Feedback Loops

A feedback loop closes the circle: a stock's level influences the very flows that change it. The effect reaches back and becomes a cause.

In a simple chain, A causes B and the story ends. In a system, B loops back to change A. The more rabbits, the more baby rabbits. Output feeds back into input.

That closed loop is the fundamental unit of a system's behavior. Wherever a quantity affects a rate that then affects the quantity, you have a loop.

Loops, not linear chains, are what make systems grow, stabilize, cycle, and surprise. Ask not just what caused this, but what the effect will do when it circles back.

Trace the circle, not the line

#03

Look for the return path

When you spot a cause and effect, ask what the effect does to the cause. If it feeds back — amplifying or dampening — you've found a loop, and the loop, not the arrow, governs behavior.

Follow it all the way around

Trace each link until you return to where you started. A loop half-drawn is a loop misunderstood; the behavior lives in the complete circuit.

Where does this effect feed back?
Does the return strengthen or oppose the original push?

Expect the loop to talk back

Plan for your intervention to circle around and change the very thing you pushed on. Straight-line plans fail because systems answer back.

Systems don't move in lines. They move in loops that answer their own questions.

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