Bulverism

Miracles 3.14 While Lewis does not call it [|Bulverism] here, it is the term which he coined in 1941 to name the fallacy of dismissing an opponents argument (Ground and Consequent) by simply saying he was wrong and assigning a cause (Cause and Effect) reason, usually a motivation independent of the argument. Here in Miracles he simply says "... the most popular way of discrediting a person's opinions is to explain them causally ..." This is a fallacy but it is rhetorically very effective. It leads however to unfortunate consequences since it often dismisses the qualified in favor of the unqualified. "You can't talk seriously about artifical substances, because you're a chemist." -- might be an example.