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No. 50 · Risk · Fallacy

Monte Carlo Fallacy

A roulette wheel has no memory, however long the streak.

The Monte Carlo Fallacy, or gambler's fallacy, is the belief that a run of one result makes the opposite more likely next time. But independent events like coin tosses and roulette spins have no memory.

When you catch yourself thinking something is due, ask whether the events are truly independent. If they are, the streak means nothing. If they aren't, like health or job performance, look for the real cause.

In the Almanac

“Casanova’s martingale”, 1750s · “Roulette on camera”, 2005

Both stories in full, three ways to use it and where it misleads.

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Monte Carlo Fallacy

Questions

What is Monte Carlo Fallacy?

The Monte Carlo Fallacy, or gambler's fallacy, is the belief that a run of one result makes the opposite more likely next time. But independent events like coin tosses and roulette spins have no memory.

How do you avoid Monte Carlo Fallacy?

When you catch yourself thinking something is due, ask whether the events are truly independent. If they are, the streak means nothing. If they aren't, like health or job performance, look for the real cause.

When does Monte Carlo Fallacy matter?

Monte Carlo Fallacy is one of the 32 mental models for risk, the situations where you ask: What could go wrong, and what will I do if it does? Within that, it belongs to “Misreading chance”, alongside Availability Bias, Conjunction Fallacy and Gambler’s Fallacy.

What is an example of Monte Carlo Fallacy?

Two stories show it at work: Casanova’s martingale (1750s) and Roulette on camera (2005). Both are told in full in The Mental Models Daily Almanac, which has two stories for each of its 365 models.

Which mental models are related to Monte Carlo Fallacy?

Gambler’s Fallacy, Law of Large Numbers and Causal Fallacy. Monte Carlo Fallacy itself comes from fallacy.