Gottlob Frege (1848-1925) was a German logician and philosopher whose work laid the foundations for modern analytic philosophy. His seminal 1892 essay, “On Sense and Reference” (Über Sinn und Bedeutung), established the descriptivist theory of names that Kripke identifies as his principal target. For Frege, a proper name has both a reference (Bedeutung), which is the object it picks out, and a sense (Sinn), which is the descriptive mode of presentation that determines the reference. This distinction was designed to solve puzzles about informative identity statements. For example, “Hesperus is Phosphorus” is cognitively significant, unlike the tautology “Hesperus is Hesperus,” because the two names have different senses (e.g., “the evening star” and “the morning star”) even though they share the same reference (the planet Venus).

In Naming and Necessity, Frege’s theory represents the classic formulation of descriptivism, which holds that a name is synonymous with a definite description. Kripke argues that this view fails to account for the modal profile of names. If “Aristotle” simply meant “the teacher of Alexander the Great,” then the statement “Aristotle taught Alexander the Great” would be a necessary truth (30). However, it is a contingent fact since Aristotle might have never pursued philosophy. Kripke uses such counterexamples to show that names are rigid designators, whereas descriptions are non-rigid.

Kripke contends that Frege conflated two distinct functions: giving the meaning of a name and fixing its reference. A description might be used to fix the reference of a name (e.g., “Neptune is the planet causing anomalies in Uranus’s orbit”), but this does not make the name synonymous with the description. By driving a wedge between meaning and reference-fixing, Kripke dismantles the Fregean framework and clears the way for his own causal-historical theory of reference.

Bertrand Russell (1872-1970) was a British philosopher and logician who, alongside Frege, developed the descriptivist theory of names that dominated early analytic philosophy. In his 1905 paper “On Denoting,” Russell proposed his theory of definite descriptions, which analyzes phrases like “the present King of France” in a way that avoids positing non-existent entities. He extended this analysis to ordinary proper names, arguing that they are not “logically proper names” but are instead disguised or abbreviated definite descriptions (20). For Russell, a name like “Walter Scott” is shorthand for a description such as “the author of Waverley.”

Kripke critiques Russell’s theory for its failure to handle modal contexts. Kripke argues that names function as rigid designators, while the descriptions that Russell equates them with are non-rigid. For example, while Walter Scott is the author of Waverley, it is possible that someone else could have written it. In that counterfactual situation, Russell’s theory implies that the name “Walter Scott” would refer to that other person. This clashes with the intuition that a discussion about what might have happened to Scott refers to that specific man, not whoever happened to write Waverley.

Furthermore, Kripke argues that Russell’s use of scope distinctions is insufficient to save the theory. A description can be given wide or narrow scope relative to a modal operator. For example, “The number of planets is necessarily greater than 7” is false, but “Necessarily, the number of planets is greater than 7” is nonsensical. Kripke shows that this mechanism cannot reproduce the consistent rigidity of names. He concludes that Russell’s analysis, like Frege’s, fundamentally misunderstands the semantic function of a proper name, which is to refer directly to an object without being mediated by a descriptive sense.

Hilary Putnam (1926-2016) was an American philosopher whose work on the philosophy of language and science provided crucial, parallel support for Kripke’s views on natural kinds. In his influential 1975 essay “The Meaning of ‘Meaning,’” Putnam introduced his theory of semantic externalism and the famous “Twin Earth” thought experiment. He argued that the reference of natural kind terms like “water” is determined by the underlying scientific essence of the substance in the external world.

Putnam’s Twin Earth scenario illustrates this point. Imagine a planet identical to Earth in every way, except that the clear, drinkable liquid in its lakes and rivers, called “water” by its inhabitants, has the chemical structure XYZ instead of H₂O. Putnam argues that when an Earthling and a Twin Earthling both say “water,” they are referring to different substances, despite having identical concepts in mind. This demonstrates that meaning depends on the physical world. This complements Kripke’s thesis. Just as Kripke argues that names refer via a causal link to an individual, Putnam argues that natural kind terms refer via a causal link to a substance with a specific microstructure.

Putnam’s work provides reinforcement for Kripke’s concept of the necessary a posteriori. The statement “Water is H₂O” is an empirical discovery, rather than an analytic truth known a priori. However, given that our term “water” rigidly designates the substance with the chemical structure H₂O, it is a necessary truth that water is H₂O. Anything with a different chemical structure, like the XYZ on Twin Earth, would not be water, no matter how much it resembled it. Putnam’s analysis of natural kinds thus serves as a counterpart to Kripke’s analysis of proper names, solidifying the argument that science discovers the essential, necessary properties of things in the world.

Keith Donnellan (1931-2015) was an American philosopher of language whose work provided a steppingstone for Kripke’s attack on descriptivism. In his 1966 article “Reference and Definite Descriptions,” Donnellan introduced a distinction between the “attributive” and “referential” uses of definite descriptions, which challenged the unified theory proposed by Bertrand Russell. In an attributive use, a speaker asserts something about whoever or whatever satisfies a description (e.g., “The captain of the soccer team is tall”). In a referential use, a speaker uses a description to pick out a particular individual they have in mind, even if that individual does not actually fit the description.

Donnellan’s key insight is most famously illustrated by his “champagne” example. If a speaker at a party, pointing to a man holding a martini, says, “The man over there with the champagne in his glass is happy” (25), they have successfully referred to that specific man, even though the description is inaccurate. This shows that a speaker’s reference can succeed despite misdescription, undermining the theory that a name is synonymous with a description or that reference is determined solely by satisfying a description’s content. This separation of a speaker’s intended referent from the semantic content of the description used deviates from the Frege-Russell tradition.

Kripke builds on Donnellan’s insight to motivate his own distinction between what fixes a name’s reference and what constitutes its meaning. Donnellan’s work demonstrates that the primary function of a linguistic expression can be to pick out a specific object, with its descriptive content playing a secondary, and possibly erroneous, role. This prepares the ground for Kripke’s causal-historical picture, where the chain of communication, not a speaker’s internal descriptive beliefs, fixes reference. Donnellan’s analysis helps show why the descriptivist model is too rigid and fails to capture the pragmatic realities of how reference works.

Ruth Barcan Marcus (1921-2012) was an American logician and philosopher who made foundational contributions to quantified modal logic, the formal systems that allow modern discussions of necessity and possibility. Her work provides a logical backdrop for Kripke’s central theses in Naming and Necessity. In the 1940s, she developed the first formal systems of modal logic that included quantifiers, and in doing so, she formulated what became known as the “Barcan formula.”

Most significantly for Kripke’s project, Marcus proved from basic principles of modal logic that identity is a necessary relation. That is, for any objects x and y, if x is identical to y, then it is necessarily identical to y. This formal result anticipates and supports Kripke’s philosophical argument that true identity statements between rigid designators, such as “Hesperus is Phosphorus” (20), must be necessary truths. Marcus also proposed a “tag” theory of names, viewing them as labels for objects without descriptive content, which prefigures Kripke’s concept of rigid designation. Her work thus established the formal and conceptual groundwork that Kripke would later develop into a full-fledged theory of reference and metaphysical necessity.

Ludwig Wittgenstein (1889-1951) was an Austrian British philosopher whose later work, particularly in Philosophical Investigations (1953), heavily influenced mid-20th-century philosophy. He introduced the idea of “family resemblance” to argue that many concepts are defined by a loose, overlapping network of characteristic features. For example, there is no single property shared by everything we call a “game,” but rather a series of resemblances.

This idea provided the philosophical inspiration for the “cluster theory” of proper names, a more elaborate version of descriptivism that Kripke critiques. The cluster theory holds that a name like “Moses” is not associated with a single description but with a family of descriptions (e.g., “the man who led the Israelites from Egypt” or “the man who received the Ten Commandments”). The name refers to whoever satisfies a sufficient number of these descriptions. Kripke counters this Wittgenstein-inspired view, arguing that it still fails to account for the rigidity of names. He contends that an individual could fail to satisfy all the descriptions in the cluster and still be the referent of the name, making the cluster theory, like its predecessor, incorrect.