Reasoning is generally seen as a mean to improve knowledge and make better decisions. Much evidence, however, shows that reasoning often leads to epistemic distortions and poor decisions. This suggests rethinking the function of reasoning. Our hypothesis is that the function of reasoning is argumentative. It is to devise and evaluate arguments intended to persuade.

-- Hugo Mercier & Dan Sperber, Why do humans reason? (PDF)

(Further comment on the paper turned into a full post)