Visitors passing an image of President Lincoln are reflected in a glass doorway at the Lincoln Memorial. (Evelyn Hockstein/For The Washington Post)

Danielle Allen is a political theorist at Harvard University and a contributing columnist for The Post.

Last year gave us one of the most unusual elections in our political history. In the electoral college , a political outsider upset an establishment insider who won the popular vote but did not achieve the necessary distributed majority across states. What’s more, Russian pot-stirring helped agitate the whole yeasty brew to a well-het-up boil.

This means that as we celebrate an inauguration Friday — and celebrate we should — we do so with an unusually indigestible medley of emotions — euphoria for some, and for others, despair.

Why should we celebrate the inauguration of the 45th president of the United States? Because in doing so, we celebrate the world’s oldest representative democracy and 44 peaceful transfers of power from one executive to another. The 15th transfer, from James Buchanan to Abraham Lincoln, was, of course, gossamer tissue stretched across already existing ruptures and percolating hostilities.

The present transfer also finds the fabric of our national union stretched thin against stresses and strains in our underlying political culture. Since Bill Clinton’s impeachment in 1998, none of our presidents has held office without a significant number of our fellow citizens harboring serious doubts, rightly or wrongly, about the legitimacy of his presidency.

Lincoln’s problem is therefore ours once again. Our political institutions suffer from the fundamental injury of diminished legitimacy in the eyes of too many.

What’s to be done?

We might find our solution, too, in Lincoln’s example.

With one hand, we must hold tightly, as tightly as possible, to our Constitution and political institutions. With the other, we should work as strenuously as possible to restore a broadly shared understanding of where we are headed and where we want to go.

What is the current diagnosis of the course of human events in this country? Our aim cannot be unanimity, but we should aspire to a distributed majority that roughly shares some broad understanding of who we are and what it would mean to secure our safety and happiness.

Who are we? Here’s a beginning. We are America, indivisible, with liberty and justice for all.

Friday, in this inauguration, we celebrate the people’s institutions and especially the office of the president.

For the faithful among us, we might also pray for the new president, and for ourselves, that we might all meet our responsibilities as citizens. For those among us committed to a secular path, we should bend our wills to our duties and to the work necessary to meet our responsibilities as citizens. We might also aspire to teach others through our own example to do the same.

What does this amount to for all of us?

Saturday and the day after and the day after, we should celebrate the people’s institutions by engaging in political conversation and contestation at the local level, linking those conversations upward through our federal institutions, so that from our many and unending debates, we may begin again to forge a broadly shared, common path.

With devotion to this cause once more increased, we might have yet another birth of freedom and equality, our twinned ideals.