Taking an effective authorial stance in research argumentation has been designated as both vitally important and challenging. The study investigated English as a foreign language (EFL) doctoral students' conceptions of authorial stance, the role of domains in affecting their conceptions, and the ties of the conceptions to the participants' epistemic beliefs, given that both assume a continuum of parallel values (from absolutist perspectives/assertive claims to evaluatist perspectives/tentative claims). Twenty EFL doctoral students were recruited from two disciplines, social science and pure science, for interviews and the judgment of texts. The results revealed that, while more often the participants discussed stance relevantly from a linguistic angle, their conceptions were rather superficial and polarized. Their conceptions were also affected by their disciplinary assumptions. Their epistemic beliefs, however, were quite mature, incompatible with their imprecise conceptions of stance, which may be used to novice research writers' advantage to inform and guide their learning of authorial stance.