Saul Kripke’s Naming and Necessity (1972) is a foundational work of analytic philosophy that records and annotates three lectures delivered at Princeton University in 1970. The book challenges the long-dominant descriptivist theory of reference, credited to Gottlob Frege and Bertrand Russell, which holds that proper names function as abbreviated descriptions. Kripke argues that names are instead “rigid designators” that refer to the same object or individual across all possible worlds. He uses this framework to explore the nature of identity, scientific discoveries, and the mind-body problem, ultimately making a case for metaphysical essentialism. Key themes in the work include Rigid Designation as an Alternative to Descriptivism, Identity Truths as Necessary A Posteriori, and Essence and the Necessity of Origin.

An American philosopher and logician, Kripke was a prodigy whose early work in the 1960s on “‘possible worlds’ semantics” revolutionized the field of modal logic and provided the formal apparatus for the arguments in Naming and Necessity (3). The book is widely regarded as one of the most important philosophical works of the 20th century, credited with sparking a revival of metaphysics within the analytic tradition. Its critique of the descriptivist view pioneered by Frege and Russell, alongside the introduction of concepts like the “necessary a posteriori,” fundamentally shifted the direction of the philosophy of language and philosophy of mind. Kripke’s other major work is Wittgenstein on Rules and Private Language (1982).

This guide refers to the 1991 paperback edition published by Wiley-Blackwell.

Summary

Originally delivered as three lectures at Princeton University in January 1970 and first published in 1972, this work of analytic philosophy challenges dominant theories about how proper names refer to objects, argues that necessity and a priori knowledge are distinct concepts, and draws out consequences for scientific identifications and the mind-body problem. The revised edition (1980) preserves the informal, spoken style of the original lectures and adds a preface clarifying key ideas.

In the Preface, Saul Kripke traces the genesis of his views to the early 1960s, when his formal work in modal logic (the logic of possibility and necessity) led him to conclude that identity between objects is always necessary, never contingent. He introduces the concept of a “rigid designator,” a term that picks out the same object in every possible world, and states that ordinary proper names are rigid designators. He distinguishes de jure rigidity, where a designator’s reference is stipulated to be a single object, from de facto rigidity, where a description merely happens to pick out the same object in every possible world. He contrasts his thesis with the view, associated with Gottlob Frege and Bertrand Russell, that names are abbreviated definite descriptions. Rigidity, he insists, is not reducible to a scope convention for names in modal sentences; it concerns the truth conditions of all sentences, including simple ones with no modal operators at all. He clarifies his conception of possible worlds through an analogy with the 36 possible outcomes of rolling two dice, noting how these outcomes are abstract states, not phantom physical objects. No special criterion of “transworld identity” is needed because the states are stipulated to involve those particular dice.

The first lecture lays the philosophical groundwork. Kripke presents John Stuart Mill’s view that proper names have denotation (they pick out an object) but not connotation (they do not encode a meaning or definition). He then presents the opposing Frege-Russell view that names are disguised definite descriptions: “Aristotle” might mean “the last great philosopher of antiquity” (6). This view explains how speakers determine a name’s referent, how identity statements like “Hesperus is Phosphorus” can be informative (20), and how existence statements make sense. Kripke acknowledges the power of this framework but argues it is false. He also introduces the “cluster concept” modification, associated with Ludwig Wittgenstein and John R. Searle, which holds that a name’s reference is determined by a weighted family of descriptions rather than a single one. He argues that this variant is also mistaken.

Kripke draws a crucial distinction between a priori truth (an epistemological notion concerning what can be known independently of experience), necessity (a metaphysical notion concerning what could not have been otherwise), and analyticity (truth by virtue of meaning). He argues that the a priori and the necessary are not coextensive. He illustrates this with the Goldbach conjecture, the unproven hypothesis that every even number greater than two is the sum of two primes: If true, it is necessarily true since mathematical truths cannot be contingently true, yet no one currently knows a priori whether it is true.

He defends essentialism, the view that objects possess some properties necessarily and others contingently, independent of how they are described. Against the skepticism of philosopher Willard Van Orman Quine, who argued that whether a property is necessary depends on how the object is described, Kripke appeals to ordinary intuition. Anyone would agree that Richard Nixon might have lost the 1968 election, regardless of whether we call him “Nixon” or “the winner.” Kripke introduces the formal notion of a rigid designator and illustrates the distinction between fixing a reference and giving a synonym with the example of the standard meter stick in Paris. He then formally states the cluster theory as six theses plus a non-circularity condition and argues that all but the first thesis are false.

The second lecture provides detailed counterexamples. Against the thesis that speakers’ associated properties uniquely identify the referent, Kripke observes that many people who use “Feynman” know only that he is a physicist. Against the thesis that the referent is the object satisfying most of the associated properties, he presents a thought experiment involving the mathematician Kurt Gödel and a fictional man, Schmidt, who actually accomplished Gödel’s work. Regarding the cluster theory, speakers who associate “Gödel” primarily with the incompleteness theorem would really be referring to Schmidt, but Kripke argues that this is wrong. He extends the point with real cases, noting that common misconceptions about historical figures do not redirect the reference of their names.

In place of the description theory, Kripke sketches a causal-historical picture of reference. A name is introduced in an initial baptism, by ostension or by fixing the reference through a description, and thereafter passes from speaker to speaker through a chain of communication, with each speaker intending to preserve the reference. He then argues that identity statements between proper names, if true, are necessarily true. Since “Hesperus” and “Phosphorus” are both rigid designators of the planet Venus, “Hesperus is Phosphorus” is necessarily true even though it was discovered empirically (98). The appearance of contingency is epistemic—that is, an illusion produced by culturally contingent methods of knowledge production.

The third lecture extends these arguments to natural kind terms such as “gold,” “water,” and “tiger.” Kripke argues that these terms function more like rigid designators than like dictionary definitions. Gold is not defined as “yellow metal” since iron pyrites, or fool’s gold, has all the superficial appearances of gold but is not gold because it is a different substance. Scientific investigation discovers the essential nature of kinds, such as that gold is the element with atomic number 79. These identities are necessary truths.

Kripke also argues for essential properties of individuals. Queen Elizabeth II could not have originated from completely different biological parents. He then applies his framework to the mind-body problem. If “pain” and “C-fiber stimulation” are both rigid designators, the identity “[P]ain is […] the stimulation of C-fibers” (99), if true, must be necessary. He compares this identity with “[H]eat is molecular motion” (132). In the heat case, the appearance of contingency arises because “heat” is picked out by the contingent property of sensation, so one can imagine molecular motion without sensation. Pain is picked out by the property of being pain itself, so the apparent possibility of C-fiber stimulation without pain cannot be explained away. Kripke offers a theological thought experiment in which God creates molecular motion, thereby creating heat even without sentient beings. However, if God creates C-fiber stimulation, he has not thereby created pain. He must additionally make creatures feel the stimulation as pain. This asymmetry shows that the relation between C-fiber stimulation and pain cannot be identity. Kripke concludes that these considerations argue against standard forms of materialism, though the mind-body problem remains “wide open and extremely confusing” (155).

The Addenda clarify several points, such as the existence of unicorns and other fictional people and creatures, as well as the possibility of references changing over time.