How to identify the No True Scotsman fallacy?

Why do definitions shift to protect beliefs?

The No True Scotsman fallacy occurs when someone redefines the criteria of a group to exclude counterexamples and protect a generalization. When presented with evidence that contradicts a universal claim, the person changes the definition instead of revising the claim.

An example is claiming that “no real journalist would report something like that” after being shown examples that disprove the point. This fallacy avoids admitting exceptions by tightening the definition.

To identify it, look for situations where definitions change mid-argument to maintain a belief. Sound reasoning requires acknowledging valid counterexamples, not redefining them away.