The chain of communication is Kripke’s alternative to the description theory of names, proposing that a name refers to an object through a historical, social process rather than through a speaker’s private descriptive beliefs. This process begins with an initial “baptism,” where an object is given a name either by ostension or through a reference-fixing description. The name is then passed from speaker to speaker, with each new user intending to preserve the reference of the person from whom they learned it. As Kripke illustrates, “the name is spread from link to link as if by a chain” (91). This model explains how a person can successfully refer to a historical figure despite having minimal or even inaccurate knowledge about them.

The speaker’s reference is secured by their connection to a community of speakers that traces back to the referent itself, not by their ability to provide a uniquely identifying description. This causal-historical picture is more robust than descriptive theories, accounting for reference despite widespread misinformation (as in the Gödel-Schmidt case) and avoiding the circularity inherent in descriptions that rely on the community’s beliefs. While the chain preserves reference, Kripke notes that it can be intentionally broken or overridden by the social function of language, as in cases where a name like “Madagascar” shifts its reference from a part of the African mainland to an island due to a widely adopted error, as noted in the Addenda.

Essential properties are those attributes that an object could not possibly lack. In Naming and Necessity, Kripke defends the meaningfulness of this concept, arguing that we can intuitively and coherently ask what must be true of a particular individual or object across all counterfactual situations. This revindicates de re modality, or necessity that applies to things themselves, independent of how they are described. Kripke moves beyond abstract defense to propose specific kinds of essential properties, most notably the necessity of origin. For a person, this means they could not have originated from a different sperm and egg.

This principle extends to material objects, as well. Kripke argues that a particular wooden table could have had a different history, but it could not have been made from a completely different block of wood or another substance like ice. The object’s origin is a core part of its identity. As he posits, “If a material object has its origin from a certain hunk of matter, it could not have had its origin in any other matter” (114). Such essential properties are not known a priori since an object’s origins are determined empirically. However, once discovered, these facts are understood to be metaphysically necessary truths about that specific object, further illustrating the distinction between epistemology and metaphysics.

This distinction is a central tool that Kripke uses to dismantle the description theory of names and explain the function of rigid designators. To fix a reference is to use a description to identify the object a term will refer to, while to give a meaning is to make the term synonymous with that description. Kripke’s primary example is the standard meter. If one stipulates that “one meter” is the length of a specific bar, S, in Paris at a given time, this act fixes the reference of the term “one meter” to that specific length. It does not, however, make “one meter” mean “the length of stick S” (54). This is because the statement “Stick S is one meter long” expresses a contingent truth (54); the bar could have been heated and expanded. The term “one meter” rigidly designates a specific length, while the description used to identify it does not. This model shows how a contingent property can establish the reference for a rigid term without becoming part of its meaning.

Kripke extends his analysis of proper names to terms for natural kinds, such as “gold,” “water,” or “tiger.” He argues that these terms function like rigid designators for kinds, species, or substances, which are identified by their underlying essential structure. Just as a proper name refers to a specific individual, a kind term refers to a specific kind. As Kripke states, “[T]erms for natural kinds are much closer to proper names than is ordinarily supposed” (127). For example, “gold” rigidly refers to the element with atomic number 79. A substance with all the surface properties of gold (yellowness, malleability) but a different atomic structure, like iron pyrites, would be “fool’s gold,” not a different kind of gold, nor does the existence of fool’s gold undermine the existence of gold.

This understanding recasts major scientific discoveries as necessary truths. The statement “Water is H₂O” is a theoretical identity that expresses a necessary fact about the essence of the substance we call water. Before this discovery, the reference of “water” was fixed by observable properties like being clear, tasteless, and liquid. However, once science revealed its molecular structure, that structure is understood to be the essence of what water is in any possible world. These identities are known a posteriori, but they state what is metaphysically necessary, providing a key class of examples for Kripke’s category of the necessary a posteriori.