Moving the Goal Posts

F107 • Informal - Evidence/Evasion

Also known as: Raising the Bar, Shifting Standards, Changing the Rules

Difficulty 3/10Low LoadVery Common

Changing the criteria for proof, success, or acceptance after those original criteria have been met, by demanding additional or different evidence that was not part of the initial challenge. The person retroactively alters what would count as sufficient evidence to avoid conceding the point.

Why Invalid

This is a form of intellectual dishonesty that makes genuine discourse impossible. When someone asks for evidence and then dismisses it by demanding different evidence, they reveal they were never arguing in good faith. The fallacy undermines rational debate because it makes the target impossible to hit - no matter what evidence is provided, new requirements appear. It violates the implicit contract of argumentation: that if certain conditions are met, the point should be conceded. Moving the goal posts converts a falsifiable claim into an unfalsifiable one by perpetually adding escape clauses.

Examples

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Scope of Applicability

Identify the original criteria or challenge that was posed
Check whether those original criteria were actually met
Look for new requirements introduced after the original ones were satisfied
Assess whether the new requirements were reasonable extensions or complete shifts
Determine if the person would ever accept any evidence as sufficient
Ask: 'What would it take to change your mind?' and see if the answer keeps changing

Common Mistakes

Confusing legitimate follow-up questions with moving the goal posts (asking for clarification on provided evidence is not the same as dismissing it)
Not recognizing when the original criteria were genuinely ambiguous and clarification is reasonable
Confusing this with Ad Hoc Rescue (which modifies the claim itself rather than the criteria for evaluating claims)
Thinking that all requests for additional evidence are fallacious (sometimes more evidence is legitimately needed)
Not recognizing when you yourself are moving the goal posts

Shifting Burden of ProofBurden of Proof FallacyAd Hoc RescueNo True Scotsman

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F106 Argument from Ignorance F403 No True Scotsman

Return to 3.1 Who Has to Prove What

Fallacy 3 of 4