Donald Trump has taken a battering ram to longstanding political norms -- the unwritten conventions that make governance possible. But even before he decided to run for president, those norms were under assault. Immediately after the election, one of the most pressing questions will be how to restore them.

To answer that question, let’s assume what philosophers call a “veil of ignorance.” If we didn’t know whether the president would be Democratic or Republican -- if it could turn out to be Clinton or Trump -- what are the minimal norms on which we might agree? Here are four suggestions.

1: Civility now. You can speak about members of the opposing party with respect, or you can treat them with contempt. You can attack their motivations or accuse them of betraying their country, or you can argue that their proposals are unlikely to achieve legitimate goals. For all their differences, Sens. Bernie Sanders and Ted Cruz (both likely to be highly influential in 2017) sometimes practice Manichean politics: In their worlds, decent, ordinary people are struggling against a self-interested and dishonest elite.

Enough of that. It’s ugly, unproductive and (usually) wrong. Right after the election, the losing and winning candidates should strike notes of humility and grace, and Democratic and Republican leaders should join them.

2: Compromise, early and often. On some issues, Republicans and Democrats disagree so sharply that compromise is nearly impossible. Republicans are not going to support a cap-and-trade program to limit greenhouse gases, and Democrats won’t support a 3,000-kilometer wall on the border with Mexico.

Nonetheless, 2017 could be the year of splitting differences. On gun control, for example, Clinton has a number of ideas, such as forbidding the sale of guns to people on the terrorist watch list, that many Republicans could accept. On border security, Trump has several proposals that Democrats should be able to support, including increased funding of US Immigration and Customs Enforcement and stronger steps to ensure detention and deportation of illegal aliens who have committed violent crimes. Clinton, Trump, and Speaker Paul Ryan all favor an expansion of the earned income tax credit, and while their approaches differ, there should be room for a deal.

3: Identify a set of attractive proposals from “the other side,” and champion them. With a compromise, one party yields to another; it gives something up. But there is an even more appealing possibility, which is to find domains in which the two parties agree with one another, and no one has to yield a thing.

There is no question that Republicans (including Trump) have some proposals that Democrats already embrace, and that Democrats (including Clinton) have some proposals that Republicans might like. Trump favors greater infrastructure spending -- significantly more, in fact, than Clinton does. Clinton wants to make life much easier for small businesses, for example by reducing occupational licensing requirements (long a Republican pet peeve) and rethinking regulations that hold them back.

There are many opportunities here. Whoever is elected, a productive step would be for the president-elect and members of her or his party to endorse and highlight reforms that the other party has favored.

Steps of this kind would help break a terrible tendency in recent years, which is to evaluate proposals not in terms of their substance or on their merits, but by simply rejecting whatever the opposing party embraces.

4: Ease up on the process for confirming executive branch nominees. This is more important than it may seem, because the current system, in which nominations are held up for months or even years, discourages good people from entering public service, wastes time and money, creates acrimony, and makes it much harder for government to serve the American people, even on the most routine matters.

Within broad limits, the president should be allowed to select his own employees. Whether it’s the attorney general, the secretary of agriculture or an assistant secretary in the Department of Treasury, the Senate should generally confirm presidential nominees so long as they meet standards of competence and probity. One reason is that executive officials work under the president and the White House. Even if they have embraced controversial positions in the past, they are hardly free agents.

It follows that conservative senators should not oppose nominees because they have quite liberal views and that liberal senators should support nominees who are quite conservative. It also follows -- and this is exceedingly important -- that very liberal senators, such as Sanders, should not cause problems for Clinton nominees who are definitely to their right (even if they have worked on Wall Street). So too, very conservative senators (such as Cruz) should be willing to vote in favor of Trump nominees who are definitely to their left.

Sure, some views are beyond the pale. Senators need not support a nominee to head the Environmental Protection Agency who pledges to repeal the Clean Air Act -- or who thinks that by 2020, all cars should have to be electric. But it just isn’t appropriate for executive branch nominees to be held up merely because senators disagree with them -- and much less because they had some tax problem, or supported a controversial idea or organization, a decade ago.

The biggest obstacle to this four-part plan is simple: political self-interest. Concerned about re-election, interest-group reactions, the media or fundraising, many legislators have found it in their interest to refuse to cooperate with members of the opposing party -- or to treat them as enemies in some kind of war, in which the whole point is to defeat and humiliate them.

But the American people have been the real losers. On Nov. 9, public officials should embark on an eminently manageable project: rebuilding institutional norms that have long served the nation well.

By Cass R. Sunstein

Cass R. Sunstein is a Bloomberg View columnist. -- Ed.
Bloomberg