 The reader with prior acquaintance with the literature of linguistics will notice that we have not made reference to any partitioning of linguists into two camps called ‘empiricists’ and ‘rationalists’ (see e.g. Matthews 1984, Cowie 1999). We draw a different distinction relating to the psychological and biological prerequisites for first language acquisition. It divides nearly all Emergentists and Externalists from most Essentialists. It has often been confused with the classical empiricist/rationalist issue.