This is really an interesting discussion. Jonathon Haidt, a social psychologist, has written The Righteous Mind and Chris Mooney, a linguist, has written The Republican Brain. Chris Hayes interviewed them May 5th.
The discussion is around the idea of how we think and argue politically. It begins with Jonathon Haidt describing how humans do not take an idea in, rationally analyze it and decide whether to accept it or not, then explain the rational decision to others. Psychology has established that we make our decisions for reasons other than rational ones, then develop a rationale which we present to others to convince them we are right.
That sounds like it throws rational science into a cocked hat, but it doesn't. What happens is that others take the rational idea presented, analyze that, then others make a decision which is probably more rational than the first person's decision was. It sounds to me as though rational decision making is more of a group process than an individual process.
Watch this clip and see if they don't offer a convincing argument.