I use this example to introduce formal and functional approaches to topics in the social sciences. Any argument you try to make within the debate ends up including a variant of “…because sandwiches [abstraction about what formally defines a sandwich]”, which itself presumes that the “right” way to carve up the world is in categories of form. You could also conceive of sandwiches functionally, where something isn’t a sandwich if we (some cultural or linguistic group) just don’t think of them that way.

From a functional view, the very fact the debate exists at all means hot dogs aren’t sandwiches, cereal isn’t soup, pop tarts aren’t ravioli, etc.

Then I make them think about it in contexts like language, Durkheim, and policy making and watch their little minds explode.

I absolutely consider Phantom Tollbooth a masterpiece. There’s nothing else like it, and it has extraordinary persistence.