The fallacy of assuming that it's possible to convince or argue with anyone about
anything—
even the most absurd, unacceptable, or monstrous positions—through sufficient rationality, evidence, and persuasion. The fallacy ignores that some positions are not reached through reason and cannot be dislodged by it. You cannot argue someone out of a position they didn't argue themselves into. The defender of slavery, the apologist for
genocide, the advocate of
racist policies—these are not positions that yield to evidence because they were not based on evidence. The Fallacy of Impossible Convincing is beloved of those who believe that all disagreement is misunderstanding, that all conflict can be resolved through dialogue, that the only problem is insufficient communication. It's a
noble fallacy, but a fallacy nonetheless.
Example: "He spent years trying to convince his
racist uncle that
racism was wrong—studies, arguments, personal stories, everything. Nothing worked. The Fallacy of Impossible Convincing had promised that reason would prevail; reason didn't. Some positions are not reachable by argument because they were not reached by argument. He finally understood: you can't reason someone out of something they didn't reason themselves into."