Saul Kripke's Modal Logic and Philosophy

Saul Kripke, The Prodigy

Saul Kripke is hailed as the greatest living philosopher in the analytic philosophy tradition. He has made major contributions to the fields of logic, philosophy of language, modality, and truth (Carneades). His brilliance over the course of his career shows how and why this has been the case.

Kripke was born in 1940 in Long Island, New York, and was the child of a rabbi and a Jewish children's book author. He revealed his intellectual talents very quickly from a young age. For example he had taught himself ancient Hebrew by the age of six. By the age of nine, it was said that he had read all the works of Shakespeare and had begun to explore the works of Descartes (Carneades). For a child not yet in adolescence, this is of course astonishing. In time, Kripke would show how quickly his mind worked. Indeed, the next demonstration of his talent was when, before graduating high school, he wrote an incredibly impressive academic paper on modal logic. This paper was so impressive in the academic community that he was actually invited to teach in the mathematics department at Harvard. However, he declined, stating his mother believed he should finish high school first. That is just a quick synopsis of the tremendous talent that Kripke had as a young person.

He would go on to pursue an academic career. It was the case that while pursuing an undergraduate mathematics degree at Harvard, Kripke also taught graduate-level logic courses at MIT. He was academically sophisticated enough to be teaching higher level courses than he was taking, in other words. And so it should not be surprising to find that he later taught at Harvard, Rockefeller University, and, after giving a lecture series called "Naming and Necessity" at Princeton, he joined their faculty as well. Currently, he is a distinguished professor of philosophy at the City University of New York (Carneades).

Kripke had a significant impact on modal logic to say the least. In fact, the most basic axiom of modal logic is named "axiom k" after him (Carneades). He also developed the standard semantics for modal logic, known as "Kripke semantics." His work has become a framework for statements about possibility and necessity, as well as other types of modal logic like temporal, deontic, and epistemic logic.

It is worth noting that Kripke built upon the work of Alfred Tarski, proposing that truth is a partially defined predicate. This eliminated the need for a hierarchy of truth predicates, making his theory more intuitive than Tarski's.

Another accomplishment of Kripke is that he gave an influential reading of Wittgenstein's "Philosophical Investigations." In so doing, he admitted that his views might not align with Wittgenstein's, but his interpretation, which is often referred to as "Kripkenstein" (because it combines the approaches of Kripke and Wittgenstein in a new way that is neither wholly adherent to the usual approaches of either one respectively) presented a skeptical argument against interpretation and meaning.

Possibly his most renowned contribution is his series of lectures titled "Naming and Necessity" which looked at the applications of names and rigid designators across possible worlds. In that series, he argued against descriptivist positions, suggesting that names can identify a person (the same person) across all possible worlds irrespective of description. For example, the “Morning Star” and the “Evening Star” are the same (“Venus”). However, in connection with this idea, he also introduced the idea of a posteriori necessary truths, which are facts true in all worlds that can only be learned through experience (Carneades).