In the 1990s, the question started to emerge: Why are natural human languages the way they are? Why do they differ in the way they do? And why do almost all, if not all languages, use the device of displacing elements, as English and many other languages do with words like where and what, pronouncing them on the left, and understanding them somewhere else, characteristically on the right, as shown by the answers to simple what and where questions?

And 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 eliminated 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.

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.