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Ambiguity and LanguageAKA: Appeal to Purity

The No True Scotsman Fallacy

Redefines a group to exclude counterexamples and protect a generalisation.

Quick summary
  • Definition: Redefines a group to exclude counterexamples and protect a generalisation.
  • Impact: No True Scotsman distorts reasoning by Changing definitions to dodge counterexamples shields a claim from testing. The assertion becomes unfalsifiable.
  • Identify: Look for patterns like Make a broad claim about a group.

What is the No True Scotsman fallacy?

When presented with a counterexample, the speaker revises the definition of the group so the counter no longer counts, instead of updating the claim.

People lean on this pattern because It protects identity or ideology from uncomfortable evidence and keeps group narratives intact.

The Pattern
  • 1Make a broad claim about a group.
  • 2Face a counterexample.
  • 3Redefine the group to exclude the counterexample.

Why the No True Scotsman fallacy matters

This fallacy distorts reasoning by Changing definitions to dodge counterexamples shields a claim from testing. The assertion becomes unfalsifiable.. It often shows up in contexts like Debate, Media, Everyday conversation, where quick takes and ambiguity can hide weak arguments.

Examples of No True Scotsman in Everyday Life

Everyday Scenario
"Sports fandom debate."
A:“No true fan ever criticises the team.”
B:“I criticise the team and still support them.”
A:“Then you’re not a true fan.”
Serious Context

A movement claims it is peaceful. When violence occurs by members, leaders insist those individuals were never “real” members, avoiding responsibility.

Why it is fallacious

Changing definitions to dodge counterexamples shields a claim from testing. The assertion becomes unfalsifiable.

Why people use it

It protects identity or ideology from uncomfortable evidence and keeps group narratives intact.

How to Counter It

Recognition

  • Definitions shift after counterexamples appear.
  • Membership is retroactively revoked to salvage a claim.
  • Standards for being “true” are vague or newly introduced.

Response

  • Fix the definition and ask whether the counterexample fits it.
  • Point out the moving goalposts.
  • Invite revising the generalisation instead of redefining membership.
Common phrases that signal this fallacy
  • “No True Scotsman” style claim: Redefines a group to exclude counterexamples and protect a generalisation.
  • Watch for phrasing that skips evidence, e.g. "Redefines a group to exclude counterexamples and protect a generalisation"
  • Pattern hint: Make a broad claim about a group.
Better reasoning / Repair the argument

Fix the definition and ask whether the counterexample fits it.

Often confused with

No True Scotsman is often mistaken for Equivocation, but the patterns differ. Compare the steps above to see why this fallacy misleads in its own way.

Variants

Close variations that are easy to confuse with No True Scotsman.

Frequently Asked Questions

Is No True Scotsman always invalid?

No True Scotsman signals a weak reasoning pattern. Even if the conclusion is true, the path to it is unreliable and should be rebuilt with sound support.

How does No True Scotsman differ from Equivocation?

No True Scotsman follows the pattern listed here, while Equivocation fails in a different way. Looking at the pattern helps choose the right diagnosis.

Where does No True Scotsman commonly appear?

You will find it in everyday debates, opinion columns, marketing claims, and quick social posts—anywhere speed or emotion encourages shortcuts.

Can No True Scotsman ever be reasonable?

It can feel persuasive, but it remains logically weak. A careful version should replace the fallacious step with evidence or valid structure.

Further reading