Chapter One Introduction
In recent decades， the research on language change has attracted a lot of attention in both functionalist and formalist circles， and one of the newly thriving branches under such a historical study on language change is termed grammaticalization， which focuses mainly on how grammatical categories rise in a language from certain linguistic expressions， usually content words， such as nouns and verbs (Meillet， 1912; Traugott， 1982; Traugott， 1995a， 1995b; Hopper & Traugottt， 2003; Sun & Traugott， 2011， etc.). Research on language change such as grammaticalization has also inspired a growing number of in-vestigations on the historical development of pragmatic markers and other similar linguistic items. However， problems begin to arise when previous scholars try to approach pragmatic markers as they have done to other lin-guistic items from the perspective of grammaticalization.