Why are there so many labels for discourse markers?

There are many different labels used to refer to what in linguistics is probably most frequently termed ‘discourse markers’ (Schiffrin 1987, Fraser 1990, Stenström 1994, Swan 1995, Aijmer 1996, Biber et al. 1999). The aim of this paper is to contribute to the study of these markers, which are typical in particular of the spoken variety of language, namely by attempting to compare different approaches adopted by linguists in their investigations. In addition, the author’s tentative goal is to place the approaches applied into several groups according to their most relevant aspects and thus explain why so many different labels are used to denote the above-mentioned language phenomena. Since the author’s broader research is concerned with clausal forms such as you know, you see, I mean and I think, some of which can be considered discourse markers (cf. Schiffrin 1987, Stenström 1994, Swan 1995), she pays attention to these items, too, while searching for the most appropriate label