When do complicated systems become complex?

Complicated systems become complex when their behavior changes, as this indicates that the interactions within the system have reached a level of sophistication that can lead to unpredictable outcomes. Complexity arises from the non-linear interactions between the components of the system, where small changes can lead to disproportionately large effects.

When behavior changes, it suggests that the system can no longer be understood merely by analyzing its components in isolation; rather, the relationships and interactions must be considered as a whole. This interconnectedness can result in emergent properties that are not present when the system is viewed as a collection of separate parts, highlighting the transition from a complicated structure—where components can be extensively analyzed and understood—to a complex one.

Understanding this shift is crucial in systems engineering, as it affects design, analysis, and management strategies. Complex systems often require different methodologies and approaches for effective modelling and problem-solving compared to complicated systems, which may simply be intricate but predictable.