Fallacy Summary: Redefine a group to exclude counterexamples.

Definitions are tightened ad hoc so contradictory cases are dismissed rather than the claim being revised. Research context: Informal-logic and argumentation research treats fallacies as structural problems in reasoning. A conclusion can sound persuasive while still being weak if the link between premises, evidence, and conclusion is not valid. Pattern-specific focus: Redefine a group to exclude counterexamples. Practical review method: separate factual claims from interpretation, check source quality, and test whether the conclusion survives alternative explanations.

How to recognize no true scotsman yourself

• A rhetorical move replaces proof (for example, popularity, authority, or insult).
• Causation is claimed without ruling out alternatives or coincidence.
• The argument is reduced to an artificial either/or choice.
• Emotion is used to drive agreement where evidence should carry the burden.

Verification questions

• Which premise is doing the critical work, and is it actually supported?
• Does the conclusion logically follow, or does rhetoric bridge the gap?
• What alternative explanation would still fit the observed facts?

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High offenders