Most Americans are spectators in today’s most critical struggle for democratic values — being battled at every hour of every day in Ukraine. But in another vital struggle for democracy, a third of Americans are spectators.

That’s the rate of Americans who did not vote in the last presidential election, perhaps the most important in a generation. Even though voter participation in 2020 was the highest since 1900, only 66.8% of Americans voted in an election with perhaps the most flexible voting requirements ever.

That is not enough, at least in the view of E.J. Dionne Jr., the Washington Post columnist, and Miles Rapoport, a fellow at the Harvard Kennedy School’s Ash Center for Democratic Governance and Innovation. In their new book, “100% Democracy: The Case for Universal Voting,” published less than a month ago, they argue that voting should be a duty, much like serving on a jury, registering for the draft and paying taxes.

It’s a provocative idea, embraced in 26 countries, at once consistent with American tradition (the Constitution begins with the phrase “We the people,” which suggests all of us) and at odds with it (Americans don’t like to be told what to do, as the debates over masks and vaccines prove).

Voting is a precious right that Americans, in their affluence and ease, have taken for granted, believing, like Otto von Bismarck, that “God has a special providence for fools, drunkards and the United States of America.” We shared the conviction that democracy was durable, that elections didn’t much matter, and that the stakes weren’t that high. Some of us voted, some didn’t. No problem.

But in four contests in less than 30 years — two of them in the United States — the world has seen the thirst of people for elections, the consequence of elections and the fragility of elections.

In 1994, in the first election in which Blacks were permitted to vote in South Africa, lines at polling places stretched out more than a half-mile. The next year, when Quebec voted on whether to declare itself a separate country, 93.5% of those registered to vote actually did so, and the province remained within Canada by 1 percentage point. In 2000, the U.S. presidency was determined by hanging chads and haggling lawyers in a Florida contest decided by 537 votes — or by some other minuscule number, depending on who was counting and what you believe — in an electorate of about 6 million souls.

And in 2020, vast numbers of Americans did not trust the verdict of the most sacred public act that our citizens perform.

Concern about voter turnout has been building for 25 years. In the late years of the last century, Curtis Gans, the respected co-founder of the Center for the Study of the American Electorate, wrote this, applicable today even with the relatively high 2020 turnout:

“Every year, the nation seems further and further from the political comity, cohesion and consensus that makes possible the constructive address of citizen needs … The nation that prides itself on being the best example of government of, for and by the people is rapidly becoming a nation whose participation is limited to the interested or zealous few.”

The big surprise in 2020: This new generation of young voters is performing better than its predecessors, with record turnouts in both the 2018 and 2020 general elections. The 2020 election was the first time that a majority of those 18 to 29 actually voted.

“This is a highly anxious, highly knowledgeable, depressed group of young people,” said John Della Volpe, director of polling at Harvard Kennedy School of Government’s Institute of Politics and the author of “Fight: How Gen Z Is Channeling Their Fear and Passion To Save America.” “Everything they were shaped by was negative. They don’t remember a time of national unity. Rather than turning away from politics, they turned in, and actually turned out to vote. I don’t think we’ll see a diminution in that.”

And yet there are whispers — not yet shouts — that some young people will not vote in this autumn’s midterm congressional elections if President Biden does not cancel student loans. This has Democratic political professionals in a swivet; that would be another disadvantage as Democrats try to preserve their majorities on Capitol Hill.

Midterm elections are more challenging for the Democrats, because younger people, poorer people and people of color are major components of the Democratic coalition — and tend to vote in midterm elections at lower levels than older white voters. The expectation that the Democrats are going to take a shellacking in November also could lower participation. “Voting groups that are disengaged could become even more so because they feel their vote won’t matter,” said Michael McDonald, a University of Florida expert on voter participation.

For 40 years, Dionne and I have competed as rival national political writers, shared friendly dinners and spots on panels, exchanged warm emails and good wishes. We have not spoken about this idea, and he had no inkling I would write about his book. And I’m not sure whether universal voting would change the outcome of elections, just as I’m not sure time-consuming NBA and NFL instant replays are an improvement over the imperfect verdicts of officials, whose judgments might even themselves out over the course of a game or a season.

But I am certain of this: An election is a civic ritual, and — with the decline of local newspapers, the proliferation of television news and streaming services, the sorting out of Americans by wealth, education, political inclination, and ethnic and gender identity — we have fewer civic rituals than ever and thus fewer shared experiences.

I understand the value of mail voting; as a political correspondent traveling with a candidate on a final offensive on Election Day, I often voted that way. But I always saw poetry and purpose in an entire country doing the same thing on the same day, seeking to define the country and to set its course.

Election Day is Walt Whitman’s verse on foot, for in people trooping to the polls, I always have heard America — some of us altos, some tenors — singing. We sang different parts. But all of us — Whitman’s mechanic, carpenter, mason, shoemaker and wood cutter — sang “with open mouths [our] strong melodious songs.” It is a shame that voting might be required. But our time might require it.

David M. Shribman is the former executive editor of the Pittsburgh Post-Gazette.