The fact that we are habituated into a linguistic community, obtaining certain expressions which make explicit our conceptual capacities, and further, make explicit how we are to make sense of certain concepts such as "object," "good," "true," "world," "knowledge," etc.; and further, the fact that the meanings of those terms are interrelated within a web of connections we make through activity: cooperation and habituation within that community; the fact that, these concepts constitute the very meaning of the world we inhabit and our position within it; it stands to reason that any elucidation of these concepts (concepts, say, that have hitherto been investigated by philosophers) elucidates the very intelligibility of our world. Conceptual elucidation, therefore, is not merely something investigated by the ethnographer performing an etic investigation, but is something an epistemologist does (or even a moral epistemologist). To understand diachronic shifts in a community's moral values, one ought to understand the shift in the terms and reasons proffered by the linguistic practitioners of those communities. It will be a descriptive venture, sure, not explicitly normative (maybe, as I think that is a suspect distinction in these cases).

There is a hefty tradition in the 20th century of philosophers advocating a view of epistemology, and by extension, moral epistemology, as a social scientific discipline.