I agree with @aeismail regarding the subdiscipline, as those are very localized, but I'm wondering whether we should relax this for broad disciplines (i.e. mathematics, history, political science, etc). Note that we already allow questions specific to a single location; many approve of that, with no negative feedback on that at all. On the other hand, we have also agreed that university-specific questions are too specific (I couldn't find a link for that one, but that's how we tend to vote). I don't see how disciplines are different from locations in that respect.
As an example, this question was flagged as off-topic. While I agree it's argumentative, using the above argument it's sufficiently broad to be relevant to many users, and with a simple edit it could be quite useful.