A thermostat is the simplest feedback system most of us interact with daily, and it already contains the seed of every surprise that complex systems have ever handed us. You set a target. The system measures the gap. It acts to close it. So far, so legible. But the moment a second feedback loop is introduced — say, the heat generated by the people in the room — the system’s behaviour becomes harder to predict, not because anything mysterious has happened, but because the interactions multiply faster than intuition can track.

Control, in such systems, is always approximate. The engineer who claims to have a complex system under control is using the word loosely: what she means is that she has understood the dominant feedback loops well enough to nudge the system toward a preferred region of behaviour. The system is still doing what it wants to do. She has learned to want something compatible with it.

This is not a counsel of despair. It is an invitation to a more honest relationship with the designed world. We do not control systems; we participate in them. The city does not obey its planners; it incorporates their decisions as inputs and produces its own outputs, which become the next set of inputs. Understanding this, a planner stops trying to determine outcomes and starts trying to shape conditions.

The same shift applies in the mind. We do not control our thoughts by suppressing or forcing them. We shape the conditions — the environment, the habits, the questions we live with — and the thinking that emerges is the system’s response.