In the 1990s, the question started to emerge: Why are languages the way they are? And for that matter, why is natural language so different from all the artificial languages that have been invented for various purposes, inluding logic, computer programming, for better international understanding, as a substitute for natural language where this is impaired, and more? Chomsky suggested that this new reseach direction should be regarded as a program rather than a theory because it seemed to raise as many more questions as it gave answers to  previous questions.

At the same time, it was becoming apparent that one derivational category, namely what had originally been called ‘Deep structure’, and by the 1990s had come to be known as D-structure, was in fact unnecessary. This suggested that S-structures, originally known as ‘Surface structures’ were unnecessary too. The notion of government which had defined the relations between D-structures and S-structures could be eleminated at the same time. This elimination of three huge areas of research over a decade and more and the largely exploratory nature of the new thinking would seem to have very much dictated Chomsky’s title of a collection of papers in 1995 as The Minimalist Program.

Without contradicting the minimalist impulse, at least five new topics emerged,

• The notion of Merge, as an irreducible process in syntax, as the major innovation by the Minimalist Program;
• The division of Merge into two separate processes, External Merge and Internal Merge, as a way of eliminating the notion of movement;
• A notion of syntactic phenomena distributed across phases, hugely reducing the search and computation at any given point in the derivation;
• The notion of evolvability, as a new criterion of adequacy;
• The representation of Merge by Hopf algebra.

Again without seeking to compromise the minimalist agenda, by another line of inquiry there was a return to the traditional task of describing the grammar in greater and greater detail. This became known as cartography, as a sort of counterweight to minimalism.