Which fallacy involves dismissing a contradiction on the basis that it is not considered true?

The No True Scotsman fallacy occurs when someone dismisses a counterexample to a general claim by redefining the criteria of the group or category in question to exclude the counterexample. This fallacy is characterized by the refusal to acknowledge evidence that contradicts a broad claim by asserting that the evidence does not represent the true members of that group.

For example, if someone claims that “no Scotsman would commit a crime,” and when presented with evidence of a Scotsman who has committed a crime, they respond by saying, “Well, no true Scotsman would do such a thing,” they are effectively dismissing the contradiction without addressing the validity of the counterexample. This shifts the goalposts rather than engaging with the evidence presented, leading to a flawed argument.

Understanding this fallacy highlights the importance of maintaining consistent definitions and engaging with evidence rather than altering the criteria to suit one’s claims.