What do our movies say about our decadent civilization?

Last fall, American pop culture celebrated “Back to the Future Day” — marking the date, 10/21/2015, to which Marty McFly leaps forward from the Reagan ’80s in Back to the Future Part II.

It was a slightly daft commemoration of a pleasant but hardly memorable sequel, and it felt almost like a way for people not to come to grips with the most striking thing about Back to the Future’s 30th anniversary: that we’re now as far from the Reagan 1980s as the teenage Marty was from his parents’ 1950s, and yet the gulf of years separating us from 1985 feels far narrower than the distance from the Eisenhower era that the original film used to such great effect.

The power of the first Back to the Future depended not just on an arbitrary 30-year period, that is, but on how radically America had changed across those decades: Marty’s adolescence and his parents’ courtship lay on opposite sides of (among many other things) rock ’n’ roll, civil rights, Vietnam, the sexual revolution, drug culture, the moon landing, feminism, the apocalyptic ’70s, and, finally, the conservative turn that made this magazine’s 30th anniversary a happy one.

Whereas if you remade Back to the Future now and sent Martina McFly back to ’85, you would have a lot of jokes about life without the iPhone, some shocking shoulder pads, and some sort of “comic” critique of Reagan-era unenlightenment on same-sex marriage. But you wouldn’t have the sense of visiting a past that’s actually another country.