In Western thought, theories of consciousness have largely focused on four fundamental problems: What is consciousness? How are we to understand the causal relationships between consciousness and matter? What is the function of consciousness? And what forms of matter are associated with consciousness - for example, what are the neural substrates of consciousness in the brain?
Current theories about these issues have been influenced by ancient debates about the fundamental nature of the universe (ontology) and the ways it can be known (epistemology). Is the universe composed of one thing (monism)? Or are there two (dualism)? Does the world have an observer-independent existence (realism)? Or does its existence depend in some way on the operations of the mind (idealism)? Is knowledge of our own experience private and subjective rather than public and objective? If so, how can one make the study of consciousness into a science?
Answers to some of these questions require further empirical evidence, answers to others require theoretical advances, and some require both. For example, conventional cognitive and neuropsychological techniques might reveal the neural substrates of consciousness and the forms of information processing associated with consciousness. But questions about the fundamental nature, causal efficacy, and function of consciousness present paradoxes that need to be resolved. In everyday life, brain states and conscious experiences appear to have many causal influences on each other. However the 'objective' material of brains and the 'subjective' stuff of conscious experience seem to be so different that it is not easy to envisage how these might influence each other. Similarly, evolutionary theory suggests that consciousness must have a function, otherwise it would not have evolved to be so central in our lives. Yet, once one can specify how such functions work in information-processing terms, one no longer seems to need consciousness to explain them - the same processes might operate in mechanical or electrical systems without consciousness. What, then, does subjective experience add? These questions also interconnect. If one is not clear about what consciousness is, how can one develop methods to study it, or hope to find its neural substrates in the brain? Nor can questions about causal efficacy be dissociated from questions about function. If consciousness has no causal influence on neuronal activity, what could its function in the brain's activity be? Showing how these questions interconnect, and finding a path through the paradoxes is a requirement of any good theory of consciousness.
In Western thought, theories of consciousness broadly divide into dualism and monism. Dualism comes in interactionist and non-interactionist forms: consciousness and brain are distinct and either do or don't have causal interactions. Monism comes in reductionist and non-reductionist forms: consciousness is nothing more than brain (or vice-versa) or they are both aspects of something more fundamental. In the 20th Century the most commonly defended positions are "physicalism" and "functionalism" (consciousness is nothing more than a state or function of the brain). Neural correlates of consciousness undoubtedly exist in the brain, however no current reductionist theory provides an understanding of the phenomenology of consciousness. In the 21st Century, the challenge is to understand what this conscious phenomenology is and does.
Dr Max Velmans is reader in psychology at Goldsmiths College, London. Particularly interested in the exploration of consciousness from varied perspectives; teacher, writer and researcher in this area; changing scientific paradigms; therapeutic implications. Founder of the Mind/Body special interest group within the British Psychological Society. Extensive publications on consciousness, including the recent edited collection 'The Science of Consciousness'.
The list begins with a classic text and an overview of the field.
James, W (1890) The Principles of Psychology. New York: Dover. (Reprinted 1950) The source of much modern psychological theorising about consciousness, this early text remains a classic. James' "radical empiricism" included a study of all the things that one can experience, a description of the stream of consciousness, and links between consciousness memory and attention which, 100 years later, are still major topics of research.
Velmans, M (2000) Understanding Consciousness. London: Routledge. Much praised for its lucidity, balance and engaging style, this book reviews the strengths and weaknesses of all currently dominant theories of consciousness. It also introduces "reflexive monism", a new, nonreductive analysis of what consciousness is and does that is consistent with both science and common sense. Overall - a novel route to an ancient place.
An in-depth understanding of the major protagonists in the "international consciousness debate" requires a close reading of their writings. The following monographs sample from a range of positions that are currently influential. Searle and the Churchlands respectively defend emergent and reductive forms of "physicalism". Dennett and Baars respectively defend eliminative and non-eliminative forms of functionalism. Chalmers and Foster both attack reductionism and respectively defend "naturalistic" and "Cartesian" forms of dualism.
Searle, J (1992) The Rediscovery of the Mind, Cambridge Mass: MIT Press ISBN 0 262 6914X. Clear, engaging, and one of the best defences of "emergent physicalism" - the view that consciousness both emerges from neural activity and just is a macroproperty of the brain. Does not cope well with the problem that higher order physical properties of the brain do not resemble the properties of conscious appearances.
Churchland, Paul M. (1990) Matter and Consciousness. ISBN 0 262 53074 0 And Churchland, Patricia S. (1989) Neurophilosophy: Towards a Unified Science of the Mind and Brain. ISBN 0 262 53085 6 Both Bradford Books, MIT Press: Cambridge, Mass. These are well-written overviews of the problems of mind and consciousness intended to show that all problems of mind and consciousness will be resolved by neurophysiology. Both are good on the strengths of reductive materialism, but skate over its weaknesses.
Dennett, D. (1991) Consciousness Explained, Allen Lane: The Penguin Press ISBN 0 713 99037. This tries hard to argue that phenomenal consciousness does not exist although it seems to - only functions that we find it convenient to describe as "conscious" actually exist in the activities of brain. It attempts to translate all facts about what it is like to experience something into what it is like to do something. Cleverly written, but ultimately convincing only to zombies.
Baars, B. (1988) A Cognitive Theory of Consciousness, Cambridge: Cambridge University Press ISBN 0 521 42743 6. A cognitive psychological book that synthesises a large body of consciousness research into a "global workspace" model of the mind. Assumes consciousness to be nothing more than a form of information processing. Well-written, and integrative, although more fundamental questions surrounding the mind/body problem and the nature and function of phenomenal consciousness are ignored.
Chalmers, D. (1996) The Conscious Mind: In Search of a Fundamental Theory. New York and Oxford: Oxford University Press ISBN 00000000. Gives a strong case against reductionism, arguing that facts about consciousness are determined by (supervene on) functional relationships within any system without reducing to such relationships. Defends some implausible claims, for example, it tries to argue that all functioning has associated consciousness, with the consequence that unconscious processes in the brain are also conscious (but only to themselves). Clear, but complex, this book is written mainly for professional philosophers.
Foster, J. (1991) The Immaterial Self: A Defence of the Cartesian Dualist Conception of Mind. London: Routledge ISBN 0 415 02989 9. Not often cited as it defends an unfashionable position. Nevertheless, a well-argued case for not dismissing dualism as a tenable theory of consciousness and mind, with an accompanying attack on reductionist materialism.
The many variants of the above positions and the many issues addressed are best accessed through compendia and collections of readings. Useful ones include:
Guttenplan, S (ed) (1994) A Companion to the Philosophy of Mind, Oxford: Blackwell ISBN 0 631 19996 9. This takes the form of an encyclopaedia covering both topics and major philosophers, with position papers often written by the protagonists themselves. Has a good introductory overview by the editor. A useful resource for those interested in the philosophy of mind.
Vesey (ed.) G.N.A. (1970) Body and mind: Readings in philosophy. London: Allen & Unwin SBN 0 413 0014 9. A nice selection of some of the most important writings on consciousness and mind over the millennia by both philosophers and scientists. Particularly useful for those interested in tracing the antiquity of many, still current positions.
Hameroff, S., Kaszniak, A and Scott, A (eds) (1998) Towards a Science of Consciousness II: The Second Tucson Discussions and Debates, Cambridge, Mass.: MIT Press ISBN 0 262 08249 7. Sixty-four chapters selected from around 140 papers and 500 posters presented at a conference on consciousness held at the University of Arizona, Tucson in 1996. With contributions from psychology, philosophy, neuropsychology, artificial intelligence, parapsychology, physics and Eastern philosophy. Some good chapters and overall a nice illustration of the multidisciplinary nature of consciousness studies. Provides attractive ballast to one's coffee table.
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