Abstract

The possibility that what looks red to me may look green to you has traditionally been known as "spectrum inversion." This possibility is thought to create difficulties for any attempt to define mental states in terms of behavioral dispositions or functional roles. If spectrum inversion is possible, then it seems that two perceptual states may have identical functional antecedents and effects yet differ in their qualitative content. In that case the qualitative character of the states could not be functionally defined.