According the Lockean view, it is justified to believe P iff it’s rational to have a high credence in P. A theory of degrees of justification fits this view well: the degree to which one is justified in believing P is one’s rational credence in P. On that theory degrees of justification obey the probability axioms. I give reasons to prefer an alternative, the “probable knowledge” view, according to which it is justified to believe P iff it’s rational to have a high credence that one knows P (or is in a position to know P). A theory of degrees of justification fits that view well: the degree of which one is justified in believing P is one’s rational credence that one knows (or is in a position to know) P. On that theory, degrees of justification typically violate the probability axioms. I explore their shape; in particular, I show that under the assumption that knowledge obeys the normal logic KT, degrees of justification turn out to be Belief functions (aka Dempster-Shafer belief functions).
Oxford Epistemology Group, 12.30pm-2pm. A weekly seminar of visiting speakers, work-in-progress talks, and discussion of recent work in epistemology, for faculty and graduate students. Please email Nick Hughes to be added to the mailing list.
Oxford Epistemology Group Convenor: Nick Hughes