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Cognitive Bias Cards
Cognitive Bias Cards · Card 6

Herd Mentality

Reasoning changes when everyone around you is doing the same thing — the crowd's confidence quietly substitutes for your own.

Reasoning Alone
My own judgment
Reasoning in a Crowd
The crowd's confidence, borrowed
In Practice

A stock everyone is suddenly talking about feels safer to buy simply because of the crowd — not because the underlying reasoning actually improved.

Generic Example

A queue outside a shop makes people join it before asking what it's even for — the crowd itself becomes the reason.

If no one else were doing this, would I still think it was a good idea?