An incoherency argument is a logical argument that attempts to show that two or more propositions are contradictory, and therefore that at least one (and possibly more) of those propositions must be incorrect.
Well-known incoherency arguments include the problem of evil and the argument from nonbelief. One that may have had a significant impact on world history is "The Incoherence of the Philosophers" by Al-Ghazali, which argued effectively that all philosophy was necessarily incoherent. Ibn Rushd responded with "The Incoherence of the Incoherence". The triumph of Al-Ghazali effectively ended early Muslim philosophy itself.
