The universal structure of categories : towards a formal typology Using data from a variety of languages such as Blackfoot Halkomelem and Upper Austrian German this book explores a range of grammatical categories and constructions including tense aspect subjunctive case and demonstratives. It presents a new theory of grammatical categories the Universal Spine Hypothesis and reinforces generative notions of Universal Grammar while accommodating insights from linguistic typology. In essence this new theory shows that language specific categories are built from a small set of universal categories and language specific units of language. Throughout the book the Universal Spine Hypothesis is compared to two alternative theories the Universal Base Hypothesis and the No Base Hypothesis. This valuable addition to the field will be welcomed by graduate students and researchers in linguistics