The Narrative Fallacy — The Trap of a Plausible Story
After a crash ends, the news always neatly explains 'this is why it fell.' So why couldn't anyone tell that story before it fell?
What the Narrative Fallacy Is
The narrative fallacy is the human tendency to simplify complex, random facts into a single story with a clear chain of cause and effect.
It is a concept popularized by the writer and investor Nassim Taleb in his book The Black Swan (2007). Our brains find it hard to tolerate 'it just happened by chance,' so we attach to each event a smooth narrative with a cause and an ending. That makes the world feel understood and comforting, but reality is far more complex and governed by chance than the story suggests.
After-the-Fact Narratives and the Black Swan
The narrative fallacy becomes especially strong when combined with hindsight bias.
After an unpredictable major event (what Taleb called a 'black swan') occurs, people insist 'there were signs, actually' and construct a tidy cause-and-effect story. This makes the event look as though it had been predictable all along. But that story is stitched together backward, only after the outcome is already known.
Such after-the-fact narratives plant the dangerous confidence that 'next time I'll notice it in advance too.' The smoother the explanation, the better it fools us.
Taleb's core message is that 'the rarer and more shocking an event, the easier it is to package it into a plausible story after the fact — and so we underestimate the event's true unpredictability.'
What to Watch Out for in Investing
The market is always overflowing with stories explaining 'why it rose, why it fell.' Most are after-the-fact commentary attached once the outcome is in. It's dangerous to be persuaded by a plausible narrative and then become certain that 'therefore, next it will go like this.'
An appealing growth story for a single stock is a powerful narrative, but a good story doesn't mean high odds. The defense is to separate story from data. Ask: 'If this explanation is correct, is it confirmed by the data too?' and 'Couldn't the opposite story be made to sound just as plausible?'
The same reason is why this site focuses on showing the return, drawdown, and recovery data of holding for a long time — not the narrative of a particular stock. Rough data is often more honest than a smooth story.
よくある質問
Q. Why is understanding things through stories a problem?
Stories are essential tools for learning and communication. The problem is when a story makes the world feel 'simpler and more predictable than it really is.' In particular, becoming certain about the future based on an after-the-fact narrative built once the outcome was known causes you to underestimate risks you cannot control.
Q. What exactly is a black swan?
Taleb's black swan means a rare event that ① is very hard to predict, ② has an extremely large impact when it occurs, and ③ is explained after the fact as if it had been predictable. A major financial crisis is a classic example. The key lesson is that, rather than trying to predict such events precisely, you should prepare (diversification, spare cash, manageable risk) so you don't collapse under any shock.
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