Poor Groundskeeper Willie, not only is he forced to live in a shed, he can’t put sugar on his porridge either. The “No true Scotsman” fallacy is a classic and it gets the name from the following “discussion”:
Player 1: No Scotsman puts sugar on his porridge
Player 2: My friend Angus is from Scotland and puts sugar on his porridge
Player 1: Well, no TRUE Scotsman puts sugar on his porridge
Usually, this fallacy happens when someone is trying to distance themselves from facts that undermine their argument or position. As I’m sure you remember from my post on basic logic, if premises are proven not to be true, then the conclusions are invalid. This goes to both soundness and validity in that, if premises are proven untrue, then the argument is invalid, and if empirical observation contradicts the argument, then it is also not sound; in short, it is a poor argument.
The fun version:
Player 1: Feminism is about equality of the sexes
Player 2: Valerie Solanas is a feminist and she wants to kill men.
Player 1: Then she’s obviously not a real feminist.