   According to the modal argument, if the proper name ‘Cicero’ were just short for some definite description, e.g., ‘the Roman orator who denounced Catiline,’ then it would follow that the sentence ‘Cicero is the Roman orator who denounced Catiline’ would express a necessary truth, i.e., a proposition true in all possible worlds. But this seems absurd: there certainly is a possible world in which Cicero did not denounce Catiline.