ABSTRACT
The notion of rigidity, introduced by Saul Kripke in his 1970 lectures on Naming and Necessity, was at the origin of an important revolution in semantics. Kripke provided powerful arguments against the well-established descriptivist theory, a theory that postulated that names are in fact abbreviated definite descriptions. The notion of rigidity is introduced by Kripke to apply to singular terms, but Kripke also claimed that the distinction between rigid and non-rigid terms applies to at least some general terms. On the essentialist characterization of the rigidity of kind terms, a general term is rigid just in case it expresses a property that is essential to its bearers, where an essential property is taken to be a property an object cannot fail to possess if it exists. The essentialist characterization of rigidity treats natural kind terms as predicates. The essentialist characterization of rigidity privileges the predicative function of kind terms as the basic one.
