<philosophical terminology> an expression that refers to the same thing in every possible world. According to Saul Kripke, proper names and terms that signify natural kinds (unlike definite descriptions) designate rigidly, so that we can make counterfactual assertions about their referents whether or not they exist in our world. Recommended Reading: Saul A. Kripke, Naming and Necessity (Harvard, 1982) and The New Theory of Reference - Kripke, Marcus, and Its Origins, ed. by Paul W. Humphreys and James H. Fetzer (Kluwer, 1999).
[A Dictionary of Philosophical Terms and Names]
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