‘The definitive version is available at http://www3.interscience.wiley.com '. Copyright The Aristotelian Society. DOI: 10.1111/1467-8349.00031 [Full text of this article is not available in the UHRA]In this paper I introduce and critically examine a paradox about perceiving that is in some ways analogous to the paradox about meaning which Kripke puts forward in his exegesis of Wittgenstein's views on Rule-following. When applied to vision, the paradox of perceiving raises a metaphysical scepticism about which object a person is seeing if he looks, for example, at an apple on a tree directly in front of him. Physical objects can be seen when their appearance is distorted in various ways by illusions. The question therefore arises as to how c...