An argument which purports to prove one thing instead proves a different conclusion.
- You should support the new housing bill. We can’t continue to see people living in the streets; we must have cheaper housing. (We may agree that housing is important even though we disagree with the housing bill.)
- I say we should support affirmative action. White males have run the country for 500 years. They run most of government and industry today. You can’t deny that this sort of discrimination is intolerable. (The author has proven that there is discrimination, but not that affirmative action will end that discrimination.)
Show that the conclusion proved by the author is not the conclusion that the author set out to prove.