 There are at least two common ways of understanding the controversy. It is sometimes taken to be a controversy over whether or not one can identify epistemic properties with “internal” states of believers. According to the view we might call “internal state internalism” (sometimes called “mentalism”), justification is analyzed in terms of or depends essentially and only on what is inside the mind. It follows on this view that no two individuals can be internally or mentally alike in all respects and yet differ in the justification they have for the same beliefs. In one sense, then, to be an externalist (a non-mentalist) is to claim that one’s justification involves or depends essentially on some facts or states of affairs outside the mind. Others take the controversy to center over the question of whether one requires certain sorts of access for justification. The “access internalist” holds (roughly) that being justified in believing that P requires that there be something within or at least available to one’s perspective or awareness which is relevant to the truth or justification of P. (While some access internalists seem to have held that everything that determines justification must be accessible, as we are about to see, hardly any internalists hold such a strong position.) The “access externalist” denies that justification requires any such access. The access externalist need not deny that something relevant to the truth of P is, at least sometimes, accessible to the subject who has justification for P; but paradigm externalists deny that access is always required for justification.