Bulverism

Bulverism is the logical fallacy of assuming without discussion that a person is wrong and/or ill-informed, then distracting their attention from this (which is the only real issue) by explaining how they became so silly, usually associating it to a psychological condition. The fallacy deals with secondary questions about ideas rather than the primary one, thus avoiding the basic question or evading the issues raised by trains of reasoning. It is essentially dodging your opponent's argument by treating them like a psychiatry patient who needs your evaluation to explain why they came up with such a ridiculous argument in the first place.

The fallacy was coined by C.S. Lewis in his essay, First and Second things.

Strict usage
The form of the Bulverism fallacy can be expressed as follows:


 * You claim that A is true.
 * Because of B, you personally desire that A should be true.
 * Therefore, A is false.

or
 * You claim that A is false.
 * Because of B, you personally desire that A should be false.
 * Therefore, A is true.

Examples

 * Used by atheists: "Religion is just a silly idea made up by people to cope with the discomfort of living in a purposeless, Godless universe."
 * Used by those of a religious bent: "Atheists only deny the existence of God because they're angry at him."
 * Used by those on the fringes of the political spectrum: "Liberals only support a Nanny State because they're crazy and neurotic," or "Conservatives only support capitalism because they're psychopaths and hate the poor."