Last week on our show, I spoke with Lillianna Mason, a University of Maryland political psychologist,

and author of Uncivil Agreement, how politics became our identity.

We talked about the reasons behind the tribalism and enmity that characterizes our modern politics.

Our conversation covered a lot of ground, and much of it,

including the political decisions that have shaped the two major parties over the past 50 years,

as well as the distinct ways that Republicans and Democrats deploy partisan rage, didn't make it

into our tightly packed show. But it's too interesting and important to leave

on the cutting room floor forever. So we've shared it now as this week's podcast Extra. And here it is,

my extended conversation with Lillianna Mason. Enjoy. Lillianna, welcome to On the Media.

Thanks so much for having me.

In the midst of destructive reality-bending hyperpartisanship,

this seems almost unimaginable,

but there was a time not all that long ago

when the country was deemed by political scientists

not to be polarized enough. Can you take us

back to 1950? Yes. In the best possible way, parties are what we call heuristics. So there's cognitive

shortcuts that we use to make political decisions because we can't ask our citizens to read every page of

every bill that comes before

Congress. And so parties have been a useful way for people to make pretty easy and quick

political choices. In 1950, the American Political Science Association put out a report

recommending that our parties were not distinct enough from each other,

and that they therefore did not provide a clear enough choice for voters,

...