 A great deal of work has been done on the semantics of (characterizing) generics, particularly on bare plural (characterizing) generics. It is easy to see why this is so: “Ducks lay eggs” is a true generic, while “ducks are female” is false, yet it is only the female ducks who ever lay eggs. “Mosquitoes carry the West Nile virus” is true, and “books are paperbacks” is false, yet less than one percent of mosquitoes carry the virus, while over eighty percent of books are paperbacks. How are we to account for these puzzling facts?