This fallacy occurs when, in order to preserve a claim or generalisation against counterexamples, the definition of the group or attribute in question is altered so that the opposing examples no longer fit.
Definition:
The No True Scotsman fallacy is a reasoning error in which, when a counterexample is presented that contradicts a general statement, instead of revising the claim, the scope of the definition is changed to exclude that example from the group. In this way, the claim becomes resistant to criticism, not through sound logic but by arbitrarily changing the criteria.
Typical structure of this fallacy:
1. All members of group X have characteristic Y.
2. Person A is a member of group X but does not have characteristic Y.
3. Response: Then A is not a true member of group X.
Examples from real life:
1. Culture and nationality:
“No true Scotsman puts sugar on his porridge.”
When it is said: “But John is Scottish and he puts sugar on his porridge,” the reply is: “Then he is not a true Scotsman.”
2. Sport:
“No true football fan abandons their team in difficult times.”
When it is said: “But Peter, a long-time fan, stopped going to matches after the team’s decline,” the reply is: “Then he was never a true fan.”
3. Morality and religion:
“No true believer ever commits a moral wrongdoing.”
When it is said: “But this particular believer did commit such a wrongdoing,” the reply is: “Then they were never a true believer.”
4. Everyday life:
“No professional chef ever burns food.”
When it is said: “But this famous chef burnt their dish,” the reply is: “Then they are not a real professional chef.”
Why is this fallacy dangerous?
● It removes the claim from being testable by altering the definition arbitrarily.
● It prevents honest dialogue and the revision of beliefs.
● It can be used to exclude dissenting voices or discredit individuals.
How can we recognise and respond to it?
Ask:
– Has the definition of the group or attribute changed after encountering a counterexample?
– Was this change based on evidence and logic, or merely to preserve the claim?
A suitable response might be: “If someone fits the original definition of the group, their example should be considered when evaluating the claim, even if it contradicts our belief.”
Conclusion:
The No True Scotsman fallacy shields a claim from logical criticism by altering definitions to exclude counterexamples. To avoid it, definitions should be made clear and fixed before making a claim, and all examples, including opposing ones, should be considered in the evaluation.