about this sort of formative racial discrimination. >> all in starts right now. good evening from new york, i'm chris hayes, rebecca country here in america and we are essentially split between two large factions. you have a two party system. and so, naturally, there was going to be internal dissent. each political party is made up of millions of different people with lots of different views inside it. it's the nation of coalition politics. but ultimately what defines a party, even with all that in turn all dissent and conflict, and disagreement, is what's lines you can across. these are often called litmus test or, in other context, the party line. one of the common examples is abortion rights. it used to be much more common for people inside each party to have conflicting views on abortion. you would see pro-choice republicans, a lot of them, a lot of antiabortion democrats.