Sophistry
No. 08 Cognitive bias

Confirmation Bias

Notice and remember evidence that confirms what you already believe, and overlook what doesn't.

Evidence approaching a screen: some passes through into a store of belief, the rest is stopped and never arrives. a b c
FIG. 8a, the belief already held. b, evidence that agrees, let through. c, evidence that disagrees, screened out.

Illustrative example

Convinced a certain diet works, someone tracks every good day on it and forgets the bad ones.

Confirmation bias isn’t dishonesty, it’s a filtering habit. Evidence that fits an existing belief gets noticed and remembered; evidence that doesn’t tends to get explained away or simply forgotten.

It’s strongest when the belief matters emotionally, which is exactly when clear thinking matters most.

The countermeasure is deliberately asking “what would change my mind” and then actually looking for that evidence, not just the evidence that supports the existing view.

Seen in the wild

Real, sourced instances of this technique in actual public debate.

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