Philosophers tend to be pretty impressed by human self-knowledge. Descartes (1641/1984) thought our knowledge of our own stream of experience was the secure and indubitable foundation upon which to build our knowledge of the rest of the world. Hume – who was capable of being skeptical about almost anything – said that the only existences we can be certain of are our own sensory and imagistic experiences (1739/1978, p. 212). Perhaps the most prominent writer on self-knowledge in contemporary philosophy is Sydney Shoemaker. The central aim of much of his work has been to show that certain sorts of error are impossible (1963, 1988, 1994). David Chalmers has likewise attempted to show that, for a suitably constrained class of beliefs about one’s own consciousness, error is impossible (2003, sec. 4.1). Even philosophers most of the community thinks of as pessimistic about self-knowledge of consciousness seem to me, really, to be fairly optimistic. Paul Churchland, famous for his disdain of ordinary people’s knowledge about the mind, compares the accuracy of introspection to the accuracy of sense perception – pretty good, presumably, about medium-sized, nearby matters (1985, 1988). Dan Dennett, often cited as a pessimist about introspective report, actually says that we can come close to infallibility when charitably interpreted (2002). The above references concern knowledge of the stream of conscious experience, but philosophers have also tended to be impressed with our self-knowledge of our attitudes, such as our beliefs and desires. Consider this: Although I can be wrong about its being sunny outside, I can’t in the same way be wrong, it seems, about the fact that I think it’s sunny outside. Some...