“Unity” is quickly becoming the most overused word in Washington. It was the theme of the inaugural speech that President Biden just delivered and the thing people in both parties say they want. “Politics doesn’t have to be a raging fire,” Biden said in his speech, “destroying everything in its path.”

But the nature of unity can make it a trap, simply because it gives power to your opponents to make your unity project a failure at any time, simply by withholding their cooperation.

Yet Biden might actually succeed in bringing unity to our politics — if he can shift our understanding of what it is and what we should expect from it. And in his speech he showed signs of understanding how to approach it.

To start, he has to make clear what kind of unity is neither possible nor desirable. The two parties will never agree on everything, or even on most things. That’s why we have separate parties, because they have competing ideas. And that’s fine. That’s what politics is for: We consider those ideas, try to convince the public that we’re right, win power so we can put our ideas into action, and see if the voters like the results.

“Hear me out as we move forward," Biden said, “If you still disagree, so be it. That’s democracy.”

“Unity” doesn’t mean that the president abandons his agenda just because the opposition disagrees with it. But it does mean that both sides agree to some basic ground rules about how our democracy works.

Among those is that the side that lost has to respect the victory of the side that won. This is what much of the Republican Party has abandoned. Donald Trump and many Republican supporters have attacked one of the key foundations of democracy, that sometimes our side will win and sometimes it will lose, and when we lose we’ll accept that we lost and try to win next time.

So Biden’s unity project has to begin with a demand he makes of the Republican Party: They have to accept the legitimacy of his victory, period. That’s the first step toward unity.

Anyone who continues pandering to the deranged elements of their base with bogus conspiracy theories about fraud should simply be disqualified from any role in the coming policy debates. If Sen. Josh Hawley has something to say about Biden’s tax plan, the only response should be, “When Hawley acknowledges that Biden is the legitimate president, then we’ll consider what he thinks about the capital gains tax. But not before.”

Unity sometimes means excluding those who won’t agree to respect basic ground rules. You wouldn’t play basketball with someone who throws the ball over the fence as soon as the other team makes a basket; the game won’t work unless you tell him that if he does that, he won’t be allowed to play.

This will have to be repeated and reinforced over and over, because the Republican Party has been so corrupted by Trump and those who are trying to win the affection of his supporters: If you don’t agree to the rules, you don’t get to participate. We’ll just treat you as another fringe nutbar who is irrelevant to the work of governing.

Next, Biden should work to define unity as a common commitment to vigorous, honest debate, but not any particular outcome. It’s not a betrayal of the idea of unity to say, “This is what our side would like to do; we think your approach to this problem is the wrong one.”

As president, he’s going to put forward legislation on the agenda items he ran on; Republicans will object to them. Then we can talk about it, see which side is able to persuade the public, and maybe sometimes come up with a compromise.

But sometimes not — and that doesn’t subvert the quest for unity either. We can all be unified in our support for the idea that if the voters choose to elect a president and a Congress from one party, they’re going to pass some of their preferred legislation. That doesn’t mean you can’t criticize it. But you have to accept that the result itself is legitimate.

Biden should also promise that in the name of unity he’ll be fair and honest about why he thinks Republicans are wrong — and demand the same of them. If and when they try to base their policy arguments on lies, as they have in the past (Death panels!), then he should suggest that such behavior should get you excluded from any debate or negotiation over the legislation.

It’s not easy to do — if Sen. Ted Cruz (R-Tex.) continues to insist that maybe Trump won, you can shut him out of legislative negotiations, but you can’t stop him from spouting his baloney on Fox News. You can, however, make sure that everyone knows he has decided for himself that he won’t be a participant in the sane debate the rest of us are trying to have.

In sum, Biden has to show the public that unity and disagreement are not mutually exclusive. It’s the American system that we have to unify around, not any particular belief about which problems are the most urgent or which policy solutions are the best ones.

“We must end this uncivil war that pits red against blue," Biden said. “Rural versus urban, conservative versus liberal. We can do this if we open our souls instead of hardening our hearts.”

Those divisions are going to remain, and they’ll be intense. The idea that we can all just open our souls is almost certainly too optimistic.

So he should set his sights just a little lower, with the understanding that redefining unity not as agreement on policy but as a commitment to maintaining a functioning democracy is the way to keep his promise. It’ll be up to Republicans to decide if they want to join him.

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