Simple comes after complex

Society likes simple answers and particularly likes calling them a mark of genius. “Everything great is simple” sounds best once somebody else has done the difficult work.

A good explanation really can be short. A well-found formula fits a large number of observations into one line. An elegant design gets by with few parts. But the simplicity of the result does not mean the subject, or the road to it, was simple.

To say something clearly you usually have to spend a long time working it out.

A short formula hides definitions, measurements, limits and earlier theories. A clean design appeared after a mass of versions that did not work. An obvious safety rule was not obvious once, or it would not have had to be introduced after a series of accidents.

So the demand to explain things simply is useful but has a limit.

If an explanation has become so simple that important conditions have disappeared, that is no longer clarity but loss of data. A metro map is more convenient than a detailed city plan as long as the task is to travel by metro. Using it to find a footbridge over the river would be somewhat presumptuous.

Real understanding lets you change the scale: give the short explanation, unfold the mechanism, name the exceptions, show the calculation and admit the point where the simple model stops working. Simplicity is an achievement of packaging, not a property of the whole of reality.

Every short rule is a compressed archive of accidents. “Do not stand under a suspended load” fits into six words and cost several funerals. “Isolate the supply and hang a warning tag before starting work” looks like bureaucracy right up to the story about the mate who came back from lunch and threw the switch because he did not know anyone was still in the panel. The simplicity of the wording was achieved by moving all the circumstances outside it.

So “explain it more simply” is a request to be handed the result of somebody else’s compression. Often that is sensible: a passenger does not need a course in aerodynamics. It goes wrong when the simplified version starts being used in exactly the places where the discarded conditions are doing the work.