Question
What is a cognitive bias, and how does it differ from a logical fallacy?
Answer
A cognitive bias is a systematic, predictable error in how the mind perceives, remembers or judges; a logical fallacy is a flaw in the structure of an argument.
The two are easy to confuse because both lead to wrong conclusions, but they live in different places:
| Cognitive bias | Logical fallacy | |
|---|---|---|
| Where it sits | In your thinking/judgement | In an argument's structure |
| Nature | A built-in mental shortcut that misfires | A reasoning step that doesn't follow |
| Example | Believing a claim more because you've heard it often | "Everyone believes it, so it's true" (ad populum) |
| Fix | Notice it and consciously correct for it | Point out the broken inference |
A bias is something your brain does to you automatically — a side-effect of shortcuts (heuristics) that are usually efficient but predictably wrong in certain situations. A fallacy is something in the words of an argument you can lay out and inspect. The same mistaken belief can involve both: a bias makes the conclusion feel right, and a fallacy is the broken reasoning you'd use to defend it.
Tip: Biases are about the thinker; fallacies are about the argument. "Know thyself" targets biases — you can't audit an argument you're too biased to question.
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