The perfect-solution fallacy, also called letting the perfect be the enemy of the good, is the logical fallacy of assuming that just because a solution does not perfectly solve a problem, it is not worth trying at all. It is a particular form of a false dilemma. The perfect-solution fallacy is similar but not identical to the Nirvana fallacy.
Liberals often commit the perfect-solution fallacy, as in the following examples:
- Because abstinence-only education does not completely eliminate teen pregnancy, abstinence should not even be mentioned in schools. (See abstinence denial)
- Because sodomy laws did not completely eliminate HIV, there was no point in enforcing them.