No True Scotsman

“I am not an Englishman, I was never an Englishman, and I don't ever want to be one. I am a Scotsman! I was a Scotsman and I will always be one.”-Sean Connery (James Bond)

While I “almost” have a PhD in mathematical logic (all but dissertation), I lack training in rhetorical logic. Since ancient Greece, rhetoricians have studied the ways we can lie or dissemble or deceive with speech and writing. Collectively these are called logical fallacies. I’m aware of some of the techniques; for instance:

Poisoning the Well: oppose a position by discrediting the opposing advocate.
“My opponent was once wrong about X, so how can we trust him on Y?”

A Straw man Argument: exaggerating or distorting or misquoting the subject to something that is easily dismissed.
Person A: We should liberalize the laws on beer.
Person B: No, any society with unrestricted access to intoxicants loses its work ethic and goes only for immediate gratification.
(Here the argument has been extended from beer to all "intoxicants" thereby creating a straw man to attack.).

Today I came across a new one called “No true Scotsman”. According to Wikipedia is goes like this:

Teacher: All Scotsmen enjoy haggis.
Student: But my Scottish uncle Scotty McScottscott doesn't like haggis!
Teacher: Well, all true Scotsmen like haggis.

When faced with a counterexample to a claim, rather than denying the counterexample or rejecting the original claim, this fallacy is employed to modify the original claim to something that is “true” by definition. Think about it, what is a “true” Scotsman? It’s a tautological phrase which is self-fulling. A true Scotsman is one who eats hagis. Who eats hagis? All true Scotsmen.

Today you might see a “True Scotsman” claim in regards to Obama Healthcare. As it starts to unravel, some of the centralist Democrats are distancing themselves from it. But rather than recognize division in the party, one might counter that no “true” Democrat opposes Obama care. Or with Global Warming: no true scientist doubts global warming.

This is solidarity by dismissing the exceptions as irrelevant.

Here is a recent example of changing a label to save the argument: "Avoid the term 'global warming'," Thomas Friedman says. "I prefer the term global weirding.'”
How does one disprove Global Weirding? How can one measure and claim that the world is more weird this year than last!

Bottom Line

Here is Wikipedia’s list of Fallacies: http://en.wikipedia.org/wiki/List_of_fallacies

And a few related articles:
http://en.wikipedia.org/wiki/Logical_fallacy
http://en.wikipedia.org/wiki/Rhetoric