Keith Allen

What are hallucinations? A common view in the philosophical literature is that hallucinations are degenerate kinds of perceptual experience. I argue instead that hallucinations are degenerate kinds of sensory imagination. As well as providing a good account of many actual cases of hallucination, the view that hallucination is a kind of imagination represents a promising account of hallucination from the perspective of a disjunctivist theory of perception like naïve realism. This is because it provides a way of giving a positive characterisation of hallucination—rather than characterising hallucinations in negative, relational, terms as mental events that are subjectively indistinguishable from veridical perceptual experiences.

Variations in colour perception have featured prominently in recent attempts to argue against the view that colours are objective mind-independent properties of the perceptual environment. My aim in this paper is to defend the view that colours are mind-independent properties in response to worries arising from one type of empirically documented case of perceptual variation: variation in the perception of the «unique hues». §1 sets out the challenge raised by variation in the perception of the unique hues. I argue in §2 that the empirical findings are less dramatic than they might initially appear, and in §3 that accounting for the inter-personal differences is consistent with the view that colours are mind-independent properties that normal subjects veridically perceive, at least roughly speaking.

Ralph Cudworth (1617–1688) is a member of the group of philosophers and theologians commonly called ‘the Cambridge Platonists’. Although not part of the canon of great early modern philosophers, Cudworth’s work is of more than merely passing interest. Cudworth was an influential philosopher in the early modern period both for his criticisms of contemporaries like Hobbes, Descartes, and Spinoza, and for his own distinctive philosophical views. This entry focusses on Cudworth’s views on mind and body, considering both his criticisms of contemporaries’ theories of mind and body, and outlining his alternative form of dualism in which plastic nature plays a central role.

Inter-species variation in colour perception poses a serious problem for the view that colours are mind-independent properties. Given that colour perception varies so drastically across species, which species perceives colours as they really are? In this paper, I argue that all do. Specifically, I argue that members of different species perceive properties that are determinates of different, mutually compatible, determinables. This is an instance of a general selectionist strategy for dealing with cases of perceptual variation. According to selectionist views, objects simultaneously instantiate a plurality of colours, all of them genuinely mind-independent, and subjects select from amongst this plurality which colours they perceive. I contrast selectionist views with relationalist views that deny the mind-independence of colour, and consider some general objections to this strategy.