This is the editor's letter in the current issue of The Week magazine.

Historian Henry Adams once defined politics as the "systematic organization of hatreds." It was true in the Civil War era, and just as true today. In 2020, who you hate is who you are. Voters are largely driven by what they're against, rather than what they're for. Political scientists call this phenomenon negative partisanship, and its dominance has been on full display at both the Democratic and Republican national conventions. At the Democrats' soiree, a parade of speakers from former President Obama to several disaffected Republicans echoed the same message: Our nation cannot survive another four years of Donald Trump, who has shown he "will tear our democracy down if that's what it takes to win." The Republicans this week countered with dire warnings that Democrats "won't let you go to church" and will empty the prisons and fire the police and "invite MS-13 to live next door." It's a far cry from Ronald Reagan's "shining city on a hill" or Obama's "hope and change," but as political scientist Rachel Bitecofer observes, "Partisanship is a hell of a drug, especially when it's cut with a heavy dose of existential fear."

It's hard to dispute the point. Both Democratic and Republican partisans, research has found, have come to despise the other tribe and their elected leaders more than they like their own leaders. Ticket splitting by voters has become rare, and in any given election, 90 percent of Democrats and Republicans vote for their party's nominee. Harnessing fear and hatred can drive turnout, which has become the key to winning national elections. But as America stumbles further down this road, we are headed toward profound danger: For democracies to function, voters and parties must be willing to accept defeat. Once the votes are counted, the losers must concede that their opponents have a legitimate, if temporary, claim on power. Will that happen this November — and if it doesn't, what then?