Naming and Necessity

The central argument is that proper names are rigid designators—they refer to the same individual in every possible world where that individual exists—and that true identity statements between rigid designators are therefore necessarily true. Kripke rejects the descriptivist view, associated with Frege and Russell, that names are abbreviated or disguised definite descriptions whose reference is fixed by associated properties. The modal objection is decisive: 'Aristotle might not have been the teacher of Alexander' is true, but 'Aristotle might not have been Aristotle' is not, showing that the name and the description cannot be synonymous . The book also rejects the assumption that necessary truths must be knowable a priori.

The necessary a posteriori is a truth that is metaphysically necessary—true in all possible worlds—but knowable only through empirical investigation. Kripke's central example is 'Hesperus is Phosphorus': since both names rigidly designate Venus, the identity is necessary if true, yet it was discovered astronomically, not a priori . This overturns the Kantian assumption that necessity and apriority are coextensive, and that a posteriori truths are merely contingent. The distinction between epistemic and metaphysical modality—between what could have been the case for all we knew and what could have been the case in reality—became a foundational tool of post-Kripkean metaphysics .

Kripke's alternative to descriptivism is a causal-historical picture, which he explicitly declines to call a 'theory.' Reference is established by an initial baptism, in which an object is named, and is then transmitted through a community by a chain of communication linking subsequent uses to the original act . A speaker who uses 'Aristotle' need not know any identifying description of Aristotle; what matters is that their use is causally connected, through the linguistic community, to the man himself. This picture accommodates the ignorance and error that plague descriptive accounts: most people know few or no uniquely identifying facts about Aristotle, yet their use of the name still refers to him .

Naming and Necessity is the fuller development of the argument first compressed in Identity and Necessity, delivered in 1971 and published in Munitz's Identity and Individuation. The earlier essay establishes the necessity of identity statements between rigid names using the Leibnizian indiscernibility of identicals. Naming and Necessity expands the framework in several directions: it adds the sustained critique of descriptivism, the causal-historical picture of reference, the extension to natural kind terms ('water is H2O' as necessary a posteriori), and the revival of essentialism about individuals and kinds . The book version of 1980 also includes a substantial new preface responding to critics and clarifying the argument.

The material was first delivered as three lectures at Princeton University in January 1970. It was published as an essay in 1972 in Semantics of Natural Language, edited by Donald Davidson and Gilbert Harman, with addenda added in 1972 . The standalone book edition, published by Harvard University Press in 1980, includes a substantial new preface in which Kripke responds to criticisms, clarifies the status of his 'picture' of reference, and addresses misunderstandings . The book edition is the standard citation for scholarly work, though the 1972 essay remains historically significant as the first published form of the argument.

Philosophers of science have criticized Kripke's claim that statements like 'water is H2O' are necessary truths about the essence of a natural kind. The objection is that such identities may be relativized to actual-world chemistry rather than holding across all possible worlds, and that Kripke's essentialism imposes a metaphysical framework on science that the science itself does not require. Scott Soames and others have pressed related concerns about whether the rigidity of kind terms is coherent. Defenders, including some in the fortieth-anniversary reflections on the book, argue that the relevant sciences do support Kripke's essentialist claims about chemical and biological kinds, and that the critics' alternative accounts fail to capture the necessity of theoretical identifications .