If the Purpose of Reason Is to Win Arguments…

According to scientists quoted by The New York Times:

Now some researchers are suggesting that reason evolved for a completely different purpose: to win arguments. Rationality, by this yardstick (and irrationality too, but we’ll get to that) is nothing more or less than a servant of the hard-wired compulsion to triumph in the debating arena. According to this view, bias, lack of logic and other supposed flaws that pollute the stream of reason are instead social adaptations that enable one group to persuade (and defeat) another. Certitude works, however sharply it may depart from the truth.

I have two questions:

• If the purpose of reason is to win arguments, what was the purpose of the arguments in the first place? In other words, why pay any attention?
• Why are these scientists bothering to argue their point?

My earlier comments on this line of research can be found here.