One of the version of cosmological argument is known as conceptualistic. Based on theory of truth in semantics of modal logic, this argument attempts to prove the existence of God. Given that a proposition is product of mind, and without mind there is no proposition, the advocates of this argument believe that the existence of true propositions in all possible worlds proves the existence of God, since there is no human mind in all possible worlds, it must be a divine mind to which true proposition belongs. In addition to reciting different versions of this argument, the author has criticized them and with respect to Muslim philosophers' view about the unity of the world, has shown invalidity of this argument.