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Linear vs Non-Linear
Systems / Dualities
Doubling the input doesn't always double the output.
The Tension
Linear systems: output is proportional to input. Non-linear systems: relationships bend, compound, flip. Most real systems are non-linear; most of our intuition is linear.
| Linear | Non-Linear |
|---|
| Predictable | Surprising |
| Additive | Multiplicative |
| Small cause → small effect | Small cause → any effect |
| Easy to model | Hard to model |
Why It Matters
- Linear thinking underestimates thresholds, tipping points, compounding.
- Adding more people doesn't always deliver more output.
- Small investments sometimes produce huge returns — and vice versa.
How to Apply
- Suspect non-linearity in biological, social, economic systems.
- Look for thresholds: when does behaviour change qualitatively?
- When estimating, ask: does this scale proportionally?
Examples
- Mythical Man-Month: adding engineers to a late project.
- Network effects: value grows faster than membership.
- Burnout: effort is linear until it collapses.
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