Definitions of consciousness need to be sufficiently broad to include all examples of conscious states and sufficiently narrow to exclude entities, events and processes that are not conscious. Unfortunately, deviations from these simple principles are common in modern consciousness studies, with consequent confusion and internal division in the field. The present paper gives example of ways in which definitions of consciousness can be either too broad or too narrow. It also discusses some of the main ways in which pre-existing theoretical (...) commitments (about the nature of consciousness, mind and world) have intruded into definitions. Similar problems can arise in the way a “conscious process” is defined, potentially obscuring the way that conscious phenomenology actually relates to its neural correlates and antecedent causes in the brain, body and external world. Once a definition of “consciousness” is firmly grounded in its phenomenology, investigations of its ontology and its relationships to entities, events and processes that are not conscious can begin, and this may in time transmute the meaning (or sense) of the term. As our scientific understanding of these relationships deepen, our understanding of what consciousness is will also deepen. A similar transmutation of meaning (with growth of knowledge) occurs with basic terms in physics such as "energy", and "time.". (shrink)

This review summarises why it is difficult for Darwinian evolutionary theory to explain the existence and function of consciousness. It then evaluates whether Humphrey's book Soul Dust overcomes these problems. According to Humphrey, consciousness is an illusion constructed by the brain to enhance reproductive fitness by motivating creatures that have it to stay alive. Although the review entirely accepts that consciousness gives a first-person meaning to existence, it concludes that Humphrey does not give a convincing account of how this can (...) arise from random variations in the genome. Nor does he demonstrate how first-person experiences might enter into or be reducable to third-person functioning. The review concludes that Humphrey's case is unconvincing, and goes on to suggest that an entirely different, non-reductive approach may be required to understand consciousness. (shrink)