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 attempts to protect a universal generalization from counterexamples by changing the definition in an ad hoc fashion to exclude the counterexample. Rather than denying the counterexample or rejecting the original claim, this fallacy modifies the subject of the assertion to exclude the specific case or others like it by rhetoric, without reference to any new specific objective rule or criterion: "no true Scotsman would do such a thing"; i.e., those who perform that action are not part of our group and thus criticism of that action is not criticism of the group.

Examples

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

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."

Origin

The description of the fallacy in this form is attributed to British philosopher Antony Flew, because the term originally appeared in Flew's 1971 book An Introduction to Western Philosophy. In his 1975 book Thinking About Thinking, he wrote:

Imagine some Scottish chauvinist settled down one Sunday morning with his customary copy of The News of the World. He reads the story under the headline, 'Sidcup Sex Maniac Strikes Again'. Our reader is, as he confidently expected, agreeably shocked: 'No Scot would do such a thing!' Yet the very next Sunday he finds in that same favourite source a report of the even more scandalous on-goings of Mr Angus McSporran in Aberdeen. This clearly constitutes a counter example, which definitively falsifies the universal proposition originally put forward. ('Falsifies' here is, of course, simply the opposite of 'verifies'; and it therefore means 'shows to be false'.) Allowing that this is indeed such a counter example, he ought to withdraw; retreating perhaps to a rather weaker claim about most or some. But even an imaginary Scot is, like the rest of us, human; and none of us always does what we ought to do. So what he is in fact saying is: 'No true Scotsman would do such a thing!'

And even earlier in God & Philosophy in 1966;

The Berkeley-Newman contention could be defended only by resort to the No-true-Scotsman Move, and the consequent castration of the thesis. (In this ungracious move a brash generalization, such as No Scotsmen put sugar on their porridge, when faced with falsifying facts, is transformed while you wait into an impotent tautology: if ostensible Scotsmen put sugar on their porridge, then this is by itself sufficient to prove them not true Scotsmen.)

— Antony Flew

Non-fallacious usage

The phrase "No true Scotsman" is not always fallacious: it depends on the syntactical context of the term "true" inserted into the phrase "no Scotsman".

See also

• Ad hoc hypothesis
• Begging the question
• Epistemic commitment
• Equivocation
• List of fallacies
• Loaded language
• Moving the goalposts
• Persuasive definition
• Reification (fallacy)
• Republican In Name Only
• Special pleading
• Tautology (language)
• True Pole

Further reading

• Almossawi, Ali (2014). An Illustrated Book of Bad Arguments. The Experiment. ISBN 978-1-61519-225-0.
• Lockie, Robert (1998). "What's Wrong with Moral Internalism". Ratio. 11 (1): 14–36. doi:10.1111/1467-9329.00049.
• Manninen, Tuomas W. (2018). "No True Scotsman". Bad Arguments. John Wiley & Sons, Ltd. pp. 374–377. ISBN 978-1-119-16581-1.
• Zangwill, Nick (2002). "Are There Counterexamples to Aesthetic Theories of Art?". The Journal of Aesthetics and Art Criticism. 60 (2): 111–118. ISSN 0021-8529.