This kind of leadership poisons the body politic, a little more each day. Presidents are role models. Their words and comportment influence their supporters and, more generally, set the tone for the national discourse. Mr. Trump has not merely normalized cruelty and boorishness; he has given it the imprimatur of the Oval Office.
One of Mr. Biden’s most basic jobs will be to model a different leadership — to reclaim what it means to be presidential in a way that restores dignity and humanity to the office. Some of what this requires is straightforward: Don’t demean political opponents or fellow world leaders. Don’t insult members of your own administration. Don’t accuse people who merely disagree with you of treason. Don’t have a Twitter tantrum every time your feelings get bruised. Or, maybe, stay off Twitter altogether.
More specifically, Mr. Biden will need to restore and reinforce some guardrails and norms that Mr. Trump tore down, in the recognition that not even presidents are above the law. He has already made his tax returns public, a welcome step back toward accountability. Going forward, he will need to make clear that key institutions — the Department of Justice, the intelligence community and the military, for starters — will be free from partisan meddling. His administration’s inspectors general must be treated as guardians, not turncoats, and they may need to be granted additional protections. He will need to acknowledge that oversight of the executive branch is a legitimate function of Congress, not something to be dismissed out of hand.
Speaking to the concerns of Mr. Trump’s supporters, without condemnation or condescension, will be crucial to Mr. Biden’s unification efforts. It helps that the new president has an unpolished, regular-guy appeal and a knack for connecting on a personal level that keeps him from seeming like a snooty elitist. His Catholic faith is important to him, which will resonate in many enclaves. In pursuing his governing agenda, disagreements will arise over deeply held beliefs, and the arguments are bound to get heated. But, unlike his predecessor, Mr. Biden knows the difference between opponents and enemies.
Mr. Trump has stoked cultural conflict — by, for instance, declaring war on N.F.L. players who kneel during the national anthem. Mr. Biden presumably will find better uses of his time and energy. Not every culture-war skirmish merits presidential involvement, and many would be better managed without it. QAnon may be a disturbing sign of the times, but it does not yet rise to the level of a presidential talking point. Neither do the “thin blue line” flags that are a sign of police solidarity and, depending on whom you ask, white supremacy.
With the coronavirus holding center stage, even core culture-war issues — abortion, L.G.B.T.Q. rights, religious freedom, assault weapons — may wind up relegated to the political background. There will be movement on all of these issues outside of Mr. Biden’s control, either in Congress or the courts. But he need not celebrate or mourn each of these developments as an existential victory or defeat. Not because they aren’t important, but precisely because they incite such passion and fury. All of these questions will be contested long after Mr. Biden’s term in office is over. These long-simmering challenges will still be there, waiting, when the acute trauma of the pandemic has passed and the nation begins its recovery.
Mr. Biden has the temperament and the tools to moderate rather than maximize conflict. When the death of George Floyd this spring sparked nationwide protests over racial injustice and police brutality, forcing those issues to the forefront of the presidential race, Mr. Trump sought to inflame tensions. Who can forget his Twitter invocation of the civil rights-era phrase, “When the looting starts, the shooting starts”?