No True Scotsman
Redefining a category on the fly to dodge a counterexample.
When someone meets a counterexample by narrowing the definition — “no *true* member would do that” — they’re protecting a claim from evidence instead of updating it. The move quietly changes the subject: the category is being redrawn to stay true by definition. Catch it by fixing the definition *before* the argument, and holding it still when the inconvenient example shows up.
Where it applies
Skills this lens bears on — open any to see the lesson.