Frank Jackson

Color is an incredibly controversial topic. Here is a sample of views taken seriously: colors are dispositions to look coloured; colors are physical properties of surfaces or of light; colors are properties of certain mental states, which get projected onto the surfaces of objects or onto reflected or transmitted light; colors are an illusion; colors are sui generis. One hopes to break the impasse by finding a compelling starting point—one drawing on obvious points that are common ground—which naturally evolves into the theory of color one likes. I start with remarks about the utility of having mental states with a phenomenology, remarks which are, I urge, non-controversial. I develop them into the theory of color I favor. According to it, colors are properties of objects as objective as their shapes. The final section explains how the theory handles the best argument for subjectivism about color.

David Lewis argues that believing something is self‐ascribing a property rather than holding true a proposition. But what is self‐ascription? Is it some new mysterious primitive? Is Lewis saying that every belief you have is about you? Several recent authors have suggested that, in the light of these questions, Lewis's theory should be rejected, despite its enormous influence. But this neglects the fact that Lewis makes two relevant proposals about belief: one about belief de se , another about belief de re . It is the second that prompts these questions but the first that is central to his theory.

Suppose that, for one reason or another, the knowledge argument fails as a refutation of physicalism. Even so, it remains the case that there is a pressing question for physicalists raised by the argument. Does Mary acquire old information or misinformation when she leaves the black and white room? Answering this question requires physicalists to address the tricky question of the informational content of colour experiences – what information do colour experiences deliver by virtue of being the kinds of experiences they are?

1. Reflecting on possible cases can be very valuable in differing ways. Sometimes it makes clear a consequence of a theory, a consequence that then plays an important role in debates about the theory. Utilitarians who favour maximising average happiness confront utilitarians who favour maximising total happiness with possible cases where there are enormously many sentient beings whose lives are barely worth living. Sometimes reflecting on possible cases serves to clarify a doctrine. Classical versions of consequentialism value equity for its good results; they don't value it per se. What this means is that in cases where we have two actions alike in the value of their consequences but differing in that one delivers a more equitable distribution, classical consequentialism treats the two actions as morally equivalent. Sometimes reflections on possible cases reveal relationships that are not immediately obvious. Take Galileo's famous thought experiment directed against the view that the heavier a body is the faster it falls in a vacuum. He describes a possible case where the only way to retain the view requires embracing independently implausible views about how various ways two bodies are connected to each other make a big difference to how fast the joined bodies fall. The thought experiment reveals a connection that might otherwise escape notice.This reminds us that we should not expect a uniform answer to the question, What role do thought experiments play? However, it is conventional wisdom that very often their role is to make trouble for one or another proffered conceptual analysis. Take two thought experiments that have been found especially compelling by the analytical philosophical community: Edmund Gettier's examples of true, justified belief, where the beliefs are true by some kind of fluke, and Ned Block's example of a being that makes ‘intelligent’ responses to the challenges the …