7. Altered states of consciousness

‘Altered states of consciousness’ discusses the states of consciousness during sleep, dreaming, hallucinations, out-of-body experiences, near-death experiences, meditation, and after taking psychoactive drugs. Psychologist Charles Tart defines an altered state of consciousness (ASC) as ‘a qualitative alteration in the overall pattern of mental functioning, such that the experiencer feels his consciousness is radically different from the way it functions ordinarily’. This certainly captures the idea of ASCs, but also creates problems, such as knowing what a ‘normal’ state is. In both mystical experiences and long-term meditation, people describe seeing through the illusions of duality and seeing the world as it truly is.

5. The self

Who—or what—am I? ‘The self’ shows that this question is intimately bound up with the problem of consciousness because whenever there are conscious experiences it is easy to assume they must be happening to someone; that there cannot be experiences without an experiencer. Philosopher Derek Parfit distinguishes between ego theories and bundle theories to try to sort out some of the confusion. Buddhism is the only major religion to reject the idea of a persisting self and therefore subscribe to bundle theory. The concepts of hypnosis, dissociation, and the default mode network are also discussed along with the theories of William James, Ramachandran, and Daniel Dennett.

4. A grand illusion

Is consciousness an illusion? If so, it isn’t that consciousness doesn’t exist, but that it isn’t what it seems. ‘A grand illusion’ considers change and inattentional blindness, challenging the way we think about our visual experiences. Traditional vision theories, with their detailed inner representations, cannot explain how or why those representations become conscious experiences or why we seem to be someone looking at those representations. Sensorimotor theory, proposed by psychologist Kevin O’Regan and philosopher Alva Noë, suggests vision means mastering sensorimotor contingencies. It turns the problem upside down, making the viewer into an actor and the visions into actions. This theory must now explain how actions can be subjective experiences.

2. The human brain

‘The human brain’ considers the brain as a vast network of connections from which come our extraordinary abilities: perception, learning, memory, reasoning, language, and somehow or another—consciousness. Different areas deal with vision, hearing, speech, body image, motor control, and forward planning. They are all linked, but this is not done through one central processor, but by millions of criss-crossing connections. By contrast, human consciousness seems to be unified. A successful science of consciousness must therefore explain the contents of consciousness, the continuity of consciousness, and the self who is conscious. Research linking consciousness to brain function is discussed along with conditions such as synaesthesia, blindsight, stroke damage, and amnesia.

8. The evolution of consciousness

‘The evolution of consciousness’ begins with two questions. First, which living creatures are conscious and in what way? Secondly, when and how did consciousness evolve? Consciousness could be an all-or-nothing phenomenon, with some creatures having it and others not. Or it might be a continuous variable, with some having more than others. Different theories of evolution of consciousness are considered alongside the function of consciousness. Why are we conscious at all? Is consciousness an adaptation or a useless by-product of some other adaptation? It concludes with the suggestion that consciousness is an enticing and compelling illusion that lures us into believing that our minds are separate from our bodies.

6. Conscious will

Do we have free will? ‘Conscious will’ considers this question and shows that the issue raises strong feelings because freedom implies responsibility. Part of the problem lies with determinism, which some philosophers accept is incompatible with free will. They argue that either determinism is false or free will must be an illusion. The timing of conscious acts, using the experiments of Benjamin Libet, and psychologist Daniel Wegner’s theories on the illusion of conscious will are discussed. Even if free will is an illusion, it is a very powerful illusion and so the feeling of being free carries on, especially for those people who fear that society would collapse without it.

3. Time and space

‘Time and space’ discusses a range of experiments and theories of consciousness including neuroscientist Benjamin Libet’s ‘half second lag’ and the ‘cutaneous rabbit’ illusion, dualism, ‘higher-order thought’, varieties of global workspace theory (GWT; proposed by psychologist Bernard Baars in the 1980s), and Daniel Dennett’s ‘multiple drafts theory’. GWTs have been popular and influential, but can be interpreted in different ways: items ‘become conscious’ by virtue of being broadcast, and a previously unconscious item becomes a subjective experience; or nothing changes and the broadcast is all there is. There is obviously something we call ‘consciousness’ that demands explanation. But is it really the unified stream of experiences we think it is?

1. Why the mystery?

What is consciousness? What does it do? Could we have evolved without it? ‘Why the mystery?’ considers the definition of consciousness and how psychologists, neuroscientists, and philosophers have tried to explain it. From the Cartesian dualism of René Descartes to the ‘hard problem’ of consciousness, a phrase coined in 1994 by the Australian philosopher David Chalmers, and the question ‘What is it like to be a bat?’ of American philosopher Thomas Nagel, it is shown that there is no generally agreed definition of consciousness. Subjectivity (or phenomenality), qualia, and the ideas of philosopher Daniel Dennett are also discussed.