It draws on a number of philosophical concepts such as necessity, the causal theory of reference, rigidity, and the a priori–a posteriori distinction.
It was first introduced by philosopher Saul Kripke in his 1970 series of lectures at Princeton University.
The transcript of these lectures was then compiled and assembled into his seminal book, Naming and Necessity.
[2] A posteriori necessity existing would make the distinction between a prioricity, analyticity, and necessity harder to discern because they were previously thought to be largely separated from the a posteriori, the synthetic, and the contingent.
Hilary Putnam comments on the significance of Kripke's counter-examples: "Since Kant there has been a big split between philosophers who thought that all necessary truths were analytic and philosophers who thought that some necessary truths were synthetic a priori.