What is the difference between a filler word and a discourse marker?

Question

What is the difference between a filler and a discourse marker? There are words that seem fall into both categories.

The Wikipedia article on the latter is sparse and lacks examples, but what it does say on the matter is:

Traditionally, some of the words or phrases that were considered discourse markers were treated as "fillers" or "expletives": words or phrases that had no function at all. [...]

And then goes into linguistic jargon. What is the difference between the two groups? Can the difference be explained to someone without an education in linguistics?

Answer 1

I would say that filler words are one sort of discourse marker, but the former term is less well defined and less consistently used than the latter. The sense that I consider most central is epitomized in English by "um" or "like": a sound that indicates that the speaker is not currently emitting content, but will presently do so, and wishes to retain the floor. ("like" is usually used to fill a much shorter gap, but the usage is otherwise quite similar)

Other discourse markers can impart some connotative nuance to an utterance - the difference between the connectives in "He's a programmer, [and/but] he likes poetry" don't distinguish any denotational sense, but the contrast does convey two greatly differing sets of beliefs (real or adopted for effect) about programmers and poetry.

Answer 2

Discourse markers are really just a catch all term for all the different lexical ways of making text (discourse) hold together beyond the level of the clause. As all linguistic categories (including nouns and verbs) the discourse marker category has fuzzy boundaries and is subject to prototype effects, family resemblances (and the like) - sort of like Lakoff's radial categories. Which is why it is hard to find an easy definition that would include all the things that look like discourse markers and exclude those that don't. But ultimately it's not all that important. What's important is that all those little words that are hard to categorize play an important role.

Words that are often called 'fillers' (like, so, uhm, etc.) are a type of discourse marker that is used to manage attention, conversation turn taking, or just the flow of the speakers speech, work together with intonation and other non-segmental elements. Whether you call them fillers, discourse markers or something else is less important than it is to recognize the role they play in speech or writing.