Nae true Scotsman

Nae true Scotsman, or appeal tae purity, is an informal fallacy in whilk a body ettles at weirin a universal generalisàtion frae coonterexemplars bi chyngin the defineetion in an ad hoc gate fur tae exclude the coonterexamplar. Raither nor denyin the coonterexemplar or rejectin the oreeginal claim, this fallacy modifies the subject o the assertion tae exclude the speceefic case or ithers like it bi rhetoric, wioot reference tae ony speceefic objective rule - "nae true Scotsman wad dae sic a thing"; i.e., thaim wha performs that action are nae pairt o oor group an thus creeticism o that action is nae creeticism o the group.

Exemplars

Philosophy professor Bradley Dowden explains the fallacy as an "ad hoc rescue" o a refutit generalisation attempt. The follaein is a simplifee'd version o the fallacy:

Body A: "Nae Scotsman puts succar on his porridge."
Body B: "But ma uncle Angus is a Scotsman an he puts succar on his porridge."
Body A: "But nae true Scotsman puts succar on his porridge."

The essayist David P. Goldman, scrievin unner his pseudonym "Spengler," compared distinguishin atween "mature" democracies, whilk niver stairt wars, an "emergin democracies", whilk may stairt thaim, wi the "nae true Scotsman" fallacy. Spengler alleges that poleetical scientists hae attemptit tae save the "US academic dogma" that democracies niver stairt wars against ither democracies frae coonterexamplars bi declarin ony democracy that daes indeed stairt a war against anither democracy tae be flawed, thus maintainin that no true democracy stairts a war agin a fellow democracy.

Coonterexemplars

Arguments o this kynd isnae necessarly ay fauty. For exemplar:

A: "Nae pacifist stabs fowk tae daith."
B: "I ken o ane wha stabbed a couple fowk tae daith."
A: "That man wisna a true pacifist."

In this case, the "Nae true Scotsman" analogy disna haud. The defineetion o pacifism includes opposeetion tae veeolence an abstinence o its uise in aw situations. Stabbin bodies an pacifism are in a logical conflict. The logical conclusion is that the stabber wisna really a pacifist (awtho mibbe claimin tae hae been).

It forby isnae wrang tae say "nae true vegetarian woud eat steak", acause the defineetion o bein a vegetarian includes nae eatin meat (see beggin the question).

Oreegin

The introduction o the term is attributit tae Inglis philosopher Antony Flew, acause the term oreeginally appeared in Flew's 1971 beuk An Introduction to Western Philosophy. In his 1975 beuk 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!'