Let us call something a rigid designator if in all possible worlds it designates the same object, (Kripke 1980, 48)That is to say that the referent of a rigid designator, speaking of a possible world or a counterfactual situation, is the same as its referent in the real world. For example the term "President of the United States" is not a rigid term for Omaba, because there exists a possible world in which the President of the United States is not Obama and therefore the term does not refer to him (does not does not refer to Omaba) in this world. But “Obama” means Obama in all possible worlds, so it’s a rigid designator. Please note, saying that in world W the referent of “Obama” is Omaba does not mean that the inhabitants of W use the term “Obama” to designate Obama. This simply means that when describing W when we use "Obama", we are referring to Obama. Krikpe also argues that proper names are rigid designators. For example, consider these two sentences: 1) Aristotle joined the Academy. 2) Alexander the Great's teacher joined the Academy. Intuitively, “Aristotle” in the first sentence refers to Aristotle but “the teacher of Alexander the Great” does not. This does not necessarily refer to Aristotle (e.g. in a world in which Plato is the teacher of Alexander the Great). Moreover, his arguments for the rigidity of proper names rely on our linguistic intuition, that is, language users use proper names in modal contexts as if they were rigid: One intuitive theses that I will maintain in these presentations is that nouns are rigid designators. (Kripke 1980, 48) Or elsewhere: In these lectures, I will argue, intuitively, that proper names are rigid designators, (Kripke 1980, 49) Now let's talk a little about the different theories on the semantics of proper names. The......middle of the article......by (1)! Second, DQ also, with the very intuitive principle called the translation principle, results in another paradox. Third, the following scenario shows that DQ, at least in the form presented previously, cannot be true: consider a possible world in which Venus and many other celestial bodies would be called "Phosphorus". Also in this world I sincerely believe that phosphorus (= Venus) is visible in the morning and I don't know if it is also visible in the evening. Now suppose that a man, pointing to Venus in the evening, wants me to agree or disagree with the sentence "Phosphorus is visible in the morning." As I don't know if the term "Phosphorus" used in this sentence refers to Venus, I can't agree with that and according to DQ I don't believe that Phosphorus is visible in the morning. Therefore, I believe and I do not believe that phosphorus is visible in the morning.!