That joke has always been funny to me. Every time I see that tweet by @pronounced_kyle, I end up thinking about the same thing: how often we assume the world works in straight lines when it really doesn’t.
Take a baby’s early weight gain and extend it forever, and the result becomes absurd very quickly. The arithmetic can be perfectly fine. The model is what breaks. That, in a simple way, is what false linearity is.
The dotted line runs off the top of the chart before the second birthday. I just cut it and wrote the number. Real growth (green) barely looks like it is moving next to it.
Why the shortcut feels natural
Linear thinking is not bad. In many everyday situations it is useful, cheap, and intuitive. If 10 km takes an hour, 20 km takes two. If 1 kg of plov feeds 4 people, 2 kg feeds 8. The problem starts when we carry that same shortcut into systems that bend, flatten, accelerate, or hit limits.
The mistake is not using a line. The mistake is forgetting that the line is only a simplification.
Hero visual drawn from WHO child growth-chart medians; the doubling line is an illustrative extrapolation.
Where the line bends
Once you notice it, you start seeing false linearity everywhere. A lot of important relationships in life are not straight lines. They flatten, peak, bend, or change direction entirely.
1. Money and happiness
Money matters — especially when you do not have enough of it. But the jump from too little to enough changes life much more than the jump from comfortable to richer.
Based on income and well-being research (Kahneman & Deaton).
2. Study hours and exam performance
The first extra hours of study often help a lot. Later hours may add less, and at some point fatigue starts eating into performance.
An inverted-U: more is better, until it isn’t.
3. Work hours and useful output
Longer hours are not the same as better work. Past a certain point, fatigue, mistakes, and diminishing returns start showing up.
Hours present is not the same as work produced.
4. Savings and compound interest
Here the line fails the other way: reality curves up faster than we expect. Interest earns interest, so the balance bends away from the steady climb we imagine.
Wonderful in a savings account, brutal on a credit card.
5. Technology adoption
New things often look like a failure early on, then spread all at once, then level off as the market fills. Slow, then sudden, then saturated — an S, not a line.
Judging the slow start as the whole story is the trap.
A few other places this shows up
exercise and recovery
product features and usability
advertising spend and new customers
medication dose and effect
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So it is worth holding three ideas apart. Linear thinking is a tool — a simplification, and often a good one. Linearity bias is our preference for that tool: the reflex to reach for the line even when it does not fit. And false linearity is the last, quietest step — mistaking the line for the world itself, and then being genuinely surprised when the world curves.
