 The second type of approach views appearance beliefs as justified by something extrinsic to them, so that an appearance belief is justified when it is accompanied by acquaintance with the experiential fact that the appearance belief describes. Laurence BonJour (2003), for example, understands acquaintance in terms of constitutivity, though in a very different way from Chalmers. BonJour claims that awareness of the sensory content of an experience is partly constitutive of what it is to have a conscious experience. That awareness is thus infallible, but appearance beliefs—which purport to describe the experience and constituent awareness—are fallible.