c r a

ch O u orof consciousness, in spite of the valiant endeavours of numerous groups and individuals. Various models of the neural bases of consciousness of differing levels of specificity have been proposed; none has gained universal acceptance. This difference of opinion has a variety of causes, among these being (a) The nature of consciousness itself has not been universally agreed upon; (b) The manner in which objective experimental results can indicate how subjective experience is created appears still a difficult bridge to cross (the old London Underground adage for passengers to ‘mind the gap ’ springs to mind here); (c) There has been considerable debate in the past about the possible usefulness of consciousness. With no clear function agreed on, the nature of any explanation is not yet properly tied down to suitable functional ground truth. As noted under (a), the nature of consciousness is still unclear. The epiphenomenal (dualist) approach to the topic posits that consciousness floats above the material world on a parallel dynamic track to the grinding machinery of the physical to do something does not seem to be irrelevant, yet would seem to be so according to the strict dualist thesis. Moreover the ability of a person when unconscious, such as under the influence of anaesthetic, is considerably reduced, especially in any purposive manner. This implies that consciousness plays an important role in decision making, although exactly what is unclear; that uncertainty does not seem clarified by the dualist (nor presently any other) approach. The alternative to dualism is some form of physicalism: all is based on the physical activity of the brain. The other extreme possibility of mentalism, that all is mind, is not able to bear the weight of advances in the physical sciences. For example grand unified gauge theories of matter and the discovery of the W and Z mesons are infinitely more precise and involve energies and distances completely remote from the normal human range. In physicalism, various levels of dependence on brain activity have been posited. These go from supervenience (a very limited form of dependence on the physical) to out-and-out physicalism (brain activity somehow describes every aspect of inner experience). We will assume this latter approach here,Neural Networks 20 (