That Democrats and Republicans have different views on issues — even issues about race and rights — is not surprising. But recent work by Stanford University’s Shanto Iyengar and his co-authors shows something else has been brewing in the electorate: a growing hostility toward members of the opposite party. This enmity, they argue, percolates into opinions about everyday life.

Partisans, for example, are now more concerned that their son or daughter might marry someone of the opposite party (compared with Britain today and the United States in 1960). They also found that partisans are surprisingly willing to discriminate against people who are not members of their political party.

We’ve entered an age of party-ism.

Writing in The Washington Post, Michael Tesler, a University of California, Irvine, political scientist, explained that because the growing partisan divide is partly fueled by racial attitudes, partisans (in Washington and in the electorate) also take increasingly opposite positions on many racially inflected controversies.