Rigid Designator - Essentialism

Essentialism

In Naming and Necessity, Kripke argues that proper names and certain natural kind terms—including biological taxa and types of natural substances (most famously, "water" and "H₂O") designate rigidly. He argues for a form of scientific essentialism not unlike Aristotelian essentialism. Essential properties are common to an object in all possible worlds, and so they pick out the same objects in all possible worlds - they rigidly designate.