The 1995 movie Waterworld opens with a spinning globe showing the ice caps receding and the continents flooding. “The future,” says the unnecessary, disembodied ’90s narrator. “The polar ice caps have melted, covering the Earth with water.” The camera pans down from the heavens, and we watch Kevin Costner’s unnamed protagonist drink his own piss.

It’s a handy summary of the movie as a whole: a condescending voice tells you something you already know, then you watch something unbearably stupid.

The Postman (1997) plays it the opposite way, with the same result. Costner, again in the role of an unnamed hero, wanders “the Great Salt Flats of Utah” with his mule, bouncing on an abandoned diving board in a desert. Another disembodied narrator explains that “the last of the great cities died” after a war, then plagues, a three-year winter, and a sixteen-year drought. Then there’s a lion pawing a tin can in the rain.