What Is Sunstein's Big-Tent Liberalism Argument?

Sarah and JVL talk about big-tent liberalism—who’s in and who’s out of the l-word tent. JVL goes on a riff on Henry Kissinger, which you are absolutely going to HATE.

And then we get the main event: JVL doesn’t think [gestures broadly] all this is fixable. Sarah has a plan to fix it. 

Who’s right?