This leaves us at a standstill. Currently, not only is deep dish not pizza, but the overwhelming majority of pizza produced worldwide is also not pizza. Legally, we’ve all been unknowingly eating open-faced grilled cheese sandwiches our whole lives, under the false impression that we were enjoying a melty slice of pizza. The question then becomes whether or not this legal definition is at all helpful. If nothing is pizza, isn’t everything pizza? This is where linguistics might help.
Julia Davidson, a local teacher with a masters in both literature and education, tackles the debate from a more utilitarian perspective. "I think that 'deep dish' accurately modifies the noun 'pizza' to describe deep dish as a type of pizza," says Davidson. "I think part of the decision has to be composition -- what is the difference between deep dish dough and flat pizza? For me, ingredients would determine it."
In short, she views the category of “pizza” as a large set, with many different subsets inside it. It implies that there is no one true pizza -- that all pizza types need to be modified with descriptors in order to have any real meaning. And this holds up in common usage. Cracker-crust pizza, French bread pizza, taco pizza, hell, even pizza bagels are all ostensibly cousins under the larger pizza umbrella. Davidson goes on, though, to say that much like pizza bagels and French bread pizza, thin-crust and deep-dish pizza each fulfill different culinary and gustatory goals. A craving for deep-dish pizza will not be sated with a thin, head-sized slice of New York-style pizza, and vice versa.