In the middle of the lead crisis in his home town of Flint, Mich., and a hotly contested Democratic primary, the last thing you might expect from the crusading filmmaker Michael Moore is optimism. But not only is “Where to Invade Next,” which opens this weekend, a vote of confidence in America at odds with the bleak tone Moore has often taken on everything from gun policy to American engagement abroad, it’s a surprising, even subtle intervention into one of the core ideological disputes that animate American politics today.

Even if Moore doesn’t say so explicitly, “Where to Invade Next” is aimed squarely at the nature of what makes America a remarkable place. Is America’s greatness in the country’s ability to grow and evolve, adapting new ideas and at times, new categories of people into citizenship? Or is America’s greatness located firmly in the past, something we have to restore from the degradation it has suffered, or protect from future encroachments?

This disagreement shows up in the Supreme Court’s escalating fights over the nature of the Constitution: Is it a living document that helps guide us through changing circumstances, or an expression of the Founding Fathers’ intentions that can be used to curb the pace of that change?

The 2016 presidential election has been defined, on the Republican side, by a vision of American exceptionalism that’s squarely rooted in the past. The leading candidates have different riffs on this concept. Marco Rubio focuses on the idea that “Judeo-Christian values are one of the reasons why America is such a special country.” Ted Cruz embraces an originalist vision of the Constitution rooted in his legal training; he has dubbed his campaign plane Constitution One. And Donald Trump, always an odd fit in the Republican Party, appealed to a broader sense that America’s best years are in the past with his omnipresent “Make America Great Again” slogan.

At first, it seems like “Where to Invade Next” embraces the evolutionary vision of American greatness. Moore’s shtick this time around involves visiting various countries to talk with vacationing Italians, French schoolchildren eating their way through gourmet meals, middle-class workers in a German pencil factory and residents of Norway’s prison system. He then plants an American flag and claims those nations’ wonderful ideas for America.

The whole device is a not-particularly-subtle riff on the contention that America invaded Iraq for its oil. And Moore being Moore, he is occasionally didactic. “You know it’s bad when the French pity you,” he says in one scene where the children recoil at photos of American cafeteria lunches. The message initially seems clear: America has fallen behind the rest of the world and has a great deal of urgent catching-up to do.

But in its final moments, “Where to Invade Next” offers a rather different solution to what seems to be a gaping difference of opinion running through American political life. He goes back to his interview subjects, who tell the audience how their policy innovations were inspired by American ideas.

The seemingly luxurious Italian vacation system and worker benefits? An attempt to catch up with America’s move toward the eight-hour workday. Norway’s prison system? A response to the American ideals that forbid cruel and unusual punishment. “They weren’t European ideas,” Moore notes. “They weren’t new ideas. They were our ideas.”

Moore’s argument in “Where to Invade Next” is ultimately that America’s past willingness to evolve — whether to adopt a more humane standard of work or a less-punitive approach to punishment — is the key to its future success. He’s all for making America great again. It’s just that Moore’s vision of the past might not be what Rubio, Cruz or Trump has in mind.