From The New Yorker
In a new book, “The Enigma of Reason” (Harvard), the cognitive scientists Hugo Mercier and Dan Sperber take a stab at answering this question. Mercier, who works at a French research institute in Lyon, and Sperber, now based at the Central European University, in Budapest, point out that reason is an evolved trait, like bipedalism or three-color vision. It emerged on the savannas of Africa, and has to be understood in that context.
Stripped of a lot of what might be called cognitive-science-ese, Mercier and Sperber’s argument runs, more or less, as follows: Humans’ biggest advantage over other species is our ability to coöperate. Coöperation is difficult to establish and almost as difficult to sustain. For any individual, freeloading is always the best course of action. Reason developed not to enable us to solve abstract, logical problems or even to help us draw conclusions from unfamiliar data; rather, it developed to resolve the problems posed by living in collaborative groups.
“Reason is an adaptation to the hypersocial niche humans have evolved for themselves,” Mercier and Sperber write. Habits of mind that seem weird or goofy or just plain dumb from an ‘intellectualist’ point of view prove shrewd when seen from a social “interactionist” perspective.
“If reason is so useful and reliable, why didn’t it evolve in other animals and why do humans produce so much thoroughly reasoned nonsense? Hugo Mercier and Dan Sperber argue that reason is not geared to solitary use. It evolved to help justify our beliefs to others, evaluate their arguments, and better exploit our uniquely rich social environment.”