Joseph E. LeDoux (Harvard University Press)
John Parrington (Icon Books)
LAST month, two new books on consciousness added to the growing pile of literature on this contentious and difficult subject. One claims to give us a 鈥渘ew view of what makes us who we are鈥�; the other offers 鈥渁 radical new theory of human consciousness鈥�. Bold claims indeed, but do they succeed?
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The books are The Four Realms of Existence by Joseph E. LeDoux and Consciousness by John Parrington. Both authors take an evolutionary approach to the origins of language, thought and self, and survey research on perception, learning and memory in humans and other animals. Both are materialists: they try to fit consciousness into the physical world of living bodies and brains, where everything, including mental states and consciousness, results from material interactions between material things. Both deny that consciousness is terribly mysterious after all. But there the similarity ends.
LeDoux鈥檚 aim is to provide a new theory of being human by dividing our evolutionary past into four realms: biological at the bottom, then neurobiological, cognitive and conscious. Each transcends and depends on the one below, and most living things exist 鈥渙nly biologically鈥�, he writes. The integration of this ensemble is what makes humans who we are.
Along the way are excellent accounts of the evolution of brain structures and cognitive abilities. Exploring jellyfish that move and hunt without a brain, as well as the capabilities of flies, birds and mammals, LeDoux tries to place each in its realm. When it comes to cognition, he tells the fascinating story of 19th-century researchers like Hermann von Helmholtz and William James who grappled with consciousness, and how that was followed by behaviourism 鈥� the view that psychology should study only observable behaviours and events, not mind or consciousness 鈥� and how cognitive psychology broke free.
I learned much, yet I remain unpersuaded by LeDoux鈥檚 four realms. Among many previous schemes are the stages in The Major Transitions in Evolution by John Maynard Smith and Eors Szathmary (spanning life鈥檚 origins to human linguistic complexity). There are also those proposed by Daniel Dennett, who divided living beings into four ascending orders of intellectual complexity in his book . LeDoux doesn鈥檛 mention these, nor explain why his scheme is any better.
Parrington also tells an evolutionary tale, but his aim is to explain inner speech and thought, as well as the human capacity for self-conscious awareness. For him, the critical abilities are language and tool use. Seeking a materialist theory of the human mind, he claims to follow Charles Darwin in seeing the mind as produced by 鈥渢he same blind chance鈥� that guides the rest of evolution, which is distinctly odd because chance alone couldn鈥檛 account for exquisitely designed wings, eyes and brains. What Darwin saw was the power of natural selection.
Turning to consciousness, both authors mention the 鈥渉ard problem鈥� of explaining how subjective experience arises from the objective workings of a physical brain, but neither questions whether this is a soluble or well-posed question.
LeDoux lays the groundwork for his answer by describing the cognitive realm, but then seems to get confused. Briefly describing contemporary ideas such as integrated information theory and global workspace theory, he puts his money on higher-order theories, in which experiences are conscious only if re-represented or thought about. While he ably surveys which brain areas are responsible for what, such ideas rule out states like the psychedelic or deep meditation.
They also imply that since most other animals can鈥檛 sustain higher-order thoughts, they can鈥檛 be conscious. LeDoux doesn鈥檛 deny they might be, but says that 鈥渃onsciousness itself must be measured鈥� if we are to find out. In the current state of consciousness science, we have no idea whether 鈥渃onsciousness itself鈥� even exists, nor can we separate it from the functions of brain and behaviour 鈥� let alone measure it. While LeDoux has neither solved nor seriously questioned the validity of the hard problem, he is at least talking about subjective experience.
Parrington is not. Weirdly, although 鈥渃onsciousness鈥� is mentioned on almost every page, he doesn鈥檛 explain any of the major ideas about it or propose his own. His work is devoted to understanding the neural circuits involved in perception, action, behavioural control and self-modelling, and his goal is to develop 鈥渁 material explanation of human consciousness鈥�. He has done a great job of exploring material explanations of thought, perception, self-representation and behavioural control, but none of this gets at the deeper questions about subjective experience.
Are we humans different from other creatures? With his materialist understanding, Parrington puts the burden on human tool use and the inner speech other creatures lack. Yet he gives us no clue as to how inner speech can give us the ineffable experiences of the sky鈥檚 blueness, the smell of coffee, emotions of fear or sensations of hunger.
In consciousness studies, there have been three main ways of facing the hard problem. The first accepts the problem as valid but claims it is too hard and works instead on the 鈥渆asy problems鈥� of cognition, perception and so on. This, without admitting as much, is what Parrington has done.
The second approach also accepts the problem as valid and tries to explain how subjective experiences 鈥渁rise鈥� from brain processes. No one has succeeded in doing this, including these authors. The third way is to reject the idea that consciousness arises from brain activity. This is known as 鈥渋llusionism鈥�, which, in several guises, calls for the hard problem to be replaced with the 鈥渋llusion鈥� problem of how our false ideas about consciousness arise.
These two books have much to teach us about human cognition, brain structure and evolution, but, above all, they show how far consciousness studies has to go.
Susan Blackmore has written many聽books on consciousness. She聽is聽visiting professor at the University of聽Plymouth, UK
