JONATHAN HAIDT: Politics has always been about coalitions and teams fighting each other. But those teams, those teams were never evenly divided on morality. Now, well, basically it all started, as you well know, on the day Johnson signed the Civil Rights Act. You tell me what he said on that day. I think I heard you say this once.

BILL MOYERS: He actually said to me that evening, "I think we've just turned the South over to the Republican Party for the rest of my life, and yours."

JONATHAN HAIDT: Yeah. And he was prescient, that's exactly what happened. So there was this anomaly for the 20th Century that both parties were coalitions of different regions, and interest groups. But there were liberal Republicans, there were conservative Democrats. So the two teams, they had, they were people whose moralities could meet up. Even though they were playing on different teams.

And once Johnson signed the Civil Rights Act, and the South, which had been Democrat, because Lincoln had been a Republican, so once they all moved over to the Republican party, and then the moderate Republicans began to lose office in the '80s, and '90s, and the last ones going just recently, for the first time we have an ideologically pure division of the parties.

And now, this groupish tribalism, which is usually not so destructive, we can usually, you know, when you leave the playing field, you can still meet up, and be friends. But now that it truly is a moral division, now the other side is evil. And there's nobody, there aren't really pairs of people who can match up, and say, well, come on. We all agree on this, let's work together.

BILL MOYERS You remind me that when we set out to try to pass the Civil Rights Act of '64, and the Voting Rights Act of '65, LBJ commissioned us to go spend much of our time with the moderate Republicans in the House, and in the Senate. Because he said, "When push comes to shove, and when the roll is called, we're going to need them to pass this bill." And at one point, in the signing of one of those bills, he turned and handed the pen to Everett Dirksen, the senior Republican from Illinois and the leader of the Republican minority in the Senate and he was the one who, in the critical moments, brought a number of moderate Republicans to vote for the Civil Rights bill. You?re saying that was a deciding moment, a defining moment?

JONATHAN HAIDT: So there are three major historical facts, or changes, that have gotten us into the mess that we're in. So the first is the realignment of the South into the Republican column, which allowed both parties now to be pure. So that now there are basically no liberal Republicans matching up with conservative Democrats. So, the parties are totally separated. The second thing that happened was the replacement of the Greatest Generation by the Baby Boomers.