  Neither does mentalism entail accessibility internalism. It is a familiar point that not all of one's mental states are accessible, but that some are only brought to conscious awareness by medical procedures. Moreover, the example used earlier in which one gains a multitude of new justified beliefs in a rapidly changing perceptual context, all backed by a variety of sensory justifiers, strongly suggests that there will be many justifiers that will not be accessible via reflection even though they are mental states. So mentalism might well be correct even when accessibility internalism is not.