Wilfrid Sellars claims that a scientific account of human beings will find it necessary to postulate a new type of basic particular, which he calls sensa. It is not entirely clear what are the reasons for which Sellars makes this claim. Sellars makes this claim. This thesis seeks to answer this question, and subsequently to evaluate what it finds to be Sellars' argument for sensa. Three possible arguments are distinguished. The argument from the homogeneity of colours ls taken (...) to be Sellars' principal argument. A key premise this argument ls that colours, because of their ultimate homogeneity, cannot be reduced to complexes of scientific properties and relations. This premise involves a principle of reducibility which close scrutiny reveals to be more problematic than it initially appears. The conclusion ls that the argument for sensa fails because it relies on an unjustified application of the principle. (shrink)

In this paper I will present a puzzle about visual appearance. There are certain necessary constraints on how things can visually appear. The puzzle is about how to explain them. I have no satisfying solution. My main thesis is simply that the puzzle is a puzzle. I will develop the puzzle as it arises for representationalism about experience because it is currently the most popular theory of experience and I think it is along the right lines. However, everyone faces a (...) form of the puzzle, including the naïve realist. In §1 I explain representationalism about experience. In §§2-3 I develop the puzzle and criticize a response due to Ned Block and Jeff Speaks and another response based on a novel form of representationalism (“sensa representationalism”). In §4 I argue that defenders of “perceptual confidence” (Morrison, Munton, my earlier self) face an instance of the puzzle. In §5 I suggest that everyone faces a form of the puzzle. (shrink)