The family in “Captain Fantastic,” dressed up for a funeral in their own peculiar way.

U.S. director Matt Ross has a winner in his Un Certain Regard entry at Cannes, “Captain Fantastic.”

The movie stars Viggo Mortensen as Ben, a left-wing father who is raising his family in the wilds of the Pacific Northwest, where he’s home-schooling them in the ways of anti-capitalist, anti-fascist thought. His big hero is Noam Chomsky, and the family celebrates Noam Chomsky Day rather than Christmas. All the kids long for a serrated gutting knife, knowing that they’ll one day be required to stalk a deer and kill it, thus becoming a grownup.

These kids are smart. They’re physically fit. They can survive in the wilderness. And they have elaborate routines to fill their day, with plenty of reading time. Even the young ones are reading books like Dostoevsky’s “The Brothers Karamazov.” And one young woman is reading “Lolita” and being asked to analyze its morality, especially that of the older man who seduces the young girl.

It’s fascinating to watch, but you begin to wonder where the mother is. It turns out that she has a bipolar disorder and has moved back in with her parents in the American Southwest. But even this attempt to seek treatment doesn’t work, and she ends up slashing her wrists.

Ben tells his children the truth, and they’re devastated, of course. But Ben and his merry troupe decide that they must attend the mother’s funeral, so they hop into an old bus and begin venturing out into civilization. And that’s where the real fun begins, as the children marvel at everyone being overweight.

The movie strikes a delicate balance between some of the children who are fascinated by video games and others who are fascinated by the variety of choices at a restaurant. But the most touching moments involve the oder son, Bo (George Mackay), who has no idea how to respond to a young woman’s flirting. It reveals what the kids have been missing, and it’s a beautifully handled scene.

The big problem for the family is this: the mother’s parents, played by Frank Langella and Ann Dowd, want to have a proper funeral and traditional burial for their daughter. But Ben has his wife’s will, and she wants to be cremated and have her ashes flushed down a public toilet. This doesn’t sit well with the parents, of course.

So the oddball family arrives at the funeral, in the scene pictured above, and fireworks ensue.

Ross not only directs but also wrote the screenplay. And it’s wonderfully funny, full or little kids quoting philosophers and the great thinkers of the past. It makes you wonder about our educational system, even while making you also wonder about the merits of raising children in the wilderness — far from the socializing influences of public or private school.

Whatever your views, the dialogue is crisp, and the performances are wonderful, even from the little kids. There’s full frontal nudity, so this isn’t for the whole family. It is, however, a perfect film for anyone who questions the values of consumer culture.