  The view that the status of E as normative evidence for H can depend upon considerations of background theory immediately raises questions about the status of the background theory itself. Given that one's background theory consists of some set of propositions, which set is it? Is it the set of propositions that one knows? Or rather, the set of propositions that one believes? Or perhaps, the set of propositions that one justifiably believes? It seems that E might count as evidence for H relative to the set of propositions that one believes but not relative to the set of propositions that one knows (or vice versa)—which of these, if either, determines whether E is evidence for H, in the sense that one's possession of E tends to justify one in believing that H is true? The issues that arise here are subtle and delicate; Christensen (1997) is a careful and illuminating discussion.