This book presents a controlled evaluation of three widely practised syntactic theories on the basis of the extremely complex agreement system of Archi, an endangered Nakh-Daghestanian language. Even straightforward agreement examples are puzzling for syntacticians because agreement involves both redundancy and arbitrariness. Agreement is a significant source of syntactic complexity, exacerbated by the great diversity of its morphological expression. Imagine how the discipline of linguistics would be if expert practitioners of different theories met in a collaborative setting to tackle such...