Generative semantics is the name of a research program within linguistics, initiated by the work of various early students of Noam Chomsky: John R. Ross, Paul Postal, and later James McCawley. George Lakoff and Pieter Seuren were also instrumental in developing and advocating the theory.
The approach developed out of transformational generative grammar in the mid-1960s, but stood largely apart from, and in opposition to, work by Noam Chomsky and his later students. This move led to a more abstract framework and lately to the abandonment of the notion of the CFG formal grammar induced deep structure.
A number of ideas from later work in generative semantics have been incorporated into cognitive linguistics, head-driven phrase structure grammar (HPSG), construction grammar, and into mainstream Chomskyan linguistics.
The nature and genesis of the program are a matter of some controversy and have been extensively debated. Generative semanticists took Chomsky's concept of deep structure and ran with it, assuming (contrary to later work by Chomsky and Ray Jackendoff) that deep structures were the sole input to semantic interpretation. This assumption, combined with a tendency to consider a wider range of empirical evidence than Chomskyan linguists, led generative semanticists to develop considerably more abstract and complex theories of deep structure than those advocated by Chomsky and his students—and indeed to abandon altogether the notion of "deep structure" as a locus of lexical insertion.