Paul, an avid Chicago Bulls fan, hears an acquaintance arguing persuasively that the Los Angeles Lakers are the most consistent and talented basketball team ever. When he can't find reasons to support his own position, he tells the acquaintance, "You just don't know anything about basketball!"
This is an example of

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Quizplus · Accepted Answer

Paul's response is an example of source derogation, where he attacks the credibility of the person making the argument instead of addressing the argument itself.

Paul, an Avid Chicago Bulls Fan, Hears an Acquaintance Arguing