What in an earlier post was characterized as “discourse-introductory so” should now receive a more expansive characterization in terms of REFERENCE, namely either to (1) what the speaker was/is thinking before beginning the utterance headed by so; or to (2) the content of an interlocutor’s utterance, to which the utterance headed by so is a retort.

This increasingly common discourse strategy in American English has an obvious binding and linking function, in that––for younger speakers in particular–– so has become an almost obligatory opening word without a strictly semantic function. It tends in fact to add little or nothing to the preceding or following content. In this respect it resembles the near-ubiquitous (and vacuous) word basically that one hears qualifying what would in earlier times be offered up without qualification.

MICHAEL SHAPIRO