Life Emergent (MIT Press, 2002) Or Myself in Mind in Life (Harvard University Press, 2007)

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PHILOSOPHY But Incomplete Nature has shortcomings. Deacon doesn’t discuss other theorists who have given similar accounts of life and mind, such as Alicia Juarrero in Dynamics in Action Life emergent (MIT Press, 2002) or myself in Mind in Life (Harvard University Press, 2007). He also sometimes overemphasizes the differences Evan Thompson weighs up a treatise that explores the between his views and those of the theorists dynamics of matter and consciousness. he does cite. Deacon stumbles at two crucial junc- tures — his explanations for the emergence ow is mind — cognition and that self-assemble into of meaning and for the emergence of con- consciousness — related to bio- a container that then sciousness. The problem of meaning is the logical life? Current thinking in houses those reactions. problem of how it is possible for certain Hcognitive science suggests that living and Again, the absence physical phenomena, such as brain states, cognitive systems share basic organizational on which the system to have content or to be ‘about’ something properties, such as being autonomous or depends is the other beyond themselves. self-producing and self-sustaining. Anthro- ways in which the mol- Deacon’s answer is not easy to decipher. pologist Terrence Deacon’s Incomplete Nature ecules could have been Roughly, he seems to be saying that certain is a welcome contribution to this field. distributed. states of a self-generating system acquire Deacon draws on thermodynamics, com- Such self-generat- Incomplete content when they correlate reliably with Nature: How Mind plex-systems theory and biology to show how ing systems, for Dea- Emerged from features of the environment that are useful we can understand the characteristics of mind con, already have a Matter to that system. For example, a system that in relation to life, and those of life in relation minimal kind of self. TERRENCE W. DEACON needs molecules from the environment in to inanimate matter, without losing sight of Multicellular organ- W. W. Norton: 2011. order to reproduce ‘interprets’ the pres- their continuity. He plots the ways in which isms have a more 624 pp. $29.95, ence of these molecules as meaning that the non-living physical systems can self-organize complex bodily self £19.99 environment is conducive to reproduction. and evolve into living systems, and how living than these systems, But this seems little more than metaphorical. systems can evolve into cognitive systems. and animals with brains have a cognitive As many philosophers have shown, meaning Deacon takes his guiding idea from self because the brain must constantly rep- cannot be reduced to such processes. one of my favourite chapters of a classic resent its own ongoing activity in relation With consciousness, Deacon says that Chinese philosophical text from the fourth to the body and to the outside world. As sentience — the capacity to feel — arises century bc, the Tao Te Ching: “Pots are Deacon unfolds this narrative, he provides from a system being self-sustaining and fashioned from clay/But it’s the hollow that perceptive accounts of key notions, such as goal-directed. So he sees individual cells as makes a pot work.” Similarly, Deacon sees information and emergence — how com- sentient. But, as he explains, an animal’s sen- the ‘constitutive absence’ as functional, a plex systems arise from many comparatively tience is not the sum of the sentience of its defining property of life and mind. Living simple interactions. individual cells: the nervous system creates things are dynamically organized around its own sentience at the level of the whole ends, such as finding nourishment; and animal. Yet Deacon doesn’t get to grips with minds are dynamically organized around the hard problem of explaining why and meanings, such as anticipated future events. how we and other animals have conscious And like the hollowed interior of the pot, experience. these ends and meanings are both functional Simply pointing to the neural activity asso- S. CAMAZINE/SPL and absent, in the sense that they affect a sys- ciated with sentience is not enough to answer tem’s behaviour, yet are not material parts this question. What we need to know is why of it. this activity feels pleasant or painful to the This idea leads Deacon to offer a new twist animal, instead of being an absence of feeling. on theories of how inanimate matter can In my view, Deacon’s error is not that he has self-organize and evolve to become living, no answers to such questions (no one does), and how living systems can evolve to become but that he fails to recognize them. cognitive. To reflect absence, he introduces On the empirical side, Deacon’s discussion the concept of constraints in a dynamical also falls short. He doesn’t explore the neuro system. For example, water molecules heated science literature showing how large-scale in a pan organize into rotating convection brain activity is related to consciousness, and cells, with their motions constrained by the makes no use of writings that relate these geometry of the cells. In this system, absence findings to how we experience emotion, is the variety of alternative paths the water time and the self. molecules could have taken. Yet the system, Although incomplete in these ways, Deacon says, depends on their absence. Incomplete Nature contains many rewarding Applying this idea to the emergence of life, thoughts about life and mind and their place Deacon considers autocatalytic molecules. in nature. ■ These copy themselves by catalysing their own production, and can collectively build Evan Thompson is professor of philosophy systems that evolve to have a metabolism at the University of Toronto, Ontario M5R and reproduce. In Deacon’s version, auto 2M8, Canada. catalytic molecules manufacture by-products The geometry of convection cells in heated liquid. e-mail: [email protected]