Or so say philosophers Dan Sperber and Hugo Mercier, who last week had the good fortune of getting buzz from the NY Times (here, here, and here) and other sources (listed here) on an article they wrote for Behavioral and Brain Sciences. Contra the Enlightenment gloss of reasoning, or the Cartesian theory of reasoning, which states, in the words of Mercier, that "the role of reasoning is to critically examine our beliefs so as to discard wrong-headed ones and thus create more reliable beliefs—knowledge," Sperber and Mercier present the "argumentative theory of reasoning," which states that the evolutionary "function of reasoning would be to find and evaluate reasons in dialogic contexts—more plainly, to argue with others." Humans developed reasoning, in other words, to help us make and analyze arguments in rich contexts of talk.
Mercier presents two compelling predictions or outcomes of this theory: (1) Since it has an ostensibly evolutionary basis, (1) the argumentative theory of reasoning supports the conclusion that we reason better in groups, and (2) one of the most observed attributes of reasoning is confirmation bias (i.e., our relentless efforts to support our own conclusions and ignore evidence to the contrary, even when it seems irrefutable). For religion, these two predictions make me think that interfaith dialogue is one of the most important forms of American religious rhetoric we have.
I dig this theory. I like the idea that we evolved internal mechanisms of inference because we anticipate audiences for our convictions. That's the bottom line, right? For good or bad, we are the arguing animal. This is exciting research and it confirms the biases of all those rhetoricians out there who are over the moon about argumentation.