In other words, whether we follow both the written and unwritten rules of politics.
The problem, of course, is that we haven't done that for a while now, and it doesn't look as though that's about to change. That's made our democracy devolve into trench warfare even in the best of times, and maybe a democracy in name only if the worst were ever to come to pass. That might sound alarmist, but just because you're paranoid doesn't mean President Trump isn't trying to undermine the rule of law.
Most of what we're talking about, though, doesn't have anything to do with the White House's current occupant. It's more the fact that everything gets filibustered nowadays. Or that opposition parties semi-regularly shut down the government to try to get their way. Or even say that they'll force the government to default on the debt if their demands aren't met. This is not normal. Or at least it didn't used to be. While there aren't any formal rules against these things, they're the type of hardball tactics that parties rarely, if ever, used before. That's because they knew the other side would respond in kind until our consensus-driven institutions, in particular, the Senate, stopped working altogether.
What changed? Well, the Republican Party did. They're the ones who shut the government down in the 1990s, the ones who threatened to breach the debt ceiling in 2011, the ones who shut the government down again in 2013 and the ones who blocked a sitting president from filling an empty Supreme Court seat simply because they could. A big part of this is that the party was taken over by the conservative movement, which is more hostile to compromise than everybody else. The rest, though, is that it stayed white and Christian at the same time that the Democratic Party and the country at large were becoming much more diverse and secular. They didn't just see their opponents as people with different ideas, but as different people, period.
The result has been what political scientists Thomas Mann and Norm Ornstein call “asymmetric polarization”: Republicans have moved much further to the right than Democrats have to the left. Not only that, but they've been much more willing to use extreme measures to get what they want. They think that everything is their final chance to stop the country from changing forever — “the 2012 election may be the last opportunity for Republicans,” wrote former South Carolina senator and Heritage Foundation president Jim DeMint, because “Republican supporters will continue to decrease every year as Americans become more dependent on the government" — and that their opponents aren't “real Americans” like they are. Who cares, then, if what they're doing isn't considered proper? There are bigger issues at stake.
But in politics, as in physics, every action has a (mostly) equal and opposite reaction. Sure, Democrats haven't held the full faith and credit of the United States hostage as Republicans have, but they did just shut down the government and have embraced the filibuster with equal vigor. What else are they supposed to do? Both parties would be better off cooperating with each other than they are now, but they'd be even better off if they were the only ones not working together. That's a prisoner's dilemma, and it's easy to get stuck in a negative equilibrium. After all, you can't just start cooperating on your own. You both have to do it — and why would you trust someone who hasn't been? Take the Supreme Court. If a seat comes up and Democrats have won the Senate back, should they let Trump fill it? Almost certainly not. There's just no reason to think that this would make a Republican majority ever extend a Democratic president the same courtesy again. Virtue, then, wouldn't be its own reward, but rather the self-righteousness you feel at being on the wrong end of Supreme Court decisions for the next 30 years.
Which brings us to the bleakest part of all. The only way democracies stop being so polarized is after some kind of catastrophe — a catastrophe that more often than not is brought on by, yes, polarization. Indeed, the two most optimistic examples that Levitsky and Ziblatt can come up with are the way Chile's parties from across the ideological spectrum were eventually able to set aside their rather substantial differences to support democracy in the years after Augusto Pinochet's coup and how German conservatives managed to overcome their traditional Catholic-Protestant divide to do the same in the wake of World War II. Remember, the fact that democracy can come back after a dictatorship is supposed to be the good news here. The bad news, Ziblatt told me, is that there hasn't been any other way out once one side starts treating politics as war by other means. "No matter how long the other one holds out,” he said, “they will eventually respond tit for tat,” and he “can't think of” any countries that have broken this cycle of partisan retribution.
The point is that people have to believe in a higher principle than winning. When they don't, when they're willing to ignore a court's order to stop gerrymandering and try to keep their opponents from even getting to the polls with a voter ID law that a federal court said would “target African Americans with almost surgical precision,” well, that's when they'd go so far as to vote for someone they'd said was a “kook” and a “con man” and the type of person who'd made “the textbook definition of a racist comment.” And once they've done that, there's no telling how far they might go. Maybe they'd turn a blind eye to the president's conflicts of interests overseas, or participate in low-level corruption by holding events at his hotels, or even attack law enforcement officials for investigating him.
Democracy doesn't end with a bang or a whimper, but rather a laugh about your enemies losing.