[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.
The "no true Scotsman" fallacy is committed when the arguer satisfies the following conditions:[3][4][6] An appeal to purity is commonly associated with protecting a preferred group.
[4] The description of the fallacy in this form is attributed to British philosopher Antony Flew, who wrote, in his 1966 book God & Philosophy, 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.In his 1975 book Thinking About Thinking, Flew wrote:[4] Imagine some Scottish chauvinist settled down one Sunday morning with his customary copy of The News of the World.
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.