How did Saul Kripke argue that proper names refer directly to the same object in every possible world?

In his influential work Naming and Necessity, Saul Kripke challenged the prevailing "description" theory of reference, which suggested that names function as shorthand for definite descriptions (e.g., "the teacher of Alexander the Great"). Kripke argued that such descriptions are not synonymous with proper names because their referents can change across different possible worlds—someone other than Aristotle could have been Alexander’s teacher.12

Instead, Kripke proposed that proper names are "rigid designators." He argued that once the referent of a name is fixed in the actual world—often through an initial "baptismal" event and maintained via a causal-historical chain of usage—the name must refer to that same object in every possible world in which the object exists. Because the referent remains constant regardless of the properties the individual might possess in different scenarios, the connection between the name and its bearer is direct rather than mediated by descriptive content. This framework fundamentally shifted the study of semantics and modal logic within analytic philosophy.12