a metaphor to describe correlationism

General/President Ulysses S. Grant, one of my favorite figures in American history, was famously tone-deaf. He used to joke as follows: “I only know two songs. One of them is ‘Yankee Doodle,’ the other one isn’t.”

And isn’t the correlationist just this way? “I only know two kinds of entities: one of them is human, the other one isn’t.”