Simple · Complicated · Complex
Three words that resemble one another but belong to three different ways of thinking.
The difference between simple, complicated and complex seems small, but it partly determines how we think about problems in care and which methods suit them.
Simple is what was still manageable in a secondary-school physics lesson. If you push a block, it moves; if you push harder, it moves faster. If you open a tap, the water flows. Cause and effect are clear and roughly linearly connected: more of the one gives more of the other.
Complicated is a clock, an aeroplane or a diesel engine: many parts, but predictable for anyone who knows the rules. The whole can be taken apart, each part studied and everything put back together without the logic being lost. Here the whole is the sum of its parts, and cause and effect remain traceable in principle.
Complex is of a different order. Here too there are many parts, but they influence one another in non-linear ways, and from that interaction properties arise that cannot be predicted from the sum of the parts. Examples are an ant in an anthill, a neuron in a brain region or a person in a social system. Taking such a system apart leaves one holding something that is no longer alive.
What this means for psychology
Van der Maas (2024) clearly places psychology in the third category. A fear response may lead to flight, but also to attack. Whether a stimulus is experienced as threatening depends on the context, on the state of the person and on his or her history, and may even differ from one second to the next. A calm situation may, moreover, suddenly tip into panic without the stimulus itself having changed in any essential way.
"In psychology, cause-and-effect relations are rarely simple, and effects are often non-linear." (Van der Maas, 2024)
This has consequences. In mental health care we have developed many diagnostic and treatment methods that implicitly assume a complicated model: as if parts can be addressed separately and the sum of interventions will lead to recovery of its own accord. For some problems this works reasonably well. For many others, such as depression, anxiety, personality problems, eating disorders and addiction, it seems to work only in part. In our view this is due not so much to the quality of the methods as to the type of system we are treating: a complex rather than a complicated one.
Other methods for a different type of system
Working with complex systems calls for other methods: measuring patterns over time, recognising transitions, taking context into account as a natural part of treatment, and accepting that trying things out and adjusting course are not a sign of unprofessionalism, but of a fitting way of engaging with a system that does not allow itself to be dissected.
Making this distinction is also a form of professional modesty. It need not lead to discouragement: we can certainly influence a complex system, only not predict or steer it the way we would a complicated one. It is, with a wink, working with a system that talks back.