Complicated or Complex?

For years I had occasionally wondered about the difference in meaning between the words complicated and complex.

Today I found out, and I want to share the difference with you. After all, if you get your words right, your writing will be better.

First, complicated. A rube goldberg is complicated. (Google “image rube goldberg” to see more like this, and others besides, including ones that are real.)

Something complicated has 1. parts that are different from one another, and 2. a small disturbance makes it not work. Rube goldbergs are funny because they are so full of ways to not work. Complicated things require a lot of effort to make them function, and if they encounter something you didn’t think of, they break. Sometimes we call this “rocket science.” Robots, space ships, and automobiles are complicated. They have parts that differ from each other, and repair or the prevention of the need to repair is important.

Complexity is not like that. Complex things have 1. many similar parts and 2. a few simple rules that they all follow, and hence 3. You get an emergent behavior, something that you might not expect and can’t precisely predict. And 4. This emergent behavior tends to keep the thing from breaking. A flock of birds is complex.

So is a school of fish, so is a pile of sand. If you pour a stream of sand into a pile, it makes a mound with a 15 degree slope, but you can’t predict where those little cascades of sand will happen next as the pile grows.

So there you have it. And now I ask you: Is the universe complicated or complex?