ABSTRACT
In his well-known paper, ‘What is it like to be a bat?’, Thomas Nagel argues that no purely “objective” description of the world — that is, no description equally accessible to observers, regardless of their points of view — could give us knowledge of what it is like to be a bat. Such knowledge, he argues, is available only to those who, unlike ourselves, are capable of having the experiences of bats. Therefore, he concludes, there are facts about the sub jective character of experience, e.g. what it is like to be a bat, that no physi calist, functionalist, or otherwise “objective” theory of mental states could adequately describe. 1
Frank Jackson, in his paper ‘Epiphenomenal qualia’, argues similarly, choosing an example that is closer to home. Jackson argues that Mary, a brilliant physicist and neuropsychologist who has grown up and pursued her career in a black-and-white environment, would clearly gain some knowledge about color and color-experience upon first viewing the world outside: she would come to know what it is like to see colors. Therefore, he concludes, “it is inescapable that her previous knowledge was incomplete. But she had all the physical information. Ergo there is more to have than that, and Physi calism is false. ” 2
It has been objected, however, that both arguments depend upon an equivocation. For the premises to be plausible, “knowledge of what it is like to be a bat” or “knowledge of what it is like to see colors” must be under stood as a kind of practical knowledge or ability: 3 in Nagel’s case, the ability to imaginatively project oneself into another’s point of view; in Jackson’s, an ability that is not so clearly defined. But the lack of such an ability, it is argued, is not the same as a gap in one’s theoretical knowledge, or knowledge of the facts. Further, there does not seem to be any important tie between these two sorts of knowledge, as it is hard to see why even the most com-
prehensive description of mental states should be expected to provide one with the practical abilities in question.4
