Systems

A set of connected parts where what one does changes what the others do, so the whole behaves in ways no part does alone.

The other parts respond, changing their own behaviour until the system returns to where it started.

A change to the connections — what is measured, rewarded or paid for — rather than to quantity.

“What will push back is…” — naming the response is what turns a wish into an answer.

Elements, connections, boundary, purpose, feedback.

Everything outside it is treated as fixed, so it decides which solutions the analysis can even consider.

Read it from what the system reliably produces, not from what its owner says it is for.

Output returning as input, so the system learns from behaviour it caused — which is why systems drift.

Steady (returns to a level), growing (each round bigger), tipping (flips and stays).

No single step is unusual, so nothing triggers attention until the total is already large.

Removing the pressure does not undo the change — the way back is not the way you came.

Steady: change the rule. Growing: act early. Tipping: keep a margin.

A simplified version of something, built to answer one question — useful because of what it leaves out.

What did it leave out, and does that matter for the question being asked of it?

A model simplifies; a simulation runs a model forward in time; a visualization shows data so a person can read it.

They are read in about a second, and axis, scale and colour have already made an argument by then.