anderson & Johnson)

a group of interacting, interrelated, or interdependent components that form a complex and unified whole.

A system (Kim)

any group of interacting, interrelated, or interdependent parts that form a complex and unified whole that has a specific purpose

A system (Meadows)

An interconnected set of elements that is coherently organized in a way that achieves something consisting of three kinds of things: elements, interconnections, and a function or purpose.

A social system (Parsons)

a plurality of individual actors interacting with each other in a situation which has at least a physical or environmental aspect, actors who are motivated in terms of a tendency to the “optimization of gratification” and whose relation to their situations, including each other, is defined and mediated in terms of a system of culturally structured and shared symbols.

structure

the overall pattern of relationships among a system’s components, the way they are organized and connected

Patterns 

recurring trends

System pyramid

Events (top)

Patterns

Structure (bottom)

in a nonlinear system...

twice the push could produce one-sixth the response

Reductionism

the process of breaking down or reducing systems to their constituent parts and then describing the whole system primarily as merely the sum of these constituent elements.

Analysis approach

Top down approach on a system

Synthesis approach

Bottoms up approach on a system

Synthesis

the combination of components or elements to form a connected whole

Epistemology

the theory of knowledge and seeks to understand one or another kind of cognitive success or when knowledge is good to pursue.

The equivalence assumption

the effect is always equal to the cause, both quantitatively and qualitatively

The continuity assumption

the idea that a process or relationship is stable, or changes smoothly over time or across situations, without sudden, unpredictable jumps or breaks

The mechanistic presupposition

Organismic processes are interpreted in terms of the interlocking of the parts of a machine

The elementaristic presupposition

A complex system can be analysed by breaking it down into its elements and examining the functioning of these elements. The function of the whole system is then explained by the composition of the detailed processes in the elements.

The realist notion

That the physical world surrounding us is actually as it looks to us.

Systems Thinking Tools

Are used to understand and communicate the behaviour of dynamic systems.

Cause-and-Effect Focus

Illustrate relationships between system elements and how changes in one part of the system affect others.

Feedback Loops

Help identify feedback loops (reinforcing and balancing), which are critical for understanding system behaviour over time.

Purpose Causal Loop Diagram (CLD)

To visualize feedback and causal relationships

Support Modelling

are often part of the model-building process in system dynamics and serve as conceptual precursors to simulation models.

Focus Causal Loop Diagram (CLD)

Emphasizes qualitative feedback structure

Elements Causal Loop Diagram (CLD)

Variables (concepts), arrows, polarity (+/-), loops

Representation Causal Loop Diagram (CLD)

No distinction between stocks and flows

Time Behaviour Causal Loop Diagram (CLD)

Shows relationships, but not how variables accumulate over time

Quantifiability Causal Loop Diagram (CLD)

Typically not quantitative, used for thinking, not simulating

Usage Example Causal Loop Diagram (CLD)

Understanding why burnout is increasing in a team (e.g., “Stress → Productivity → Mistakes → Stress”)

Purpose Stock and Flow Diagram (SFD)

To model the accumulation and flow of quantities over time

Focus Stock and Flow Diagram (SFD)

Emphasizes quantitative dynamics (levels, rates, equations)

Elements Stock and Flow Diagram (SFD)

Stocks, flows, valves, and auxiliaries

Representation Stock and Flow Diagram (SFD)

Explicit distinction between stocks (levels) and flows (rates of change)

Time Behaviour Stock and Flow Diagram (SFD)

Tracks how quantities change over time through inflows and outflows

Quantifiability Stock and Flow Diagram (SFD)

Designed for simulation, requires numerical inputs

Usage Example Stock and Flow Diagram (SFD)

Modelling how inventory changes with shipments and deliveries

Stocks

the elements of the system that you can see, feel, count, or measure at any given time.

Flows

the inputs and outputs per time unit that increase or decrease stocks.

Feedback

the effect that a change in one part of an ecosystem or social system has on the very same part after passing through a chain of effects in other parts of the system.

Inflow

The information that flows into a Stock and flow diagram

Outflow

The information that flows out of a Stock and flow diagram

Balancing feedback provides…

stability through a circular chain of effects that opposes change. It keeps things the same.

Reinforcing feedback can create…

drastic change, like exponential growth which can result in a downfall.

Causal loop diagrams (CLDs)

tools for representing and exploring the feedback structures in systems.

Causal loop diagrams (CLDs) process are…

iterative

Benefit Causal loop diagrams (CLDs)

it helps us to come to a holistic understanding of real-world systems by broadening our perspective and emphasizing the role feedback has in dictating the behaviour of non-linear, dynamic, complex systems

A good Causal loop diagrams (CLDs)…

accounts for complexity and non-linearity within real-world systems while also teaching us about problem and solution spaces.

Elements

The individual parts that make up a system.

Interconnections

The relationships and interactions between elements in a system.

Function / Purpose

The goal or outcome the system is organized to achieve.

Holism

The view that a system should be understood as a whole rather than merely as a collection of parts.

Linear causation

A cause-and-effect relationship in which effects are proportional and directly linked to causes.

Non-linear causation

A cause-and-effect relationship in which small causes can produce large effects and vice versa.

Five Characteristics of Systems

A system’s parts must be present, arranged in a specific way, serve a purpose within a larger system, maintain stability through adjustments, and rely on feedback.

Presence of Parts

All parts must be present for a system to function optimally.

Arrangement of Parts

Parts must be organized in a specific way.

Purpose within Larger Systems

Systems exist to fulfil purposes within larger systems.

Stability through Adjustments

Systems maintain stability through fluctuations and adaptations.

Reliance on Feedback

Systems depend on feedback to regulate behavior.

Variable (CLD)

A factor that can change within a system and is represented in a causal loop diagram.

Polarity (+)

A causal relationship where variables change in the same direction.

Polarity (-)

A causal relationship where variables change in opposite directions.

Reinforcing Loop (R)

A feedback loop that amplifies change.

Balancing Loop (B)

A feedback loop that counteracts change and promotes stability.

Stock Memory Principle

A stock is the present memory of the history of changing flows within a system.

Bifurcation

A point at which a small change causes a system to shift into a different state or behaviour.

Phases

Distinct states or modes in which a system can exist.

Self-interaction

A process in which parts of a system indirectly influence themselves through feedback mechanisms.

Constructivist notion

The idea that reality is interpreted and constructed through human perception and understanding.

System Thinking Paradigm

An approach that focuses on understanding systems as wholes, emphasizing relationships, feedback, and non-linear causation.

Classical (Realist) Model

A view of knowledge based on equivalence, continuity, mechanistic explanations, and a realist understanding of the world.

Systems Thinking Model

A view emphasizing bifurcations, phases, self-interaction, and a constructivist understanding of reality.

Systems Engineering

A methodical, multidisciplinary approach to the design, realization, technical management, operation, and retirement of a system.

Building the system right

Meeting the technical requirements correctly.

Building the right system

Delivering the intended operational outcomes and stakeholder value.

System boundary

The line between what is included in the system and what belongs to the environment.

Environment

Everything outside the system that can influence the system.

System vs collection

A system has interacting parts and a purpose; a collection is just a group of things without meaningful interconnections or shared function.

Purpose is deduced from behaviour

A system’s real purpose is shown by what it does, not by what people say it should do.

Additivity principle

In linear systems, the total response to multiple inputs equals the sum of the separate responses.

Homogeneity principle

In linear systems, output is proportional to input.

Emergence

New properties or behaviours arise from interactions between parts and cannot be explained by the parts alone.

Exponential growth

Growth where the increase becomes faster over time, often caused by reinforcing feedback.

Rule of 70

A shortcut for estimating doubling time: 70 divided by the growth percentage.

Paradigm

A worldview that shapes how research is done and how the world is understood.

Mereology

The theory of part-whole relationships.

Source

A stock outside the system boundary from which an inflow comes.

Sink

A stock outside the system boundary to which an outflow goes.

Valve

A control point that regulates the rate of a flow.

Homeostasis

Stability maintained through balancing feedback, such as body temperature regulation.

Delay

A time gap between cause and effect in a system or causal loop.

Mental model

A person’s internal understanding of how a system works.

Narrative in CLD

A coherent story that explains the causal relationships shown in a causal loop diagram.

Unintended side effects

Effects of actions that were not expected because the larger system was not fully considered.

Success trap

A situation where a previously successful strategy becomes harmful when the system changes.

No silver bullet

The idea that complex system problems usually cannot be solved by one single intervention.