  Evidence, whatever else it is, is the kind of thing which can make a difference to what one is justified in believing or (what is often, but not always, taken to be the same thing) what it is reasonable for one to believe. Some philosophers hold that what one is justified in believing is entirely determined by one's evidence. This view—which sometimes travels under the banner of ‘Evidentialism’—can be formulated as a supervenience thesis, according to which normative facts about what one is justified in believing supervene on facts about one's evidence (See especially Conee and Feldman 2004). Thus, according to the Evidentialist, any two individuals who possessed exactly the same evidence would be exactly alike with respect to what they are justified in believing about any given question.