This is a Lexicon entry: the mechanism, when it shows up, and the countermeasure. The full correction, with real-world cases and the audit prompt, hasn't been written yet.
Definition
Nathan Ballantyne's concept: a person who is genuinely expert in one field crosses into another and makes confident pronouncements that their qualifications do not support - often with the social authority of their original expertise intact. The domain crossing is often invisible to audiences, who hear "expert" and do not notice the "in a different field." Common among scientists commenting on policy, economists on psychology and technologists on governance.
When it shows up
Celebrity scientists on non-science topics. Physicists on economics. Economists on public health. Experts in one field making confident claims in another.
Failure mode
Domain expertise creates confidence that generalises beyond its competence. The audience treats the title as authority on the new topic. The trespasser may be genuinely expert in origin domain; that doesn't transfer.
Countermeasure
Check whether the expert's credential is in the specific field of the claim. A Nobel in physics doesn't authorize claims about nutrition. Cross-domain confidence is usually uncalibrated.
Related traps
Also connected in the map4 more, locked
Credit & first seen
CoinedCoined by philosopher Nathan Ballantyne inEpistemic Trespassing(2019, Mind).
Also revealed
Entry #152 of 631 in The Lexicon · see the full Lexicon