No true Scotsman

For the practice of wearing a kilt without undergarments, see True Scotsman.

No true Scotsman or appeal to purity is an informal fallacy in which one modifies a prior claim in response to a counterexample by asserting the counterexample is excluded by definition.[1][2][3] Rather than admitting error or providing evidence to disprove the counterexample, the original claim is changed by using a non-substantive modifier such as "true", "pure", "genuine", "authentic", "real", or other similar terms.[4][2]

Philosophy professor Bradley Dowden explains the fallacy as an "ad hoc rescue" of a refuted generalization attempt.[1] The following is a simplified rendition of the fallacy:[5]

Person A: "No Scotsman puts sugar on his porridge."
Person B: "But my uncle Angus is a Scotsman and he puts sugar on his porridge."
Person A: "But no true Scotsman puts sugar on his porridge."

  1. ^ a b "Fallacies". Internet Encyclopedia of Philosophy. Retrieved 2022-02-09.
  2. ^ a b Curtis, Gary N. "The No-True-Scotsman Fallacy". Fallacy Files. Retrieved 2016-11-12.
  3. ^ Antony Flew (1966). God & Philosophy. Hutchinson. p. 104.
  4. ^ Cite error: The named reference Flew1975 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference atimes was invoked but never defined (see the help page).