And if it’s hard for you to get fired up about the scientific rationales for defining planethood one way or another, try starting with a debate you can get entrenched in: is a hot dog a sandwich? Take a moment to consider it. Maybe you think that it is, because a sandwich is anything that has filling between two pieces of bread product. Does it matter what kind of bread product? Flour tortillas are bread products, so is a quesadilla a sandwich or a layer cake with filling? What about an open-faced sandwich? That only has one piece of bread. If you think that an open-faced sandwich is still a sandwich, then maybe a pizza is a sandwich too—they’re both just bread products with toppings. Does it make any sense to have hot dogs and pizza both be sandwiches? That just seems wrong, so maybe we should come up with a definition that separates them. Maybe it has to do with the type of bread product you use or the toppings you put on it.