In the opening scenes of Disney and Pixar’s WallE, the titular robot returns home from a full day of garbage cleanup with a little pile of treasures to add to his extensive collection. Carefully, Wall-E puts each item in its place, but a spork stumps him. Does it go with the spoons or with the forks?

Like Wall-E, many of us like to fit things, people, and ideas into neatly structured categories. (more…)