No True Scotsman’ Fallacy
Explanation
The no true scotsman fallacy is a way of reinterpreting evidence in order to prevent the refutation of one’s position. Proposed counter-examples to a theory are dismissed as irrelevant solely because they are counter-examples, but purportedly because they are not what the theory is about.
Example
The No True Scotsman fallacy involves discounting evidence that would refute a proposition, concluding that it hasn’t been falsified when in fact it has.
If Angus, a Glaswegian, who puts sugar on his porridge, is proposed as a counter-example to the claim “No Scotsman puts sugar on his porridge”, the ‘No true Scotsman’ fallacy would run as follows:
(1) Angus puts sugar on his porridge.
(2) No (true) Scotsman puts sugar on his porridge.
Therefore:
(3) Angus is not a (true) Scotsman.
Therefore:
(4) Angus is not a counter-example to the claim that no Scotsman puts sugar on his porridge.
This fallacy is a form of circular argument, with an existing belief being assumed to be true in order to dismiss any apparent counter-examples to it. The existing belief thus becomes unfalsifiable.


Done in Convention by the Unanimous Consent of the States present the Seventeenth Day of September in the Year of our Lord one thousand seven hundred and Eighty seven.