No True Scotsman

"No true Scotsman" is an argument based in stereotypes about what a particular group would or would not do. The name comes from an argument about putting sugar on porridge:

• No Scotsman would ever put sugar on his porridge!
• Well, my grandfather William MacDonald put sugar on his porridge every morning.
• As I said, no true Scotsman would put sugar on his porridge.

Notice how the definition of "Scotsman" in that quote changes from "a person from Scotland" to "a person who meets my standards for being a Scotsman".

In Mafia, this argument can be used either to argue that one's behavior is not indicative of being Scum, or to refute a roleclaim by claiming they are not following "typical" behavior. While there are typical ways in which certain roles are played (for instance, a Doctor may try to avoid notice during the day, so as not to be Night Killed), many players will deliberately play against type in order to diminish the benefit of these stereotypical behaviors.

A subset of this behavior in Mafia can involve analyzing a player's behavior when they have a particular Role in prior games. "So-and-so always lurks when they're a Cop, and they've been active, therefore they are not a Cop this time. Die scum!"