 How is the liberal to establish this? Nagel (1987) endorses what he calls ‘epistemological restraint,’ which holds that it can be reasonable for an individual to hold certain beliefs yet simultaneously unreasonable to attempt to decide matters of public policy on the basis of such beliefs. Such beliefs, which tend to be moral or religious in nature, are said to be viewed differently from the inside (from which standpoint they have perfect authority) than from the outside (from which standpoint they are regarded as questionable). The difficulty, as Barry (1995) and Raz (1990) have pointed out, is to explain why doubts visible from the outside would not infect the internal point of view, thus weakening these beliefs’ internal authority as well. (It should be noted that Nagel himself has expressed doubts about this argument; see Nagel 1991.)