Appearances and Illusions

Abstract

This paper deals with the nature of perceptual appearances. It argues that they are objective relational properties of external objects. In perceptual experience, we are acquainted with such appearances. These are not sense data, as usually understood, and they are not identical to the properties we attribute to external objects through the usage of qualitative concepts such as ‘red’, ‘square’ and ‘sweet.’ We use such concepts in order to describe properties that are manifest in perception, not in order to describe appearances. One and the same property, such as the bent shape of a stick, can appear in different ways in different contexts. None of those ways is more or less appropriate, because things simply appear the way they do. The choice of a certain context determines the normal conditions for the possession of qualitative concepts. Standard perceptual illusions are perceptual experiences. They mislead us, not because they are incorrect, but because they prompt us to use concepts that are not appropriate under the obtaining conditions.