Online research in philosophy

This article supplements our earlier paper on synaesthesia published in JCS (Ramachandran & Hubbard, 2001a). We discuss the phenomenology of synaesthesia in greater detail, raise several new questions that have emerged from recent studies, and suggest some tentative answers to these questions.

“Synaesthesia” is most often characterised as a union or mixing of the senses.i Richard Cytowic describes it thus: “It denotes the rare capacity to hear colours, taste shapes or experience other equally startling sensory blendings whose quality seems difficult for most of us to imagine” ([1995] 1997, 7). One famous example is of a man who “tasted shapes”. When he experienced flavours he also experienced shapes rubbing against his face or hands.ii Such popular characterisations are rough and ready. What is certainly true about synaesthesia is that it involves the interaction between sensory phenomena: in response to certain stimuli some sensory phenomena are elicited in synaesthetes that are not elicited in non-synaesthetes. However, the exact nature of the additional sensory phenomena forms a large part of the debate on the nature of synaesthesia. Synaesthesia is a condition that has been known about for some time. In the late nineteenth century, and early twentieth, century very many articles appeared on the topic in the psychological literature.iii Much of this work on synaesthesia relied on introspective reports of subjects. In consequence, when later in the twentieth century psychologists eschewed introspective reports and radical behaviourist methodology became the order of the day, synaesthesia was rarely a topic of research. In more recent times, however, psychology has once again changed tack. With the advent of cognitive psychology and of objective techniques that try to probe the nature of conscious states of the mind that are reported in introspection, psychological interest in synaesthesia has resumed. Many new findings about the subject have recently been brought to light. In philosophy, interest in synaesthesia is only just beginning to arise. The phenomenon is potentially philosophically interesting for several reasons..

Synaesthesia is considered a rare perceptual capacity, and one that is not capable of cultivation. However, meditators report the experience quite commonly, and in questionnaire surveys, respondents claimed to experience synaesthesia in 35% of meditation retreatants, in 63% of a group of regular meditators, and in 86% of advanced teachers. These rates were significantly higher than in nonmeditator controls, and displayed significant correlations with measures of amount of meditation experience. A review of ancient texts found reports suggestive of synaesthesia in advanced meditators from India and China. These findings suggest that synaesthesia may be cultivated by meditation, and that laboratory studies of meditators could be rewarding.

Gray argues that my three earlier counterexamples fail to refute representational theories of phenomenal character. I maintain that, despite Gray's arguments, each example does in fact work against the particular representational theory at which it is targeted. Further, I question whether my internalism regarding phenomenal character and Gray's externalism regarding modularity are in genuine conflict with one another.

Representationism¹, as I use the term, says that the phenomenal character of an experience just is its representational content, where that representational content can itself be understood and characterized without appeal to phenomenal character. Representationists seem to have a harder time handling pain than visual experience. (I say 'seem' because in my view, representationists cannot actually handle either type of experience successfully, but I will put that claim to one side here.) I will argue that Michael Tye's (2004) heroic attempt at a representationist theory of pain, although ingenious and enlightening, does not adequately come to terms with the root of this difference.

Fodor claims that cognitive modules can be thought of as constituting a psychological natural kind in virtue of their possession of most or all of nine specified properties. The challenge to this considered here comes from synaesthesia. Synaesthesia is a type of cross-modal association: input to one sensory modality reliably generates an additional sensory output that is usually generated by the input to a distinct sensory modality. The most common form of synaesthesia manifests Fodor's nine specified properties of modularity, and hence, according to Segal (1997), it should be understood as involving an extra module. Many psychologists believe that synaesthesia involves a breakdown in modularity. After outlining how both theories can explain the manifestation of the nine alleged properties of modularity in synaesthesia, I discuss the two concepts of function which initially motivate the respective theories. I argue that only a teleological concept of function is properly able to adjudicate between the two theories. The upshot is a further application of so-called externalist considerations to mental phenomena.

As Gert says, the basic claim of representationism is that the phenomenal character of an experience supervenes on its representational content. Restricted to color experience, representationism may be put as follows.

J. A. Gray et al. have recently argued that synaesthesia can be used as a counterexample to functionalism. They provide empirical evidence which they hold supports two anti-functionalist claims: disparate functions share the same types of qualia and the effects of synaesthetic qualia are, contrary to what one would expect from evolutionary considerations, adverse to those functions with which those types of qualia are normally linked. I argue that the empirical evidence they cite does not rule out functionalism, rather the reverse. The fact that the effects of synaesthesia are adverse shows that understanding synaesthetic experiences requires a concept of dysfunction, which in turn presupposes a functionalist account. Such an account, moreover, shows how tokens of the same types of qualia can be associated with different causal histories, thus disarming their first objection.

Wager has argued that synaesthesia provides material for a counterexample to representational theories of the phenomenal character of experience. He gives a series of three cases based on synaesthesia; he requires the second and third cases to bolster the doubtfulness of the first. Here I further endorse the problematic nature of the first case and then show why the other two cases do not save his argument. I claim that whenever synaesthesia is a credible possibility its phenomenal character can be understood in terms of misrepresentation.