Nick Unwin

It is very natural to wonder if other people see colours in the same way as we do (for example, that you see red where I see green, and vice versa), for there is no obvious way of telling one way or the other. The hypothesis of inverted qualia, in particular of inverted colour hues, goes back at least as far as the Cyrenaics, and is still a major topic of philosophical investigation. There are several reasons for this. Sometimes, the hypothesis is used to argue for a general scepticism about other minds. Sometimes, it is used to argue against functionalist analyses of mental concepts. My suggestion is that its most important philosophical purpose concerns explanation: in particular the explanation of why colours actually look the way they do. This is a scientific-cum-philosophical task of considerable importance in its own right, and it does not require us to take sceptical hypotheses unduly seriously, or to provide alternative analyses of mental concepts.

Properties and concepts are similar kinds of thing in so far as they are both typically understood to be whatever it is that predicates stand for. However, they are generally supposed to have different identity criteria: for example, heat is the same property as molecular kinetic energy, whereas the concept of heat is different from the concept of molecular kinetic energy. This paper examines whether this discrepancy is really defensible, and concludes that matters are more complex than is generally thought. The distinction between canonical and non-canonical designators, as applied to such entities as propositions, properties and concepts, is examined, as are causal realist accounts of the semantics of such terms as ‘electricity’ and ‘mass’.

The question of whether it is permissible to quantify into a modal context is re-examined from an empiricist perspective. Following Wiggins, it is argued that an ontology of continuants implies essentialism, but it is also argued, against Wiggins, that the only conception of necessity that we need to start out with is that of analyticity. Essentialism, of a limited kind, can then be actually generated from this. An exceptionally fine-grained identity criterion for continuants is defended in this context. The debate between Wiggins and Ayer over the legitimacy of de re modality is then examined in the light of these results, and it is argued that my position is consistent with Ayer’s minimalist assumptions. It is also argued that non-continuants will not sustain the essential/accidental distinction, thus giving some concessions to the sceptics. It is also shown that there are close connections between these issues and the more modern two-dimensionalist way of disentangling the necessary from the a posteriori, and that the latter needs to learn from the former.

It is argued that it is very hard to analyse causation in such a way that prevents everything from causing everything else. This is particularly true if we assume that the causal relation is transitive, for it all too often happens that causal chains that we wish to keep separate pass through common intermediate events. It is also argued that treating causes as aspects of events, rather than the events themselves, will not solve this problem. This is because aspects have to be highly disjunctive, and disjunctive conditions tend to undermine causal connections, a fact that is most clearly seen when causation is analysed in terms of INUS conditions. It is concluded that reductive analyses of causation do not work, and that transitivity can only be guaranteed in cases where the elements of the causal chain constitute an independently understood causal process

It is often claimed, following Joseph Levine, that there is an ‘explanatory gap’ between ordinary physical facts and the way we perceive things, so that it is impossible to explain, among other things, why colours actually look the way they do. C.L. Hardin, by contrast, argues that there are sufficient asymmetries between colours to traverse this gap. This paper argues that the terms we use to characterize colours, such as ‘warm’ and ‘cool’, are not well understood, and that we need to understand the neurological basis for such associations if we are even to understand what is fully meant by saying, for example, that red is a warm colour. This paper also speculates on how Hardin’s strategy can be generalized. A PowerPoint presentation that depicts inverted colour qualia is attached as an appendix.

A major part of the mind–body problem is to explain why a given set of physical processes should give rise to perceptual qualities of one sort rather than another. Colour hues are the usual example considered here, and there is a lively debate as to whether the results of colour vision science can provide convincing explanations of why colours actually look the way they do. The internal phenomenological structure of colours is considered here in some detail, and a comparison is drawn with sounds and their synthesis. This paper examines the type of explanation that is needed, and it is concluded that it does not have to be reductive to be effective. What needs to be explained more than anything is why inverted hue scenarios are more intuitive than other sensory inversions: and the issue of physicalism versus dualism is argued to be of only marginal relevance