No True Scotsmen

‪#‎FallacyFriday‬ is back! Every week, Oliver Diaz-Neda will post a logical fallacy and an example to help you all become better debaters, persuaders and rational thinkers. What is a logical fallacy? It is defined as – a flaw in the structure of an argument which renders the argument invalid.

Today’s fallacy

No True Scotsmen (appeal to purity)

A fallacious appeal to purity occurs when a speaker makes an absolutist assertion, is rebutted with an example or evidence that proves the assertion is incorrect, and then subsequently disqualifies the opposing evidence by redefining what constitutes a “true” example of their claim.

Example:

Rob

No real liberal would ever support a Presidential candidate who has a SuperPAC and accepts money from corporations.

William

Barack Obama had a SuperPAC that accepted corporate money and he is widely regarded as a liberal. Not to mention, he was endorsed by Ted Kennedy, one of the most liberal Senators in the United States. I can name a laundry list of elected liberals who have endorsed Clinton. How about that…?

Rob

Yeah, sure, but Obama and Kennedy are not true liberals. They are just part of the fake liberal Washington establishment. Sander is a true liberal.

Rob’s premise is full of logical holes. What constitutes a “liberal” in American politics is a highly subjective matter off the bat. A reasonable debater can articulate a broad framework for what constitutes liberalism in America, with evidence. By any objective measure, Kennedy and Obama are liberals in the context of US politics. But when presented with evidence to counter his argument, Rob moves the goalpost on who is considered a “true” liberal. He renders his claim unfalsifiable through fallacious reasoning. Don’t be like Rob. Rob’s the worst.