(1) The evidence that is relevant in a proceeding is evidence that, if it were accepted, could rationally affect (directly or indirectly) the assessment of the probability of the existence of a fact in issue in the proceeding.
(2) In particular, evidence is not taken to be irrelevant only because it relates only to--(a) the credibility of a witness, or(b) the admissibility of other evidence, or(c) a failure to adduce evidence.