“Professor ‘X’ has argued in favor of academic tenure. But why should we even…

Concept

An ad hominem fallacy sets aside the reasons an argument actually offers and targets the person offering them. In its circumstantial form, known as attacking the motive, a claim is dismissed because the arguer stands to gain from it, so a motive for holding a view is treated as evidence that the view is false. A stake in a conclusion can bear on how far we trust a speaker, but it never shows the speaker's reasoning to be unsound.

Application

The passage never examines a single reason offered in favour of academic tenure. It moves straight to the arguer's own situation: he holds tenure himself, so “of course” he supports it. The argument is set aside purely because the arguer benefits from its conclusion, which is exactly the vested-interest pattern of attacking the motive.

Contrast with the near misses

• Look who's talking, the tu quoque form, requires an alleged inconsistency between what the arguer says and what the arguer does; the passage alleges no such hypocrisy.

• Scare tactics requires a threat or an appeal to fear standing in place of evidence; the passage holds no harm over the audience.

• Bandwagon Argument requires an appeal to how many people accept a claim; the passage cites neither numbers nor popular opinion.

Because the argument is rejected on the ground of the arguer's vested interest rather than on its merits, the passage illustrates the fallacy of attacking the motive.