   For a long time, people thought that Moore’s Open Question Argument (as it has come to be called) established that no version of moral naturalism was defensible. However, recent developments in the philosophy of language and metaphysics have raised concerns about Moore’s argument. Of special concern is the fact that the argument seems to rule out inappropriately the possibility of establishing—on grounds other than semantic analysis—that two terms actually refer to the same property, substance, or entity.