This is very cool, and right up my alley:

Cognitive scientists Hugo Mercier and Dan Sperber recently introduced what they call “The Argumentative Theory.” Scientists such as Steven Pinker and Jonah Lehrer have hailed it as an important breakthrough in understanding human behavior. Jonathan Haidt believes that the new theory has solved “one of the most important puzzles in psychology.”

The puzzle is this: Why are human beings so good at reasoning in some situations and so hopelessly wrong in others? Mercier and Sperber provide an elegant answer: It is because the function of reasoning is not to arrive at the “right answer,” but rather to find support for a conclusion the reasoner has already intuited. In a nutshell, reasoning is not intended to discover truth; rather, its role is to win arguments with other people.

Mercier and Sperber’s empirically-supported argument reflects what theorists such as Jerome Frank, Richard Posner, and Stanley Fish have long contended about legal reasoning: that conclusions drive reasoning and not vice versa.

Yet ironically, recently-appointed Supreme Court justices such as Elena Kagan, Sonia Sotomayor, and John Roberts have adamantly contended — at least at their confirmation hearings — that simple application of law should drive legal decisions.

This Essay examines why, at the very time cognitive scientists are offering increasingly sophisticated analyses of reasoning, the views offered by these recent appointees to the Supreme Court should be so simplistic. It goes on to suggest what both judges and lawyers can learn from the Mercier-Sperber theory.

From the article:

Jonathan Haidt summarized the Mercier and Sperber thesis thusly: ―Reasoning was not designed to pursue the truth. Reasoning was designed by evolution to help us win arguments.

That‘s why they call it the Argumentative Theory of Reasoning.‖5 And another commentator reduced the thesis to one sentence: ―Reasoning isn‘t about logic—it‘s about arguing.‖6

And Why Do Humans Reason? Arguments for an Argumentative Theory looks cooler:

Reasoning is generally seen as a means to improve knowledge and make better decisions. However, much evidence shows that reasoning often leads to epistemic distortions and poor decisions. This suggests that the function of reasoning should be rethought. Our hypothesis is that the function of reasoning is argumentative. It is to devise and evaluate arguments intended to persuade. Reasoning so conceived is adaptive given the exceptional dependence of humans on communication and their vulnerability to misinformation. A wide range of evidence in the psychology of reasoning and decision making can be reinterpreted and better explained in the light of this hypothesis. Poor performance in standard reasoning tasks is explained by the lack of argumentative context. When the same problems are placed in a proper argumentative setting, people turn out to be skilled arguers. Skilled arguers, however, are not after the truth but after arguments supporting their views. This explains the notorious confirmation bias. This bias is apparent not only when people are actually arguing but also when they are reasoning proactively from the perspective of having to defend their opinions. Reasoning so motivated can distort evaluations and attitudes and allow erroneous beliefs to persist. Proactively used reasoning also favors decisions that are easy to justify but not necessarily better. In all these instances traditionally described as failures or flaws, reasoning does exactly what can be expected of an argumentative device: Look for arguments that support a given conclusion, and, ceteris paribus, favor conclusions for which arguments can be found.

And this conversation about the Argumentative Theory: