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About systems

A system is a set of interacting pieces that combine in a particular way that creates a specific set of outcomes. A system is not only the sum of its parts but the product of their interaction.

Systems thinking is about understanding relationships and their implications. In this way, we can be better problem solvers and shift or recombine the parts in the system in ways that offer an improved outcome.


Systems thinking has been successfully used in engineering, defence, economics, ecology and business since the mid-1950s. It is a way to understand and manage complex problems at a local, regional and global level, and is both a way of thinking and a practical tool to aid decision-making when tackling complex problems.

It helps us to see the big picture – how the problem we’re trying to solve is made up of connected and inter-related components, so that a change in one part will influence other parts. It is also a way to understand the complex nature of the problems we’re dealing with and how relationships and behaviours change over time to cause the situation to be as it is.

Systems approaches and tools help us to better understand the relationships that cause complex problems and to find the most efficient, effective and equitable solutions.

Systems thinking poses two fundamental questions about each interacting part of a complex problem: What does it influence and what influences it?

Beneath the surface

Traditional approaches to problem solving often address just the obvious symptoms of complex problems through quick fixes, and fail to recognise and intervene in the root causes of problems. Rather than just tackling the tip of the iceberg, systems thinking delves below the surface and identifies the fundamental and interconnecting causes of complex issues – the patterns of behaviour, the underlying structure and the beliefs (mental models) of the people and organisations responsible for creating that complex issue.

If we try to improve a situation without understanding these connected underlying causes, we can make things worse or create new problems that we or others have to solve in the future.

Systems thinking also refers to theories, tools or methods that help us describe, understand and analyse a system. Some of these tools provide ways to think about public health issues as problems within systems. Other tools allow us to map elements in a system and the connections among them, which helps to highlight the complexity of public health issues and allows us to test different interventions or policy options to see which are likely to produce the desired change.

Systems thinking can be useful in dealing with complex problems when:

  • We’re dealing with a stubborn long-term problem – not a one-off event – that has a known history
  • There are multiple actors (organisations and people) and multiple causes that interact and influence each other
  • There are competing or conflicting interests – or different views of the situation or problem
  • There’s no single explanation for what is causing the problem and no single solution that fits all situations.