Saul Kripke

Naming and Necessity, published as a book in 1980, argues that names are rigid designators rather than disguised descriptions. Kripke's lectures changed debates about reference, necessity, and possible worlds.

A rigid designator refers to the same object in every possible world where that object exists. Kripke used names such as Aristotle and terms such as water to challenge descriptivist theories of meaning.

Kripke developed possible-worlds semantics for modal logic while still very young. Kripke semantics became a standard tool for analyzing necessity, possibility, and related logical systems.

Kripke's 1982 book on Wittgenstein presents a skeptical problem about what makes someone mean one rule rather than another. The discussion is often called "Kripkenstein" because it combines Kripke's interpretation with Wittgenstein's Philosophical Investigations.