Schools teach “complicated,” but they need to teach “complex” too.

Complicated systems are made up of lots of pieces, but each part can be designed or solved on its own. You can put it into a giant block diagram. You can control its behavior and assume it will behave the same every time.

Since the Industrial Revolution, we've dramatically improved our ability to build reliable complicated systems. Largely because of expertise.

Complex systems are different. Lots of factors affect behavior, but they're so intertwined, uncertain, and time-varying that predicting behavior from intervention is always imprecise.

It's hard to define where one complex system ends and another begins.Complex systems can have emergent properties not predictable from individual pieces. Beehives. Life-form evolution. The social Internet. Most modern AI.

As Donella Meadows indicates, "The behavior of a system cannot be known just by knowing the elements of which the system is made."

Goals of complicated systems can be written in specifications. For complex systems the goals and even problem statements are debatable.

Complex systems require wisdom.