F403 • Informal - Evidence/Evasion
Also known as: Appeal to Purity, No True Christian, Definitional Retreat
When someone offers a counterexample to a claim we care about, we sometimes protect the claim by quietly redefining the group -- 'well, no real member of that group would do that.' The counterexample is not addressed; it is reclassified. The definition moves just enough to keep the belief intact.
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We form generalizations about groups because it helps us navigate the world, and most of the time those generalizations are useful enough. The problem comes when a counterexample appears and, instead of reconsidering the generalization, we adjust who counts as a member. This feels like holding a standard, but it is actually making the standard unfalsifiable. Once 'true' membership requires having the trait you are trying to prove all members have, the claim becomes circular -- it is true by definition, which means it has stopped saying anything about the actual world. The original claim might have been meaningful ('people in this community value honesty'), but after the retreat it has become trivially true ('people I define as truly in this community value honesty') -- and the definition of 'truly in this community' now secretly includes 'values honesty.'
| When there genuinely are established criteria for group membership that the counterexample fails to meet |
| When the original claim was clearly about a defined subset, not the general group |
| When clarifying an ambiguous term rather than retreating from a refuted claim |
| Watch for the word 'true,' 'real,' or 'genuine' appearing in a claim only after a counterexample has been raised. If those qualifiers were not there at the beginning, their arrival is a signal that the definition is being adjusted to absorb the challenge. |
| You might notice yourself feeling defensive when someone offers a counterexample to a group you identify with. That defensiveness is natural -- it is protecting something that matters to you. But if your response is to reclassify the counterexample rather than reconsider the claim, it is worth pausing. |
| Ask: was the group defined before the counterexample appeared, or did the definition shift in response to it? If the boundary moved to exclude exactly the evidence that challenged the claim, the move was probably a retreat rather than a clarification. |
| Notice when a claim about a group starts to feel impossibly clean -- no exceptions, no messiness, no counterexamples. Real groups are messy. A claim that has no counterexamples might be true, but it also might have quietly redefined the group to exclude all the counterexamples. |
| Pay attention to whether the 'true member' test can be applied independently of the trait being discussed. If you can only tell whether someone is a 'true' member by checking whether they have the trait in question, the definition has gone circular. |
| Thinking every use of 'true' or 'real' is this fallacy. Sometimes there genuinely are established criteria for group membership, and pointing out that a counterexample does not meet those criteria is legitimate clarification, not a definitional retreat. |
| Not recognizing when you yourself are making this move. It is easier to spot in others than in ourselves, precisely because the beliefs we protect this way tend to be the ones that matter most to us. |
| Confusing this with Moving the Goal Posts. Both involve evasion, but they work differently: No True Scotsman redefines who is in the group, while Moving the Goal Posts changes what evidence would count as sufficient. One protects the subject; the other protects the standard. |
| No True Scotsman |
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| Dismissing counterexamples to a universal claim by retroactively redefining the group to exclude them, rather than accepting the counterexample as evidence against the claim. |
| This makes the original claim unfalsifiable by definition. Instead of accepting evidence that contradicts a generalization, the arguer simply redefines the group so the counterexample no longer counts. The claim becomes circular: the group is defined by the very trait being attributed to it, making the statement trivially true but informationally empty. |
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