No 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 specific objective rule: "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.
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."
The essayist David P. Goldman, writing under his pseudonym "Spengler," compared distinguishing between "mature" democracies, which never start wars, and "emerging democracies", which may start them, with the "no true Scotsman" fallacy. Spengler alleges that political scientists have attempted to save the "US academic dogma" that democracies never start wars against other democracies from counterexamples by declaring any democracy which does indeed start a war against another democracy to be flawed, thus maintaining that no true democracy starts a war against a fellow democracy.
Arguments of this kind are not necessarily always faulty. For example:
Person A: "No pacifist stabs people to death."
Person B: "I know one who stabbed a couple of people to death."
Person A: "That guy was not a true pacifist."
In this case, the "No true Scotsman" analogy does not hold. The definition of pacifism includes opposition to violence and abstinence of its use in all situations. Stabbing people and pacifism are in a logical conflict. The logical conclusion is that the stabber was not really a pacifist (although they might have claimed to have been).
It is also not wrong to say "no true vegetarian would eat steak", because the definition of being a vegetarian includes not eating meat (see begging the question).
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 by is by itself sufficient to prove them not true Scotsmen.)— Antony Flew
No doubt Flew used the phrase because it could frequently be found in print, and in speech, for centuries;
Stevenson was a Scotsman, and he would have been no true Scotsman had he not been something of a moralist and theologian as well as writer of romance.
To the end of time, no true Scotsman shall ever hear the strains of
- "Scots, wha hae wi Wallace bled,"
without feeling his inmost soul stirred within him.
He who does not feel ths distinction to be a disgrace to his country is no true Scotsman.
We have had proof enough of her Majesty's gracious Intentions on that Head already: Her Letter to the Parliament of Scotland last Year, and her Royal assent to the Act of Security, are such earnests of it, that no true Scotsman will presume to call it in question: And since the Parliament of England have also provisionally agreed to a Treaty, we have as little Reason to doubt their Justice when the matter is fairly laid before 'em.
- No True Scotsman, Internet Encyclopedia of Philosophy
- Curtis, Gary N. "Redefinition". Fallacy Files. Retrieved 2016-11-12.
- Antony Flew (1975). Thinking About Thinking (or, Do I Sincerely Want to be Right?). Fontana/Collins. p. 47.
- Goldman, David P. (31 Jan 2006). "No true Scotsman starts a war". Asia Times. Archived from the original on 5 January 2019. Retrieved 1 December 2014.
political-science professors... Jack Mansfield and Ed Snyder distinguish between "mature democracies", which never, never start wars ("hardly ever", as the captain of the Pinafore sang), and "emerging democracies", which start them all the time, in fact far more frequently than do dictatorships
- "Obituary: Prof. Antony Flew", The Scotsman, 16 April 2010
- Antony Flew, God & Philosophy, p. 104, Hutchinson, 1966.
- John Henry Muirhead, Philosophy and Life: And Other Essays, p. 38, London: Swan Sonnenschein and Co., 1902.
- David Hay Fleming, The Martyrs and Confessors of St. Andrews, p. 2, Cupar: Fife Herald Office, 1887.
- Debates in the General Assembly of the Church of Scotland, p. 51, London, J. Pridden, 27 May 1790.
- George Ridpath, The Reducing of Scotland by Arms, and Annexing it to England as a Province Considered, p. 31, London: Benjamin Bragg, 1705