Viewed from a certain perspective, nothing can seem more secure than introspection. Consider an ordinary conscious episode—say, your current visual experience of the colour of this page. You can judge, when reflecting on this experience, that you have a visual experience as of something white with black marks before you. Does it seem reasonable to doubt this introspective judgement? Surely not—such doubt would seem utterly fanciful. The trustworthiness of introspection is not only assumed by commonsense, it is also taken for granted by many of theorists about the mind. Within both philosophy and the science of consciousness it is widely held that introspection is generally reliable, at least with respect to the question of one’s current (or immediately prior) conscious states. Without this assumption, we could not make sense of theorists’ widespread use of introspection, both in support of their own position and to undermine that of their opponents.