  Some philosophers associated with the disjunctive theory of perception are simply concerned to argue that certain common element claims lack adequate justification, thereby leaving us free to resist arguments about perception that depend upon such claims in their premises. For example, Paul Snowdon, one of the philosophers most associated with disjunctivism, appeals to the possibility of a disjunctive approach to perceptual experience in order to undermine an argument for a thesis about our concept of perception. According to the thesis that Snowdon aims to challenge it is a conceptual requirement that, necessarily, if S (a subject) sees O (an object) then O is causally responsible for an experience undergone by (or had by) S. This thesis has been labelled the Causal Theory of Perception (henceforth it will be referred to as the CTP).